Convert the sites that pull and do version and ihl checks on the ipv4 header and validate the packet transport offset to use ip4_parse.
Sites that validate a read-only copy instead of pulling - the nft and nft_inner header_pointer validators, ip_check_defrag()'s skb_copy_bits, the flow dissector - stay open-coded for now. Signed-off-by: Michael S. Tsirkin <[email protected]> Assisted-by: LLM --- net/bridge/br_netfilter_hooks.c | 15 +++++---------- net/ipv4/ip_input.c | 13 +++++-------- net/ipv4/netfilter/nf_reject_ipv4.c | 13 +++++-------- 3 files changed, 15 insertions(+), 26 deletions(-) diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c index 0a394e5f43916..e89da0e415426 100644 --- a/net/bridge/br_netfilter_hooks.c +++ b/net/bridge/br_netfilter_hooks.c @@ -206,18 +206,13 @@ static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb) static int br_validate_ipv4(struct net *net, struct sk_buff *skb) { const struct iphdr *iph; - u32 len; + u32 len, thoff; - if (!pskb_may_pull(skb, sizeof(struct iphdr))) + iph = ip4_parse(skb, 0, &thoff); + if (!iph) goto inhdr_error; - iph = ip_hdr(skb); - - /* Basic sanity checks */ - if (iph->ihl < 5 || iph->version != 4) - goto inhdr_error; - - if (!pskb_may_pull(skb, iph->ihl*4)) + if (!pskb_may_pull(skb, thoff)) goto inhdr_error; iph = ip_hdr(skb); @@ -228,7 +223,7 @@ static int br_validate_ipv4(struct net *net, struct sk_buff *skb) if (skb->len < len) { __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); goto drop; - } else if (len < (iph->ihl*4)) + } else if (len < thoff) goto inhdr_error; if (pskb_trim_rcsum(skb, len)) { diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c index 9860178752b8c..5adf01763e857 100644 --- a/net/ipv4/ip_input.c +++ b/net/ipv4/ip_input.c @@ -500,7 +500,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) { const struct iphdr *iph; int drop_reason; - u32 len; + u32 len, thoff; /* When the interface is in promisc. mode, drop all the crap * that it receives, do not try to analyse it. @@ -520,10 +520,6 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) } drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; - if (!pskb_may_pull(skb, sizeof(struct iphdr))) - goto inhdr_error; - - iph = ip_hdr(skb); /* * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum. @@ -536,7 +532,8 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) * 4. Doesn't have a bogus length */ - if (iph->ihl < 5 || iph->version != 4) + iph = ip4_parse(skb, 0, &thoff); + if (!iph) goto inhdr_error; BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); @@ -546,7 +543,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); - if (!pskb_may_pull(skb, iph->ihl*4)) + if (!pskb_may_pull(skb, thoff)) goto inhdr_error; iph = ip_hdr(skb); @@ -559,7 +556,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL; __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); goto drop; - } else if (len < (iph->ihl*4)) + } else if (len < thoff) goto inhdr_error; /* Our transport medium may have padded the buffer out. Now we know it diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index 59ec465a9df98..42d639854ddf1 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -25,22 +25,19 @@ nf_reject_ip_tcphdr_get(struct sk_buff *oldskb, static int nf_reject_iphdr_validate(struct sk_buff *skb) { struct iphdr *iph; - u32 len; + u32 len, thoff; - if (!pskb_may_pull(skb, sizeof(struct iphdr))) - return 0; - - iph = ip_hdr(skb); - if (iph->ihl < 5 || iph->version != 4) + iph = ip4_parse(skb, 0, &thoff); + if (!iph) return 0; len = ntohs(iph->tot_len); if (skb->len < len) return 0; - else if (len < (iph->ihl*4)) + else if (len < thoff) return 0; - if (!pskb_may_pull(skb, iph->ihl*4)) + if (!pskb_may_pull(skb, thoff)) return 0; return 1; -- MST
