linux/kernel/bpf/bpf_struct_ops.c, branch v6.12

bpf: Check unsupported ops from the bpf_struct_ops's cfi_stubs

2024-07-29T19:54:13Z

The bpf_tcp_ca struct_ops currently uses a "u32 unsupported_ops[]" array to track which ops is not supported. After cfi_stubs had been added, the function pointer in cfi_stubs is also NULL for the unsupported ops. Thus, the "u32 unsupported_ops[]" becomes redundant. This observation was originally brought up in the bpf/cfi discussion: https://lore.kernel.org/bpf/CAADnVQJoEkdjyCEJRPASjBw1QGsKYrF33QdMGc1RZa9b88bAEA@mail.gmail.com/ The recent bpf qdisc patch (https://lore.kernel.org/bpf/20240714175130.4051012-6-amery.hung@bytedance.com/) also needs to specify quite many unsupported ops. It is a good time to clean it up. This patch removes the need of "u32 unsupported_ops[]" and tests for null-ness in the cfi_stubs instead. Testing the cfi_stubs is done in a new function bpf_struct_ops_supported(). The verifier will call bpf_struct_ops_supported() when loading the struct_ops program. The ".check_member" is removed from the bpf_tcp_ca in this patch. ".check_member" could still be useful for other subsytems to enforce other restrictions (e.g. sched_ext checks for prog->sleepable). To keep the same error return, ENOTSUPP is used. Cc: Amery Hung Signed-off-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20240722183049.2254692-2-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko

bpf: Replace 8 seq_puts() calls by seq_putc() calls

2024-07-29T19:53:00Z

Single line breaks should occasionally be put into a sequence. Thus use the corresponding function “seq_putc”. This issue was transformed by using the Coccinelle software. Signed-off-by: Markus Elfring Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/e26b7df9-cd63-491f-85e8-8cabe60a85e5@web.de

bpf: Use precise image size for struct_ops trampoline

2024-07-01T15:10:46Z

For trampoline using bpf_prog_pack, we need to generate a rw_image buffer with size of (image_end - image). For regular trampoline, we use the precise image size generated by arch_bpf_trampoline_size to allocate rw_image. But for struct_ops trampoline, we allocate rw_image directly using close to PAGE_SIZE size. We do not need to allocate for that much, as the patch size is usually much smaller than PAGE_SIZE. Let's use precise image size for it too. Signed-off-by: Pu Lehui Signed-off-by: Daniel Borkmann Tested-by: Björn Töpel #riscv Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20240622030437.3973492-2-pulehui@huaweicloud.com

bpf: support epoll from bpf struct_ops links.

2024-05-30T22:34:13Z

Add epoll support to bpf struct_ops links to trigger EPOLLHUP event upon detachment. This patch implements the "poll" of the "struct file_operations" for BPF links and introduces a new "poll" operator in the "struct bpf_link_ops". By implementing "poll" of "struct bpf_link_ops" for the links of struct_ops, the file descriptor of a struct_ops link can be added to an epoll file descriptor to receive EPOLLHUP events. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240530065946.979330-4-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: enable detaching links of struct_ops objects.

2024-05-30T22:34:13Z

Implement the detach callback in bpf_link_ops for struct_ops so that user programs can detach a struct_ops link. The subsystems that struct_ops objects are registered to can also use this callback to detach the links being passed to them. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240530065946.979330-3-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops.

2024-05-30T22:34:13Z

Pass an additional pointer of bpf_struct_ops_link to callback function reg, unreg, and update provided by subsystems defined in bpf_struct_ops. A bpf_struct_ops_map can be registered for multiple links. Passing a pointer of bpf_struct_ops_link helps subsystems to distinguish them. This pointer will be used in the later patches to let the subsystem initiate a detachment on a link that was registered to it previously. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240530065946.979330-2-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: Check return from set_memory_rox()

2024-03-18T21:18:47Z

arch_protect_bpf_trampoline() and alloc_new_pack() call set_memory_rox() which can fail, leading to unprotected memory. Take into account return from set_memory_rox() function and add __must_check flag to arch_protect_bpf_trampoline(). Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/fe1c163c83767fde5cab31d209a4a6be3ddb3a73.1710574353.git.christophe.leroy@csgroup.eu Signed-off-by: Martin KaFai Lau

bpf: Remove unnecessary err < 0 check in bpf_struct_ops_map_update_elem

2024-03-18T19:48:10Z

There is a "if (err)" check earlier, so the "if (err < 0)" check that this patch removing is unnecessary. It was my overlook when making adjustments to the bpf_struct_ops_prepare_trampoline() such that the caller does not have to worry about the new page when the function returns error. Fixes: 187e2af05abe ("bpf: struct_ops supports more than one page for trampolines.") Signed-off-by: Martin KaFai Lau Signed-off-by: Andrii Nakryiko Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20240315192112.2825039-1-martin.lau@linux.dev

bpf: struct_ops supports more than one page for trampolines.

2024-03-04T22:09:20Z

The BPF struct_ops previously only allowed one page of trampolines. Each function pointer of a struct_ops is implemented by a struct_ops bpf program. Each struct_ops bpf program requires a trampoline. The following selftest patch shows each page can hold a little more than 20 trampolines. While one page is more than enough for the tcp-cc usecase, the sched_ext use case shows that one page is not always enough and hits the one page limit. This patch overcomes the one page limit by allocating another page when needed and it is limited to a total of MAX_IMAGE_PAGES (8) pages which is more than enough for reasonable usages. The variable st_map->image has been changed to st_map->image_pages, and its type has been changed to an array of pointers to pages. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240224223418.526631-3-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf, net: validate struct_ops when updating value.

2024-03-04T18:03:57Z

Perform all validations when updating values of struct_ops maps. Doing validation in st_ops->reg() and st_ops->update() is not necessary anymore. However, tcp_register_congestion_control() has been called in various places. It still needs to do validations. Cc: netdev@vger.kernel.org Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240224223418.526631-2-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau