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Version : 2022.01

Dernière mise-à-jour : 2022/10/10 04:09

Topic 2: Linux Kernel

Contenu du Module

Topic 2: Linux Kernel
- Contenu du Module
- Rôle du noyau
- LAB #1 - Modules
- LAB #2 - Compilation et installation du noyau et des modules sous CentOS 8
  - 2.1 - Déplacer /home
  - 2.2 - Préparer l'Environnement
  - 2.3 - Préparer l'Arborescence Source du Noyau
    - Le Fichier .config
    - Le Fichier Makefile
  - 2.4 - Paramétrage du noyau
  - 2.5 - Compiler le Noyau
  - 2.6 - Installer le Nouveau Noyau
- LAB #3 - Compilation et installation du noyau sous Debian 11
  - 1.1 - Déplacer /home
  - 1.2 - Télécharger le Code Source du Noyau
  - 1.3 - Configurer le Noyau
  - 1.4 - Compiler le Noyau
  - 1.5 - Installer le Nouveau Noyau
  - 1.6 - Désinstaller un Noyau
- LAB #4 - Mise à Jour du Noyau avec le Gestionnaire des Paquets

Rôle du noyau

Le noyau ou kernel est la partie du système d'exploitation qui gère les entrées/sorties avec des périphériques. Dans certains cas il est préférable de recompiler le noyau de Linux. La motivation de cette recompilation peut être :

la diminution de la taille du noyau,
la prise en charge de nouveau matériel,
l'ajout de fonctionnalités,
l'optimisation du code,
la correction de bogues,
le besoin d'une fonctionnalité expérimentale.

Commencez par mettre à jour CentOS 8 :

[root@centos8 ~]# dnf update
...
[root@centos8 ~]# reboot

Identifiez ensuite le noyau utilisé par votre machine virtuelle :

[root@centos8 ~]# uname -r
4.18.0-305.7.1.el8_4.x86_64

LAB #1 - Modules

Dans le cas d'une utilisation courante de Linux, il est cependant préférable de faire appel aux modules. Les modules se trouvent dans le répertoire /lib/modules/<version-du-noyau> :

[root@centos8 ~]# ls /lib/modules/`uname -r`/
bls.conf           modules.builtin      modules.networking   System.map
build              modules.builtin.bin  modules.order        updates
config             modules.dep          modules.softdep      vdso
kernel             modules.dep.bin      modules.symbols      vmlinuz
modules.alias      modules.devname      modules.symbols.bin  weak-updates
modules.alias.bin  modules.drm          source
modules.block      modules.modesetting  symvers.gz

Les commandes pour manipuler les modules sont :

insmod
rmmod
lsmod
modprobe

Par exemple :

[root@centos8 ~]# lsmod
Module                  Size  Used by
xt_CHECKSUM            16384  1
ipt_MASQUERADE         16384  3
xt_conntrack           16384  1
ipt_REJECT             16384  2
nft_compat             20480  16
nf_nat_tftp            16384  0
nft_objref             16384  1
nf_conntrack_tftp      16384  3 nf_nat_tftp
nft_counter            16384  33
tun                    53248  1
bridge                192512  0
stp                    16384  1 bridge
llc                    16384  2 bridge,stp
nft_fib_inet           16384  1
nft_fib_ipv4           16384  1 nft_fib_inet
nft_fib_ipv6           16384  1 nft_fib_inet
nft_fib                16384  3 nft_fib_ipv6,nft_fib_ipv4,nft_fib_inet
nft_reject_inet        16384  5
nf_reject_ipv4         16384  2 nft_reject_inet,ipt_REJECT
nf_reject_ipv6         16384  1 nft_reject_inet
nft_reject             16384  1 nft_reject_inet
nft_ct                 20480  19
nf_tables_set          49152  21
nft_chain_nat          16384  12
nf_nat                 45056  3 ipt_MASQUERADE,nf_nat_tftp,nft_chain_nat
nf_conntrack          172032  6 xt_conntrack,nf_nat,nf_conntrack_tftp,nft_ct,ipt_MASQUERADE,nf_nat_tftp
nf_defrag_ipv6         20480  1 nf_conntrack
nf_defrag_ipv4         16384  1 nf_conntrack
ip_set                 49152  0
nf_tables             172032  414 nft_ct,nft_compat,nft_reject_inet,nft_fib_ipv6,nft_objref,nft_fib_ipv4,nft_counter,nft_chain_nat,nf_tables_set,nft_reject,nft_fib,nft_fib_inet
nfnetlink              16384  4 nft_compat,nf_tables,ip_set
sunrpc                540672  1
ext4                  761856  1
mbcache                16384  1 ext4
jbd2                  131072  1 ext4
virtio_balloon         20480  0
pcspkr                 16384  0
i2c_piix4              24576  0
joydev                 24576  0
ip_tables              28672  0
xfs                  1515520  1
libcrc32c              16384  4 nf_conntrack,nf_nat,nf_tables,xfs
sr_mod                 28672  0
sd_mod                 53248  3
cdrom                  65536  1 sr_mod
t10_pi                 16384  1 sd_mod
sg                     40960  0
ata_generic            16384  0
bochs_drm              16384  1
drm_vram_helper        28672  1 bochs_drm
drm_kms_helper        233472  4 drm_vram_helper,bochs_drm
syscopyarea            16384  1 drm_kms_helper
sysfillrect            16384  1 drm_kms_helper
sysimgblt              16384  1 drm_kms_helper
fb_sys_fops            16384  1 drm_kms_helper
drm_ttm_helper         16384  1 drm_vram_helper
ttm                   114688  2 drm_vram_helper,drm_ttm_helper
drm                   569344  7 drm_kms_helper,drm_vram_helper,bochs_drm,drm_ttm_helper,ttm
ahci                   40960  2
libahci                40960  1 ahci
virtio_net             53248  0
net_failover           24576  1 virtio_net
ata_piix               36864  0
serio_raw              16384  0
failover               16384  1 net_failover
libata                270336  4 ata_piix,libahci,ahci,ata_generic
dm_mirror              28672  0
dm_region_hash         20480  1 dm_mirror
dm_log                 20480  2 dm_region_hash,dm_mirror
dm_mod                151552  8 dm_log,dm_mirror
fuse                  151552  3

Pour ajouter un module, on peut utiliser la commande insmod ou modprobe. Cette dernière ajoute non seulement le module passé en argument mais également ses dépendances :

[root@centos8 ~]# modprobe bonding
[root@centos8 ~]# lsmod | more
Module                  Size  Used by
bonding               196608  0
xt_CHECKSUM            16384  1
ipt_MASQUERADE         16384  3
xt_conntrack           16384  1
ipt_REJECT             16384  2
nft_compat             20480  16
nf_nat_tftp            16384  0
nft_objref             16384  1
nf_conntrack_tftp      16384  3 nf_nat_tftp
nft_counter            16384  33
tun                    53248  1
bridge                192512  0
stp                    16384  1 bridge
llc                    16384  2 bridge,stp
nft_fib_inet           16384  1
nft_fib_ipv4           16384  1 nft_fib_inet
nft_fib_ipv6           16384  1 nft_fib_inet
nft_fib                16384  3 nft_fib_ipv6,nft_fib_ipv4,nft_fib_inet
nft_reject_inet        16384  5
nf_reject_ipv4         16384  2 nft_reject_inet,ipt_REJECT
nf_reject_ipv6         16384  1 nft_reject_inet
--More--

Pour supprimer un module, on peut utiliser la commande rmmod ou modprobe -r. Cette dernière essaie de supprimer les dépendances non-utilisées :

[root@centos8 ~]# modprobe -r bonding
[root@centos8 ~]# lsmod | more
Module                  Size  Used by
xt_CHECKSUM            16384  1
ipt_MASQUERADE         16384  3
xt_conntrack           16384  1
ipt_REJECT             16384  2
nft_compat             20480  16
nf_nat_tftp            16384  0
nft_objref             16384  1
nf_conntrack_tftp      16384  3 nf_nat_tftp
nft_counter            16384  33
tun                    53248  1
bridge                192512  0
stp                    16384  1 bridge
llc                    16384  2 bridge,stp
nft_fib_inet           16384  1
nft_fib_ipv4           16384  1 nft_fib_inet
nft_fib_ipv6           16384  1 nft_fib_inet
nft_fib                16384  3 nft_fib_ipv6,nft_fib_ipv4,nft_fib_inet
nft_reject_inet        16384  5
nf_reject_ipv4         16384  2 nft_reject_inet,ipt_REJECT
nf_reject_ipv6         16384  1 nft_reject_inet
nft_reject             16384  1 nft_reject_inet
--More--

Les dépendances des modules sont résolues par la commande modprobe grâce aux fichier /lib/modules/<version-du-noyau>/modules.dep. Ce dernier peut être créé manuellement grâce à la commande depmod :

[root@centos8 ~]# more /lib/modules/`uname -r`/modules.dep
kernel/arch/x86/events/amd/power.ko.xz:
kernel/arch/x86/events/intel/intel-uncore.ko.xz:
kernel/arch/x86/events/intel/intel-cstate.ko.xz:
kernel/arch/x86/events/rapl.ko.xz:
kernel/arch/x86/kernel/cpu/mce/mce-inject.ko.xz:
kernel/arch/x86/crypto/des3_ede-x86_64.ko.xz: kernel/crypto/des_generic.ko.xz
kernel/arch/x86/crypto/camellia-x86_64.ko.xz:
kernel/arch/x86/crypto/blowfish-x86_64.ko.xz: kernel/crypto/blowfish_common.ko.xz
kernel/arch/x86/crypto/twofish-x86_64.ko.xz: kernel/crypto/twofish_common.ko.xz
kernel/arch/x86/crypto/twofish-x86_64-3way.ko.xz: kernel/arch/x86/crypto/twofish-x86_64.ko.
xz kernel/crypto/twofish_common.ko.xz
kernel/arch/x86/crypto/chacha20-x86_64.ko.xz: kernel/crypto/chacha20_generic.ko.xz
kernel/arch/x86/crypto/serpent-sse2-x86_64.ko.xz: kernel/crypto/serpent_generic.ko.xz
kernel/arch/x86/crypto/ghash-clmulni-intel.ko.xz:
kernel/arch/x86/crypto/crc32c-intel.ko.xz:
kernel/arch/x86/crypto/crc32-pclmul.ko.xz:
kernel/arch/x86/crypto/sha512-ssse3.ko.xz: kernel/crypto/sha512_generic.ko.xz
kernel/arch/x86/crypto/crct10dif-pclmul.ko.xz:
kernel/arch/x86/crypto/poly1305-x86_64.ko.xz: kernel/crypto/poly1305_generic.ko.xz
kernel/arch/x86/crypto/camellia-aesni-avx-x86_64.ko.xz: kernel/arch/x86/crypto/camellia-x86
_64.ko.xz
kernel/arch/x86/crypto/cast5-avx-x86_64.ko.xz: kernel/crypto/cast5_generic.ko.xz kernel/cry
--More--(0%)

Il est possible d'obtenir des informations sur un module grâce à la commande modinfo :

[root@centos8 ~]# modinfo bonding
filename:       /lib/modules/4.18.0-305.7.1.el8_4.x86_64/kernel/drivers/net/bonding/bonding.ko.xz
author:         Thomas Davis, tadavis@lbl.gov and many others
description:    Ethernet Channel Bonding Driver
license:        GPL
alias:          rtnl-link-bond
rhelversion:    8.4
srcversion:     445F4CC9A2F7E64E3A87FD0
depends:        
intree:         Y
name:           bonding
vermagic:       4.18.0-305.7.1.el8_4.x86_64 SMP mod_unload modversions 
sig_id:         PKCS#7
signer:         CentOS kernel signing key
sig_key:        3B:5A:0A:B8:8E:4A:51:C0:AA:FF:97:FD:CB:94:D6:B6:D2:46:B8:17
sig_hashalgo:   sha256
signature:      B2:3A:20:BE:2B:F3:E0:5A:1A:74:0E:69:76:40:2A:D4:80:10:2C:5A:
                B7:F1:1E:7A:71:13:29:F0:0A:4A:28:EE:81:33:C8:C2:5C:BD:FF:E4:
                3F:A9:15:A3:9A:0E:A7:98:9E:99:06:23:10:47:D3:B2:48:B3:F1:61:
                BE:4B:B0:FC:62:B9:3B:D6:64:CC:E3:29:01:4D:91:92:32:FD:EB:54:
                44:F1:2C:1B:23:30:F1:3E:EE:69:EA:94:54:D9:A0:8D:16:53:F5:20:
                DE:38:A0:13:E8:2F:89:66:CB:11:D7:AA:30:37:7B:EC:DF:A1:69:29:
                7F:4E:80:4D:34:6E:F2:07:01:FA:18:23:94:58:10:C6:97:27:68:B9:
                D8:08:5E:9D:00:17:F4:1B:48:BE:CA:BF:5C:5A:A8:6D:36:EE:3F:95:
                BA:BE:59:82:EE:7B:CA:BB:32:1E:E3:05:ED:C9:C2:C8:10:64:B9:29:
                B8:09:4B:79:42:65:1A:FA:99:96:BA:7E:2D:6E:75:F1:91:0E:F4:9A:
                8F:11:10:9F:70:BD:35:06:BE:F0:4C:D8:AB:D5:C4:E1:B3:A2:2A:CA:
                58:CA:9E:16:1D:0C:BE:9C:37:A1:82:20:6F:24:CD:23:63:F7:F5:BC:
                6E:81:14:F0:52:DA:04:0E:9D:CC:17:60:2D:B0:D8:BD:6E:2C:AD:E7:
                50:48:49:B6:57:96:AC:FD:A4:29:33:01:43:92:32:88:A2:AC:CB:93:
                2F:C3:29:F3:01:77:84:00:AB:AA:C8:59:43:F1:DA:90:7B:5F:9A:A9:
                CA:60:97:34:85:5E:98:56:73:03:0D:D7:8D:A6:AB:51:D4:8C:92:91:
                0C:0A:BA:6B:92:01:16:FE:8B:86:80:11:5F:8E:21:BD:C2:2F:02:58:
                A6:CF:6C:E3:87:28:8B:4D:CE:54:8C:00:B3:F7:AE:9E:01:81:1E:83:
                AE:6D:58:B0:10:98:36:D9:69:76:E2:C0:E2:15:94:3B:D4:14:19:D9:
                59:86:75:31
parm:           max_bonds:Max number of bonded devices (int)
parm:           tx_queues:Max number of transmit queues (default = 16) (int)
parm:           num_grat_arp:Number of peer notifications to send on failover event (alias of num_unsol_na) (int)
parm:           num_unsol_na:Number of peer notifications to send on failover event (alias of num_grat_arp) (int)
parm:           miimon:Link check interval in milliseconds (int)
parm:           updelay:Delay before considering link up, in milliseconds (int)
parm:           downdelay:Delay before considering link down, in milliseconds (int)
parm:           use_carrier:Use netif_carrier_ok (vs MII ioctls) in miimon; 0 for off, 1 for on (default) (int)
parm:           mode:Mode of operation; 0 for balance-rr, 1 for active-backup, 2 for balance-xor, 3 for broadcast, 4 for 802.3ad, 5 for balance-tlb, 6 for balance-alb (charp)
parm:           primary:Primary network device to use (charp)
parm:           primary_reselect:Reselect primary slave once it comes up; 0 for always (default), 1 for only if speed of primary is better, 2 for only on active slave failure (charp)
parm:           lacp_rate:LACPDU tx rate to request from 802.3ad partner; 0 for slow, 1 for fast (charp)
parm:           ad_select:802.3ad aggregation selection logic; 0 for stable (default), 1 for bandwidth, 2 for count (charp)
parm:           min_links:Minimum number of available links before turning on carrier (int)
parm:           xmit_hash_policy:balance-alb, balance-tlb, balance-xor, 802.3ad hashing method; 0 for layer 2 (default), 1 for layer 3+4, 2 for layer 2+3, 3 for encap layer 2+3, 4 for encap layer 3+4, 5 for vlan+srcmac (charp)
parm:           arp_interval:arp interval in milliseconds (int)
parm:           arp_ip_target:arp targets in n.n.n.n form (array of charp)
parm:           arp_validate:validate src/dst of ARP probes; 0 for none (default), 1 for active, 2 for backup, 3 for all (charp)
parm:           arp_all_targets:fail on any/all arp targets timeout; 0 for any (default), 1 for all (charp)
parm:           fail_over_mac:For active-backup, do not set all slaves to the same MAC; 0 for none (default), 1 for active, 2 for follow (charp)
parm:           all_slaves_active:Keep all frames received on an interface by setting active flag for all slaves; 0 for never (default), 1 for always. (int)
parm:           resend_igmp:Number of IGMP membership reports to send on link failure (int)
parm:           packets_per_slave:Packets to send per slave in balance-rr mode; 0 for a random slave, 1 packet per slave (default), >1 packets per slave. (int)
parm:           lp_interval:The number of seconds between instances where the bonding driver sends learning packets to each slaves peer switch. The default is 1. (uint)

Dernièrement, les fichiers dans le repertoire /etc/modprobe.d sont utilisés pour spécifier les options éventuelles à passer aux modules lors de leur chargement ainsi que les alias utilisés pour leur faire référence :

[root@centos8 ~]# ls /etc/modprobe.d
firewalld-sysctls.conf  lockd.conf  nvdimm-security.conf  tuned.conf
kvm.conf                mlx4.conf   truescale.conf        vhost.conf

[root@centos8 ~]# cat /etc/modprobe.d/kvm.conf 
# Setting modprobe kvm_intel/kvm_amd nested = 1
# only enables Nested Virtualization until the next reboot or
# module reload. Uncomment the option applicable
# to your system below to enable the feature permanently.
#
# User changes in this file are preserved across upgrades.
#
# For Intel
#options kvm_intel nested=1
#
# For AMD
#options kvm_amd nested=1

LAB #2 - Compilation et installation du noyau et des modules sous CentOS 8

Activez le dépôt CentOS-Linux-PowerTools en passant la directive enabled à 1 :

[root@centos8 ~]# vi /etc/yum.repos.d/CentOS-Linux-PowerTools.repo 
[root@centos8 ~]# cat /etc/yum.repos.d/CentOS-Linux-PowerTools.repo 
# CentOS-Linux-PowerTools.repo
#
# The mirrorlist system uses the connecting IP address of the client and the
# update status of each mirror to pick current mirrors that are geographically
# close to the client.  You should use this for CentOS updates unless you are
# manually picking other mirrors.
#
# If the mirrorlist does not work for you, you can try the commented out
# baseurl line instead.

[powertools]
name=CentOS Linux $releasever - PowerTools
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=PowerTools&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/PowerTools/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

Installez maintenant les paquets nécessaires :

[root@centos8 ~]# dnf groupinstall "Development Tools"
...
[root@centos8 ~]# dnf install asciidoc audit-libs-devel bash bc binutils binutils-devel bison diffutils elfutils elfutils-devel elfutils-libelf-devel findutils flex gawk gcc gettext gzip hmaccalc hostname make module-init-tools ncurses-devel net-tools newt-devel numactl-devel openssl patch pciutils-devel perl perl-ExtUtils-Embed pesign redhat-rpm-config rpm-build rpmdevtools sh-utils tar xmlto xz zlib-devel
...

2.1 - Déplacer /home

Important - Il n'est pas conseillé de compiler en tant que root pour des raisons de sécurité. Pour pouvoir utiliser le compte d'un utilisateur pour créer un nouveau noyau, celui-ci doit disposer de plus de 10 Go d'espace libre.

A faire - Déconnectez-vous de votre session CentOS8_SSH_10.0.2.45 et re-connectez-vous à la VM en tant que root en utilisant la connexion CentOS8_ROOT_10.0.2.45.

Créez ensuite une seule partition sur /dev/sdc :

[root@centos8 ~]# fdisk /dev/sdc

Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xc321702b.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): 

Using default response p.
Partition number (1-4, default 1): 
First sector (2048-41943039, default 2048): 
Last sector, +sectors or +size{K,M,G,T,P} (2048-41943039, default 41943039): 

Created a new partition 1 of type 'Linux' and of size 20 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Créez maintenant un système de fichiers ext4 sur /dev/sdc1 :

[root@centos8 ~]# mkfs.ext4 /dev/sdc1
mke2fs 1.45.6 (20-Mar-2020)
Discarding device blocks: done                            
Creating filesystem with 16776960 4k blocks and 4194304 inodes
Filesystem UUID: dc92c0d7-919b-4fff-8719-53e9e7e628dd
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
        4096000, 7962624, 11239424

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (65536 blocks): done
Writing superblocks and filesystem accounting information: done

Montez /dev/sdc1 sur /mnt :

[root@centos8 ~]# mount /dev/sdc1 /mnt

Copiez le contenu de /home vers /mnt :

[root@centos8 ~]# cp -a /home/* /mnt

Démontez /dev/sdc1 et déplacez /home vers /root :

[root@centos8 ~]# umount /mnt
[root@centos8 ~]# mv /home /root

Identifiez l'UUID de /dev/sdc1 :

[root@centos8 ~]# ls -l /dev/disk/by-uuid/ | grep sdc1
lrwxrwxrwx. 1 root root 10 Jul 19 12:02 f76d6b66-985b-4a91-af9c-4987e8c1443c -> ../../sdc
[root@centos8 ~]#

Editez le fichier /etc/fstab et ajoutez une ligne pour /dev/sdc1 :

[root@centos8 ~]# vi /etc/fstab
[root@centos8 ~]# cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Wed Jun 16 06:21:32 2021
#
# Accessible filesystems, by reference, are maintained under '/dev/disk/'.
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.
#
# After editing this file, run 'systemctl daemon-reload' to update systemd
# units generated from this file.
#
/dev/mapper/cl_centos8-root /                       xfs     defaults        0 0
UUID=1c04981e-5317-4b73-9695-3ce25246835d /boot                   ext4    defaults        1 2
/dev/mapper/cl_centos8-swap swap                    swap    defaults        0 0
UUID=f76d6b66-985b-4a91-af9c-4987e8c1443c /home     ext4          defaults            1 2

Créez le point de montage /home :

[root@centos8 ~]# mkdir /home

Montez /dev/sdc1 :

[root@centos8 ~]# mount -a
[root@centos8 ~]# mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=1882880k,nr_inodes=470720,mode=755)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime,seclabel)
bpf on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,hugetlb)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,memory)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,cpu,cpuacct)
cgroup on /sys/fs/cgroup/rdma type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,rdma)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,pids)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,cpuset)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,perf_event)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,freezer)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,blkio)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,net_cls,net_prio)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,seclabel,devices)
none on /sys/kernel/tracing type tracefs (rw,relatime,seclabel)
configfs on /sys/kernel/config type configfs (rw,relatime)
/dev/mapper/cl_centos8-root on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel,pagesize=2M)
debugfs on /sys/kernel/debug type debugfs (rw,relatime,seclabel)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=40,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=6022)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
/dev/sda1 on /boot type ext4 (rw,relatime,seclabel)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime)
tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=382500k,mode=700,uid=1000,gid=1000)
tmpfs on /run/user/42 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=382500k,mode=700,uid=42,gid=42)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=382500k,mode=700)
gvfsd-fuse on /run/user/0/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=0,group_id=0)
/dev/sdc1 on /home type ext4 (rw,relatime,seclabel)

Notez la taille de /home :

[root@centos8 ~]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
devtmpfs                     1.8G     0  1.8G   0% /dev
tmpfs                        1.9G     0  1.9G   0% /dev/shm
tmpfs                        1.9G  9.4M  1.9G   1% /run
tmpfs                        1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mapper/cl_centos8-root   28G  5.2G   23G  19% /
/dev/sda1                    976M  289M  620M  32% /boot
tmpfs                        374M   16K  374M   1% /run/user/1000
tmpfs                        374M  1.2M  373M   1% /run/user/42
/dev/sdc1                     63G   67M   60G   1% /home

A faire - Déconnectez-vous de votre session CentOS8_ROOT_10.0.2.45 et re-connectez-vous à la VM en tant que trainee en utilisant la connexion CentOS8_SSH_10.0.2.45.

2.2 - Préparer l'Environnement

Pour créer l'arborescence de l'environnement de création de paquets dans /home/trainee, utilisez la commande rpmdev-setuptree :

[trainee@centos8 ~]$ rpmdev-setuptree
...>
[trainee@centos8 ~]$ ls -laR rpmbuild/
rpmbuild/:
total 28
drwxrwxr-x.  7 trainee trainee 4096 Jul 19 12:10 .
drwxr-xr-x. 17 trainee trainee 4096 Jul 19 12:10 ..
drwxrwxr-x.  2 trainee trainee 4096 Jul 19 12:10 BUILD
drwxrwxr-x.  2 trainee trainee 4096 Jul 19 12:10 RPMS
drwxrwxr-x.  2 trainee trainee 4096 Jul 19 12:10 SOURCES
drwxrwxr-x.  2 trainee trainee 4096 Jul 19 12:10 SPECS
drwxrwxr-x.  2 trainee trainee 4096 Jul 19 12:10 SRPMS

rpmbuild/BUILD:
total 8
drwxrwxr-x. 2 trainee trainee 4096 Jul 19 12:10 .
drwxrwxr-x. 7 trainee trainee 4096 Jul 19 12:10 ..

rpmbuild/RPMS:
total 8
drwxrwxr-x. 2 trainee trainee 4096 Jul 19 12:10 .
drwxrwxr-x. 7 trainee trainee 4096 Jul 19 12:10 ..

rpmbuild/SOURCES:
total 8
drwxrwxr-x. 2 trainee trainee 4096 Jul 19 12:10 .
drwxrwxr-x. 7 trainee trainee 4096 Jul 19 12:10 ..

rpmbuild/SPECS:
total 8
drwxrwxr-x. 2 trainee trainee 4096 Jul 19 12:10 .
drwxrwxr-x. 7 trainee trainee 4096 Jul 19 12:10 ..

rpmbuild/SRPMS:
total 8
drwxrwxr-x. 2 trainee trainee 4096 Jul 19 12:10 .
drwxrwxr-x. 7 trainee trainee 4096 Jul 19 12:10 ..

Téléchargez le rpm source du noyau :

[trainee@centos8 ~]$ uname -a
Linux centos8.ittraining.loc 4.18.0-305.7.1.el8_4.x86_64 #1 SMP Tue Jun 29 21:55:12 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

[trainee@centos8 ~]$ cat /etc/centos-release
CentOS Linux release 8.4.2105

[trainee@centos8 ~]$ wget https://vault.centos.org/8.4.2105/BaseOS/Source/SPackages/kernel-4.18.0-305.7.1.el8_4.src.rpm
--2021-07-14 02:54:14--  https://vault.centos.org/8.4.2105/BaseOS/Source/SPackages/kernel-4.18.0-305.7.1.el8_4.src.rpm
Resolving vault.centos.org (vault.centos.org)... 81.171.33.194, 2a05:d014:10:7803:4af1:9320:7050:d28e
Connecting to vault.centos.org (vault.centos.org)|81.171.33.194|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 123000617 (117M) [application/x-rpm]
Saving to: ‘kernel-4.18.0-305.7.1.el8_4.src.rpm’

kernel-4.18.0-305.7.1. 100%[===========================>] 117.30M  1.49MB/s    in 79s     

2021-07-14 02:55:33 (1.49 MB/s) - ‘kernel-4.18.0-305.7.1.el8_4.src.rpm’ saved [123000617/123000617]

Installez maintenant les dépendances pour le rpm source en tant que root :

[trainee@centos8 ~]$ su -
Mot de passe : fenestros

[root@centos8 ~]# dnf install yum-utils
...

[root@centos8 ~]# yum-builddep /home/trainee/kernel-4.18.0-305.7.1.el8_4.src.rpm 
...

Installez maintenant le paquet kernel-4.18.0-305.7.1.el8_4.src.rpm :

[root@centos8 ~]# exit
logout
[trainee@centos8 ~]$ rpm -Uvh kernel-4.18.0-305.7.1.el8_4.src.rpm
Updating / installing...
   1:kernel-4.18.0-305.7.1.el8_4      warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
################################# [100%]
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root
warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root

Important - Les erreurs sont sans importance.

2.3 - Préparer l'Arborescence Source du Noyau

Naviguez vers le repertoire ~/rpmbuild/SPECS et utilisez la commande rpmbuild pour préparer l'arborescence source du noyau :

[trainee@centos7 ~]$ cd ~/rpmbuild/SPECS
[trainee@centos7 SPECS]$ rpmbuild -bp --target=$(uname -m) kernel.spec
...

A l'issu du processus, examinez l'arborescence :

[trainee@centos8 SPECS]$ ls -la ~/rpmbuild/BUILD/kernel-4.18.0-305.7.1.el8_4/linux-4.18.0-305.7.1.el8.x86_64/
total 812
drwxr-xr-x.  26 trainee trainee   4096 Jul 14 03:13 .
drwxr-xr-x.   3 trainee trainee   4096 Jul 14 03:12 ..
drwxr-xr-x.  27 trainee trainee   4096 Jul 14 03:13 arch
drwxr-xr-x.   3 trainee trainee   4096 Jun 14 10:33 block
drwxr-xr-x.   2 trainee trainee   4096 Jul 14 03:13 certs
-rw-r--r--.   1 trainee trainee  13079 Jun 14 10:33 .clang-format
-rw-r--r--.   1 trainee trainee     59 Jun 14 10:33 .cocciconfig
drwxr-xr-x.   2 trainee trainee   4096 Jul 14 03:13 configs
-rw-r--r--.   1 trainee trainee    423 Jun 14 10:33 COPYING-4.18.0
-rw-r--r--.   1 trainee trainee  98651 Jun 14 10:33 CREDITS
drwxr-xr-x.   4 trainee trainee   4096 Jun 14 10:33 crypto
drwxr-xr-x. 119 trainee trainee   4096 Jul 14 03:13 Documentation
drwxr-xr-x. 137 trainee trainee   4096 Jun 14 10:33 drivers
drwxr-xr-x.   2 trainee trainee   4096 Jul 14 03:13 firmware
drwxr-xr-x.  73 trainee trainee   4096 Jun 14 10:33 fs
-rw-r--r--.   1 trainee trainee     68 Jun 14 10:33 .get_maintainer.conf
-rw-r--r--.   1 trainee trainee     31 Jun 14 10:33 .get_maintainer.ignore
-rw-r--r--.   1 trainee trainee     76 Jun 14 10:33 .gitattributes
-rw-r--r--.   1 trainee trainee   1639 Jun 14 10:33 .gitlab-ci-private.yml
-rw-r--r--.   1 trainee trainee   1668 Jun 14 10:33 .gitlab-ci.yml
drwxr-xr-x.  30 trainee trainee   4096 Jun 14 10:33 include
drwxr-xr-x.   2 trainee trainee   4096 Jun 14 10:33 init
drwxr-xr-x.   2 trainee trainee   4096 Jun 14 10:33 ipc
-rw-r--r--.   1 trainee trainee   2245 Jun 14 10:33 Kbuild
-rw-r--r--.   1 trainee trainee    575 Jun 14 10:33 Kconfig
drwxr-xr-x.  19 trainee trainee   4096 Jul 14 03:13 kernel
drwxr-xr-x.  20 trainee trainee  12288 Jul 14 03:13 lib
drwxr-xr-x.   5 trainee trainee   4096 Jun 14 10:33 LICENSES
-rw-r--r--.   1 trainee trainee   9559 Jun 14 10:33 .mailmap
-rw-r--r--.   1 trainee trainee 471696 Jun 14 10:33 MAINTAINERS
-rw-r--r--.   1 trainee trainee  61558 Jun 14 10:33 Makefile
-rw-r--r--.   1 trainee trainee   1324 Jun 14 10:33 Makefile.rhelver
-rw-r--r--.   1 trainee trainee      0 Jul 14 03:13 .mismatches
drwxr-xr-x.   3 trainee trainee   4096 Jun 14 10:33 mm
drwxr-xr-x.  72 trainee trainee   4096 Jun 14 10:33 net
-rw-r--r--.   1 trainee trainee    800 Jun 14 10:33 README
drwxr-xr-x.  28 trainee trainee   4096 Jun 14 10:33 samples
-rw-r--r--.   1 trainee trainee      0 Jul 14 03:12 .scmversion
drwxr-xr-x.  14 trainee trainee   4096 Jul 14 03:13 scripts
drwxr-xr-x.  10 trainee trainee   4096 Jun 14 10:33 security
drwxr-xr-x.  26 trainee trainee   4096 Jun 14 10:33 sound
drwxr-xr-x.  33 trainee trainee   4096 Jun 14 10:33 tools
drwxr-xr-x.   2 trainee trainee   4096 Jul 14 03:13 usr
drwxr-xr-x.   4 trainee trainee   4096 Jun 14 10:33 virt

Le Fichier .config

Changez de répertoire de travail :

[trainee@centos8 SPECS]$ cd ~/rpmbuild/BUILD/kernel-*/linux-*/

Copiez le fichier configs/kernel-4.18.0-`uname -m`.config vers .config dans le répertoire courant :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ cp configs/kernel-4.18.0-`uname -m`.config .config

Mettez à jour le fichier .config par rapport à la configuration actuelle du noyau :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ make oldconfig
scripts/kconfig/conf  --oldconfig Kconfig
#
# configuration written to .config
#

Important - Cette commande lit le fichier .config du noyau actuel et le compare avec celui des sources du noyau. S'il existent des nouvelles configurations à effectuer dans les sources du noyau, la commande vous pose des questions.

La configuration du noyau se trouve dans un fichier dénommé .config. Le fichier .config est généré par une des trois commandes suivantes et ne doit pas être édité manuellement :

make config
make menuconfig
make xconfig

Exécutez la commande make menuconfig :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ make menuconfig
  UPD     scripts/kconfig/.mconf-cfg
  HOSTCC  scripts/kconfig/mconf.o
  HOSTCC  scripts/kconfig/lxdialog/checklist.o
  HOSTCC  scripts/kconfig/lxdialog/inputbox.o
  HOSTCC  scripts/kconfig/lxdialog/menubox.o
  HOSTCC  scripts/kconfig/lxdialog/textbox.o
  HOSTCC  scripts/kconfig/lxdialog/util.o
  HOSTCC  scripts/kconfig/lxdialog/yesno.o
  HOSTLD  scripts/kconfig/mconf
scripts/kconfig/mconf  Kconfig
#
# using defaults found in /boot/config-4.18.0-305.7.1.el8_4.x86_64
#

Dans l'interface, vous pouvez constater la présence de lignes correspondantes à des fonctionalités suivies par une lettre ou une valeur. Dans le cas d'une lettre, la signification est la suivante :

y,
- la fonctionalité est incluse dans le noyau monolithique ou dans le cas d'une dépendance d'un module, dans le module concerné,
m,
- la fonctionalité est incluse en tant que module,
n,
- la fonctionalité n'est pas incluse.

Important - Cette commande permet la modification de la configuration du noyau.

Sauvegardez simplement la configuration actuelle et sortez de l'interface :

*** End of the configuration.
*** Execute 'make' to start the build or try 'make help'.

Vérifiez que le fichier .config a été“ créé par l'exécution de makeconfig :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ ls -a
.      certs          configs         Documentation  .get_maintainer.conf    .gitlab-ci.yml  Kbuild   LICENSES     Makefile.rhelver  README       security  virt
..     .clang-format  COPYING-4.18.0  drivers        .get_maintainer.ignore  include         Kconfig  .mailmap     .mismatches       samples      sound
arch   .cocciconfig   CREDITS         firmware       .gitattributes          init            kernel   MAINTAINERS  mm                .scmversion  tools
block  .config        crypto          fs             .gitlab-ci-private.yml  ipc             lib      Makefile     net               scripts      usr

Consultez ce fichier :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ more .config
#
# Automatically generated file; DO NOT EDIT.
# Linux/x86 4.18.0 Kernel Configuration
#

#
# Compiler: gcc (GCC) 8.4.1 20200928 (Red Hat 8.4.1-1)
#
CONFIG_64BIT=y
CONFIG_X86_64=y
CONFIG_X86=y
CONFIG_INSTRUCTION_DECODER=y
CONFIG_OUTPUT_FORMAT="elf64-x86-64"
CONFIG_ARCH_DEFCONFIG="arch/x86/configs/x86_64_defconfig"
CONFIG_LOCKDEP_SUPPORT=y
CONFIG_STACKTRACE_SUPPORT=y
CONFIG_MMU=y
CONFIG_ARCH_MMAP_RND_BITS_MIN=28
CONFIG_ARCH_MMAP_RND_BITS_MAX=32
CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN=8
CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX=16
CONFIG_GENERIC_ISA_DMA=y
CONFIG_GENERIC_BUG=y
CONFIG_GENERIC_BUG_RELATIVE_POINTERS=y
CONFIG_GENERIC_HWEIGHT=y
CONFIG_ARCH_MAY_HAVE_PC_FDC=y
CONFIG_GENERIC_CALIBRATE_DELAY=y
CONFIG_ARCH_HAS_CPU_RELAX=y
CONFIG_ARCH_HAS_CACHE_LINE_SIZE=y
CONFIG_ARCH_HAS_FILTER_PGPROT=y
CONFIG_HAVE_SETUP_PER_CPU_AREA=y
CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK=y
CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK=y
CONFIG_ARCH_HIBERNATION_POSSIBLE=y
CONFIG_ARCH_SUSPEND_POSSIBLE=y
CONFIG_ARCH_WANT_HUGE_PMD_SHARE=y
CONFIG_ARCH_WANT_GENERAL_HUGETLB=y
CONFIG_ZONE_DMA32=y
CONFIG_AUDIT_ARCH=y
CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING=y
CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC=y
CONFIG_HAVE_INTEL_TXT=y
CONFIG_X86_64_SMP=y
--More--(0%)

Le Fichier Makefile

Le fichier Makefile contient le nom du noyau et spécifie les informations suivantes :

VERSION,
PATCHLEVEL,
SUBLEVEL,
EXTRAVERSION.

Les trois premières informations sont gérées par kernel.org et Linus Torvalds en personne tandis que l'EXTRAVERSION est gérée par Red Hat :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ more Makefile
# SPDX-License-Identifier: GPL-2.0
VERSION = 4
PATCHLEVEL = 18
SUBLEVEL = 0
EXTRAVERSION =
NAME = Merciless Moray

#
# DRM backport version
#
RHEL_DRM_VERSION = 5
RHEL_DRM_PATCHLEVEL = 9
RHEL_DRM_SUBLEVEL = 14

# *DOCUMENTATION*
# To see a list of typical targets execute "make help"
# More info can be located in ./README
# Comments in this file are targeted only to the developer, do not
# expect to learn how to build the kernel reading this file.

# That's our default target when none is given on the command line
PHONY := _all
_all:

# o Do not use make's built-in rules and variables
#   (this increases performance and avoids hard-to-debug behaviour);
# o Look for make include files relative to root of kernel src
MAKEFLAGS += -rR --include-dir=$(CURDIR)

# Avoid funny character set dependencies
unexport LC_ALL
LC_COLLATE=C
LC_NUMERIC=C
export LC_COLLATE LC_NUMERIC

# Avoid interference with shell env settings
unexport GREP_OPTIONS

# Set RHEL variables
# Use this spot to avoid future merge conflicts
include Makefile.rhelver

# We are using a recursive build, so we need to do a little thinking
--Plus--(2%)

Important - La version 2.6 du noyau a vu le jour en 2003. Les SUBLEVEL se suivaient régulièrement. Avec la version 2.6 du noyau, la valeur paire du PATCHLEVEL indiquait que le noyau était stable. Quand vous recompilez le noyau à partir des sources, vous devez modifier la valeur de l'EXTRAVERSION. Le passage à la version 3.0 fut décidé par Linus Torvalds à l'occasion des 20 ans du noyau Linux. Depuis l'arrivée de la version 3 du noyau, la signification de la valeur de PATCHLEVEL paire et impaire a été abondonnée.

2.4 - Paramétrage du noyau

Insérez la sortie de la commande uname -i sur la première ligne du fichier .config :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ uname -i
x86_64
[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ vi .config
[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ head .config
# x86_64
#
# Automatically generated file; DO NOT EDIT.
# Linux/x86 4.18.0 Kernel Configuration
#

#
# Compiler: gcc (GCC) 8.4.1 20200928 (Red Hat 8.4.1-1)
#
CONFIG_64BIT=y

Renommez le fichier .config en le plaçant dans le répertoire ~/rpmbuild/SOURCES/ :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ cp .config ~/rpmbuild/SOURCES/config-`uname -m`-generic
[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ ls ~/rpmbuild/SOURCES
centos-ca-secureboot.der  cpupower.config            filter-x86_64.sh                           kernel-s390x.config                mod-extra.list           Module.kabi_s390x
centos-dup.x509           cpupower.service           generate_all_configs.sh                    kernel-s390x-debug.config          mod-internal.list        Module.kabi_x86_64
centos-kpatch.x509        debrand-rh-i686-cpu.patch  generate_bls_conf.sh                       kernel-s390x-zfcpdump.config       mod-sign.sh              parallel_xz.sh
centos.pem                debrand-rh_taint.patch     kernel-aarch64.config                      kernel-x86_64.config               Module.kabi_aarch64      process_configs.sh
centossecureboot001.der   debrand-single-cpu.patch   kernel-aarch64-debug.config                kernel-x86_64-debug.config         Module.kabi_dup_aarch64  x509.genkey
centossecureboot201.der   filter-aarch64.sh          kernel-abi-stablelists-4.18.0-305.tar.bz2  kvm_stat.logrotate                 Module.kabi_dup_ppc64le
centossecurebootca2.der   filter-modules.sh          kernel-kabi-dw-4.18.0-305.tar.bz2          linux-4.18.0-305.7.1.el8_4.tar.xz  Module.kabi_dup_s390x
check-kabi                filter-ppc64le.sh          kernel-ppc64le.config                      linux-kernel-test.patch            Module.kabi_dup_x86_64
config-x86_64-generic     filter-s390x.sh            kernel-ppc64le-debug.config                mod-blacklist.sh                   Module.kabi_ppc64le

Copiez le contenu du répertoire configs vers le répertoire ~/rpmbuild/SOURCES/ :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ cp configs/* ~/rpmbuild/SOURCES/

Editez la directive buildid dans le fichier ~/rpmbuild/SPECS/kernel.spec :

[trainee@centos8 linux-4.18.0-305.7.1.el8.x86_64]$ cd ~/rpmbuild/SPECS

[trainee@centos8 SPECS]$ vi kernel.spec

[trainee@centos8 SPECS]$ head -n 50 kernel.spec
# We have to override the new %%install behavior because, well... the kernel is special.
%global __spec_install_pre %{___build_pre}

# At the time of this writing (2019-03), RHEL8 packages use w2.xzdio
# compression for rpms (xz, level 2).
# Kernel has several large (hundreds of mbytes) rpms, they take ~5 mins
# to compress by single-threaded xz. Switch to threaded compression,
# and from level 2 to 3 to keep compressed sizes close to "w2" results.
#
# NB: if default compression in /usr/lib/rpm/redhat/macros ever changes,
# this one might need tweaking (e.g. if default changes to w3.xzdio,
# change below to w4T.xzdio):
%define _binary_payload w3T.xzdio

# For a kernel released for public testing, released_kernel should be 1.
# For internal testing builds during development, it should be 0.
%global released_kernel 1

%global distro_build 305

# Sign the x86_64 kernel for secure boot authentication
%ifarch x86_64 aarch64
%global signkernel 1
%else
%global signkernel 0
%endif

# Sign modules on all arches
%global signmodules 1

# Compress modules only for architectures that build modules
%ifarch noarch
%global zipmodules 0
%else
%global zipmodules 1
%endif

%if %{zipmodules}
%global zipsed -e 's/\.ko$/\.ko.xz/'
%endif

%define buildid .i2tch

%define rpmversion 4.18.0
%define pkgrelease 305.7.1.el8_4

# allow pkg_release to have configurable %%{?dist} tag
%define specrelease 305.7.1%{?dist}

%define pkg_release %{specrelease}%{?buildid}

2.5 - Compiler le Noyau

La compilation du noyau peut prendre beaucoup de temps (~5 heures). La commande utilisée est la suivante :

[trainee@centos7 SPECS]$ rpmbuild -bb --target=`uname -m` kernel.spec 2> build-err.log | tee build-out.log &

Important - La compilation peut prendre des heures. Arrêtez donc le processus avec les touches ^C. Arrêtez ensuite votre VM. Demandez à votre formateur de démarrer la VM contenant le noyau déjà compilé.

A l'issu du processus, les RPMs se trouvent dans le répertoire /home/trainee/rpmbuild/RPMS/x86_64/ :

...
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-headers-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-cross-headers-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debuginfo-common-x86_64-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/perf-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/perf-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/python3-perf-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/python3-perf-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-tools-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-tools-libs-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-tools-libs-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-tools-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/bpftool-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/bpftool-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-selftests-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-core-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-modules-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debug-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-core-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-modules-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Wrote: /home/trainee/rpmbuild/RPMS/x86_64/kernel-ipaclones-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.rkOgfs

[1]+  Done                    rpmbuild -bb --target=`uname -m` kernel.spec 2> build-err.log | tee build-out.log

[trainee@centos8 SPECS]$ cd ../RPMS
[trainee@centos8 RPMS]$ ls
x86_64
[trainee@centos8 RPMS]$ cd x86_64/
[trainee@centos8 x86_64]$ ls
bpftool-4.18.0-305.7.1.el8.i2tch.x86_64.rpm                 kernel-debuginfo-common-x86_64-4.18.0-305.7.1.el8.i2tch.x86_64.rpm  kernel-selftests-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
bpftool-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm       kernel-debug-modules-4.18.0-305.7.1.el8.i2tch.x86_64.rpm            kernel-tools-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm                  kernel-debug-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64.rpm      kernel-tools-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-core-4.18.0-305.7.1.el8.i2tch.x86_64.rpm             kernel-debug-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm   kernel-tools-libs-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-cross-headers-4.18.0-305.7.1.el8.i2tch.x86_64.rpm    kernel-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm                    kernel-tools-libs-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-debug-4.18.0-305.7.1.el8.i2tch.x86_64.rpm            kernel-headers-4.18.0-305.7.1.el8.i2tch.x86_64.rpm                  perf-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-debug-core-4.18.0-305.7.1.el8.i2tch.x86_64.rpm       kernel-ipaclones-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm       perf-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-debug-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm  kernel-modules-4.18.0-305.7.1.el8.i2tch.x86_64.rpm                  python3-perf-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-debug-devel-4.18.0-305.7.1.el8.i2tch.x86_64.rpm      kernel-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64.rpm            python3-perf-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm
kernel-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64.rpm        kernel-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64.rpm

Notez que la génération du nouveau noyau peut consommer jusqu'à 21 Go d'espace disque :

[trainee@centos8 x86_64]$ df -h
Filesystem                   Size  Used Avail Use% Mounted on
devtmpfs                     1.8G     0  1.8G   0% /dev
tmpfs                        1.9G     0  1.9G   0% /dev/shm
tmpfs                        1.9G  9.4M  1.9G   1% /run
tmpfs                        1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mapper/cl_centos8-root   28G  5.5G   23G  20% /
/dev/sda1                    976M  289M  620M  32% /boot
tmpfs                        374M   24K  374M   1% /run/user/1000
tmpfs                        374M  1.2M  373M   1% /run/user/42
/dev/sdc1                     63G   21G   39G  35% /home

2.6 - Installer le Nouveau Noyau

Installez maintenant les paquets kernel*. L'installation du noyau peut prendre beaucoup de temps (~2 heures). La commande utilisée est la suivante : :

[root@centos8 x86_64]# dnf localinstall kernel-*.rpm
Last metadata expiration check: 2:25:32 ago on Tue 20 Jul 2021 08:37:00 EDT.
Dependencies resolved.
===============================================================================================================================================================================================================
 Package                                                       Architecture                          Version                                                 Repository                                   Size
===============================================================================================================================================================================================================
Installing:
 kernel                                                        x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                5.9 M
 kernel-core                                                   x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 36 M
 kernel-cross-headers                                          x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 11 M
 kernel-debug                                                  x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                5.9 M
 kernel-debug-core                                             x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 63 M
 kernel-debug-debuginfo                                        x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                683 M
 kernel-debug-devel                                            x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 19 M
 kernel-debug-modules                                          x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 54 M
 kernel-debug-modules-extra                                    x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                7.2 M
 kernel-debug-modules-internal                                 x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                6.3 M
 kernel-debuginfo                                              x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                570 M
 kernel-debuginfo-common-x86_64                                x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 75 M
 kernel-devel                                                  x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 18 M
 kernel-ipaclones-internal                                     x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 20 M
 kernel-modules                                                x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 28 M
 kernel-modules-extra                                          x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                6.5 M
 kernel-modules-internal                                       x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                6.1 M
 kernel-selftests-internal                                     x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                 19 M
 kernel-tools-debuginfo                                        x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                6.2 M
 kernel-tools-libs-devel                                       x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                5.9 M
Downgrading:
 kernel-headers                                                x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                7.1 M
 kernel-tools                                                  x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                6.1 M
 kernel-tools-libs                                             x86_64                                4.18.0-305.7.1.el8.i2tch                                @commandline                                5.9 M

Transaction Summary
===============================================================================================================================================================================================================
Install    20 Packages
Downgrade   3 Packages

Total size: 1.6 G
Is this ok [y/N]: y

A l'issu de l'installation, re-démarrez la VM :

[root@centos7 ~]# reboot

Connectez-vous en tant que trainee et devenez root. Listez ensuite les noyaux installés :

[root@centos8 ~]# rpm -qa | grep kernel
kernel-modules-4.18.0-305.3.1.el8.x86_64
kernel-tools-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-headers-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-core-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-modules-4.18.0-305.7.1.el8_4.x86_64
kernel-debug-modules-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-devel-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-tools-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-tools-libs-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-modules-internal-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-cross-headers-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-core-4.18.0-305.7.1.el8_4.x86_64
kernel-devel-4.18.0-305.7.1.el8_4.x86_64
kernel-debuginfo-common-x86_64-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-devel-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-tools-libs-devel-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-modules-extra-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-4.18.0-305.7.1.el8_4.x86_64
kernel-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-core-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-selftests-internal-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-debuginfo-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-debug-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-4.18.0-305.3.1.el8.x86_64
kernel-core-4.18.0-305.3.1.el8.x86_64
kernel-modules-4.18.0-305.7.1.el8.i2tch.x86_64
kernel-ipaclones-internal-4.18.0-305.7.1.el8.i2tch.x86_64

Constatez l'entrée saved-entry du fichier /boot/grub2/grubenv :

[root@centos8 ~]# grep i2tch /boot/grub2/grubenv 
saved_entry=95bd69e34a7444a7b58cb74fbfb86df2-4.18.0-305.7.1.el8.i2tch.x86_64

Dernièrement, vérifiez l'utilisation du nouveau noyau :

[root@centos8 ~]# uname -r
4.18.0-305.7.1.el8.i2tch.x86_64

LAB #3 - Compilation et installation du noyau sous Debian 11

Commencez par installer les paquets necessaires :

root@debian11:~# apt-get update
Hit:1 http://deb.debian.org/debian bullseye InRelease
Get:2 http://deb.debian.org/debian bullseye-updates InRelease [39.4 kB]
Get:3 http://security.debian.org/debian-security bullseye-security InRelease [44.1 kB]
Fetched 83.5 kB in 1s (158 kB/s)              
Reading package lists... Done

root@debian11:~# apt-get -y install build-essential linux-source bc kmod cpio flex libncurses5-dev libelf-dev libssl-dev dwarves debconf-utils dpkg-dev debhelper ncurses-dev

1.1 - Déplacer /home

Créez une seule partition sur /dev/sdb :

root@debian11:~# fdisk /dev/sdb

Welcome to fdisk (util-linux 2.36.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xa10c368d.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): 

Using default response p.
Partition number (1-4, default 1): 
First sector (2048-134217727, default 2048): 
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-134217727, default 134217727): 

Created a new partition 1 of type 'Linux' and of size 64 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Créez maintenant un système de fichiers ext4 sur /dev/sdb1 :

root@debian11:~# mkfs.ext4 /dev/sdb1
mke2fs 1.46.2 (28-Feb-2021)
Discarding device blocks: done                            
Creating filesystem with 16776960 4k blocks and 4194304 inodes
Filesystem UUID: 24f1821e-1d5b-4256-8ee3-c9ee6b382ddc
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
        4096000, 7962624, 11239424

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (65536 blocks): done
Writing superblocks and filesystem accounting information: done

Editez le fichier /etc/ssh/sshd_config et modifiez la directive PermitRootLogin :

root@debian11:~# vi /etc/ssh/sshd_config
root@debian11:~# cat /etc/ssh/sshd_config
#       $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

Include /etc/ssh/sshd_config.d/*.conf

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
PermitRootLogin yes 
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

...

Re-démarrez le serveur ssh :

root@debian11:~# systemctl restart sshd
root@debian11:~# systemctl status sshd
● ssh.service - OpenBSD Secure Shell server
     Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
     Active: active (running) since Sun 2022-05-01 15:35:50 CEST; 6s ago
       Docs: man:sshd(8)
             man:sshd_config(5)
    Process: 2793 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
   Main PID: 2794 (sshd)
      Tasks: 1 (limit: 4656)
     Memory: 1.1M
        CPU: 25ms
     CGroup: /system.slice/ssh.service
             └─2794 sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups

May 01 15:35:50 debian11 systemd[1]: Starting OpenBSD Secure Shell server...
May 01 15:35:50 debian11 sshd[2794]: Server listening on 0.0.0.0 port 22.
May 01 15:35:50 debian11 sshd[2794]: Server listening on :: port 22.
May 01 15:35:50 debian11 systemd[1]: Started OpenBSD Secure Shell server.

A Faire - Déconnectez-vous en ssh. Connectez-vous directement en tant que root en ssh.

Montez /dev/sdb1 sur /mnt :

root@debian11:~# mount /dev/sdb1 /mnt

Copiez le contenu de /home vers /mnt :

root@debian11:~# cp -a /home/* /mnt

Démontez /dev/sdb1 :

root@debian11:~# umount /mnt

Identifiez l'UUID de /dev/sdb1 :

root@debian11:~# ls -l /dev/disk/by-uuid/ | grep sdb1
lrwxrwxrwx 1 root root 10 May  1 15:31 24f1821e-1d5b-4256-8ee3-c9ee6b382ddc -> ../../sdb1

Editez le fichier /etc/fstab en ajoutant la ligne pour le montage de /home :

root@debian11:~# vi /etc/fstab
root@debian11:~# cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# systemd generates mount units based on this file, see systemd.mount(5).
# Please run 'systemctl daemon-reload' after making changes here.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sda1 during installation
UUID=9887a74f-a680-4bde-8f04-db5ae9ea186e /               ext4    errors=remount-ro 0       1
UUID=24f1821e-1d5b-4256-8ee3-c9ee6b382ddc /home           ext4    defaults      0 0
# swap was on /dev/sda5 during installation
UUID=1f9439f5-4b19-49b1-b292-60c2c674cee9 none            swap    sw              0       0
/dev/sr0        /media/cdrom0   udf,iso9660 user,noauto     0       0

Créez le point de montage /home :

root@debian11:~# rm -rf /home
root@debian11:~# mkdir /home

Montez /dev/sdb1 :

root@debian11:~# mount -a

root@debian11:~# mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=1986968k,nr_inodes=496742,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,noexec,relatime,size=402560k,mode=755)
/dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=29,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=11732)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,pagesize=2M)
tracefs on /sys/kernel/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,size=402556k,nr_inodes=100639,mode=700)
/dev/sdb1 on /home type ext4 (rw,relatime)

Notez la taille de /home :

root@debian11:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            1.9G     0  1.9G   0% /dev
tmpfs           394M  892K  393M   1% /run
/dev/sda1        31G  4.1G   25G  14% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           394M   36K  394M   1% /run/user/0
/dev/sdb1        63G  1.4M   60G   1% /home

A Faire - Fermez la session de root et connectez-vous en tant que trainee en ssh.

1.2 - Télécharger le Code Source du Noyau

Le code source est disponible sur le site www.kernel.org :

trainee@debian11:~$ wget https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.11.1.tar.gz
--2022-05-01 15:46:58--  https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.11.1.tar.gz
Resolving www.kernel.org (www.kernel.org)... 145.40.68.75, 2604:1380:4601:e00::1
Connecting to www.kernel.org (www.kernel.org)|145.40.68.75|:443... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.11.1.tar.gz [following]
--2022-05-01 15:46:58--  https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.11.1.tar.gz
Resolving mirrors.edge.kernel.org (mirrors.edge.kernel.org)... 147.75.101.1, 2604:1380:2001:3900::1
Connecting to mirrors.edge.kernel.org (mirrors.edge.kernel.org)|147.75.101.1|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 186370882 (178M) [application/x-gzip]
Saving to: ‘linux-5.11.1.tar.gz’

linux-5.11.1.tar.gz                                  100%[====================================================================================================================>] 177.74M  83.4MB/s    in 2.1s    

2022-05-01 15:47:01 (83.4 MB/s) - ‘linux-5.11.1.tar.gz’ saved [186370882/186370882]

Désarchivez le tar.xz que vous avez téléchargé :

trainee@debian8:~$ tar xf linux-5.11.1.tar.gz

Notez que l'occupation disque du code source du noyau linux-5.11.1 est de 1.2 Go :

trainee@debian11:~$ du -hs ./linux-5.11.1
1.2G    ./linux-5.11.1

1.3 - Configurer le Noyau

Le fichier Makefile contient le nom du noyau et spécifie les informations suivantes :

VERSION,
PATCHLEVEL,
SUBLEVEL,
EXTRAVERSION.

Les trois premières informations sont gérées par kernel.org et Linus Torvalds en personne tandis que l'EXTRAVERSION est gérée par Debian :

trainee@debian11:~$ cat ./linux-5.11.1/Makefile | head
# SPDX-License-Identifier: GPL-2.0
VERSION = 5
PATCHLEVEL = 11
SUBLEVEL = 1
EXTRAVERSION =
NAME = 💕 Valentine's Day Edition 💕

# *DOCUMENTATION*
# To see a list of typical targets execute "make help"
# More info can be located in ./README

Utilisez maintenant la commande make defconfig pour créer le fichier de configuration .config :

trainee@debian11:~$ su -
Password: fenestros
root@debian11:~# cd /home/trainee/linux-5.11.1/
root@debian11:/home/trainee/linux-5.11.1# make defconfig
  HOSTCC  scripts/basic/fixdep
  HOSTCC  scripts/kconfig/conf.o
  HOSTCC  scripts/kconfig/confdata.o
  HOSTCC  scripts/kconfig/expr.o
  LEX     scripts/kconfig/lexer.lex.c
  YACC    scripts/kconfig/parser.tab.[ch]
  HOSTCC  scripts/kconfig/lexer.lex.o
  HOSTCC  scripts/kconfig/parser.tab.o
  HOSTCC  scripts/kconfig/preprocess.o
  HOSTCC  scripts/kconfig/symbol.o
  HOSTCC  scripts/kconfig/util.o
  HOSTLD  scripts/kconfig/conf
*** Default configuration is based on 'x86_64_defconfig'
#
# configuration written to .config
#

Ce fichier est configuré par une des trois commandes suivantes :

make config
make menuconfig
make xconfig

Dans ce fichier, vous pouvez constater la présence de lignes correspondantes à des fonctionalités suivies par une lettre ou une valeur. Dans le cas d'une lettre, la signification est la suivante :

y
- la fonctionalité est incluse dans le noyau monolithique ou dans le cas d'une dépendance d'un module, dans le module concerné,
m
- la fonctionalité est incluse en tant que module,
n
- la fonctionalité n'est pas incluse. Cette option est rarement visible car dans bien les cas, la fonctionalité est simplement commentée dans le fichier lui-même.

root@debian11:/home/trainee/linux-5.11.1# more .config 
#
# Automatically generated file; DO NOT EDIT.
# Linux/x86 5.11.1 Kernel Configuration
#
CONFIG_CC_VERSION_TEXT="gcc (Debian 10.2.1-6) 10.2.1 20210110"
CONFIG_CC_IS_GCC=y
CONFIG_GCC_VERSION=100201
CONFIG_LD_VERSION=235020000
CONFIG_CLANG_VERSION=0
CONFIG_LLD_VERSION=0
CONFIG_CC_CAN_LINK=y
CONFIG_CC_CAN_LINK_STATIC=y
CONFIG_CC_HAS_ASM_GOTO=y
CONFIG_CC_HAS_ASM_INLINE=y
CONFIG_IRQ_WORK=y
CONFIG_BUILDTIME_TABLE_SORT=y
CONFIG_THREAD_INFO_IN_TASK=y

#
# General setup
#
CONFIG_INIT_ENV_ARG_LIMIT=32
# CONFIG_COMPILE_TEST is not set
CONFIG_LOCALVERSION=""
# CONFIG_LOCALVERSION_AUTO is not set
CONFIG_BUILD_SALT=""
CONFIG_HAVE_KERNEL_GZIP=y
CONFIG_HAVE_KERNEL_BZIP2=y
CONFIG_HAVE_KERNEL_LZMA=y
CONFIG_HAVE_KERNEL_XZ=y
CONFIG_HAVE_KERNEL_LZO=y
CONFIG_HAVE_KERNEL_LZ4=y
CONFIG_HAVE_KERNEL_ZSTD=y
CONFIG_KERNEL_GZIP=y
# CONFIG_KERNEL_BZIP2 is not set
# CONFIG_KERNEL_LZMA is not set
# CONFIG_KERNEL_XZ is not set
# CONFIG_KERNEL_LZO is not set
# CONFIG_KERNEL_LZ4 is not set
# CONFIG_KERNEL_ZSTD is not set
CONFIG_DEFAULT_INIT=""
CONFIG_DEFAULT_HOSTNAME="(none)"
CONFIG_SWAP=y
CONFIG_SYSVIPC=y
CONFIG_SYSVIPC_SYSCTL=y
CONFIG_POSIX_MQUEUE=y
CONFIG_POSIX_MQUEUE_SYSCTL=y
# CONFIG_WATCH_QUEUE is not set
CONFIG_CROSS_MEMORY_ATTACH=y
CONFIG_USELIB=y
CONFIG_AUDIT=y
CONFIG_HAVE_ARCH_AUDITSYSCALL=y
CONFIG_AUDITSYSCALL=y

#
# IRQ subsystem
#
CONFIG_GENERIC_IRQ_PROBE=y
--More--(1%)
[q]

1.4 - Compiler le Noyau

La compilation du noyau peut prendre beaucoup de temps. La commande utilisée est la suivante :

root@debian11:/home/trainee/linux-5.11.1# make deb-pkg clean
...
dpkg-buildpackage: info: full upload (original source is included)
  CLEAN   arch/x86/entry/vdso
  CLEAN   arch/x86/kernel/cpu
  CLEAN   arch/x86/kernel
  CLEAN   arch/x86/realmode/rm
  CLEAN   arch/x86/lib
  CLEAN   certs
  CLEAN   drivers/firmware/efi/libstub
  CLEAN   drivers/scsi
  CLEAN   drivers/tty/vt
  CLEAN   drivers/video/logo
  CLEAN   lib
  CLEAN   net/wireless
  CLEAN   security/selinux
  CLEAN   usr/include
  CLEAN   usr
  CLEAN   arch/x86/boot/compressed
  CLEAN   arch/x86/boot
  CLEAN   arch/x86/tools
  CLEAN   vmlinux.symvers modules.builtin modules.builtin.modinfo

A l'issu du processus, les paquets du nouveau noyau se trouvent dans le répertoire /home/trainee :

root@debian11:/home/trainee/linux-5.11.1# cd ..
root@debian11:/home/trainee# ls
Desktop    linux-5.11.1                           linux-5.11.1_5.11.1-1.diff.gz    linux-5.11.1.tar.gz                      linux-libc-dev_5.11.1-1_amd64.deb  Public
Documents  linux-5.11.1_5.11.1-1_amd64.buildinfo  linux-5.11.1_5.11.1-1.dsc        linux-headers-5.11.1_5.11.1-1_amd64.deb  Music                              Templates
Downloads  linux-5.11.1_5.11.1-1_amd64.changes    linux-5.11.1_5.11.1.orig.tar.gz  linux-image-5.11.1_5.11.1-1_amd64.deb    Pictures                           Videos

1.5 - Installer le Noyau

Installez maintenant les paquets deb :

root@debian11:/home/trainee# dpkg -i /home/trainee/linux*.deb

Constatez la création d'un nouveau grub.cfg :

root@debian11:/home/trainee# grep 5.11.1 /boot/grub/grub.cfg
        echo    'Loading Linux 5.11.1 ...'
        linux   /boot/vmlinuz-5.11.1 root=UUID=9887a74f-a680-4bde-8f04-db5ae9ea186e ro  quiet
        initrd  /boot/initrd.img-5.11.1
        menuentry 'Debian GNU/Linux, with Linux 5.11.1' --class debian --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.11.1-advanced-9887a74f-a680-4bde-8f04-db5ae9ea186e' {
                echo    'Loading Linux 5.11.1 ...'
                linux   /boot/vmlinuz-5.11.1 root=UUID=9887a74f-a680-4bde-8f04-db5ae9ea186e ro  quiet
                initrd  /boot/initrd.img-5.11.1
        menuentry 'Debian GNU/Linux, with Linux 5.11.1 (recovery mode)' --class debian --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.11.1-recovery-9887a74f-a680-4bde-8f04-db5ae9ea186e' {
                echo    'Loading Linux 5.11.1 ...'
                linux   /boot/vmlinuz-5.11.1 root=UUID=9887a74f-a680-4bde-8f04-db5ae9ea186e ro single 
                initrd  /boot/initrd.img-5.11.1

1.6 - Désinstaller un Noyau

Lister les noyaux installés :

root@debian11:/home/trainee# dpkg -l | grep -i "linux-image*" | awk '{print $2}'
linux-image-5.10.0-13-amd64
linux-image-5.11.1
linux-image-amd64

Le noyau se désinstalle comme tout autre paquet :

root@debian11:/home/trainee# apt-get -y purge "linux-image-5.11.1"
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages will be REMOVED:
  linux-image-5.11.1*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 15.1 MB disk space will be freed.
(Reading database ... 118012 files and directories currently installed.)
Removing linux-image-5.11.1 (5.11.1-1) ...
update-initramfs: Deleting /boot/initrd.img-5.11.1
Generating grub configuration file ...
Found background image: /usr/share/images/desktop-base/desktop-grub.png
Found linux image: /boot/vmlinuz-5.10.0-13-amd64
Found initrd image: /boot/initrd.img-5.10.0-13-amd64
done
(Reading database ... 117967 files and directories currently installed.)
Purging configuration files for linux-image-5.11.1 (5.11.1-1) ...

Vérifiez que le fichier grub.cfg a été modifié :

root@debian11:/home/trainee# grep 5.11.1 /boot/grub/grub.cfg
root@debian11:/home/trainee#

Dernièrement, listez les noyaux disponibles :

root@debian11:/home/trainee# dpkg -l | grep -i "linux-image*" | awk '{print $2}'
linux-image-5.10.0-13-amd64
linux-image-amd64

LAB #4 - Mise à Jour du Noyau avec le Gestionnaire des Paquets

Afin d'obtenir la dernière version du noyau pré-compliée par Debian, il convient d'ajouter les dépôts unstable :

root@debian11:/home/trainee# echo "deb http://deb.debian.org/debian unstable main contrib non-free" | sudo tee -a /etc/apt/sources.list
deb http://deb.debian.org/debian unstable main contrib non-free
root@debian11:/home/trainee# echo "deb-src http://deb.debian.org/debian unstable main contrib non-free" | sudo tee -a /etc/apt/sources.list
deb-src http://deb.debian.org/debian unstable main contrib non-free

Afin de ne faire que des mises à jour du noyau à partir de ce dépôt, créez le fichier /etc/apt/preferences :

root@debian11:/home/trainee# vi /etc/apt/preferences
root@debian11:/home/trainee# cat /etc/apt/preferences
Package: *
Pin: release a=bullseye
Pin-Priority: 500

Package: linux-image-amd64
Pin: release a=unstable
Pin-Priority: 1000

Package: *
Pin: release a=unstable
Pin-Priority: 100

Mettez à jour apt :

root@debian11:/home/trainee# apt update
Hit:1 http://security.debian.org/debian-security bullseye-security InRelease
Hit:2 http://deb.debian.org/debian bullseye InRelease
Get:3 http://deb.debian.org/debian bullseye-updates InRelease [39.4 kB]
Get:4 http://deb.debian.org/debian unstable InRelease [165 kB]
Get:5 http://deb.debian.org/debian unstable/contrib Sources [57.6 kB]
Get:6 http://deb.debian.org/debian unstable/main Sources [9,700 kB]
Get:7 http://deb.debian.org/debian unstable/non-free Sources [89.6 kB]
Get:8 http://deb.debian.org/debian unstable/main amd64 Packages [9,154 kB]
Get:9 http://deb.debian.org/debian unstable/main Translation-en [6,780 kB]
Get:10 http://deb.debian.org/debian unstable/contrib amd64 Packages [65.4 kB]
Get:11 http://deb.debian.org/debian unstable/contrib Translation-en [55.9 kB]
Get:12 http://deb.debian.org/debian unstable/non-free amd64 Packages [112 kB]
Get:13 http://deb.debian.org/debian unstable/non-free Translation-en [103 kB]
Fetched 26.3 MB in 5s (4,955 kB/s)                         
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
2 packages can be upgraded. Run 'apt list --upgradable' to see them.

Installez ensuite les mises-à-jour du noyau :

root@debian11:/home/trainee# apt -y  upgrade

Re-démarrez votre VM :

root@debian11:/home/trainee# reboot

Connectez-vous de nouveau à la VM et contrôlez la version du noyau :

trainee@debian11:~$ uname -a
Linux debian11 5.17.0-1-amd64 #1 SMP PREEMPT Debian 5.17.3-1 (2022-04-18) x86_64 GNU/Linux

Déconnectez-vous et re-connectez-vous directement en tant que root.

Piste : • LDF501 - Gestion des Utilisateurs • DOF606 - Overlay Network Management with Docker in Swarm Mode • LDF512 - Gestion du Noyau et des Quotas • Topic 210: Network Client Management • LDF600 - Debian 10 Linux - System Administrator • Topic 208: HTTP Services • RH13407 - Gestion des Machines Virtuelles avec KVM • RES401 - Comprendre les Réseaux • LCF104 - Commandes de Base et Outils de Manipulation de Fichiers Texte • Topic 201: Linux Kernel

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