security: Define CAP_SYSLOG

Privileged syslog operations currently require CAP_SYS_ADMIN.  Split
this off into a new CAP_SYSLOG privilege which we can sanely take away
from a container through the capability bounding set.

With this patch, an lxc container can be prevented from messing with
the host's syslog (i.e. dmesg -c).

Changelog: mar 12 2010: add selinux capability2:cap_syslog perm
Changelog: nov 22 2010:
	. port to new kernel
	. add a WARN_ONCE if userspace isn't using CAP_SYSLOG

Signed-off-by: Serge Hallyn <[email protected]>
Acked-by: Andrew G. Morgan <[email protected]>
Acked-By: Kees Cook <[email protected]>
Cc: James Morris <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Stephen Smalley <[email protected]>
Cc: "Christopher J. PeBenito" <[email protected]>
Cc: Eric Paris <[email protected]>
Signed-off-by: James Morris <[email protected]>

include/linux/capability.h

@@ -246,7 +246,6 @@ struct cpu_vfs_cap_data {
 /* Allow configuration of the secure attention key */
 /* Allow administration of the random device */
 /* Allow examination and configuration of disk quotas */
-/* Allow configuring the kernel's syslog (printk behaviour) */
 /* Allow setting the domainname */
 /* Allow setting the hostname */
 /* Allow calling bdflush() */
@@ -352,7 +351,11 @@ struct cpu_vfs_cap_data {
 
 #define CAP_MAC_ADMIN        33
 
-#define CAP_LAST_CAP         CAP_MAC_ADMIN
+/* Allow configuring the kernel's syslog (printk behaviour) */
+
+#define CAP_SYSLOG           34
+
+#define CAP_LAST_CAP         CAP_SYSLOG
 
 #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)