The patch titled
smackfs: do not trust `count' in inodes write()s
has been removed from the -mm tree. Its filename was
smackfs-do-not-trust-count-in-inodes-writes.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: smackfs: do not trust `count' in inodes write()s
From: "Ahmed S. Darwish" <darwish.07@xxxxxxxxx>
Smackfs write() implementation does not put a higher bound on the number of
bytes to copy from user-space. This may lead to a DOS attack if a malicious
`count' field is given.
Assure that given `count' is exactly the length needed for a /smack/load rule.
In case of /smack/cipso where the length is relative, assure that `count'
does not exceed the size needed for a buffer representing maximum possible
number of CIPSO 2.2 categories.
Signed-off-by: Ahmed S. Darwish <darwish.07@xxxxxxxxx>
Acked-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
security/smack/smack.h | 8 --------
security/smack/smackfs.c | 31 ++++++++++++++++++++-----------
2 files changed, 20 insertions(+), 19 deletions(-)
diff -puN security/smack/smack.h~smackfs-do-not-trust-count-in-inodes-writes security/smack/smack.h
--- a/security/smack/smack.h~smackfs-do-not-trust-count-in-inodes-writes
+++ a/security/smack/smack.h
@@ -26,14 +26,6 @@
#define SMK_MAXLEN 23
#define SMK_LABELLEN (SMK_MAXLEN+1)
-/*
- * How many kinds of access are there?
- * Here's your answer.
- */
-#define SMK_ACCESSDASH '-'
-#define SMK_ACCESSLOW "rwxa"
-#define SMK_ACCESSKINDS (sizeof(SMK_ACCESSLOW) - 1)
-
struct superblock_smack {
char *smk_root;
char *smk_floor;
diff -puN security/smack/smackfs.c~smackfs-do-not-trust-count-in-inodes-writes security/smack/smackfs.c
--- a/security/smack/smackfs.c~smackfs-do-not-trust-count-in-inodes-writes
+++ a/security/smack/smackfs.c
@@ -81,10 +81,23 @@ static struct semaphore smack_write_sem;
/*
* Values for parsing cipso rules
* SMK_DIGITLEN: Length of a digit field in a rule.
- * SMK_CIPSOMEN: Minimum possible cipso rule length.
+ * SMK_CIPSOMIN: Minimum possible cipso rule length.
+ * SMK_CIPSOMAX: Maximum possible cipso rule length.
*/
#define SMK_DIGITLEN 4
-#define SMK_CIPSOMIN (SMK_MAXLEN + 2 * SMK_DIGITLEN)
+#define SMK_CIPSOMIN (SMK_LABELLEN + 2 * SMK_DIGITLEN)
+#define SMK_CIPSOMAX (SMK_CIPSOMIN + SMACK_CIPSO_MAXCATNUM * SMK_DIGITLEN)
+
+/*
+ * Values for parsing MAC rules
+ * SMK_ACCESS: Maximum possible combination of access permissions
+ * SMK_ACCESSLEN: Maximum length for a rule access field
+ * SMK_LOADLEN: Smack rule length
+ */
+#define SMK_ACCESS "rwxa"
+#define SMK_ACCESSLEN (sizeof(SMK_ACCESS) - 1)
+#define SMK_LOADLEN (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)
+
/*
* Seq_file read operations for /smack/load
@@ -229,14 +242,10 @@ static void smk_set_access(struct smack_
* The format is exactly:
* char subject[SMK_LABELLEN]
* char object[SMK_LABELLEN]
- * char access[SMK_ACCESSKINDS]
+ * char access[SMK_ACCESSLEN]
*
- * Anything following is commentary and ignored.
- *
- * writes must be SMK_LABELLEN+SMK_LABELLEN+4 bytes.
+ * writes must be SMK_LABELLEN+SMK_LABELLEN+SMK_ACCESSLEN bytes.
*/
-#define MINIMUM_LOAD (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSKINDS)
-
static ssize_t smk_write_load(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
@@ -253,7 +262,7 @@ static ssize_t smk_write_load(struct fil
return -EPERM;
if (*ppos != 0)
return -EINVAL;
- if (count < MINIMUM_LOAD)
+ if (count != SMK_LOADLEN)
return -EINVAL;
data = kzalloc(count, GFP_KERNEL);
@@ -513,7 +522,7 @@ static ssize_t smk_write_cipso(struct fi
return -EPERM;
if (*ppos != 0)
return -EINVAL;
- if (count <= SMK_CIPSOMIN)
+ if (count < SMK_CIPSOMIN || count > SMK_CIPSOMAX)
return -EINVAL;
data = kzalloc(count + 1, GFP_KERNEL);
@@ -547,7 +556,7 @@ static ssize_t smk_write_cipso(struct fi
if (ret != 1 || catlen > SMACK_CIPSO_MAXCATNUM)
goto out;
- if (count <= (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
+ if (count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
goto out;
memset(mapcatset, 0, sizeof(mapcatset));
_
Patches currently in -mm which might be from darwish.07@xxxxxxxxx are
git-kvm.patch
git-security-testing.patch
smack-do-not-dereference-null-ipc-object.patch
lsm-introduce-inode_getsecid-and-ipc_getsecid-hooks-checkpatch-fixes.patch
lsm-audit-introduce-generic-audit-lsm-hooks-checkpatch-fixes.patch
selinux-use-new-audit-hooks-remove-redundant-exports-checkpatch-fixes.patch
audit-final-renamings-and-cleanup-checkpatch-fixes.patch
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