entry->addr.id is u8 with a range from 0 to 255 and MAX_ADDR_ID is 255.
We should drop both false expressions of (entry->addr.id > MAX_ADDR_ID).
We should also remove the obsolete parentheses in the first if branch.
Use U8_MAX for MAX_ADDR_ID and add a comment to show the link to
mptcp_addr_info.id as suggested by Mr. Matthieu Baerts.
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The MPTCP packet scheduler has sub-optimal behavior with asymmetric
subflows: if the faster subflow-level cwin is closed, the packet
scheduler can enqueue "too much" data on a slower subflow.
When all the data on the faster subflow is acked, if the mptcp-level
cwin is closed, and link utilization becomes suboptimal.
The solution is implementing blest-like[1] HoL-blocking estimation,
transmitting only on the subflow with the shorter estimated time to
flush the queued memory. If such subflows cwin is closed, we wait
even if other subflows are available.
This is quite simpler than the original blest implementation, as we
leverage the pacing rate provided by the TCP socket. To get a more
accurate estimation for the subflow linger-time, we maintain a
per-subflow weighted average of such info.
Additionally drop magic numbers usage in favor of newly defined
macros and use more meaningful names for status variable.
[1] http://dl.ifip.org/db/conf/networking/networking2016/1570234725.pdf
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/137
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The mptcp ULP extension relies on sk->sk_sock_kern being set correctly:
It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from
working for plain tcp sockets (any userspace-exposed socket).
But in case of fallback, accept() can return a plain tcp sk.
In such case, sk is still tagged as 'kernel' and setsockopt will work.
This will crash the kernel, The subflow extension has a NULL ctx->conn
mptcp socket:
BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0
Call Trace:
tcp_data_ready+0xf8/0x370
[..]
Fixes: cf7da0d66c ("mptcp: Create SUBFLOW socket for incoming connections")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
TCP_ULP setsockopt cannot be used for mptcp because its already
used internally to plumb subflow (tcp) sockets to the mptcp layer.
syzbot managed to trigger a crash for mptcp connections that are
in fallback mode:
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0
RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline]
[..]
__tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline]
tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160
do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391
mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638
Remove support for TCP_ULP setsockopt.
Fixes: d9e4c12918 ("mptcp: only admit explicitly supported sockopt")
Reported-by: syzbot+1fd9b69cde42967d1add@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
First, add cork and nodelay fields to the mptcp_sock structure
so they can be used in sync_socket_options(), and fill them on setsockopt
while holding the msk socket lock.
Then, on setsockopt set proper tcp_sk(ssk)->nonagle values for subflows
by calling __tcp_sock_set_cork() or __tcp_sock_set_nodelay() on the ssk
while holding the ssk socket lock.
tcp_push_pending_frames() will be invoked on the ssk if a cork was cleared
or nodelay was set. Also set MPTCP_PUSH_PENDING bit by calling
mptcp_check_and_set_pending(). This will lead to __mptcp_push_pending()
being called inside mptcp_release_cb() with new tcp_sk(ssk)->nonagle.
Also add getsockopt support for TCP_CORK and TCP_NODELAY.
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Maxim Galaganov <max@internet.ru>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Expose the mptcp_check_and_set_pending() function for use inside MPTCP
sockopt code. The next patch will call it when TCP_CORK is cleared or
TCP_NODELAY is set on the MPTCP socket in order to push pending data
from mptcp_release_cb().
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Maxim Galaganov <max@internet.ru>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
earlier patch added IP_TOS setsockopt support, this allows to get
the value set by earlier setsockopt.
Extends mptcp_put_int_option to handle u8 input/output by
adding required cast.
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
a non-zero 'id' is sufficient to identify MPTCP endpoints: allow changing
the value of 'backup' bit by simply specifying the endpoint id.
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/158
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Allows to query in-sequence data ready for read(), total bytes in
write queue and total bytes in write queue that have not yet been sent.
v2: remove unneeded READ_ONCE() (Paolo Abeni)
v3: check for new data unconditionally in SIOCINQ ioctl (Mat Martineau)
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Support the TCP_INQ setsockopt.
This is a boolean that tells recvmsg path to include the remaining
in-sequence bytes in the cmsg data.
v2: do not use CB(skb)->offset, increment map_seq instead (Paolo Abeni)
v3: adjust CB(skb)->map_seq when taking skb from ofo queue (Paolo Abeni)
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/224
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Scheduling a delack in mptcp_established_options_mp() is
not a good idea: such function is called by tcp_send_ack() and
the pending delayed ack will be cleared shortly after by the
tcp_event_ack_sent() call in __tcp_transmit_skb().
Instead use the mptcp delegated action infrastructure to
schedule the delayed ack after the current bh processing completes.
Additionally moves the schedule_3rdack_retransmission() helper
into protocol.c to avoid making it visible in a different compilation
unit.
Fixes: ec3edaa7ca ("mptcp: Add handling of outgoing MP_JOIN requests")
Reviewed-by: Mat Martineau <mathew.j.martineau>@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
To compute the rtx timeout schedule_3rdack_retransmission() does multiple
things in the wrong way: srtt_us is measured in usec/8 and the timeout
itself is an absolute value.
Fixes: ec3edaa7ca ("mptcp: Add handling of outgoing MP_JOIN requests")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau>@linux.intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
These options also need to be set before bind, so do the sync of msk to
new ssk socket a bit earlier.
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>
SOL_IP provides a way to configure network layer attributes in a
socket. This patch adds support for IP_TOS for setsockopt(.. ,SOL_IP, ..)
Support for SOL_IP is added in mptcp_setsockopt() and IP_TOS is handled in
a private function. The idea here is to take in the value passed for IP_TOS
and set it to the current subflow, open subflows as well new subflows that
might be created after the initial call to setsockopt(). This sync is done
using sync_socket_options(.., ssk) and setting the value of tos using
__ip_sock_set_tos(ssk,..).
The patch has been tested using the packetdrill script here -
https://github.com/multipath-tcp/mptcp_net-next/issues/220#issuecomment-947863717
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/220
Signed-off-by: Poorva Sonparote <psonparo@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
MPTCP hard codes it, let us instead provide this helper.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp_memory_allocated and tcp_sockets_allocated often share
a common cache line, source of false sharing.
Also take care of udp_memory_allocated and mptcp_sockets_allocated.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
using packetdrill it's possible to observe that the receiver key contains
random values when clients transmit MP_CAPABLE with data and checksum (as
specified in RFC8684 §3.1). Fix the layout of mptcp_out_options, to avoid
using the skb extension copy when writing the MP_CAPABLE sub-option.
Fixes: d7b2690837 ("mptcp: shrink mptcp_out_options struct")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/233
Reported-by: Poorva Sonparote <psonparo@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Link: https://lore.kernel.org/r/20211027203855.264600-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Setting skb->ip_summed to CHECKSUM_PARTIAL can be centralized
in tcp_stream_alloc_skb() and __mptcp_do_alloc_tx_skb()
instead of being done multiple times.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
TCP/MPTCP sendmsg() no longer puts payload in skb->head,
we can remove not needed code.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All tcp_remove_empty_skb() callers now use tcp_write_queue_tail()
for the skb argument, we can therefore factorize code.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since mptcp_set_timeout() had removed from mptcp_push_release() in
commit 33d41c9cd7 ("mptcp: more accurate timeout"), the argument
sk in mptcp_push_release() became useless. Let's drop it.
Fixes: 33d41c9cd7 ("mptcp: more accurate timeout")
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
All the mptcp receive path is protected by the msk socket
spinlock. As consequences, the tx path has to play a few tricks to
allocate the forward memory without acquiring the spinlock multiple
times, making the overall TX path quite complex.
This patch tries to clean-up a bit the tx path, using completely
separated fwd memory allocation, for the rx and the tx path.
The forward memory allocated in the rx path is now accounted in
msk->rmem_fwd_alloc and is (still) protected by the msk socket spinlock.
To cope with the above we provide a few MPTCP-specific variants for
the helpers to charge, uncharge, reclaim and free the forward memory
in the receive path.
msk->sk_forward_alloc now accounts only the forward memory for the tx
path, we can use the plain core sock helper to manipulate it and drop
quite a bit of complexity.
On memory pressure, both rx and tx fwd memories are reclaimed.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This function is only used within pm_netlink.c now.
Fixes: 067065422f ("mptcp: add the outgoing MP_PRIO support")
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The current default does not allowing additional subflows, mostly
as a safety restriction to avoid uncontrolled resource consumption
on busy servers.
Still the system admin and/or the application have to opt-in to
MPTCP explicitly. After that, they need to change (increase) the
default maximum number of additional subflows.
Let set that to reasonable default, and make end-users life easier.
Additionally we need to update some self-tests accordingly.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Coverity complains of a possible NULL dereference in
mptcp_getsockopt_subflow_addrs():
861 } else if (sk->sk_family == AF_INET6) {
3. returned_null: inet6_sk returns NULL. [show details]
4. var_assigned: Assigning: np = NULL return value from inet6_sk.
862 const struct ipv6_pinfo *np = inet6_sk(sk);
Fix this by checking for NULL.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/231
Fixes: c11c5906bc ("mptcp: add MPTCP_SUBFLOW_ADDRS getsockopt support")
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
[mjm: Added WARN_ON_ONCE() to the unexpected case]
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tools/testing/selftests/net/ioam6.sh
7b1700e009 ("selftests: net: modify IOAM tests for undef bits")
bf77b1400a ("selftests: net: Test for the IOAM encapsulation with IPv6")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Using snmp_get_cpu_field_batch() allows for better cpu cache
utilization, especially on hosts with large number of cpus.
Also remove special handling when mptcp mibs where not yet
allocated.
I chose to use temporary storage on the stack to keep this patch simple.
We might in the future use the storage allocated in netstat_seq_show().
Combined with prior patch (inlining snmp_get_cpu_field)
time to fetch and output mptcp counters on a 256 cpu host [1]
goes from 75 usec to 16 usec.
[1] L1 cache size is 32KB, it is not big enough to hold all dataset.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The retransmit head will be NULL in case there is no in-flight data
(meaning all data injected into network has been acked).
In that case the retransmit timer is stopped.
This is only correct if there is no more pending, not-yet-sent data.
If there is, the retransmit timer needs to set the PENDING bit again so
that mptcp tries to send the remaining (new) data once a subflow can accept
more data.
Also, mptcp_subflow_get_retrans() has to be called unconditionally.
This function checks for subflows that have become unresponsive and marks
them as stale, so in the case where the rtx queue is empty, subflows
will never be marked stale which prevents available backup subflows from
becoming eligible for transmit.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/226
Acked-by: Paolo Abeni <pabeni@redhat.com>
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>
The update on recovery is not correct.
msk->tx_pending_data += msk->snd_nxt - rtx_head->data_seq;
will update tx_pending_data multiple times when a subflow is declared
stale while earlier recovery is still in progress.
This means that tx_pending_data will still be positive even after
all data as has been transmitted.
Rather than fix it, remove this field: there are no consumers.
The outstanding data byte count can be computed either via
"msk->write_seq - rtx_head->data_seq" or
"msk->write_seq - msk->snd_una".
The latter is more recent/accurate estimate as rtx_head adjustment
is deferred until mptcp lock can be acquired.
Acked-by: Paolo Abeni <pabeni@redhat.com>
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>
We have a few more places where the mptcp code duplicates
lockdep_assert_held_once(). Let's use the existing macro and
avoid a bunch of compiler's conditional.
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since OPTIONS_MPTCP_MPC has been defined, use it instead of open-coding.
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When recovering after a link failure, snd_nxt should not be set to a
lower value. Else, update of snd_nxt is broken because:
msk->snd_nxt += ret; (where ret is number of bytes sent)
assumes that snd_nxt always moves forward.
After reduction, its possible that snd_nxt update gets out of sync:
dfrag we just sent might have had a data sequence number even past
recovery_snd_nxt.
This change factors the common msk state update to a helper
and updates snd_nxt based on the current dfrag data sequence number.
The conditional is required for the recovery phase where we may
re-transmit old dfrags that are before current snd_nxt.
After this change, snd_nxt only moves forward and covers all in-sequence
data that was transmitted.
recovery_snd_nxt is retained to detect when recovery has completed.
Fixes: 1e1d9d6f11 ("mptcp: handle pending data on closed subflow")
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>
current Linux refuses to change the 'backup' bit of MPTCP endpoints, i.e.
using MPTCP_PM_CMD_SET_FLAGS, unless it finds (at least) one subflow that
matches the endpoint address. There is no reason for that, so we can just
ignore the return value of mptcp_nl_addr_backup(). In this way, endpoints
can reconfigure their 'backup' flag even if no MPTCP sockets are open (or
more generally, in case the MP_PRIO message is not sent out).
Fixes: 0f9f696a50 ("mptcp: add set_flags command in PM netlink")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
mptcp_token_get_sock() may return a mptcp socket that is in
a different net namespace than the socket that received the token value.
The mptcp syncookie code path had an explicit check for this,
this moves the test into mptcp_token_get_sock() function.
Eventually token.c should be converted to pernet storage, but
such change is not suitable for net tree.
Fixes: 2c5ebd001d ("mptcp: refactor token container")
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>
We want to revert the skb TX cache, but MPTCP is currently
using it unconditionally.
Rework the MPTCP tx code, so that tcp_tx_skb_cache is not
needed anymore: do the whole coalescing check, skb allocation
skb initialization/update inside mptcp_sendmsg_frag(), quite
alike the current TCP code.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This retrieves the address pairs of all subflows currently
active for a given mptcp connection.
It re-uses the same meta-header as for MPTCP_TCPINFO.
A new structure is provided to hold the subflow
address data:
struct mptcp_subflow_addrs {
union {
__kernel_sa_family_t sa_family;
struct sockaddr sa_local;
struct sockaddr_in sin_local;
struct sockaddr_in6 sin6_local;
struct sockaddr_storage ss_local;
};
union {
struct sockaddr sa_remote;
struct sockaddr_in sin_remote;
struct sockaddr_in6 sin6_remote;
struct sockaddr_storage ss_remote;
};
};
Usage of the new getsockopt is very similar to
MPTCP_TCPINFO one.
Userspace allocates a
'struct mptcp_subflow_data', followed by one or
more 'struct mptcp_subflow_addrs', then inits the
mptcp_subflow_data structure as follows:
struct mptcp_subflow_addrs *sf_addr;
struct mptcp_subflow_data *addr;
socklen_t olen = sizeof(*addr) + (8 * sizeof(*sf_addr));
addr = malloc(olen);
addr->size_subflow_data = sizeof(*addr);
addr->num_subflows = 0;
addr->size_kernel = 0;
addr->size_user = sizeof(struct mptcp_subflow_addrs);
sf_addr = (struct mptcp_subflow_addrs *)(addr + 1);
and then retrieves the endpoint addresses via:
ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS,
addr, &olen);
If the call succeeds, kernel will have added up to 8
endpoint addresses after the 'mptcp_subflow_data' header.
Userspace needs to re-check 'olen' value to detect how
many bytes have been filled in by the kernel.
Userspace can check addr->num_subflows to discover when
there were more subflows that available data space.
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
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>
Allow users to retrieve TCP_INFO data of all subflows.
Users need to pre-initialize a meta header that has to be
prepended to the data buffer that will be filled with the tcp info data.
The meta header looks like this:
struct mptcp_subflow_data {
__u32 size_subflow_data;/* size of this structure in userspace */
__u32 num_subflows; /* must be 0, set by kernel */
__u32 size_kernel; /* must be 0, set by kernel */
__u32 size_user; /* size of one element in data[] */
} __attribute__((aligned(8)));
size_subflow_data has to be set to 'sizeof(struct mptcp_subflow_data)'.
This allows to extend mptcp_subflow_data structure later on without
breaking backwards compatibility.
If the structure is extended later on, kernel knows where the
userspace-provided meta header ends, even if userspace uses an older
(smaller) version of the structure.
num_subflows must be set to 0. If the getsockopt request succeeds (return
value is 0), it will be updated to contain the number of active subflows
for the given logical connection.
size_kernel must be set to 0. If the getsockopt request is successful,
it will contain the size of the 'struct tcp_info' as known by the kernel.
This is informational only.
size_user must be set to 'sizeof(struct tcp_info)'.
This allows the kernel to only fill in the space reserved/expected by
userspace.
Example:
struct my_tcp_info {
struct mptcp_subflow_data d;
struct tcp_info ti[2];
};
struct my_tcp_info ti;
socklen_t olen;
memset(&ti, 0, sizeof(ti));
ti.d.size_subflow_data = sizeof(struct mptcp_subflow_data);
ti.d.size_user = sizeof(struct tcp_info);
olen = sizeof(ti);
ret = getsockopt(fd, SOL_MPTCP, MPTCP_TCPINFO, &ti, &olen);
if (ret < 0)
die_perror("getsockopt MPTCP_TCPINFO");
mptcp_subflow_data.num_subflows is populated with the number of
subflows that exist on the kernel side for the logical mptcp connection.
This allows userspace to re-try with a larger tcp_info array if the number
of subflows was larger than the available space in the ti[] array.
olen has to be set to the number of bytes that userspace has allocated to
receive the kernel data. It will be updated to contain the real number
bytes that have been copied to by the kernel.
In the above example, if the number if subflows was 1, olen is equal to
'sizeof(struct mptcp_subflow_data) + sizeof(struct tcp_info).
For 2 or more subflows olen is equal to 'sizeof(struct my_tcp_info)'.
If there was more data that could not be copied due to lack of space
in the option buffer, userspace can detect this by checking
mptcp_subflow_data->num_subflows.
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>
Its not compatible with multipath-tcp.org kernel one.
1. The out-of-tree implementation defines a different 'struct mptcp_info',
with embedded __user addresses for additional data such as
endpoint addresses.
2. Mat Martineau points out that embedded __user addresses doesn't work
with BPF_CGROUP_RUN_PROG_GETSOCKOPT() which assumes that copying in
optsize bytes from optval provides all data that got copied to userspace.
This provides mptcp_info data for the given mptcp socket.
Userspace sets optlen to the size of the structure it expects.
The kernel updates it to contain the number of bytes that it copied.
This allows to append more information to the structure later.
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>
Will be re-used from getsockopt path.
Since diag can be a module, we can't export the helper from diag, it
needs to be moved to core.
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>
