On Wed, 2017-11-29 at 19:16 -0800, Casey Schaufler wrote: > On 11/29/2017 4:31 PM, James Morris wrote: > > On Wed, 29 Nov 2017, Casey Schaufler wrote: > > > > > I see that there is a proposed fix later in the thread, but I > > > don't see > > > the patch. Could you send it to me, so I can try it on my > > > problem? > > > > Forwarded off-list. > > The patch does fix the problem I was seeing in Smack.
Can you guys test the following more complete patch ? It should cover IPv4 and IPv6, and also the corner cases. ( Note that I squashed ipv6 fix in https://patchwork.ozlabs.org/patch/8 42844/ that I spotted while cooking this patch ) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index c6bc0c4d19c624888b0d0b5a4246c7183edf63f5..77ea45da0fe9c746907a312989658af3ad3b198d 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1591,6 +1591,34 @@ int tcp_filter(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(tcp_filter); +static void tcp_v4_restore_cb(struct sk_buff *skb) +{ + memmove(IPCB(skb), &TCP_SKB_CB(skb)->header.h4, + sizeof(struct inet_skb_parm)); +} + +static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph, + const struct tcphdr *th) +{ + /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() + * barrier() makes sure compiler wont play fool^Waliasing games. + */ + memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb), + sizeof(struct inet_skb_parm)); + barrier(); + + TCP_SKB_CB(skb)->seq = ntohl(th->seq); + TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + + skb->len - th->doff * 4); + TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); + TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); + TCP_SKB_CB(skb)->tcp_tw_isn = 0; + TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); + TCP_SKB_CB(skb)->sacked = 0; + TCP_SKB_CB(skb)->has_rxtstamp = + skb->tstamp || skb_hwtstamps(skb)->hwtstamp; +} + /* * From tcp_input.c */ @@ -1631,24 +1659,6 @@ int tcp_v4_rcv(struct sk_buff *skb) th = (const struct tcphdr *)skb->data; iph = ip_hdr(skb); - /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() - * barrier() makes sure compiler wont play fool^Waliasing games. - */ - memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb), - sizeof(struct inet_skb_parm)); - barrier(); - - TCP_SKB_CB(skb)->seq = ntohl(th->seq); - TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + - skb->len - th->doff * 4); - TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); - TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); - TCP_SKB_CB(skb)->tcp_tw_isn = 0; - TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); - TCP_SKB_CB(skb)->sacked = 0; - TCP_SKB_CB(skb)->has_rxtstamp = - skb->tstamp || skb_hwtstamps(skb)->hwtstamp; - lookup: sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source, th->dest, sdif, &refcounted); @@ -1679,14 +1689,19 @@ int tcp_v4_rcv(struct sk_buff *skb) sock_hold(sk); refcounted = true; nsk = NULL; - if (!tcp_filter(sk, skb)) + if (!tcp_filter(sk, skb)) { + th = (const struct tcphdr *)skb->data; + iph = ip_hdr(skb); + tcp_v4_fill_cb(skb, iph, th); nsk = tcp_check_req(sk, skb, req, false); + } if (!nsk) { reqsk_put(req); goto discard_and_relse; } if (nsk == sk) { reqsk_put(req); + tcp_v4_restore_cb(skb); } else if (tcp_child_process(sk, nsk, skb)) { tcp_v4_send_reset(nsk, skb); goto discard_and_relse; @@ -1712,6 +1727,7 @@ int tcp_v4_rcv(struct sk_buff *skb) goto discard_and_relse; th = (const struct tcphdr *)skb->data; iph = ip_hdr(skb); + tcp_v4_fill_cb(skb, iph, th); skb->dev = NULL; @@ -1742,6 +1758,8 @@ int tcp_v4_rcv(struct sk_buff *skb) if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) goto discard_it; + tcp_v4_fill_cb(skb, iph, th); + if (tcp_checksum_complete(skb)) { csum_error: __TCP_INC_STATS(net, TCP_MIB_CSUMERRORS); @@ -1768,6 +1786,8 @@ int tcp_v4_rcv(struct sk_buff *skb) goto discard_it; } + tcp_v4_fill_cb(skb, iph, th); + if (tcp_checksum_complete(skb)) { inet_twsk_put(inet_twsk(sk)); goto csum_error; @@ -1784,6 +1804,7 @@ int tcp_v4_rcv(struct sk_buff *skb) if (sk2) { inet_twsk_deschedule_put(inet_twsk(sk)); sk = sk2; + tcp_v4_restore_cb(skb); refcounted = false; goto process; } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 6bb98c93edfe2ed2f16fe5229605f8108cfc7f9a..1f04ec0e4a7aa2c11b8ee27cbdd4067b5bcf32e5 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1454,7 +1454,6 @@ static int tcp_v6_rcv(struct sk_buff *skb) struct sock *nsk; sk = req->rsk_listener; - tcp_v6_fill_cb(skb, hdr, th); if (tcp_v6_inbound_md5_hash(sk, skb)) { sk_drops_add(sk, skb); reqsk_put(req); @@ -1467,8 +1466,12 @@ static int tcp_v6_rcv(struct sk_buff *skb) sock_hold(sk); refcounted = true; nsk = NULL; - if (!tcp_filter(sk, skb)) + if (!tcp_filter(sk, skb)) { + th = (const struct tcphdr *)skb->data; + hdr = ipv6_hdr(skb); + tcp_v6_fill_cb(skb, hdr, th); nsk = tcp_check_req(sk, skb, req, false); + } if (!nsk) { reqsk_put(req); goto discard_and_relse; @@ -1492,8 +1495,6 @@ static int tcp_v6_rcv(struct sk_buff *skb) if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; - tcp_v6_fill_cb(skb, hdr, th); - if (tcp_v6_inbound_md5_hash(sk, skb)) goto discard_and_relse; @@ -1501,6 +1502,7 @@ static int tcp_v6_rcv(struct sk_buff *skb) goto discard_and_relse; th = (const struct tcphdr *)skb->data; hdr = ipv6_hdr(skb); + tcp_v6_fill_cb(skb, hdr, th); skb->dev = NULL; @@ -1590,7 +1592,6 @@ static int tcp_v6_rcv(struct sk_buff *skb) tcp_v6_timewait_ack(sk, skb); break; case TCP_TW_RST: - tcp_v6_restore_cb(skb); tcp_v6_send_reset(sk, skb); inet_twsk_deschedule_put(inet_twsk(sk)); goto discard_it;
