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Tue, 26 May 2026 21:58:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id yDTrOpYXFmrTZAAAD6G6ig (envelope-from ); Tue, 26 May 2026 21:58:46 +0000 From: Fernando Fernandez Mancera To: netfilter-devel@vger.kernel.org Cc: coreteam@netfilter.org, pablo@netfilter.org, fw@strlen.de, phil@nwl.cc, Fernando Fernandez Mancera Subject: [PATCH 1/5 nf-next v4] netfilter: synproxy: drop packets if timestamp adjustment fails Date: Tue, 26 May 2026 23:58:27 +0200 Message-ID: <20260526215831.6726-2-fmancera@suse.de> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260526215831.6726-1-fmancera@suse.de> References: <20260526215831.6726-1-fmancera@suse.de> Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Flag: NO X-Spam-Score: -6.80 X-Spam-Level: X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_TWO(0.00)[2]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCPT_COUNT_FIVE(0.00)[6]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email,suse.de:mid]; RCVD_TLS_ALL(0.00)[] 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 --- net/netfilter/nf_synproxy_core.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c index 57f57e2fc80a..e523b64bf839 100644 --- a/net/netfilter/nf_synproxy_core.c +++ b/net/netfilter/nf_synproxy_core.c @@ -182,7 +182,7 @@ 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, @@ -192,20 +192,20 @@ 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; while (optoff < optend) { unsigned char *op = skb->data + optoff; switch (op[0]) { case TCPOPT_EOL: - return 1; + return true; case TCPOPT_NOP: optoff++; continue; @@ -213,7 +213,7 @@ 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) { @@ -229,12 +229,12 @@ 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 @@ -745,7 +745,9 @@ 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); @@ -1168,7 +1170,9 @@ 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); -- 2.53.0