syslog: distinguish between /proc/kmsg and syscalls

This allows the LSM to distinguish between syslog functions originating
from /proc/kmsg access and direct syscalls.  By default, the commoncaps
will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg
file descriptor.  For example the kernel syslog reader can now drop
privileges after opening /proc/kmsg, instead of staying privileged with
CAP_SYS_ADMIN.  MAC systems that implement security_syslog have unchanged
behavior.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 529c9ca65878..a5721b373f53 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -157,12 +157,12 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
  *
  * Returns 0 on success, error code otherwise.
  */
-static int smack_syslog(int type)
+static int smack_syslog(int type, bool from_file)
 {
         int rc;
         char *sp = current_security();
 
-        rc = cap_syslog(type);
+        rc = cap_syslog(type, from_file);
         if (rc != 0)
                 return rc;