| Message ID | 20220217142538.7849-5-fw@strlen.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Mat Martineau |
| Headers | show |
| Series | mptcp: replace per-addr listener sockets | expand |
Hi Florian,
I love your patch! Yet something to improve:
[auto build test ERROR on mptcp/export]
[cannot apply to linus/master v5.17-rc4 next-20220217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Florian-Westphal/mptcp-replace-per-addr-listener-sockets/20220217-222844
base: https://github.com/multipath-tcp/mptcp_net-next.git export
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220218/202202180141.4Rse3JCH-lkp@intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/044982520ba41e284eebe48421fad7feb55f2106
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Florian-Westphal/mptcp-replace-per-addr-listener-sockets/20220217-222844
git checkout 044982520ba41e284eebe48421fad7feb55f2106
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
net/mptcp/ctrl.c: In function '__mptcp_handle_join':
>> net/mptcp/ctrl.c:251:17: error: 'struct mptcp_pernet' has no member named 'join6'; did you mean 'join4'?
251 | lsk = pernet->join6.sk;
| ^~~~~
| join4
vim +251 net/mptcp/ctrl.c
205
206 struct sock *__mptcp_handle_join(int af, struct sk_buff *skb)
207 {
208 struct mptcp_options_received mp_opt;
209 struct mptcp_pernet *pernet;
210 struct socket *ssock;
211 struct sock *lsk;
212 struct net *net;
213
214 /* paranoia check: don't allow 0 destination port,
215 * else __inet_inherit_port will insert the child socket
216 * into the phony hash slot of the pernet listener.
217 */
218 if (tcp_hdr(skb)->dest == 0)
219 return NULL;
220
221 mptcp_get_options(skb, &mp_opt);
222
223 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ))
224 return NULL;
225
226 net = dev_net(skb_dst(skb)->dev);
227 if (!mptcp_is_enabled(net))
228 return NULL;
229
230 /* RFC8684: If the token is unknown [..], the receiver will send
231 * back a reset (RST) signal, analogous to an unknown port in TCP,
232 * containing an MP_TCPRST option (Section 3.6) [..]
233 */
234 if (!mptcp_token_exists(net, mp_opt.token)) {
235 struct mptcp_ext *ext = skb_ext_add(skb, SKB_EXT_MPTCP);
236
237 if (ext) {
238 memset(ext, 0, sizeof(*ext));
239 ext->reset_reason = MPTCP_RST_EMPTCP;
240 }
241 return NULL;
242 }
243
244 pernet = mptcp_get_pernet(net);
245
246 switch (af) {
247 case AF_INET:
248 lsk = pernet->join4.sk;
249 break;
250 case AF_INET6:
> 251 lsk = pernet->join6.sk;
252 break;
253 default:
254 WARN_ON_ONCE(1);
255 return NULL;
256 }
257
258 ssock = __mptcp_nmpc_socket(mptcp_sk(lsk));
259 if (WARN_ON(!ssock))
260 return NULL;
261
262 return ssock->sk;
263 }
264
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Hi Florian,
I love your patch! Yet something to improve:
[auto build test ERROR on mptcp/export]
[cannot apply to linus/master v5.17-rc4 next-20220217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Florian-Westphal/mptcp-replace-per-addr-listener-sockets/20220217-222844
base: https://github.com/multipath-tcp/mptcp_net-next.git export
config: mips-buildonly-randconfig-r002-20220217 (https://download.01.org/0day-ci/archive/20220218/202202180141.VfybVriM-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
# https://github.com/0day-ci/linux/commit/044982520ba41e284eebe48421fad7feb55f2106
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Florian-Westphal/mptcp-replace-per-addr-listener-sockets/20220217-222844
git checkout 044982520ba41e284eebe48421fad7feb55f2106
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash net/mptcp/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
>> net/mptcp/ctrl.c:251:17: error: no member named 'join6' in 'struct mptcp_pernet'; did you mean 'join4'?
lsk = pernet->join6.sk;
^~~~~
join4
net/mptcp/ctrl.c:49:23: note: 'join4' declared here
struct mptcp_join_sk join4;
^
1 error generated.
vim +251 net/mptcp/ctrl.c
205
206 struct sock *__mptcp_handle_join(int af, struct sk_buff *skb)
207 {
208 struct mptcp_options_received mp_opt;
209 struct mptcp_pernet *pernet;
210 struct socket *ssock;
211 struct sock *lsk;
212 struct net *net;
213
214 /* paranoia check: don't allow 0 destination port,
215 * else __inet_inherit_port will insert the child socket
216 * into the phony hash slot of the pernet listener.
217 */
218 if (tcp_hdr(skb)->dest == 0)
219 return NULL;
220
221 mptcp_get_options(skb, &mp_opt);
222
223 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ))
224 return NULL;
225
226 net = dev_net(skb_dst(skb)->dev);
227 if (!mptcp_is_enabled(net))
228 return NULL;
229
230 /* RFC8684: If the token is unknown [..], the receiver will send
231 * back a reset (RST) signal, analogous to an unknown port in TCP,
232 * containing an MP_TCPRST option (Section 3.6) [..]
233 */
234 if (!mptcp_token_exists(net, mp_opt.token)) {
235 struct mptcp_ext *ext = skb_ext_add(skb, SKB_EXT_MPTCP);
236
237 if (ext) {
238 memset(ext, 0, sizeof(*ext));
239 ext->reset_reason = MPTCP_RST_EMPTCP;
240 }
241 return NULL;
242 }
243
244 pernet = mptcp_get_pernet(net);
245
246 switch (af) {
247 case AF_INET:
248 lsk = pernet->join4.sk;
249 break;
250 case AF_INET6:
> 251 lsk = pernet->join6.sk;
252 break;
253 default:
254 WARN_ON_ONCE(1);
255 return NULL;
256 }
257
258 ssock = __mptcp_nmpc_socket(mptcp_sk(lsk));
259 if (WARN_ON(!ssock))
260 return NULL;
261
262 return ssock->sk;
263 }
264
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
On Thu, 17 Feb 2022, Florian Westphal wrote: > Currently mptcp adds kernel-based listener socket for all > netlink-configured mptcp address endpoints. > > This has caveats because kernel may interfere with unrelated programs > that use same address/port pairs. > > RFC 8684 says: > Demultiplexing subflow SYNs MUST be done using the token; this is > unlike traditional TCP, where the destination port is used for > demultiplexing SYN packets. Once a subflow is set up, demultiplexing > packets is done using the 5-tuple, as in traditional TCP. > > This patch deviates from this in that it retrains the existing checks of Typo: retains > verifying the incoming requests destination vs. the list of announced > addresses. > > This can be relaxed later if deemed appropriate. > > Furthermore, TCP-only listeners take precedence: An MPTCP peer > MUST NOT announce address:port pairs that are already in use by a > non-mptcp listener. > This could be changed, but it requires move of mptcp_handle_join() > hook *before* the tcp port demux, i.e. an additional conditional in > hotpath. As-is, the additional conditional (syn && !rst && ...) is > in the 'no socket found' path. > > The pernet 'listening' socket is hidden from userspace. > It is not part of any hashes and not bound to any address or port. > > TPROXY-like semantics apply: If tcp demux cannot find a port for a given > packet, check if the packet is a syn packet with a valid join token. > > If so, the pernet listener is returned and tcp processing resumes. > Otherwise, handling is intentical. Typo: identical > > This patch does not cover timewait sockets. > Can you elaborate on what properly covering timewait sockets would look like? Does the approach used by multipath-tcp.org (handling token lookup after inet_lookup_listener() / case TCP_TW_SYN in tcp_v4_rcv()) fit? I have one more comment below, but other than that the code that's here is looking good and the big outstanding questions are the things you noted as not-yet-changed in the cover letter (MP_JOIN token lookup for established or TCP listening sockets). We did discuss that in today's meeting so I won't rehash here. > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > include/net/mptcp.h | 10 ++ > net/ipv6/tcp_ipv6.c | 19 ++-- > net/mptcp/ctrl.c | 211 ++++++++++++++++++++++++++++++++++++++++++- > net/mptcp/protocol.c | 2 +- > net/mptcp/protocol.h | 2 +- > net/mptcp/subflow.c | 3 + > 6 files changed, 233 insertions(+), 14 deletions(-) > ... > diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c > index ae20b7d92e28..6358c803ba12 100644 > --- a/net/mptcp/ctrl.c > +++ b/net/mptcp/ctrl.c ... > @@ -185,13 +203,173 @@ static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {} > > #endif /* CONFIG_SYSCTL */ > > +struct sock *__mptcp_handle_join(int af, struct sk_buff *skb) > +{ > + struct mptcp_options_received mp_opt; > + struct mptcp_pernet *pernet; > + struct socket *ssock; > + struct sock *lsk; > + struct net *net; > + > + /* paranoia check: don't allow 0 destination port, > + * else __inet_inherit_port will insert the child socket > + * into the phony hash slot of the pernet listener. > + */ > + if (tcp_hdr(skb)->dest == 0) > + return NULL; > + > + mptcp_get_options(skb, &mp_opt); > + > + if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) > + return NULL; > + > + net = dev_net(skb_dst(skb)->dev); > + if (!mptcp_is_enabled(net)) > + return NULL; > + > + /* RFC8684: If the token is unknown [..], the receiver will send > + * back a reset (RST) signal, analogous to an unknown port in TCP, > + * containing an MP_TCPRST option (Section 3.6) [..] > + */ > + if (!mptcp_token_exists(net, mp_opt.token)) { > + struct mptcp_ext *ext = skb_ext_add(skb, SKB_EXT_MPTCP); > + > + if (ext) { > + memset(ext, 0, sizeof(*ext)); > + ext->reset_reason = MPTCP_RST_EMPTCP; > + } > + return NULL; > + } > + > + pernet = mptcp_get_pernet(net); > + > + switch (af) { > + case AF_INET: > + lsk = pernet->join4.sk; > + break; > + case AF_INET6: > + lsk = pernet->join6.sk; > + break; As kbuild noted, missing an #if IS_ENABLED(CONFIG_MPTCP_IPV6) check here. -- Mat Martineau Intel
Mat Martineau <mathew.j.martineau@linux.intel.com> wrote: > > If so, the pernet listener is returned and tcp processing resumes. > > Otherwise, handling is intentical. > > Typo: identical Thanks, fixed both typos. > > This patch does not cover timewait sockets. > > > Can you elaborate on what properly covering timewait sockets would look > like? Does the approach used by multipath-tcp.org (handling token lookup > after inet_lookup_listener() / case TCP_TW_SYN in tcp_v4_rcv()) fit? Looks like its as simple as: diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2189,6 +2189,9 @@ int tcp_v4_rcv(struct sk_buff *skb) iph->daddr, th->dest, inet_iif(skb), sdif); + if (!sk2) + sk2 = mptcp_handle_join(AF_INET, skb); + if (sk2) { inet_twsk_deschedule_put(inet_twsk(sk)); sk = sk2; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 3b8608d35dcd..f2f2308c6bda 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1833,6 +1833,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) ntohs(th->dest), tcp_v6_iif_l3_slave(skb), sdif); + if (!sk2) + sk2 = mptcp_handle_join(AF_INET6, skb); + if (sk2) { struct inet_timewait_sock *tw = inet_twsk(sk); inet_twsk_deschedule_put(tw); I think I'll squash this into the previous patch and will just remove the timewait-socket bit from this patch. > > + case AF_INET6: > > + lsk = pernet->join6.sk; > > + break; > > As kbuild noted, missing an > > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > > check here. Added.
On 2/17/22 6:25 AM, Florian Westphal wrote: > Currently mptcp adds kernel-based listener socket for all > netlink-configured mptcp address endpoints. > > This has caveats because kernel may interfere with unrelated programs > that use same address/port pairs. > I assume that this refers to the potential race between a kernel listener and the application which Paolo had raised. I'm not sure if this change eliminates that possibility. Pasting Paolo's example below from the prior discussion: """ s1 = socket() bind(s1, A) listen(s1) // at this point incoming MPTCP connection can be established on s1 // and ADD_ADDR sub-options could be sent back s2 = socket() bind(s2, B) listen(s2) """ Over a new MPTCP connection following listen(s1), the PM can issue an ADD_ADDR with B. In light of this change there would be no listener created for B. But if the remote endpoint immediately established a subflow in response, then that would result in a subflow (connection) socket at B. It appears (and correct me if I'm wrong) that bind(s2, B) might fail at this point (?). In other words, it seems like the subflow creation could race with a subsequent bind() causing startup issues in the application. If my assessment is correct, then I think this change isn't sidestepping the issue that motivated it in the first place. However, I do like the fact that we don't need code to manage kernel listeners, just so long as there are no other breaking corner cases and the TCP level changes are acceptable upstream. > RFC 8684 says: > Demultiplexing subflow SYNs MUST be done using the token; this is > unlike traditional TCP, where the destination port is used for > demultiplexing SYN packets. Once a subflow is set up, demultiplexing > packets is done using the 5-tuple, as in traditional TCP. > > This patch deviates from this in that it retrains the existing checks of > verifying the incoming requests destination vs. the list of announced > addresses. > > This can be relaxed later if deemed appropriate. > > Furthermore, TCP-only listeners take precedence: An MPTCP peer > MUST NOT announce address:port pairs that are already in use by a > non-mptcp listener. > This could be changed, but it requires move of mptcp_handle_join() > hook *before* the tcp port demux, i.e. an additional conditional in > hotpath. As-is, the additional conditional (syn && !rst && ...) is > in the 'no socket found' path. > > The pernet 'listening' socket is hidden from userspace. > It is not part of any hashes and not bound to any address or port. > > TPROXY-like semantics apply: If tcp demux cannot find a port for a given > packet, check if the packet is a syn packet with a valid join token. > > If so, the pernet listener is returned and tcp processing resumes. > Otherwise, handling is intentical. > > This patch does not cover timewait sockets. > > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > include/net/mptcp.h | 10 ++ > net/ipv6/tcp_ipv6.c | 19 ++-- > net/mptcp/ctrl.c | 211 ++++++++++++++++++++++++++++++++++++++++++- > net/mptcp/protocol.c | 2 +- > net/mptcp/protocol.h | 2 +- > net/mptcp/subflow.c | 3 + > 6 files changed, 233 insertions(+), 14 deletions(-) > > diff --git a/include/net/mptcp.h b/include/net/mptcp.h > index 5ee422b56902..49c188b978e1 100644 > --- a/include/net/mptcp.h > +++ b/include/net/mptcp.h > @@ -189,6 +189,7 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req, > struct sk_buff *skb); > > __be32 mptcp_get_reset_option(const struct sk_buff *skb); > +struct sock *__mptcp_handle_join(int af, struct sk_buff *skb); > > static inline __be32 mptcp_reset_option(const struct sk_buff *skb) > { > @@ -199,6 +200,11 @@ static inline __be32 mptcp_reset_option(const struct sk_buff *skb) > } > static inline struct sock *mptcp_handle_join(int af, struct sk_buff *skb) > { > + const struct tcphdr *th = tcp_hdr(skb); > + > + if (th->syn && !th->ack && !th->rst && !th->fin) > + return __mptcp_handle_join(af, skb); > + > return NULL; > } > #else > @@ -283,9 +289,13 @@ static inline struct sock *mptcp_handle_join(int af, struct sk_buff *skb) { retu > > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > int mptcpv6_init(void); > +int mptcpv6_init_net(struct net *net); > +void mptcpv6_exit_net(struct net *net); > void mptcpv6_handle_mapped(struct sock *sk, bool mapped); > #elif IS_ENABLED(CONFIG_IPV6) > static inline int mptcpv6_init(void) { return 0; } > +static inline int mptcpv6_init_net(struct net *net) { return 0; } > +static inline void mptcpv6_exit_net(struct net *net) { } > static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { } > #endif > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c > index 788040db8e9e..3b8608d35dcd 100644 > --- a/net/ipv6/tcp_ipv6.c > +++ b/net/ipv6/tcp_ipv6.c > @@ -2233,13 +2233,22 @@ static struct inet_protosw tcpv6_protosw = { > > static int __net_init tcpv6_net_init(struct net *net) > { > - return inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6, > - SOCK_RAW, IPPROTO_TCP, net); > + int err = inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6, > + SOCK_RAW, IPPROTO_TCP, net); > + if (err) > + return err; > + > + err = mptcpv6_init_net(net); > + if (err) > + inet_ctl_sock_destroy(net->ipv6.tcp_sk); > + > + return err; > } > > static void __net_exit tcpv6_net_exit(struct net *net) > { > inet_ctl_sock_destroy(net->ipv6.tcp_sk); > + mptcpv6_exit_net(net); > } > > static struct pernet_operations tcpv6_net_ops = { > @@ -2264,15 +2273,9 @@ int __init tcpv6_init(void) > if (ret) > goto out_tcpv6_protosw; > > - ret = mptcpv6_init(); > - if (ret) > - goto out_tcpv6_pernet_subsys; > - > out: > return ret; > > -out_tcpv6_pernet_subsys: > - unregister_pernet_subsys(&tcpv6_net_ops); > out_tcpv6_protosw: > inet6_unregister_protosw(&tcpv6_protosw); > out_tcpv6_protocol: > diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c > index ae20b7d92e28..6358c803ba12 100644 > --- a/net/mptcp/ctrl.c > +++ b/net/mptcp/ctrl.c > @@ -21,6 +21,12 @@ static int mptcp_pernet_id; > static int mptcp_pm_type_max = __MPTCP_PM_TYPE_MAX; > #endif > > +struct mptcp_join_sk { > + struct sock *sk; > + struct inet_bind_bucket *tb; > + struct inet_bind_hashbucket head; > +}; > + > struct mptcp_pernet { > #ifdef CONFIG_SYSCTL > struct ctl_table_header *ctl_table_hdr; > @@ -32,6 +38,18 @@ struct mptcp_pernet { > u8 checksum_enabled; > u8 allow_join_initial_addr_port; > u8 pm_type; > + > + /* pernet listener to handle mptcp join requests > + * based on the mptcp token. > + * > + * Has to be pernet because tcp uses > + * sock_net(sk_listener) to obtain the net namespace for > + * the syn/ack route lookup. > + */ > + struct mptcp_join_sk join4; > +#if IS_ENABLED(CONFIG_MPTCP_IPV6) > + struct mptcp_join_sk join6; > +#endif > }; > > static struct mptcp_pernet *mptcp_get_pernet(const struct net *net) > @@ -185,13 +203,173 @@ static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {} > > #endif /* CONFIG_SYSCTL */ > > +struct sock *__mptcp_handle_join(int af, struct sk_buff *skb) > +{ > + struct mptcp_options_received mp_opt; > + struct mptcp_pernet *pernet; > + struct socket *ssock; > + struct sock *lsk; > + struct net *net; > + > + /* paranoia check: don't allow 0 destination port, > + * else __inet_inherit_port will insert the child socket > + * into the phony hash slot of the pernet listener. > + */ > + if (tcp_hdr(skb)->dest == 0) > + return NULL; > + > + mptcp_get_options(skb, &mp_opt); > + > + if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) > + return NULL; > + > + net = dev_net(skb_dst(skb)->dev); > + if (!mptcp_is_enabled(net)) > + return NULL; > + > + /* RFC8684: If the token is unknown [..], the receiver will send > + * back a reset (RST) signal, analogous to an unknown port in TCP, > + * containing an MP_TCPRST option (Section 3.6) [..] > + */ > + if (!mptcp_token_exists(net, mp_opt.token)) { > + struct mptcp_ext *ext = skb_ext_add(skb, SKB_EXT_MPTCP); > + > + if (ext) { > + memset(ext, 0, sizeof(*ext)); > + ext->reset_reason = MPTCP_RST_EMPTCP; > + } > + return NULL; > + } > + > + pernet = mptcp_get_pernet(net); > + > + switch (af) { > + case AF_INET: > + lsk = pernet->join4.sk; > + break; > + case AF_INET6: > + lsk = pernet->join6.sk; > + break; > + default: > + WARN_ON_ONCE(1); > + return NULL; > + } > + > + ssock = __mptcp_nmpc_socket(mptcp_sk(lsk)); > + if (WARN_ON(!ssock)) > + return NULL; > + > + return ssock->sk; > +} > + > +static struct socket *mptcp_create_join_listen_socket(struct net *net, int af) > +{ > + struct socket *s, *ssock; > + int err; > + > + err = sock_create_kern(net, af, SOCK_STREAM, IPPROTO_MPTCP, &s); > + if (err) > + return ERR_PTR(err); > + > + ssock = __mptcp_nmpc_socket(mptcp_sk(s->sk)); > + if (!ssock) { > + err = -EINVAL; > + goto out; > + } > + > + ssock->sk->sk_max_ack_backlog = SOMAXCONN; > + inet_sk_state_store(ssock->sk, TCP_LISTEN); > + > + s->sk->sk_max_ack_backlog = SOMAXCONN; > + inet_sk_state_store(s->sk, TCP_LISTEN); > + > + s->sk->sk_net_refcnt = 1; > + get_net_track(net, &s->sk->ns_tracker, GFP_KERNEL); > + sock_inuse_add(net, 1); > + > + return s; > +out: > + sock_release(s); > + return ERR_PTR(err); > +} > + > +static int mptcp_init_join_sk(struct net *net, struct sock *sk, struct mptcp_join_sk *join_sk) > +{ > + struct socket *ssock = __mptcp_nmpc_socket(mptcp_sk(sk)); > + struct inet_hashinfo *table = ssock->sk->sk_prot->h.hashinfo; > + struct inet_bind_bucket *tb; > + > + spin_lock_init(&join_sk->head.lock); > + INIT_HLIST_HEAD(&join_sk->head.chain); > + > + /* Our "listen socket" isn't bound to any address or port. > + * Conceptually, SYN packet with mptcp join request are steered to > + * this pernet socket just like TPROXY steals arbitrary connection > + * requests to assign them to listening socket with different > + * address or port. > + * > + * The bind_bucket is needed for sake of __inet_inherit_port(), > + * so it can place the new child socket in the correct > + * bind_bucket slot. > + * > + * A phony head is used to hide this socket from normal sk loookup. > + */ > + tb = inet_bind_bucket_create(table->bind_bucket_cachep, > + net, &join_sk->head, 0, 0); > + if (!tb) > + return -ENOMEM; > + > + inet_csk(ssock->sk)->icsk_bind_hash = tb; > + return 0; > +} > + > static int __net_init mptcp_net_init(struct net *net) > { > struct mptcp_pernet *pernet = mptcp_get_pernet(net); > + struct socket *sock; > + int err; > > mptcp_pernet_set_defaults(pernet); > > - return mptcp_pernet_new_table(net, pernet); > + err = mptcp_pernet_new_table(net, pernet); > + if (err) > + return err; > + > + sock = mptcp_create_join_listen_socket(net, AF_INET); > + if (IS_ERR(sock)) { > + err = PTR_ERR(sock); > + goto out_table; > + } > + > + err = mptcp_init_join_sk(net, sock->sk, &pernet->join4); > + if (err) { > + sock_release(sock); > + goto out_table; > + } > + > + /* struct sock is still reachable via sock->sk_socket backpointer */ > + pernet->join4.sk = sock->sk; > + return err; > + > +out_table: > + if (!net_eq(net, &init_net)) > + mptcp_pernet_del_table(pernet); > + return err; > +} > + > +static void __net_exit mptcp_exit_join_sk(struct mptcp_join_sk *jsk) > +{ > + struct socket *ssock = __mptcp_nmpc_socket(mptcp_sk(jsk->sk)); > + struct inet_bind_bucket *tb; > + struct inet_hashinfo *table; > + > + table = ssock->sk->sk_prot->h.hashinfo; > + > + tb = inet_csk(ssock->sk)->icsk_bind_hash; > + inet_bind_bucket_destroy(table->bind_bucket_cachep, tb); > + > + ssock = jsk->sk->sk_socket; > + sock_release(ssock); > } > > /* Note: the callback will only be called per extra netns */ > @@ -200,6 +378,7 @@ static void __net_exit mptcp_net_exit(struct net *net) > struct mptcp_pernet *pernet = mptcp_get_pernet(net); > > mptcp_pernet_del_table(pernet); > + mptcp_exit_join_sk(&pernet->join4); > } > > static struct pernet_operations mptcp_pernet_ops = { > @@ -219,12 +398,36 @@ void __init mptcp_init(void) > } > > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > -int __init mptcpv6_init(void) > +int __net_init mptcpv6_init_net(struct net *net) > { > + struct mptcp_pernet *pernet = mptcp_get_pernet(net); > + struct socket *sock; > int err; > > - err = mptcp_proto_v6_init(); > + if (net_eq(net, &init_net)) { > + err = mptcp_proto_v6_init(); > + if (err) > + return err; > + } > > - return err; > + sock = mptcp_create_join_listen_socket(net, AF_INET6); > + if (IS_ERR(sock)) > + return PTR_ERR(sock); > + > + err = mptcp_init_join_sk(net, sock->sk, &pernet->join6); > + if (err) { > + sock_release(sock); > + return err; > + } > + > + pernet->join6.sk = sock->sk; > + return 0; > +} > + > +void __net_exit mptcpv6_exit_net(struct net *net) > +{ > + struct mptcp_pernet *pernet = mptcp_get_pernet(net); > + > + mptcp_exit_join_sk(&pernet->join6); > } > #endif > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 4599bde215b2..5b54e3c8efea 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -3777,7 +3777,7 @@ static struct inet_protosw mptcp_v6_protosw = { > .flags = INET_PROTOSW_ICSK, > }; > > -int __init mptcp_proto_v6_init(void) > +int __net_init mptcp_proto_v6_init(void) > { > int err; > > diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h > index 7bd064b68b51..6a81e2a21301 100644 > --- a/net/mptcp/protocol.h > +++ b/net/mptcp/protocol.h > @@ -647,7 +647,7 @@ static inline bool mptcp_has_another_subflow(struct sock *ssk) > > void __init mptcp_proto_init(void); > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > -int __init mptcp_proto_v6_init(void); > +int __net_init mptcp_proto_v6_init(void); > #endif > > struct sock *mptcp_sk_clone(const struct sock *sk, > diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c > index 8be20f7b76df..4696d27a8994 100644 > --- a/net/mptcp/subflow.c > +++ b/net/mptcp/subflow.c > @@ -116,6 +116,9 @@ static void subflow_init_req(struct request_sock *req, const struct sock *sk_lis > > static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk) > { > + if (inet_sk(sk)->inet_sport == 0) > + return true; > + > return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; > } >
diff --git a/include/net/mptcp.h b/include/net/mptcp.h index 5ee422b56902..49c188b978e1 100644 --- a/include/net/mptcp.h +++ b/include/net/mptcp.h @@ -189,6 +189,7 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req, struct sk_buff *skb); __be32 mptcp_get_reset_option(const struct sk_buff *skb); +struct sock *__mptcp_handle_join(int af, struct sk_buff *skb); static inline __be32 mptcp_reset_option(const struct sk_buff *skb) { @@ -199,6 +200,11 @@ static inline __be32 mptcp_reset_option(const struct sk_buff *skb) } static inline struct sock *mptcp_handle_join(int af, struct sk_buff *skb) { + const struct tcphdr *th = tcp_hdr(skb); + + if (th->syn && !th->ack && !th->rst && !th->fin) + return __mptcp_handle_join(af, skb); + return NULL; } #else @@ -283,9 +289,13 @@ static inline struct sock *mptcp_handle_join(int af, struct sk_buff *skb) { retu #if IS_ENABLED(CONFIG_MPTCP_IPV6) int mptcpv6_init(void); +int mptcpv6_init_net(struct net *net); +void mptcpv6_exit_net(struct net *net); void mptcpv6_handle_mapped(struct sock *sk, bool mapped); #elif IS_ENABLED(CONFIG_IPV6) static inline int mptcpv6_init(void) { return 0; } +static inline int mptcpv6_init_net(struct net *net) { return 0; } +static inline void mptcpv6_exit_net(struct net *net) { } static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { } #endif diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 788040db8e9e..3b8608d35dcd 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -2233,13 +2233,22 @@ static struct inet_protosw tcpv6_protosw = { static int __net_init tcpv6_net_init(struct net *net) { - return inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6, - SOCK_RAW, IPPROTO_TCP, net); + int err = inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6, + SOCK_RAW, IPPROTO_TCP, net); + if (err) + return err; + + err = mptcpv6_init_net(net); + if (err) + inet_ctl_sock_destroy(net->ipv6.tcp_sk); + + return err; } static void __net_exit tcpv6_net_exit(struct net *net) { inet_ctl_sock_destroy(net->ipv6.tcp_sk); + mptcpv6_exit_net(net); } static struct pernet_operations tcpv6_net_ops = { @@ -2264,15 +2273,9 @@ int __init tcpv6_init(void) if (ret) goto out_tcpv6_protosw; - ret = mptcpv6_init(); - if (ret) - goto out_tcpv6_pernet_subsys; - out: return ret; -out_tcpv6_pernet_subsys: - unregister_pernet_subsys(&tcpv6_net_ops); out_tcpv6_protosw: inet6_unregister_protosw(&tcpv6_protosw); out_tcpv6_protocol: diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index ae20b7d92e28..6358c803ba12 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -21,6 +21,12 @@ static int mptcp_pernet_id; static int mptcp_pm_type_max = __MPTCP_PM_TYPE_MAX; #endif +struct mptcp_join_sk { + struct sock *sk; + struct inet_bind_bucket *tb; + struct inet_bind_hashbucket head; +}; + struct mptcp_pernet { #ifdef CONFIG_SYSCTL struct ctl_table_header *ctl_table_hdr; @@ -32,6 +38,18 @@ struct mptcp_pernet { u8 checksum_enabled; u8 allow_join_initial_addr_port; u8 pm_type; + + /* pernet listener to handle mptcp join requests + * based on the mptcp token. + * + * Has to be pernet because tcp uses + * sock_net(sk_listener) to obtain the net namespace for + * the syn/ack route lookup. + */ + struct mptcp_join_sk join4; +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + struct mptcp_join_sk join6; +#endif }; static struct mptcp_pernet *mptcp_get_pernet(const struct net *net) @@ -185,13 +203,173 @@ static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {} #endif /* CONFIG_SYSCTL */ +struct sock *__mptcp_handle_join(int af, struct sk_buff *skb) +{ + struct mptcp_options_received mp_opt; + struct mptcp_pernet *pernet; + struct socket *ssock; + struct sock *lsk; + struct net *net; + + /* paranoia check: don't allow 0 destination port, + * else __inet_inherit_port will insert the child socket + * into the phony hash slot of the pernet listener. + */ + if (tcp_hdr(skb)->dest == 0) + return NULL; + + mptcp_get_options(skb, &mp_opt); + + if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) + return NULL; + + net = dev_net(skb_dst(skb)->dev); + if (!mptcp_is_enabled(net)) + return NULL; + + /* RFC8684: If the token is unknown [..], the receiver will send + * back a reset (RST) signal, analogous to an unknown port in TCP, + * containing an MP_TCPRST option (Section 3.6) [..] + */ + if (!mptcp_token_exists(net, mp_opt.token)) { + struct mptcp_ext *ext = skb_ext_add(skb, SKB_EXT_MPTCP); + + if (ext) { + memset(ext, 0, sizeof(*ext)); + ext->reset_reason = MPTCP_RST_EMPTCP; + } + return NULL; + } + + pernet = mptcp_get_pernet(net); + + switch (af) { + case AF_INET: + lsk = pernet->join4.sk; + break; + case AF_INET6: + lsk = pernet->join6.sk; + break; + default: + WARN_ON_ONCE(1); + return NULL; + } + + ssock = __mptcp_nmpc_socket(mptcp_sk(lsk)); + if (WARN_ON(!ssock)) + return NULL; + + return ssock->sk; +} + +static struct socket *mptcp_create_join_listen_socket(struct net *net, int af) +{ + struct socket *s, *ssock; + int err; + + err = sock_create_kern(net, af, SOCK_STREAM, IPPROTO_MPTCP, &s); + if (err) + return ERR_PTR(err); + + ssock = __mptcp_nmpc_socket(mptcp_sk(s->sk)); + if (!ssock) { + err = -EINVAL; + goto out; + } + + ssock->sk->sk_max_ack_backlog = SOMAXCONN; + inet_sk_state_store(ssock->sk, TCP_LISTEN); + + s->sk->sk_max_ack_backlog = SOMAXCONN; + inet_sk_state_store(s->sk, TCP_LISTEN); + + s->sk->sk_net_refcnt = 1; + get_net_track(net, &s->sk->ns_tracker, GFP_KERNEL); + sock_inuse_add(net, 1); + + return s; +out: + sock_release(s); + return ERR_PTR(err); +} + +static int mptcp_init_join_sk(struct net *net, struct sock *sk, struct mptcp_join_sk *join_sk) +{ + struct socket *ssock = __mptcp_nmpc_socket(mptcp_sk(sk)); + struct inet_hashinfo *table = ssock->sk->sk_prot->h.hashinfo; + struct inet_bind_bucket *tb; + + spin_lock_init(&join_sk->head.lock); + INIT_HLIST_HEAD(&join_sk->head.chain); + + /* Our "listen socket" isn't bound to any address or port. + * Conceptually, SYN packet with mptcp join request are steered to + * this pernet socket just like TPROXY steals arbitrary connection + * requests to assign them to listening socket with different + * address or port. + * + * The bind_bucket is needed for sake of __inet_inherit_port(), + * so it can place the new child socket in the correct + * bind_bucket slot. + * + * A phony head is used to hide this socket from normal sk loookup. + */ + tb = inet_bind_bucket_create(table->bind_bucket_cachep, + net, &join_sk->head, 0, 0); + if (!tb) + return -ENOMEM; + + inet_csk(ssock->sk)->icsk_bind_hash = tb; + return 0; +} + static int __net_init mptcp_net_init(struct net *net) { struct mptcp_pernet *pernet = mptcp_get_pernet(net); + struct socket *sock; + int err; mptcp_pernet_set_defaults(pernet); - return mptcp_pernet_new_table(net, pernet); + err = mptcp_pernet_new_table(net, pernet); + if (err) + return err; + + sock = mptcp_create_join_listen_socket(net, AF_INET); + if (IS_ERR(sock)) { + err = PTR_ERR(sock); + goto out_table; + } + + err = mptcp_init_join_sk(net, sock->sk, &pernet->join4); + if (err) { + sock_release(sock); + goto out_table; + } + + /* struct sock is still reachable via sock->sk_socket backpointer */ + pernet->join4.sk = sock->sk; + return err; + +out_table: + if (!net_eq(net, &init_net)) + mptcp_pernet_del_table(pernet); + return err; +} + +static void __net_exit mptcp_exit_join_sk(struct mptcp_join_sk *jsk) +{ + struct socket *ssock = __mptcp_nmpc_socket(mptcp_sk(jsk->sk)); + struct inet_bind_bucket *tb; + struct inet_hashinfo *table; + + table = ssock->sk->sk_prot->h.hashinfo; + + tb = inet_csk(ssock->sk)->icsk_bind_hash; + inet_bind_bucket_destroy(table->bind_bucket_cachep, tb); + + ssock = jsk->sk->sk_socket; + sock_release(ssock); } /* Note: the callback will only be called per extra netns */ @@ -200,6 +378,7 @@ static void __net_exit mptcp_net_exit(struct net *net) struct mptcp_pernet *pernet = mptcp_get_pernet(net); mptcp_pernet_del_table(pernet); + mptcp_exit_join_sk(&pernet->join4); } static struct pernet_operations mptcp_pernet_ops = { @@ -219,12 +398,36 @@ void __init mptcp_init(void) } #if IS_ENABLED(CONFIG_MPTCP_IPV6) -int __init mptcpv6_init(void) +int __net_init mptcpv6_init_net(struct net *net) { + struct mptcp_pernet *pernet = mptcp_get_pernet(net); + struct socket *sock; int err; - err = mptcp_proto_v6_init(); + if (net_eq(net, &init_net)) { + err = mptcp_proto_v6_init(); + if (err) + return err; + } - return err; + sock = mptcp_create_join_listen_socket(net, AF_INET6); + if (IS_ERR(sock)) + return PTR_ERR(sock); + + err = mptcp_init_join_sk(net, sock->sk, &pernet->join6); + if (err) { + sock_release(sock); + return err; + } + + pernet->join6.sk = sock->sk; + return 0; +} + +void __net_exit mptcpv6_exit_net(struct net *net) +{ + struct mptcp_pernet *pernet = mptcp_get_pernet(net); + + mptcp_exit_join_sk(&pernet->join6); } #endif diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 4599bde215b2..5b54e3c8efea 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3777,7 +3777,7 @@ static struct inet_protosw mptcp_v6_protosw = { .flags = INET_PROTOSW_ICSK, }; -int __init mptcp_proto_v6_init(void) +int __net_init mptcp_proto_v6_init(void) { int err; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 7bd064b68b51..6a81e2a21301 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -647,7 +647,7 @@ static inline bool mptcp_has_another_subflow(struct sock *ssk) void __init mptcp_proto_init(void); #if IS_ENABLED(CONFIG_MPTCP_IPV6) -int __init mptcp_proto_v6_init(void); +int __net_init mptcp_proto_v6_init(void); #endif struct sock *mptcp_sk_clone(const struct sock *sk, diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 8be20f7b76df..4696d27a8994 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -116,6 +116,9 @@ static void subflow_init_req(struct request_sock *req, const struct sock *sk_lis static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk) { + if (inet_sk(sk)->inet_sport == 0) + return true; + return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; }
Currently mptcp adds kernel-based listener socket for all netlink-configured mptcp address endpoints. This has caveats because kernel may interfere with unrelated programs that use same address/port pairs. RFC 8684 says: Demultiplexing subflow SYNs MUST be done using the token; this is unlike traditional TCP, where the destination port is used for demultiplexing SYN packets. Once a subflow is set up, demultiplexing packets is done using the 5-tuple, as in traditional TCP. This patch deviates from this in that it retrains the existing checks of verifying the incoming requests destination vs. the list of announced addresses. This can be relaxed later if deemed appropriate. Furthermore, TCP-only listeners take precedence: An MPTCP peer MUST NOT announce address:port pairs that are already in use by a non-mptcp listener. This could be changed, but it requires move of mptcp_handle_join() hook *before* the tcp port demux, i.e. an additional conditional in hotpath. As-is, the additional conditional (syn && !rst && ...) is in the 'no socket found' path. The pernet 'listening' socket is hidden from userspace. It is not part of any hashes and not bound to any address or port. TPROXY-like semantics apply: If tcp demux cannot find a port for a given packet, check if the packet is a syn packet with a valid join token. If so, the pernet listener is returned and tcp processing resumes. Otherwise, handling is intentical. This patch does not cover timewait sockets. Signed-off-by: Florian Westphal <fw@strlen.de> --- include/net/mptcp.h | 10 ++ net/ipv6/tcp_ipv6.c | 19 ++-- net/mptcp/ctrl.c | 211 ++++++++++++++++++++++++++++++++++++++++++- net/mptcp/protocol.c | 2 +- net/mptcp/protocol.h | 2 +- net/mptcp/subflow.c | 3 + 6 files changed, 233 insertions(+), 14 deletions(-)