kernel/linux.git/include/linux/filter.h, branch v6.6.25

bpf: Mark bpf_spin_{lock,unlock}() helpers with notrace correctly

2024-03-26T22:19:29+00:00

[ Upstream commit 178c54666f9c4d2f49f2ea661d0c11b52f0ed190 ] Currently tracing is supposed not to allow for bpf_spin_{lock,unlock}() helper calls. This is to prevent deadlock for the following cases: - there is a prog (prog-A) calling bpf_spin_{lock,unlock}(). - there is a tracing program (prog-B), e.g., fentry, attached to bpf_spin_lock() and/or bpf_spin_unlock(). - prog-B calls bpf_spin_{lock,unlock}(). For such a case, when prog-A calls bpf_spin_{lock,unlock}(), a deadlock will happen. The related source codes are below in kernel/bpf/helpers.c: notrace BPF_CALL_1(bpf_spin_lock, struct bpf_spin_lock *, lock) notrace BPF_CALL_1(bpf_spin_unlock, struct bpf_spin_lock *, lock) notrace is supposed to prevent fentry prog from attaching to bpf_spin_{lock,unlock}(). But actually this is not the case and fentry prog can successfully attached to bpf_spin_lock(). Siddharth Chintamaneni reported the issue in [1]. The following is the macro definition for above BPF_CALL_1: #define BPF_CALL_x(x, name, ...) \ static __always_inline \ u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)); \ typedef u64 (*btf_##name)(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)); \ u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)); \ u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)) \ { \ return ((btf_##name)____##name)(__BPF_MAP(x,__BPF_CAST,__BPF_N,__VA_ARGS__));\ } \ static __always_inline \ u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)) #define BPF_CALL_1(name, ...) BPF_CALL_x(1, name, __VA_ARGS__) The notrace attribute is actually applied to the static always_inline function ____bpf_spin_{lock,unlock}(). The actual callback function bpf_spin_{lock,unlock}() is not marked with notrace, hence allowing fentry prog to attach to two helpers, and this may cause the above mentioned deadlock. Siddharth Chintamaneni actually has a reproducer in [2]. To fix the issue, a new macro NOTRACE_BPF_CALL_1 is introduced which will add notrace attribute to the original function instead of the hidden always_inline function and this fixed the problem. [1] https://lore.kernel.org/bpf/CAE5sdEigPnoGrzN8WU7Tx-h-iFuMZgW06qp0KHWtpvoXxf1OAQ@mail.gmail.com/ [2] https://lore.kernel.org/bpf/CAE5sdEg6yUc_Jz50AnUXEEUh6O73yQ1Z6NV2srJnef0ZrQkZew@mail.gmail.com/ Fixes: d83525ca62cf ("bpf: introduce bpf_spin_lock") Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20240207070102.335167-1-yonghong.song@linux.dev Signed-off-by: Sasha Levin

bpf: Propagate modified uaddrlen from cgroup sockaddr programs

2024-02-01T00:19:04+00:00

[ Upstream commit fefba7d1ae198dcbf8b3b432de46a4e29f8dbd8c ] As prep for adding unix socket support to the cgroup sockaddr hooks, let's propagate the sockaddr length back to the caller after running a bpf cgroup sockaddr hook program. While not important for AF_INET or AF_INET6, the sockaddr length is important when working with AF_UNIX sockaddrs as the size of the sockaddr cannot be determined just from the address family or the sockaddr's contents. __cgroup_bpf_run_filter_sock_addr() is modified to take the uaddrlen as an input/output argument. After running the program, the modified sockaddr length is stored in the uaddrlen pointer. Signed-off-by: Daan De Meyer Link: https://lore.kernel.org/r/20231011185113.140426-3-daan.j.demeyer@gmail.com Signed-off-by: Martin KaFai Lau Stable-dep-of: c5114710c8ce ("xsk: fix usage of multi-buffer BPF helpers for ZC XDP") Signed-off-by: Sasha Levin

bpf: fix inconsistent return types of bpf_xdp_copy_buf().

2023-08-04T21:38:31+00:00

Fix inconsistent return types in two implementations of bpf_xdp_copy_buf(). There are two implementations: one is an empty implementation whose return type does not match the actual implementation. Suggested-by: Alexei Starovoitov Signed-off-by: Kui-Feng Lee Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20230804005101.1534505-1-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

net: invert the netdevice.h vs xdp.h dependency

2023-08-03T15:38:07+00:00

xdp.h is far more specific and is included in only 67 other files vs netdevice.h's 1538 include sites. Make xdp.h include netdevice.h, instead of the other way around. This decreases the incremental allmodconfig builds size when xdp.h is touched from 5947 to 662 objects. Move bpf_prog_run_xdp() to xdp.h, seems appropriate and filter.h is a mega-header in its own right so it's nice to avoid xdp.h getting included there as well. The only unfortunate part is that the typedef for xdp_features_t has to move to netdevice.h, since its embedded in struct netdevice. Signed-off-by: Jakub Kicinski Acked-by: Jesper Dangaard Brouer Link: https://lore.kernel.org/r/20230803010230.1755386-4-kuba@kernel.org Signed-off-by: Martin KaFai Lau

bpf: Fix jit blinding with new sdiv/smov insns

2023-07-28T01:52:33+00:00

Handle new insns properly in bpf_jit_blind_insn() function. Acked-by: Eduard Zingerman Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20230728011225.3715812-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Support new sign-extension load insns

2023-07-28T01:52:33+00:00

Add interpreter/jit support for new sign-extension load insns which adds a new mode (BPF_MEMSX). Also add verifier support to recognize these insns and to do proper verification with new insns. In verifier, besides to deduce proper bounds for the dst_reg, probed memory access is also properly handled. Acked-by: Eduard Zingerman Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20230728011156.3711870-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Cleanup unused function declaration

2023-06-06T15:05:21+00:00

All usage and the definition of `bpf_prog_free_linfo()` has been removed in commit e16301fbe183 ("bpf: Simplify freeing logic in linfo and jited_linfo"). Clean up its declaration in the header file. Signed-off-by: Ruiqi Gong Signed-off-by: Daniel Borkmann Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/all/20230602030842.279262-1-gongruiqi@huaweicloud.com/ Link: https://lore.kernel.org/bpf/20230606021047.170667-1-gongruiqi@huaweicloud.com

bpf: Support 64-bit pointers to kfuncs

2023-04-14T04:36:41+00:00

test_ksyms_module fails to emit a kfunc call targeting a module on s390x, because the verifier stores the difference between kfunc address and __bpf_call_base in bpf_insn.imm, which is s32, and modules are roughly (1 << 42) bytes away from the kernel on s390x. Fix by keeping BTF id in bpf_insn.imm for BPF_PSEUDO_KFUNC_CALLs, and storing the absolute address in bpf_kfunc_desc. Introduce bpf_jit_supports_far_kfunc_call() in order to limit this new behavior to the s390x JIT. Otherwise other JITs need to be modified, which is not desired. Introduce bpf_get_kfunc_addr() instead of exposing both find_kfunc_desc() and struct bpf_kfunc_desc. In addition to sorting kfuncs by imm, also sort them by offset, in order to handle conflicting imms from different modules. Do this on all architectures in order to simplify code. Factor out resolving specialized kfuncs (XPD and dynptr) from fixup_kfunc_call(). This was required in the first place, because fixup_kfunc_call() uses find_kfunc_desc(), which returns a const pointer, so it's not possible to modify kfunc addr without stripping const, which is not nice. It also removes repetition of code like: if (bpf_jit_supports_far_kfunc_call()) desc->addr = func; else insn->imm = BPF_CALL_IMM(func); and separates kfunc_desc_tab fixups from kfunc_call fixups. Suggested-by: Jiri Olsa Signed-off-by: Ilya Leoshkevich Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20230412230632.885985-1-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov

bpf: Remove unused arguments from btf_struct_access().

2023-04-04T23:57:10+00:00

Remove unused arguments from btf_struct_access() callback. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: David Vernet Link: https://lore.kernel.org/bpf/20230404045029.82870-3-alexei.starovoitov@gmail.com

bpf: return long from bpf_map_ops funcs

2023-03-22T22:11:30+00:00

This patch changes the return types of bpf_map_ops functions to long, where previously int was returned. Using long allows for bpf programs to maintain the sign bit in the absence of sign extension during situations where inlined bpf helper funcs make calls to the bpf_map_ops funcs and a negative error is returned. The definitions of the helper funcs are generated from comments in the bpf uapi header at `include/uapi/linux/bpf.h`. The return type of these helpers was previously changed from int to long in commit bdb7b79b4ce8. For any case where one of the map helpers call the bpf_map_ops funcs that are still returning 32-bit int, a compiler might not include sign extension instructions to properly convert the 32-bit negative value a 64-bit negative value. For example: bpf assembly excerpt of an inlined helper calling a kernel function and checking for a specific error: ; err = bpf_map_update_elem(&mymap, &key, &val, BPF_NOEXIST); ... 46: call 0xffffffffe103291c ; htab_map_update_elem ; if (err && err != -EEXIST) { 4b: cmp $0xffffffffffffffef,%rax ; cmp -EEXIST,%rax kernel function assembly excerpt of return value from `htab_map_update_elem` returning 32-bit int: movl $0xffffffef, %r9d ... movl %r9d, %eax ...results in the comparison: cmp $0xffffffffffffffef, $0x00000000ffffffef Fixes: bdb7b79b4ce8 ("bpf: Switch most helper return values from 32-bit int to 64-bit long") Tested-by: Eduard Zingerman Signed-off-by: JP Kobryn Link: https://lore.kernel.org/r/20230322194754.185781-3-inwardvessel@gmail.com Signed-off-by: Alexei Starovoitov