4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit a08bf91ce28ed3ae7b6fef35d843fef8dc8c2cd9 upstream.
If the sysctl 'kernel.keys.maxkeys' is set to some number n, then actually users can only add up to 'n - 1' keys. Likewise for 'kernel.keys.maxbytes' and the root_* versions of these sysctls. But these sysctls are apparently supposed to be *maximums*, as per their names and all documentation I could find -- the keyrings(7) man page, Documentation/security/keys/core.rst, and all the mentions of EDQUOT meaning that the key quota was *exceeded* (as opposed to reached).
Thus, fix the code to allow reaching the quotas exactly.
Fixes: 0b77f5bfb45c ("keys: make the keyring quotas controllable through /proc/sys") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: James Morris james.morris@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/keys/key.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/security/keys/key.c +++ b/security/keys/key.c @@ -264,8 +264,8 @@ struct key *key_alloc(struct key_type *t
spin_lock(&user->lock); if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { - if (user->qnkeys + 1 >= maxkeys || - user->qnbytes + quotalen >= maxbytes || + if (user->qnkeys + 1 > maxkeys || + user->qnbytes + quotalen > maxbytes || user->qnbytes + quotalen < user->qnbytes) goto no_quota; }