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authorHimanshu Shukla <himanshu.sh@samsung.com>2016-11-10 16:19:52 +0530
committerCasey Schaufler <casey@schaufler-ca.com>2016-11-10 11:21:32 -0800
commit2097f59920ea81516d7783396683cad22c26d140 (patch)
treed64bc44cfcf43c5daa2aeb759352892746b01734 /security
parent08382c9f6efe08b8bb30645c2744480cbd8f161a (diff)
downloadlinux-stericsson-2097f59920ea81516d7783396683cad22c26d140.tar.gz
smack: parse mnt opts after privileges check
In smack_set_mnt_opts()first the SMACK mount options are being parsed and later it is being checked whether the user calling mount has CAP_MAC_ADMIN capability. This sequence of operationis will allow unauthorized user to add SMACK labels in label list and may cause denial of security attack by adding many labels by allocating kernel memory by unauthorized user. Superblock smack flag is also being set as initialized though function may return with EPERM error. First check the capability of calling user then set the SMACK attributes and smk_flags. Signed-off-by: Himanshu Shukla <himanshu.sh@samsung.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Diffstat (limited to 'security')
-rw-r--r--security/smack/smack_lsm.c50
1 files changed, 25 insertions, 25 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index e73460d5acc6..788a5faf3774 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -769,6 +769,31 @@ static int smack_set_mnt_opts(struct super_block *sb,
if (sp->smk_flags & SMK_SB_INITIALIZED)
return 0;
+ if (!smack_privileged(CAP_MAC_ADMIN)) {
+ /*
+ * Unprivileged mounts don't get to specify Smack values.
+ */
+ if (num_opts)
+ return -EPERM;
+ /*
+ * Unprivileged mounts get root and default from the caller.
+ */
+ skp = smk_of_current();
+ sp->smk_root = skp;
+ sp->smk_default = skp;
+ /*
+ * For a handful of fs types with no user-controlled
+ * backing store it's okay to trust security labels
+ * in the filesystem. The rest are untrusted.
+ */
+ if (sb->s_user_ns != &init_user_ns &&
+ sb->s_magic != SYSFS_MAGIC && sb->s_magic != TMPFS_MAGIC &&
+ sb->s_magic != RAMFS_MAGIC) {
+ transmute = 1;
+ sp->smk_flags |= SMK_SB_UNTRUSTED;
+ }
+ }
+
sp->smk_flags |= SMK_SB_INITIALIZED;
for (i = 0; i < num_opts; i++) {
@@ -809,31 +834,6 @@ static int smack_set_mnt_opts(struct super_block *sb,
}
}
- if (!smack_privileged(CAP_MAC_ADMIN)) {
- /*
- * Unprivileged mounts don't get to specify Smack values.
- */
- if (num_opts)
- return -EPERM;
- /*
- * Unprivileged mounts get root and default from the caller.
- */
- skp = smk_of_current();
- sp->smk_root = skp;
- sp->smk_default = skp;
- /*
- * For a handful of fs types with no user-controlled
- * backing store it's okay to trust security labels
- * in the filesystem. The rest are untrusted.
- */
- if (sb->s_user_ns != &init_user_ns &&
- sb->s_magic != SYSFS_MAGIC && sb->s_magic != TMPFS_MAGIC &&
- sb->s_magic != RAMFS_MAGIC) {
- transmute = 1;
- sp->smk_flags |= SMK_SB_UNTRUSTED;
- }
- }
-
/*
* Initialize the root inode.
*/