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authorSeth Forshee <seth.forshee@canonical.com>2016-04-26 14:36:20 -0500
committerEric W. Biederman <ebiederm@xmission.com>2016-06-24 11:02:54 -0500
commitaad82892af261b9903cc11c55be3ecf5f0b0b4f8 (patch)
tree63dd314cee5d53b1c17e002d2be94dfff3f23289 /security/selinux
parent809c02e091a8272bc8586a5d606565bc900f3467 (diff)
selinux: Add support for unprivileged mounts from user namespaces
Security labels from unprivileged mounts in user namespaces must be ignored. Force superblocks from user namespaces whose labeling behavior is to use xattrs to use mountpoint labeling instead. For the mountpoint label, default to converting the current task context into a form suitable for file objects, but also allow the policy writer to specify a different label through policy transition rules. Pieced together from code snippets provided by Stephen Smalley. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/hooks.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 15541756eb07..19be9d39c742 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -830,6 +830,28 @@ static int selinux_set_mnt_opts(struct super_block *sb,
goto out;
}
}
+
+ /*
+ * If this is a user namespace mount, no contexts are allowed
+ * on the command line and security labels must be ignored.
+ */
+ if (sb->s_user_ns != &init_user_ns) {
+ if (context_sid || fscontext_sid || rootcontext_sid ||
+ defcontext_sid) {
+ rc = -EACCES;
+ goto out;
+ }
+ if (sbsec->behavior == SECURITY_FS_USE_XATTR) {
+ sbsec->behavior = SECURITY_FS_USE_MNTPOINT;
+ rc = security_transition_sid(current_sid(), current_sid(),
+ SECCLASS_FILE, NULL,
+ &sbsec->mntpoint_sid);
+ if (rc)
+ goto out;
+ }
+ goto out_set_opts;
+ }
+
/* sets the context of the superblock for the fs being mounted. */
if (fscontext_sid) {
rc = may_context_mount_sb_relabel(fscontext_sid, sbsec, cred);
@@ -898,6 +920,7 @@ static int selinux_set_mnt_opts(struct super_block *sb,
sbsec->def_sid = defcontext_sid;
}
+out_set_opts:
rc = sb_finish_set_opts(sb);
out:
mutex_unlock(&sbsec->lock);