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authorCasey Schaufler <casey@schaufler-ca.com>2013-10-11 18:06:39 -0700
committerCasey Schaufler <casey@schaufler-ca.com>2013-10-18 09:39:33 -0700
commitc0ab6e56dcb7ca9903d460247cb464e769ae6e77 (patch)
tree52da39cb2798c0a4276d0d23fa3b4f1dbcd732f2 /security/smack/smack_access.c
parent5a5f2acfd04269e2e0958067216b68ff461c285c (diff)
downloadlinux-c0ab6e56dcb7ca9903d460247cb464e769ae6e77.tar.gz
Smack: Implement lock security mode
Linux file locking does not follow the same rules as other mechanisms. Even though it is a write operation a process can set a read lock on files which it has open only for read access. Two programs with read access to a file can use read locks to communicate. This is not acceptable in a Mandatory Access Control environment. Smack treats setting a read lock as the write operation that it is. Unfortunately, many programs assume that setting a read lock is a read operation. These programs are unhappy in the Smack environment. This patch introduces a new access mode (lock) to address this problem. A process with lock access to a file can set a read lock. A process with write access to a file can set a read lock or a write lock. This prevents a situation where processes are granted write access just so they can set read locks. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Diffstat (limited to 'security/smack/smack_access.c')
-rw-r--r--security/smack/smack_access.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index b3b59b1e93d6..14293cd9b1e5 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -84,6 +84,8 @@ int log_policy = SMACK_AUDIT_DENIED;
*
* Do the object check first because that is more
* likely to differ.
+ *
+ * Allowing write access implies allowing locking.
*/
int smk_access_entry(char *subject_label, char *object_label,
struct list_head *rule_list)
@@ -99,6 +101,11 @@ int smk_access_entry(char *subject_label, char *object_label,
}
}
+ /*
+ * MAY_WRITE implies MAY_LOCK.
+ */
+ if ((may & MAY_WRITE) == MAY_WRITE)
+ may |= MAY_LOCK;
return may;
}
@@ -245,6 +252,7 @@ out_audit:
static inline void smack_str_from_perm(char *string, int access)
{
int i = 0;
+
if (access & MAY_READ)
string[i++] = 'r';
if (access & MAY_WRITE)
@@ -255,6 +263,8 @@ static inline void smack_str_from_perm(char *string, int access)
string[i++] = 'a';
if (access & MAY_TRANSMUTE)
string[i++] = 't';
+ if (access & MAY_LOCK)
+ string[i++] = 'l';
string[i] = '\0';
}
/**