netfilter: nfnetlink_log: fix maximum packet length logged to userspace

don't try to queue payloads > 0xffff - NLA_HDRLEN, it does not work.
The nla length includes the size of the nla struct, so anything larger
results in u16 integer overflow.

This patch is similar to
9cefbbc9c8f9abe (netfilter: nfnetlink_queue: cleanup copy_range usage).

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit c1e7dc91eed0ed1a51c9b814d648db18bf8fc6e9)
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index a5f02eb06c51a9123a5f68e7f2585b7d41d32a6d..ebcbf072bc372d8784116392ae83369c29176f37 100644 (file)
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -41,7 +41,8 @@
 #define NFULNL_NLBUFSIZ_DEFAULT        NLMSG_GOODSIZE
 #define NFULNL_TIMEOUT_DEFAULT         100     /* every second */
 #define NFULNL_QTHRESH_DEFAULT         100     /* 100 packets */
-#define NFULNL_COPY_RANGE_MAX  0xFFFF  /* max packet size is limited by 16-bit struct nfattr nfa_len field */
+/* max packet size is limited by 16-bit struct nfattr nfa_len field */
+#define NFULNL_COPY_RANGE_MAX  (0xFFFF - NLA_HDRLEN)
 
 #define PRINTR(x, args...)     do { if (net_ratelimit()) \
                                     printk(x, ## args); } while (0);
@@ -221,6 +222,8 @@ nfulnl_set_mode(struct nfulnl_instance *inst, u_int8_t mode,
 
        case NFULNL_COPY_PACKET:
                inst->copy_mode = mode;
+               if (range == 0)
+                       range = NFULNL_COPY_RANGE_MAX;
                inst->copy_range = min_t(unsigned int,
                                         range, NFULNL_COPY_RANGE_MAX);
                break;
@@ -609,8 +612,7 @@ nfulnl_log_packet(u_int8_t pf,
                break;
 
        case NFULNL_COPY_PACKET:
-               if (inst->copy_range == 0
-                   || inst->copy_range > skb->len)
+               if (inst->copy_range > skb->len)
                        data_len = skb->len;
                else
                        data_len = inst->copy_range;