diff options
| author | Florian Westphal <fw@strlen.de> | 2019-05-23 15:44:11 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2019-05-31 18:02:48 +0200 |
| commit | fb2eb1c131f8526905a83bd98fd2d4e7c9f950a0 (patch) | |
| tree | c9fb6294ce98bb494f6a0bcf2ae9e07dcf3c5e32 /net | |
| parent | 8e03707f118cd2f8dc993b01dd15e78da147a29e (diff) | |
netfilter: tcpmss, optstrip: prefer skb_ensure_writable
This also changes optstrip to only make the tcp header writeable
rather than the entire packet.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/xt_TCPMSS.c | 2 | ||||
| -rw-r--r-- | net/netfilter/xt_TCPOPTSTRIP.c | 28 |
2 files changed, 14 insertions, 16 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index 98efb202f8b4..3e24443ab81c 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -89,7 +89,7 @@ tcpmss_mangle_packet(struct sk_buff *skb, if (par->fragoff != 0) return 0; - if (!skb_make_writable(skb, skb->len)) + if (skb_ensure_writable(skb, skb->len)) return -1; len = skb->len - tcphoff; diff --git a/net/netfilter/xt_TCPOPTSTRIP.c b/net/netfilter/xt_TCPOPTSTRIP.c index eb92bffff11c..5a274813076a 100644 --- a/net/netfilter/xt_TCPOPTSTRIP.c +++ b/net/netfilter/xt_TCPOPTSTRIP.c @@ -31,33 +31,33 @@ static inline unsigned int optlen(const u_int8_t *opt, unsigned int offset) static unsigned int tcpoptstrip_mangle_packet(struct sk_buff *skb, const struct xt_action_param *par, - unsigned int tcphoff, unsigned int minlen) + unsigned int tcphoff) { const struct xt_tcpoptstrip_target_info *info = par->targinfo; + struct tcphdr *tcph, _th; unsigned int optl, i, j; - struct tcphdr *tcph; u_int16_t n, o; u_int8_t *opt; - int len, tcp_hdrlen; + int tcp_hdrlen; /* This is a fragment, no TCP header is available */ if (par->fragoff != 0) return XT_CONTINUE; - if (!skb_make_writable(skb, skb->len)) + tcph = skb_header_pointer(skb, tcphoff, sizeof(_th), &_th); + if (!tcph) return NF_DROP; - len = skb->len - tcphoff; - if (len < (int)sizeof(struct tcphdr)) - return NF_DROP; - - tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); tcp_hdrlen = tcph->doff * 4; + if (tcp_hdrlen < sizeof(struct tcphdr)) + return NF_DROP; - if (len < tcp_hdrlen) + if (skb_ensure_writable(skb, tcphoff + tcp_hdrlen)) return NF_DROP; - opt = (u_int8_t *)tcph; + /* must reload tcph, might have been moved */ + tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); + opt = (u8 *)tcph; /* * Walk through all TCP options - if we find some option to remove, @@ -91,8 +91,7 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb, static unsigned int tcpoptstrip_tg4(struct sk_buff *skb, const struct xt_action_param *par) { - return tcpoptstrip_mangle_packet(skb, par, ip_hdrlen(skb), - sizeof(struct iphdr) + sizeof(struct tcphdr)); + return tcpoptstrip_mangle_packet(skb, par, ip_hdrlen(skb)); } #if IS_ENABLED(CONFIG_IP6_NF_MANGLE) @@ -109,8 +108,7 @@ tcpoptstrip_tg6(struct sk_buff *skb, const struct xt_action_param *par) if (tcphoff < 0) return NF_DROP; - return tcpoptstrip_mangle_packet(skb, par, tcphoff, - sizeof(*ipv6h) + sizeof(struct tcphdr)); + return tcpoptstrip_mangle_packet(skb, par, tcphoff); } #endif |