netfilter: take care of timewait sockets
Eric Dumazet [Tue, 4 Sep 2012 07:49:03 +0000 (07:49 +0000)]
Sami Farin reported crashes in xt_LOG because it assumes skb->sk is a
full blown socket.

Since (41063e9 ipv4: Early TCP socket demux), we can have skb->sk
pointing to a timewait socket.

Same fix is needed in nfnetlink_log.

Diagnosed-by: Florian Westphal <fw@strlen.de>
Reported-by: Sami Farin <hvtaifwkbgefbaei@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nfnetlink_log.c
net/netfilter/xt_LOG.c

index 14e2f39..5cfb5be 100644 (file)
@@ -381,6 +381,7 @@ __build_packet_message(struct nfulnl_instance *inst,
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;
        sk_buff_data_t old_tail = inst->skb->tail;
+       struct sock *sk;
 
        nlh = nlmsg_put(inst->skb, 0, 0,
                        NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET,
@@ -499,18 +500,19 @@ __build_packet_message(struct nfulnl_instance *inst,
        }
 
        /* UID */
-       if (skb->sk) {
-               read_lock_bh(&skb->sk->sk_callback_lock);
-               if (skb->sk->sk_socket && skb->sk->sk_socket->file) {
-                       struct file *file = skb->sk->sk_socket->file;
+       sk = skb->sk;
+       if (sk && sk->sk_state != TCP_TIME_WAIT) {
+               read_lock_bh(&sk->sk_callback_lock);
+               if (sk->sk_socket && sk->sk_socket->file) {
+                       struct file *file = sk->sk_socket->file;
                        __be32 uid = htonl(file->f_cred->fsuid);
                        __be32 gid = htonl(file->f_cred->fsgid);
-                       read_unlock_bh(&skb->sk->sk_callback_lock);
+                       read_unlock_bh(&sk->sk_callback_lock);
                        if (nla_put_be32(inst->skb, NFULA_UID, uid) ||
                            nla_put_be32(inst->skb, NFULA_GID, gid))
                                goto nla_put_failure;
                } else
-                       read_unlock_bh(&skb->sk->sk_callback_lock);
+                       read_unlock_bh(&sk->sk_callback_lock);
        }
 
        /* local sequence number */
index ff5f75f..2a4f969 100644 (file)
@@ -145,6 +145,19 @@ static int dump_tcp_header(struct sbuff *m, const struct sk_buff *skb,
        return 0;
 }
 
+static void dump_sk_uid_gid(struct sbuff *m, struct sock *sk)
+{
+       if (!sk || sk->sk_state == TCP_TIME_WAIT)
+               return;
+
+       read_lock_bh(&sk->sk_callback_lock);
+       if (sk->sk_socket && sk->sk_socket->file)
+               sb_add(m, "UID=%u GID=%u ",
+                       sk->sk_socket->file->f_cred->fsuid,
+                       sk->sk_socket->file->f_cred->fsgid);
+       read_unlock_bh(&sk->sk_callback_lock);
+}
+
 /* One level of recursion won't kill us */
 static void dump_ipv4_packet(struct sbuff *m,
                        const struct nf_loginfo *info,
@@ -361,14 +374,8 @@ static void dump_ipv4_packet(struct sbuff *m,
        }
 
        /* Max length: 15 "UID=4294967295 " */
-       if ((logflags & XT_LOG_UID) && !iphoff && skb->sk) {
-               read_lock_bh(&skb->sk->sk_callback_lock);
-               if (skb->sk->sk_socket && skb->sk->sk_socket->file)
-                       sb_add(m, "UID=%u GID=%u ",
-                               skb->sk->sk_socket->file->f_cred->fsuid,
-                               skb->sk->sk_socket->file->f_cred->fsgid);
-               read_unlock_bh(&skb->sk->sk_callback_lock);
-       }
+       if ((logflags & XT_LOG_UID) && !iphoff)
+               dump_sk_uid_gid(m, skb->sk);
 
        /* Max length: 16 "MARK=0xFFFFFFFF " */
        if (!iphoff && skb->mark)
@@ -717,14 +724,8 @@ static void dump_ipv6_packet(struct sbuff *m,
        }
 
        /* Max length: 15 "UID=4294967295 " */
-       if ((logflags & XT_LOG_UID) && recurse && skb->sk) {
-               read_lock_bh(&skb->sk->sk_callback_lock);
-               if (skb->sk->sk_socket && skb->sk->sk_socket->file)
-                       sb_add(m, "UID=%u GID=%u ",
-                               skb->sk->sk_socket->file->f_cred->fsuid,
-                               skb->sk->sk_socket->file->f_cred->fsgid);
-               read_unlock_bh(&skb->sk->sk_callback_lock);
-       }
+       if ((logflags & XT_LOG_UID) && recurse)
+               dump_sk_uid_gid(m, skb->sk);
 
        /* Max length: 16 "MARK=0xFFFFFFFF " */
        if (!recurse && skb->mark)