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author | Ondrej Mosnacek <omosnace@redhat.com> | 2018-12-21 21:18:52 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-08 07:21:54 +0200 |
commit | 574be221407e4f4780c413a87f1fc27dea86995f (patch) | |
tree | 3c0ecbe6eeab37119fd2807b112d4cb41c851dba | |
parent | 6b13ae52ac75da7970fde9d08c495a5671605473 (diff) | |
download | linux-stable-574be221407e4f4780c413a87f1fc27dea86995f.tar.gz linux-stable-574be221407e4f4780c413a87f1fc27dea86995f.tar.bz2 linux-stable-574be221407e4f4780c413a87f1fc27dea86995f.zip |
selinux: never allow relabeling on context mounts
commit a83d6ddaebe541570291205cb538e35ad4ff94f9 upstream.
In the SECURITY_FS_USE_MNTPOINT case we never want to allow relabeling
files/directories, so we should never set the SBLABEL_MNT flag. The
'special handling' in selinux_is_sblabel_mnt() is only intended for when
the behavior is set to SECURITY_FS_USE_GENFS.
While there, make the logic in selinux_is_sblabel_mnt() more explicit
and add a BUILD_BUG_ON() to make sure that introducing a new
SECURITY_FS_USE_* forces a review of the logic.
Fixes: d5f3a5f6e7e7 ("selinux: add security in-core xattr support for pstore and debugfs")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | security/selinux/hooks.c | 40 |
1 files changed, 31 insertions, 9 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 6cc780b4f9df..cba19b8c3e51 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -497,16 +497,10 @@ static int may_context_mount_inode_relabel(u32 sid, return rc; } -static int selinux_is_sblabel_mnt(struct super_block *sb) +static int selinux_is_genfs_special_handling(struct super_block *sb) { - struct superblock_security_struct *sbsec = sb->s_security; - - return sbsec->behavior == SECURITY_FS_USE_XATTR || - sbsec->behavior == SECURITY_FS_USE_TRANS || - sbsec->behavior == SECURITY_FS_USE_TASK || - sbsec->behavior == SECURITY_FS_USE_NATIVE || - /* Special handling. Genfs but also in-core setxattr handler */ - !strcmp(sb->s_type->name, "sysfs") || + /* Special handling. Genfs but also in-core setxattr handler */ + return !strcmp(sb->s_type->name, "sysfs") || !strcmp(sb->s_type->name, "pstore") || !strcmp(sb->s_type->name, "debugfs") || !strcmp(sb->s_type->name, "tracefs") || @@ -516,6 +510,34 @@ static int selinux_is_sblabel_mnt(struct super_block *sb) !strcmp(sb->s_type->name, "cgroup2"))); } +static int selinux_is_sblabel_mnt(struct super_block *sb) +{ + struct superblock_security_struct *sbsec = sb->s_security; + + /* + * IMPORTANT: Double-check logic in this function when adding a new + * SECURITY_FS_USE_* definition! + */ + BUILD_BUG_ON(SECURITY_FS_USE_MAX != 7); + + switch (sbsec->behavior) { + case SECURITY_FS_USE_XATTR: + case SECURITY_FS_USE_TRANS: + case SECURITY_FS_USE_TASK: + case SECURITY_FS_USE_NATIVE: + return 1; + + case SECURITY_FS_USE_GENFS: + return selinux_is_genfs_special_handling(sb); + + /* Never allow relabeling on context mounts */ + case SECURITY_FS_USE_MNTPOINT: + case SECURITY_FS_USE_NONE: + default: + return 0; + } +} + static int sb_finish_set_opts(struct super_block *sb) { struct superblock_security_struct *sbsec = sb->s_security; |