diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 6d85861..89c5465 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -975,6 +975,13 @@ xfrm_state_addr_cmp(struct xfrm_tmpl *tmpl, struct xfrm_state *x, unsigned short } #ifdef CONFIG_XFRM +/* + * For transport, the policy is checked before the presumed more expensive + * checksum. The transport header has already been checked for size, and is + * guaranteed to be contiguous. These policies must not alter the header or + * its position in the buffer, and should not shorten the buffer length + * without ensuring the length remains >= the header size. + */ extern int __xfrm_policy_check(struct sock *, int dir, struct sk_buff *skb, unsigned short family); static inline int __xfrm_policy_check2(struct sock *sk, int dir, diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 65b8ebf..0a76e41 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1559,7 +1559,8 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) return 0; } - if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb)) + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) goto csum_err; if (sk->sk_state == TCP_LISTEN) { @@ -1601,14 +1602,13 @@ csum_err: } /* - * From tcp_input.c + * Called by ip_input.c: ip_local_deliver_finish() */ - int tcp_v4_rcv(struct sk_buff *skb) { - const struct iphdr *iph; struct tcphdr *th; struct sock *sk; + int tcp_header_len; int ret; struct net *net = dev_net(skb->dev); @@ -1618,31 +1618,33 @@ int tcp_v4_rcv(struct sk_buff *skb) /* Count it even if it's bad */ TCP_INC_STATS_BH(net, TCP_MIB_INSEGS); + /* Check too short header */ if (!pskb_may_pull(skb, sizeof(struct tcphdr))) goto discard_it; - th = tcp_hdr(skb); - - if (th->doff < sizeof(struct tcphdr) / 4) + /* Check bad doff, compare doff directly to constant value */ + tcp_header_len = tcp_hdr(skb)->doff; + if (tcp_header_len < (sizeof(struct tcphdr) / 4)) goto bad_packet; - if (!pskb_may_pull(skb, th->doff * 4)) + + /* Check too short header and options */ + tcp_header_len *= 4; + if (!pskb_may_pull(skb, tcp_header_len)) goto discard_it; - /* An explanation is required here, I think. - * Packet length and doff are validated by header prediction, - * provided case of th->doff==0 is eliminated. - * So, we defer the checks. */ + /* Packet length and doff are validated by header prediction, + * provided case of th->doff == 0 is eliminated (above). + */ if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb)) goto bad_packet; th = tcp_hdr(skb); - iph = ip_hdr(skb); 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); + skb->len - tcp_header_len); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); TCP_SKB_CB(skb)->when = 0; - TCP_SKB_CB(skb)->flags = iph->tos; + TCP_SKB_CB(skb)->flags = ip_hdr(skb)->tos; TCP_SKB_CB(skb)->sacked = 0; sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest); @@ -1682,14 +1684,14 @@ process: bh_unlock_sock(sk); sock_put(sk); - return ret; no_tcp_socket: if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) goto discard_it; - if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) { bad_packet: TCP_INC_STATS_BH(net, TCP_MIB_INERRS); } else { @@ -1711,18 +1713,21 @@ do_time_wait: goto discard_it; } - if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) { TCP_INC_STATS_BH(net, TCP_MIB_INERRS); inet_twsk_put(inet_twsk(sk)); goto discard_it; } + switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { case TCP_TW_SYN: { struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), &tcp_hashinfo, - iph->daddr, th->dest, + ip_hdr(skb)->daddr, + th->dest, inet_iif(skb)); - if (sk2) { + if (sk2 != NULL) { inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row); inet_twsk_put(inet_twsk(sk)); sk = sk2; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index febfd59..b76939a 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1594,7 +1594,8 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb) return 0; } - if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb)) + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) goto csum_err; if (sk->sk_state == TCP_LISTEN) { @@ -1664,38 +1665,47 @@ ipv6_pktoptions: return 0; } +/* + * Called by ip6_input.c: ip6_input_finish() + */ static int tcp_v6_rcv(struct sk_buff *skb) { struct tcphdr *th; struct sock *sk; + int tcp_header_len; int ret; struct net *net = dev_net(skb->dev); if (skb->pkt_type != PACKET_HOST) goto discard_it; - /* - * Count it even if it's bad. - */ + /* Count it even if it's bad */ TCP_INC_STATS_BH(net, TCP_MIB_INSEGS); + /* Check too short header */ if (!pskb_may_pull(skb, sizeof(struct tcphdr))) goto discard_it; - th = tcp_hdr(skb); - - if (th->doff < sizeof(struct tcphdr)/4) + /* Check bad doff, compare doff directly to constant value */ + tcp_header_len = tcp_hdr(skb)->doff; + if (tcp_header_len < (sizeof(struct tcphdr) / 4)) goto bad_packet; - if (!pskb_may_pull(skb, th->doff*4)) + + /* Check too short header and options */ + tcp_header_len *= 4; + if (!pskb_may_pull(skb, tcp_header_len)) goto discard_it; + /* Packet length and doff are validated by header prediction, + * provided case of th->doff == 0 is eliminated (above). + */ if (!skb_csum_unnecessary(skb) && tcp_v6_checksum_init(skb)) goto bad_packet; th = tcp_hdr(skb); 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); + skb->len - tcp_header_len); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); TCP_SKB_CB(skb)->when = 0; TCP_SKB_CB(skb)->flags = ipv6_get_dsfield(ipv6_hdr(skb)); @@ -1711,6 +1721,7 @@ process: if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; + /* nf_reset(skb); in ip6_input.c ip6_input_finish() */ if (sk_filter(sk, skb)) goto discard_and_relse; @@ -1743,7 +1754,8 @@ no_tcp_socket: if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) goto discard_it; - if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) { + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) { bad_packet: TCP_INC_STATS_BH(net, TCP_MIB_INERRS); } else { @@ -1751,11 +1763,7 @@ bad_packet: } discard_it: - - /* - * Discard frame - */ - + /* Discard frame. */ kfree_skb(skb); return 0; @@ -1769,24 +1777,23 @@ do_time_wait: goto discard_it; } - if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) { + /* Assumes header and options unchanged since checksum_init() */ + if (tcp_checksum_complete(skb)) { TCP_INC_STATS_BH(net, TCP_MIB_INERRS); inet_twsk_put(inet_twsk(sk)); goto discard_it; } switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { - case TCP_TW_SYN: - { - struct sock *sk2; - - sk2 = inet6_lookup_listener(dev_net(skb->dev), &tcp_hashinfo, - &ipv6_hdr(skb)->daddr, - ntohs(th->dest), inet6_iif(skb)); + case TCP_TW_SYN: { + struct sock *sk2 = inet6_lookup_listener(dev_net(skb->dev), + &tcp_hashinfo, + &ipv6_hdr(skb)->daddr, + ntohs(th->dest), + inet6_iif(skb)); if (sk2 != NULL) { - struct inet_timewait_sock *tw = inet_twsk(sk); - inet_twsk_deschedule(tw, &tcp_death_row); - inet_twsk_put(tw); + inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row); + inet_twsk_put(inet_twsk(sk)); sk = sk2; goto process; } -- 1.6.3.3