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authorFlorian Westphal <fw@strlen.de>2021-04-01 16:19:44 -0700
committerDavid S. Miller <davem@davemloft.net>2021-04-02 14:21:50 -0700
commitdc87efdb1a5cd46134a9d490480160e303bc6eef (patch)
tree57040990350f1bf27ddecf5f015c445fcf4b888f /net/mptcp/options.c
parent781bf13d4f3b033002f7f6728ac0b0d1ebe8f176 (diff)
downloadlinux-dc87efdb1a5cd46134a9d490480160e303bc6eef.tar.bz2
mptcp: add mptcp reset option support
The MPTCP reset option allows to carry a mptcp-specific error code that provides more information on the nature of a connection reset. Reset option data received gets stored in the subflow context so it can be sent to userspace via the 'subflow closed' netlink event. When a subflow is closed, the desired error code that should be sent to the peer is also placed in the subflow context structure. If a reset is sent before subflow establishment could complete, e.g. on HMAC failure during an MP_JOIN operation, the mptcp skb extension is used to store the reset information. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp/options.c')
-rw-r--r--net/mptcp/options.c67
1 files changed, 62 insertions, 5 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 68361d28dc67..4b7119eb2c31 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -305,6 +305,18 @@ static void mptcp_parse_option(const struct sk_buff *skb,
mp_opt->fastclose = 1;
break;
+ case MPTCPOPT_RST:
+ if (opsize != TCPOLEN_MPTCP_RST)
+ break;
+
+ if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
+ break;
+ mp_opt->reset = 1;
+ flags = *ptr++;
+ mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
+ mp_opt->reset_reason = *ptr;
+ break;
+
default:
break;
}
@@ -327,6 +339,7 @@ void mptcp_get_options(const struct sk_buff *skb,
mp_opt->rm_addr = 0;
mp_opt->dss = 0;
mp_opt->mp_prio = 0;
+ mp_opt->reset = 0;
length = (th->doff * 4) - sizeof(struct tcphdr);
ptr = (const unsigned char *)(th + 1);
@@ -726,6 +739,22 @@ static bool mptcp_established_options_mp_prio(struct sock *sk,
return true;
}
+static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ if (remaining < TCPOLEN_MPTCP_RST)
+ return;
+
+ *size = TCPOLEN_MPTCP_RST;
+ opts->suboptions |= OPTION_MPTCP_RST;
+ opts->reset_transient = subflow->reset_transient;
+ opts->reset_reason = subflow->reset_reason;
+}
+
bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
unsigned int *size, unsigned int remaining,
struct mptcp_out_options *opts)
@@ -741,11 +770,10 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
if (unlikely(__mptcp_check_fallback(msk)))
return false;
- /* prevent adding of any MPTCP related options on reset packet
- * until we support MP_TCPRST/MP_FASTCLOSE
- */
- if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
- return false;
+ if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
+ mptcp_established_options_rst(sk, skb, size, remaining, opts);
+ return true;
+ }
snd_data_fin = mptcp_data_fin_enabled(msk);
if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
@@ -1062,6 +1090,12 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
mp_opt.mp_prio = 0;
}
+ if (mp_opt.reset) {
+ subflow->reset_seen = 1;
+ subflow->reset_reason = mp_opt.reset_reason;
+ subflow->reset_transient = mp_opt.reset_transient;
+ }
+
if (!mp_opt.dss)
return;
@@ -1289,6 +1323,12 @@ mp_capable_done:
ptr += 5;
}
+ if (OPTION_MPTCP_RST & opts->suboptions)
+ *ptr++ = mptcp_option(MPTCPOPT_RST,
+ TCPOLEN_MPTCP_RST,
+ opts->reset_transient,
+ opts->reset_reason);
+
if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
struct mptcp_ext *mpext = &opts->ext_copy;
u8 len = TCPOLEN_MPTCP_DSS_BASE;
@@ -1340,3 +1380,20 @@ mp_capable_done:
if (tp)
mptcp_set_rwin(tp);
}
+
+__be32 mptcp_get_reset_option(const struct sk_buff *skb)
+{
+ const struct mptcp_ext *ext = mptcp_get_ext(skb);
+ u8 flags, reason;
+
+ if (ext) {
+ flags = ext->reset_transient;
+ reason = ext->reset_reason;
+
+ return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
+ flags, reason);
+ }
+
+ return htonl(0u);
+}
+EXPORT_SYMBOL_GPL(mptcp_get_reset_option);