keys: make the keyring quotas controllable through /proc/sys

Make the keyring quotas controllable through /proc/sys files:

 (*) /proc/sys/kernel/keys/root_maxkeys
     /proc/sys/kernel/keys/root_maxbytes

     Maximum number of keys that root may have and the maximum total number of
     bytes of data that root may have stored in those keys.

 (*) /proc/sys/kernel/keys/maxkeys
     /proc/sys/kernel/keys/maxbytes

     Maximum number of keys that each non-root user may have and the maximum
     total number of bytes of data that each of those users may have stored in
     their keys.

Also increase the quotas as a number of people have been complaining that it's
not big enough.  I'm not sure that it's big enough now either, but on the
other hand, it can now be set in /etc/sysctl.conf.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: <kwc@citi.umich.edu>
Cc: <arunsr@cse.iitk.ac.in>
Cc: <dwalsh@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 993be634a5ef..acc9c89e40a8 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -731,10 +731,16 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 
                 /* transfer the quota burden to the new user */
                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
+                        unsigned maxkeys = (uid == 0) ?
+                                key_quota_root_maxkeys : key_quota_maxkeys;
+                        unsigned maxbytes = (uid == 0) ?
+                                key_quota_root_maxbytes : key_quota_maxbytes;
+
                         spin_lock(&newowner->lock);
-                        if (newowner->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
-                            newowner->qnbytes + key->quotalen >=
-                            KEYQUOTA_MAX_BYTES)
+                        if (newowner->qnkeys + 1 >= maxkeys ||
+                            newowner->qnbytes + key->quotalen >= maxbytes ||
+                            newowner->qnbytes + key->quotalen <
+                            newowner->qnbytes)
                                 goto quota_overrun;
 
                         newowner->qnkeys++;