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author | Ondrej Mosnacek <omosnace@redhat.com> | 2018-12-21 21:18:53 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-05 22:33:16 +0200 |
commit | e30e0b0915b67e28799f31e43ab3ead79a368ded (patch) | |
tree | 0cd1a13f1bd7a796ec6c0a95cb7b535abf64f522 | |
parent | d2053718e08769c14e704bfd1cb4d91f944ad9bf (diff) | |
download | linux-stable-e30e0b0915b67e28799f31e43ab3ead79a368ded.tar.gz linux-stable-e30e0b0915b67e28799f31e43ab3ead79a368ded.tar.bz2 linux-stable-e30e0b0915b67e28799f31e43ab3ead79a368ded.zip |
selinux: do not override context on context mounts
[ Upstream commit 53e0c2aa9a59a48e3798ef193d573ade85aa80f5 ]
Ignore all selinux_inode_notifysecctx() calls on mounts with SBLABEL_MNT
flag unset. This is achived by returning -EOPNOTSUPP for this case in
selinux_inode_setsecurtity() (because that function should not be called
in such case anyway) and translating this error to 0 in
selinux_inode_notifysecctx().
This fixes behavior of kernfs-based filesystems when mounted with the
'context=' option. Before this patch, if a node's context had been
explicitly set to a non-default value and later the filesystem has been
remounted with the 'context=' option, then this node would show up as
having the manually-set context and not the mount-specified one.
Steps to reproduce:
# mount -t cgroup2 cgroup2 /sys/fs/cgroup/unified
# chcon unconfined_u:object_r:user_home_t:s0 /sys/fs/cgroup/unified/cgroup.stat
# ls -lZ /sys/fs/cgroup/unified
total 0
-r--r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.controllers
-rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.max.depth
-rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.max.descendants
-rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.procs
-r--r--r--. 1 root root unconfined_u:object_r:user_home_t:s0 0 Dec 13 10:41 cgroup.stat
-rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.subtree_control
-rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Dec 13 10:41 cgroup.threads
# umount /sys/fs/cgroup/unified
# mount -o context=system_u:object_r:tmpfs_t:s0 -t cgroup2 cgroup2 /sys/fs/cgroup/unified
Result before:
# ls -lZ /sys/fs/cgroup/unified
total 0
-r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.controllers
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.depth
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.descendants
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.procs
-r--r--r--. 1 root root unconfined_u:object_r:user_home_t:s0 0 Dec 13 10:41 cgroup.stat
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.subtree_control
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.threads
Result after:
# ls -lZ /sys/fs/cgroup/unified
total 0
-r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.controllers
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.depth
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.descendants
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.procs
-r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.stat
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.subtree_control
-rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.threads
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: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | security/selinux/hooks.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 6ea3d3aa1a1e..4337b6d9369e 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3458,12 +3458,16 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags) { struct inode_security_struct *isec = inode_security_novalidate(inode); + struct superblock_security_struct *sbsec = inode->i_sb->s_security; u32 newsid; int rc; if (strcmp(name, XATTR_SELINUX_SUFFIX)) return -EOPNOTSUPP; + if (!(sbsec->flags & SBLABEL_MNT)) + return -EOPNOTSUPP; + if (!value || !size) return -EACCES; @@ -6612,7 +6616,10 @@ static void selinux_inode_invalidate_secctx(struct inode *inode) */ static int selinux_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen) { - return selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, ctx, ctxlen, 0); + int rc = selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, + ctx, ctxlen, 0); + /* Do not return error when suppressing label (SBLABEL_MNT not set). */ + return rc == -EOPNOTSUPP ? 0 : rc; } /* |