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cd19b88510
This patch adds a "cgroup/getsockopt" way to inspect the subflows of an MPTCP socket, and verify the modifications done by the same BPF program in the previous commit: a different mark per subflow, and a different TCP CC set on the second one. This new hook will be used by the next commit to verify the socket options set on each subflow. This extra "cgroup/getsockopt" prog walks the msk->conn_list and use bpf_core_cast to cast a pointer for readonly. It allows to inspect all the fields of a structure. Note that on the kernel side, the MPTCP socket stores a list of subflows under 'msk->conn_list'. They can be iterated using the generic 'list' helpers. They have been imported here, with a small difference: list_for_each_entry() uses 'can_loop' to limit the number of iterations, and ease its use. Because only data need to be read here, it is enough to use this technique. It is planned to use bpf_iter, when BPF programs will be used to modify data from the different subflows. mptcp_subflow_tcp_sock() and mptcp_for_each_stubflow() helpers have also be imported. Suggested-by: Martin KaFai Lau <martin.lau@kernel.org> 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> Link: https://lore.kernel.org/r/20240926-upstream-bpf-next-20240506-mptcp-subflow-test-v7-2-d26029e15cdd@kernel.org Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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#ifndef __MPTCP_BPF_H__
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#define __MPTCP_BPF_H__
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#include "bpf_experimental.h"
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/* list helpers from include/linux/list.h */
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static inline int list_is_head(const struct list_head *list,
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const struct list_head *head)
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{
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return list == head;
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}
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#define list_entry(ptr, type, member) \
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container_of(ptr, type, member)
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#define list_first_entry(ptr, type, member) \
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list_entry((ptr)->next, type, member)
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#define list_next_entry(pos, member) \
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list_entry((pos)->member.next, typeof(*(pos)), member)
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#define list_entry_is_head(pos, head, member) \
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list_is_head(&pos->member, (head))
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/* small difference: 'can_loop' has been added in the conditions */
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#define list_for_each_entry(pos, head, member) \
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for (pos = list_first_entry(head, typeof(*pos), member); \
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!list_entry_is_head(pos, head, member) && can_loop; \
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pos = list_next_entry(pos, member))
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/* mptcp helpers from protocol.h */
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#define mptcp_for_each_subflow(__msk, __subflow) \
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list_for_each_entry(__subflow, &((__msk)->conn_list), node)
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static __always_inline struct sock *
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mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
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{
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return subflow->tcp_sock;
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}
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#endif
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