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bpf: Add mptcp_subflow bpf_iter support #8280

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bpf: Add mptcp_subflow bpf_iter support #8280

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Pull request for series with
subject: bpf: Add mptcp_subflow bpf_iter support
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527

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Upstream branch: 8eef6ac
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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Upstream branch: c5d2bac
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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Upstream branch: c5d2bac
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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Upstream branch: c5d2bac
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

@kernel-patches-daemon-bpf kernel-patches-daemon-bpf bot force-pushed the bpf-next_base branch 2 times, most recently from 0cdd956 to b0c73ce Compare December 23, 2024 21:31
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Upstream branch: c5d2bac
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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Upstream branch: 4a24035
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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Upstream branch: 654a338
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

Geliang Tang added 5 commits December 30, 2024 20:19
bpf: Extend bpf_skc_to_mptcp_sock to MPTCP sock
941813b 
Currently, bpf_skc_to_mptcp_sock() can only be used with sockets that
are MPTCP subflows: TCP sockets with tp->is_mptcp, created by the kernel
from an MPTCP socket (IPPROTO_MPTCP). Typically used with BPF sock_ops
operators.

Here, this helper is extended to support MPTCP sockets, the ones created
by the userspace (IPPROTO_MPTCP). This is useful for BPF hooks involving
these sockets, e.g. [gs]etsocktopt.

bpf_skc_to_mptcp_sock() uses bpf_mptcp_sock_from_subflow(). The former
suggests any MPTCP type/subtype can be used, but the latter only accepts
subflow ones. So bpf_mptcp_sock_from_subflow is modified here to support
MPTCP socket, and renamed to avoid confusions.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
bpf: Allow use of skc_to_mptcp_sock in cg_sockopt
3ea9816 
Currently, bpf_skc_to_mptcp_sock() helper is not allowed to be used
in cg_sockopt. This patch adds this permission.

Thanks to the previous patch allowing skc_to_mptcp_sock() to be used
with MPTCP sockets, this permission allows this helper to be use it in
CGroup BPF hooks, e.g. [gs]etsocktopt.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
bpf: Register mptcp common kfunc set
57a4ec9 
MPTCP helper mptcp_sk() is used to convert struct sock to mptcp_sock.
Helpers mptcp_subflow_ctx() and mptcp_subflow_tcp_sock() are used to
convert between struct mptcp_subflow_context and sock. They all will
be used in MPTCP BPF programs too.

This patch defines corresponding wrappers of them, and put the
wrappers into mptcp common kfunc set and register the set with the
flag BPF_PROG_TYPE_UNSPEC to let them accessible to all types of BPF
programs.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
bpf: Add mptcp_subflow bpf_iter
72722bc 
It's necessary to traverse all subflows on the conn_list of an MPTCP
socket and then call kfunc to modify the fields of each subflow. In
kernel space, mptcp_for_each_subflow() helper is used for this:

	mptcp_for_each_subflow(msk, subflow)
		kfunc(subflow);

But in the MPTCP BPF program, this has not yet been implemented. As
Martin suggested recently, this conn_list walking + modify-by-kfunc
usage fits the bpf_iter use case.

So this patch adds a new bpf_iter type named "mptcp_subflow" to do
this and implements its helpers bpf_iter_mptcp_subflow_new()/_next()/
_destroy(). And register these bpf_iter mptcp_subflow into mptcp
common kfunc set. Then bpf_for_each() for mptcp_subflow can be used
in BPF program like this:

	bpf_for_each(mptcp_subflow, subflow, msk)
		kfunc(subflow);

Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
bpf: Acquire and release mptcp socket
fd7dd46 
The KF_TRUSTED_ARGS flag is used for bpf_iter_mptcp_subflow_new, it
indicates that the all pointer arguments are valid. It's necessary to
add a KF_ACQUIRE helper to get valid "msk".

This patch adds bpf_mptcp_sock_acquire() and bpf_mptcp_sock_release()
helpers for this. Increase sk->sk_refcnt in _acquire() and decrease it
in _release(). Register them with KF_ACQUIRE flag and KF_RELEASE flag.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Geliang Tang added 2 commits December 30, 2024 20:19
selftests/bpf: More endpoints for endpoint_init
a912a96 
This patch changes ADDR_2 from "10.0.1.2" to "10.0.2.1", and adds two more
IPv4 test addresses ADDR_3 - ADDR_4, four IPv6 addresses ADDR6_1 - ADDR6_4.
Add a new helper address_init() to initialize all these addresses.

Add a new parameter "endpoints" for endpoint_init() to control how many
endpoints are used for the tests. This makes it more flexible. Update the
parameters of endpoint_init() in test_subflow().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
selftests/bpf: Add mptcp_subflow bpf_iter subtest
57f18e9 
This patch adds a "cgroup/getsockopt" program "iters_subflow" to test the
newly added mptcp_subflow bpf_iter.

Export mptcp_subflow helpers bpf_iter_mptcp_subflow_new/_next/_destroy,
bpf_mptcp_sock_acquire/_release and other helpers into bpf_experimental.h.

Use bpf_mptcp_sock_acquire() to acquire the msk, then use bpf_for_each()
to walk the subflow list of this msk. From there, future MPTCP-specific
kfunc can be called in the loop. Because they are not there yet, this
test doesn't do anything very useful for the moment, but it focuses on
validating the 'bpf_iter' part and the basic MPTCP kfunc. That's why it
simply adds all subflow ids to local variable local_ids to make sure all
subflows have been seen, then invoke mptcp_subflow_tcp_sock() in the
loop to pick the subflow context.

Out of the loop, use bpf_mptcp_subflow_ctx() to get the subflow context
of the picked subflow context and do some verifications. Finally, assign
local_ids to global variable ids so that the application can obtain this
value, and release the msk.

A related subtest called test_iters_subflow is added to load and verify
the newly added mptcp_subflow type bpf_iter example in test_mptcp. The
endpoint_init() helper is used to add 3 new subflow endpoints. Then one
byte of message is sent to trigger the creation of new subflows.
getsockopt() is invoked once the subflows have been created to trigger
the "cgroup/getsockopt" test program "iters_subflow". skel->bss->ids is
then checked to make sure it equals 10, the sum of each subflow ID: we
should have 4 subflows: 1 + 2 + 3 + 4 = 10. If that's the case, the
bpf_iter loop did the job as expected.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
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Upstream branch: dfa94ce
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=919527
version: 2

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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=907855 expired. Closing PR.

@kernel-patches-daemon-bpf kernel-patches-daemon-bpf bot deleted the series/907855=>bpf-next branch January 4, 2025 23:56
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