diff options
| author | Martin KaFai Lau <kafai@fb.com> | 2020-08-20 12:00:33 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-08-24 14:35:00 -0700 |
| commit | 7656d68455891f7fc6689f95415fd59e7a1d629b (patch) | |
| tree | 256a095608155286f836b9019ee268225b404224 | |
| parent | ca584ba070864c606f3a54faaafe774726d5b4a1 (diff) | |
tcp: Add saw_unknown to struct tcp_options_received
In a later patch, the bpf prog only wants to be called to handle
a header option if that particular header option cannot be handled by
the kernel. This unknown option could be written by the peer's bpf-prog.
It could also be a new standard option that the running kernel does not
support it while a bpf-prog can handle it.
This patch adds a "saw_unknown" bit to "struct tcp_options_received"
and it uses an existing one byte hole to do that. "saw_unknown" will
be set in tcp_parse_options() if it sees an option that the kernel
cannot handle.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190033.2884430-1-kafai@fb.com
| -rw-r--r-- | include/linux/tcp.h | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 22 |
2 files changed, 18 insertions, 6 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 2088d5a079af..29d166263ae7 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -92,6 +92,8 @@ struct tcp_options_received { smc_ok : 1, /* SMC seen on SYN packet */ snd_wscale : 4, /* Window scaling received from sender */ rcv_wscale : 4; /* Window scaling to send to receiver */ + u8 saw_unknown:1, /* Received unknown option */ + unused:7; u8 num_sacks; /* Number of SACK blocks */ u16 user_mss; /* mss requested by user in ioctl */ u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 4aaedcf71973..9072d9160df9 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3801,7 +3801,7 @@ static void tcp_parse_fastopen_option(int len, const unsigned char *cookie, foc->exp = exp_opt; } -static void smc_parse_options(const struct tcphdr *th, +static bool smc_parse_options(const struct tcphdr *th, struct tcp_options_received *opt_rx, const unsigned char *ptr, int opsize) @@ -3810,10 +3810,13 @@ static void smc_parse_options(const struct tcphdr *th, if (static_branch_unlikely(&tcp_have_smc)) { if (th->syn && !(opsize & 1) && opsize >= TCPOLEN_EXP_SMC_BASE && - get_unaligned_be32(ptr) == TCPOPT_SMC_MAGIC) + get_unaligned_be32(ptr) == TCPOPT_SMC_MAGIC) { opt_rx->smc_ok = 1; + return true; + } } #endif + return false; } /* Try to parse the MSS option from the TCP header. Return 0 on failure, clamped @@ -3874,6 +3877,7 @@ void tcp_parse_options(const struct net *net, ptr = (const unsigned char *)(th + 1); opt_rx->saw_tstamp = 0; + opt_rx->saw_unknown = 0; while (length > 0) { int opcode = *ptr++; @@ -3964,15 +3968,21 @@ void tcp_parse_options(const struct net *net, */ if (opsize >= TCPOLEN_EXP_FASTOPEN_BASE && get_unaligned_be16(ptr) == - TCPOPT_FASTOPEN_MAGIC) + TCPOPT_FASTOPEN_MAGIC) { tcp_parse_fastopen_option(opsize - TCPOLEN_EXP_FASTOPEN_BASE, ptr + 2, th->syn, foc, true); - else - smc_parse_options(th, opt_rx, ptr, - opsize); + break; + } + + if (smc_parse_options(th, opt_rx, ptr, opsize)) + break; + + opt_rx->saw_unknown = 1; break; + default: + opt_rx->saw_unknown = 1; } ptr += opsize-2; length -= opsize; |