From f7dca36fc54afa2eb76bff8d0589a2ef18caea91 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 23 Oct 2023 20:21:59 +0100 Subject: net/tcp: Add tcp_parse_auth_options() Introduce a helper that: (1) shares the common code with TCP-MD5 header options parsing (2) looks for hash signature only once for both TCP-MD5 and TCP-AO (3) fails with -EEXIST if any TCP sign option is present twice, see RFC5925 (2.2): ">> A single TCP segment MUST NOT have more than one TCP-AO in its options sequence. When multiple TCP-AOs appear, TCP MUST discard the segment." Co-developed-by: Francesco Ruggeri Signed-off-by: Francesco Ruggeri Co-developed-by: Salam Noureddine Signed-off-by: Salam Noureddine Signed-off-by: Dmitry Safonov Acked-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 6ee0342b5338..fc42b172abf6 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4255,39 +4255,58 @@ static bool tcp_fast_parse_options(const struct net *net, return true; } -#ifdef CONFIG_TCP_MD5SIG +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO) /* - * Parse MD5 Signature option + * Parse Signature options */ -const u8 *tcp_parse_md5sig_option(const struct tcphdr *th) +int tcp_do_parse_auth_options(const struct tcphdr *th, + const u8 **md5_hash, const u8 **ao_hash) { int length = (th->doff << 2) - sizeof(*th); const u8 *ptr = (const u8 *)(th + 1); + unsigned int minlen = TCPOLEN_MD5SIG; + + if (IS_ENABLED(CONFIG_TCP_AO)) + minlen = sizeof(struct tcp_ao_hdr) + 1; + + *md5_hash = NULL; + *ao_hash = NULL; /* If not enough data remaining, we can short cut */ - while (length >= TCPOLEN_MD5SIG) { + while (length >= minlen) { int opcode = *ptr++; int opsize; switch (opcode) { case TCPOPT_EOL: - return NULL; + return 0; case TCPOPT_NOP: length--; continue; default: opsize = *ptr++; if (opsize < 2 || opsize > length) - return NULL; - if (opcode == TCPOPT_MD5SIG) - return opsize == TCPOLEN_MD5SIG ? ptr : NULL; + return -EINVAL; + if (opcode == TCPOPT_MD5SIG) { + if (opsize != TCPOLEN_MD5SIG) + return -EINVAL; + if (unlikely(*md5_hash || *ao_hash)) + return -EEXIST; + *md5_hash = ptr; + } else if (opcode == TCPOPT_AO) { + if (opsize <= sizeof(struct tcp_ao_hdr)) + return -EINVAL; + if (unlikely(*md5_hash || *ao_hash)) + return -EEXIST; + *ao_hash = ptr; + } } ptr += opsize - 2; length -= opsize; } - return NULL; + return 0; } -EXPORT_SYMBOL(tcp_parse_md5sig_option); +EXPORT_SYMBOL(tcp_do_parse_auth_options); #endif /* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM -- cgit