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| author | Fernando Fernandez Mancera <fmancera@suse.de> | 2026-05-26 23:58:27 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2026-06-05 13:11:54 +0200 |
| commit | 63d29ee95c4ab5976d660182d2e4733bb4a091d8 (patch) | |
| tree | 375b3eea62e0509cd0eb068cd6db3f253ba473d3 | |
| parent | f8bf5edf7157984bb8e288c8b04fdb041223b80c (diff) | |
| download | linux-63d29ee95c4ab5976d660182d2e4733bb4a091d8.tar.gz linux-63d29ee95c4ab5976d660182d2e4733bb4a091d8.zip | |
netfilter: synproxy: drop packets if timestamp adjustment fails
If a packet was malformed or if skb_ensure_writable() failed, the
synproxy_tstamp_adjust() function returned 0 indicating an error but it
was ignored on the callers.
Make the function return a boolean instead to clarify the result and
drop the packet if synproxy_tstamp_adjust() failed due to ENOMEM from
skb_ensure_writable(). In addition, if there are malformed options, skip
the tstamp update but do not drop the packet as that should be done by
the policy directly.
Fixes: 48b1de4c110a ("netfilter: add SYNPROXY core/target")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nf_synproxy_core.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c index ed00114f65f3..f99c22f57b7e 100644 --- a/net/netfilter/nf_synproxy_core.c +++ b/net/netfilter/nf_synproxy_core.c @@ -184,7 +184,7 @@ synproxy_check_timestamp_cookie(struct synproxy_options *opts) opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0; } -static unsigned int +static bool synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, struct tcphdr *th, struct nf_conn *ct, enum ip_conntrack_info ctinfo, @@ -194,13 +194,13 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, __be32 *ptr, old; if (synproxy->tsoff == 0) - return 1; + return true; optoff = protoff + sizeof(struct tcphdr); optend = protoff + th->doff * 4; if (skb_ensure_writable(skb, optend)) - return 0; + return false; th = (struct tcphdr *)(skb->data + protoff); @@ -209,7 +209,7 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, switch (op[0]) { case TCPOPT_EOL: - return 1; + return true; case TCPOPT_NOP: optoff++; continue; @@ -217,7 +217,7 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, if (optoff + 1 == optend || optoff + op[1] > optend || op[1] < 2) - return 0; + return true; if (op[0] == TCPOPT_TIMESTAMP && op[1] == TCPOLEN_TIMESTAMP) { if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) { @@ -233,12 +233,12 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, } inet_proto_csum_replace4(&th->check, skb, old, *ptr, false); - return 1; + return true; } optoff += op[1]; } } - return 1; + return true; } #ifdef CONFIG_PROC_FS @@ -749,7 +749,9 @@ ipv4_synproxy_hook(void *priv, struct sk_buff *skb, break; } - synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); + if (!synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy)) + return NF_DROP_REASON(skb, SKB_DROP_REASON_NETFILTER_DROP, ENOMEM); + return NF_ACCEPT; } EXPORT_SYMBOL_GPL(ipv4_synproxy_hook); @@ -1177,7 +1179,9 @@ ipv6_synproxy_hook(void *priv, struct sk_buff *skb, break; } - synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); + if (!synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy)) + return NF_DROP_REASON(skb, SKB_DROP_REASON_NETFILTER_DROP, ENOMEM); + return NF_ACCEPT; } EXPORT_SYMBOL_GPL(ipv6_synproxy_hook); |