netfilter: xt_recent: check for unsupported user space flags

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

2 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/netfilter/xt_recent.h b/include/linux/netfilter/xt_recent.h
index bba990ecb018..83318e01425e 100644
--- a/include/linux/netfilter/xt_recent.h
+++ b/include/linux/netfilter/xt_recent.h
@@ -20,6 +20,9 @@ enum {
 /* Only allowed with --rcheck and --update */
 #define XT_RECENT_MODIFIERS (XT_RECENT_TTL|XT_RECENT_REAP)
 
+#define XT_RECENT_VALID_FLAGS (XT_RECENT_CHECK|XT_RECENT_SET|XT_RECENT_UPDATE|\
+                               XT_RECENT_REMOVE|XT_RECENT_TTL|XT_RECENT_REAP)
+
 struct xt_recent_mtinfo {
         __u32 seconds;
         __u32 hit_count;
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index b65eca9e13a3..d2e7c80cd3c3 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -319,6 +319,11 @@ static bool recent_mt_check(const struct xt_mtchk_param *par)
                 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
                 hash_rnd_inited = true;
         }
+        if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
+                pr_info(KBUILD_MODNAME ": Unsupported user space flags "
+                        "(%08x)\n", info->check_set);
+                return false;
+        }
         if (hweight8(info->check_set &
                      (XT_RECENT_SET | XT_RECENT_REMOVE |
                       XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)