kernel/linux.git/tools/bpf, branch linux-6.9.y

bpf: Fix potential integer overflow in resolve_btfids

2024-06-12T09:39:48+00:00

[ Upstream commit 44382b3ed6b2787710c8ade06c0e97f5970a47c8 ] err is a 32-bit integer, but elf_update returns an off_t, which is 64-bit at least on 64-bit platforms. If symbols_patch is called on a binary between 2-4GB in size, the result will be negative when cast to a 32-bit integer, which the code assumes means an error occurred. This can wrongly trigger build failures when building very large kernel images. Fixes: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object") Signed-off-by: Friedrich Vock Signed-off-by: Daniel Borkmann Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20240514070931.199694-1-friedrich.vock@gmx.de Signed-off-by: Sasha Levin

bpftool: Mount bpffs on provided dir instead of parent dir

2024-05-30T07:44:16+00:00

[ Upstream commit 478a535ae54ad3831371904d93b5dfc403222e17 ] When pinning programs/objects under PATH (eg: during "bpftool prog loadall") the bpffs is mounted on the parent dir of PATH in the following situations: - the given dir exists but it is not bpffs. - the given dir doesn't exist and the parent dir is not bpffs. Mounting on the parent dir can also have the unintentional side- effect of hiding other files located under the parent dir. If the given dir exists but is not bpffs, then the bpffs should be mounted on the given dir and not its parent dir. Similarly, if the given dir doesn't exist and its parent dir is not bpffs, then the given dir should be created and the bpffs should be mounted on this new dir. Fixes: 2a36c26fe3b8 ("bpftool: Support bpffs mountpoint as pin path for prog loadall") Signed-off-by: Sahil Siddiq Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/2da44d24-74ae-a564-1764-afccf395eeec@isovalent.com/T/#t Link: https://lore.kernel.org/bpf/20240404192219.52373-1-icegambit91@gmail.com Closes: https://github.com/libbpf/bpftool/issues/100 Changes since v1: - Split "mount_bpffs_for_pin" into two functions. This is done to improve maintainability and readability. Changes since v2: - mount_bpffs_for_pin: rename to "create_and_mount_bpffs_dir". - mount_bpffs_given_file: rename to "mount_bpffs_given_file". - create_and_mount_bpffs_dir: - introduce "dir_exists" boolean. - remove new dir if "mnt_fs" fails. - improve error handling and error messages. Changes since v3: - Rectify function name. - Improve error messages and formatting. - mount_bpffs_for_file: - Check if dir exists before block_mount check. Changes since v4: - Use strdup instead of strcpy. - create_and_mount_bpffs_dir: - Use S_IRWXU instead of 0700. - Improve error handling and formatting. Signed-off-by: Sasha Levin

bpftool: Fix missing pids during link show

2024-05-30T07:44:11+00:00

[ Upstream commit fe879bb42f8a6513ed18e9d22efb99cb35590201 ] Current 'bpftool link' command does not show pids, e.g., $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 Hack the following change to enable normal libbpf debug output, # --- a/tools/bpf/bpftool/pids.c # +++ b/tools/bpf/bpftool/pids.c # @@ -121,9 +121,9 @@ int build_obj_refs_table(struct hashmap **map, enum bpf_obj_type type) # /* we don't want output polluted with libbpf errors if bpf_iter is not # * supported # */ # - default_print = libbpf_set_print(libbpf_print_none); # + /* default_print = libbpf_set_print(libbpf_print_none); */ # err = pid_iter_bpf__load(skel); # - libbpf_set_print(default_print); # + /* libbpf_set_print(default_print); */ Rerun the above bpftool command: $ tools/build/bpftool/bpftool link libbpf: prog 'iter': BPF program load failed: Permission denied libbpf: prog 'iter': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; struct task_struct *task = ctx->task; @ pid_iter.bpf.c:69 0: (79) r6 = *(u64 *)(r1 +8) ; R1=ctx() R6_w=ptr_or_null_task_struct(id=1) ; struct file *file = ctx->file; @ pid_iter.bpf.c:68 ... ; struct bpf_link *link = (struct bpf_link *) file->private_data; @ pid_iter.bpf.c:103 80: (79) r3 = *(u64 *)(r8 +432) ; R3_w=scalar() R8=ptr_file() ; if (link->type == bpf_core_enum_value(enum bpf_link_type___local, @ pid_iter.bpf.c:105 81: (61) r1 = *(u32 *)(r3 +12) R3 invalid mem access 'scalar' processed 39 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2 -- END PROG LOAD LOG -- libbpf: prog 'iter': failed to load: -13 ... The 'file->private_data' returns a 'void' type and this caused subsequent 'link->type' (insn #81) failed in verification. To fix the issue, restore the previous BPF_CORE_READ so old kernels can also work. With this patch, the 'bpftool link' runs successfully with 'pids'. $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 pids systemd(1) Fixes: 44ba7b30e84f ("bpftool: Use a local copy of BPF_LINK_TYPE_PERF_EVENT in pid_iter.bpf.c") Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Tested-by: Quentin Monnet Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240312023249.3776718-1-yonghong.song@linux.dev Signed-off-by: Sasha Levin

libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVM

2024-03-15T21:24:00+00:00

The selftests use to tell LLVM about special pointers. For LLVM there is nothing "arena" about them. They are simply pointers in a different address space. Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed: . macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST . global variables in __attribute__((address_space(N))) are now placed in section named ".addr_space.N" instead of ".arena.N". Adjust libbpf, bpftool, and selftests to match LLVM. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com

libbpf: Recognize __arena global variables.

2024-03-11T22:43:35+00:00

LLVM automatically places __arena variables into ".arena.1" ELF section. In order to use such global variables bpf program must include definition of arena map in ".maps" section, like: struct { __uint(type, BPF_MAP_TYPE_ARENA); __uint(map_flags, BPF_F_MMAPABLE); __uint(max_entries, 1000); /* number of pages */ __ulong(map_extra, 2ull << 44); /* start of mmap() region */ } arena SEC(".maps"); libbpf recognizes both uses of arena and creates single `struct bpf_map *` instance in libbpf APIs. ".arena.1" ELF section data is used as initial data image, which is exposed through skeleton and bpf_map__initial_value() to the user, if they need to tune it before the load phase. During load phase, this initial image is copied over into mmap()'ed region corresponding to arena, and discarded. Few small checks here and there had to be added to make sure this approach works with bpf_map__initial_value(), mostly due to hard-coded assumption that map->mmaped is set up with mmap() syscall and should be munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum arena size, so this smaller data size has to be tracked separately. Given it is enforced that there is only one arena for entire bpf_object instance, we just keep it in a separate field. This can be generalized if necessary later. All global variables from ".arena.1" section are accessible from user space via skel->arena->name_of_var. For bss/data/rodata the skeleton/libbpf perform the following sequence: 1. addr = mmap(MAP_ANONYMOUS) 2. user space optionally modifies global vars 3. map_fd = bpf_create_map() 4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel 5. mmap(addr, MAP_FIXED, map_fd) after step 5 user spaces see the values it wrote at step 2 at the same addresses arena doesn't support update_map_elem. Hence skeleton/libbpf do: 1. addr = malloc(sizeof SEC ".arena.1") 2. user space optionally modifies global vars 3. map_fd = bpf_create_map(MAP_TYPE_ARENA) 4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd) 5. memcpy(real_addr, addr) // this will fault-in and allocate pages At the end look and feel of global data vs __arena global data is the same from bpf prog pov. Another complication is: struct { __uint(type, BPF_MAP_TYPE_ARENA); } arena SEC(".maps"); int __arena foo; int bar; ptr1 = &foo; // relocation against ".arena.1" section ptr2 = &arena; // relocation against ".maps" section ptr3 = &bar; // relocation against ".bss" section Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd while ptr3 points to a different global array's map_fd. For the verifier: ptr1->type == unknown_scalar ptr2->type == const_ptr_to_map ptr3->type == ptr_to_map_value After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com

bpftool: Recognize arena map type

2024-03-11T22:37:24+00:00

Teach bpftool to recognize arena map type. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240308010812.89848-10-alexei.starovoitov@gmail.com

bpftool: rename is_internal_mmapable_map into is_mmapable_map

2024-03-07T22:58:48+00:00

It's not restricted to working with "internal" maps, it cares about any map that can be mmap'ed. Reflect that in more succinct and generic name. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Quentin Monnet Link: https://lore.kernel.org/r/20240307031228.42896-6-alexei.starovoitov@gmail.com Signed-off-by: Martin KaFai Lau

bpftool: Add an example for struct_ops map and shadow type.

2024-02-29T22:23:53+00:00

The example in bpftool-gen.8 explains how to use the pointer of the shadow type to change the value of a field of a struct_ops map. Signed-off-by: Kui-Feng Lee Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240229064523.2091270-5-thinker.li@gmail.com

bpftool: Generated shadow variables for struct_ops maps.

2024-02-29T22:23:53+00:00

Declares and defines a pointer of the shadow type for each struct_ops map. The code generator will create an anonymous struct type as the shadow type for each struct_ops map. The shadow type is translated from the original struct type of the map. The user of the skeleton use pointers of them to access the values of struct_ops maps. However, shadow types only supports certain types of fields, including scalar types and function pointers. Any fields of unsupported types are translated into an array of characters to occupy the space of the original field. Function pointers are translated into pointers of the struct bpf_program. Additionally, padding fields are generated to occupy the space between two consecutive fields. The pointers of shadow types of struct_osp maps are initialized when *__open_opts() in skeletons are called. For a map called FOO, the user can access it through the pointer at skel->struct_ops.FOO. Signed-off-by: Kui-Feng Lee Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240229064523.2091270-4-thinker.li@gmail.com

tools/resolve_btfids: Fix cross-compilation to non-host endianness

2024-02-07T23:56:18+00:00

The .BTF_ids section is pre-filled with zeroed BTF ID entries during the build and afterwards patched by resolve_btfids with correct values. Since resolve_btfids always writes in host-native endianness, it relies on libelf to do the translation when the target ELF is cross-compiled to a different endianness (this was introduced in commit 61e8aeda9398 ("bpf: Fix libelf endian handling in resolv_btfids")). Unfortunately, the translation will corrupt the flags fields of SET8 entries because these were written during vmlinux compilation and are in the correct endianness already. This will lead to numerous selftests failures such as: $ sudo ./test_verifier 502 502 #502/p sleepable fentry accept FAIL Failed to load prog 'Invalid argument'! bpf_fentry_test1 is not sleepable verification time 34 usec stack depth 0 processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 Summary: 0 PASSED, 0 SKIPPED, 1 FAILED Since it's not possible to instruct libelf to translate just certain values, let's manually bswap the flags (both global and entry flags) in resolve_btfids when needed, so that libelf then translates everything correctly. Fixes: ef2c6f370a63 ("tools/resolve_btfids: Add support for 8-byte BTF sets") Signed-off-by: Viktor Malik Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/7b6bff690919555574ce0f13d2a5996cacf7bf69.1707223196.git.vmalik@redhat.com