aboutsummaryrefslogtreecommitdiff
path: root/security/smack
diff options
context:
space:
mode:
authorAhmed S. Darwish <darwish.07@gmail.com>2008-03-13 12:32:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-13 13:11:43 -0700
commitb500ce8d24d1f14426643da5f6fada28c1f60533 (patch)
tree17b6084b29434a968f787e238548a843126e2ec3 /security/smack
parent93d74463d018ddf05c169ad399e62e90e0f82fc0 (diff)
downloadlinux-linaro-stable-b500ce8d24d1f14426643da5f6fada28c1f60533.tar.gz
smackfs: do not trust `count' in inodes write()s
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@gmail.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/smack')
-rw-r--r--security/smack/smack.h8
-rw-r--r--security/smack/smackfs.c31
2 files changed, 20 insertions, 19 deletions
diff --git a/security/smack/smack.h b/security/smack/smack.h
index a21a0e907ab3..62c1e982849d 100644
--- a/security/smack/smack.h
+++ b/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 --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 358c92c1a153..afe7c9b0732a 100644
--- a/security/smack/smackfs.c
+++ b/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_rule *srp)
* The format is exactly:
* char subject[SMK_LABELLEN]
* char object[SMK_LABELLEN]
- * char access[SMK_ACCESSKINDS]
- *
- * Anything following is commentary and ignored.
+ * char access[SMK_ACCESSLEN]
*
- * 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 file *file, const char __user *buf,
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 file *file, const char __user *buf,
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 file *file, const char __user *buf,
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));