wireguard-linux/tools/lib/bpf/libbpf.h, branch jd/bump-compilers

libbpf: Auto-attach struct_ops BPF maps in BPF skeleton

2024-06-06T17:06:05Z

Similarly to `bpf_program`, support `bpf_map` automatic attachment in `bpf_object__attach_skeleton`. Currently only struct_ops maps could be attached. On bpftool side, code-generate links in skeleton struct for struct_ops maps. Similarly to `bpf_program_skeleton`, set links in `bpf_map_skeleton`. On libbpf side, extend `bpf_map` with new `autoattach` field to support enabling or disabling autoattach functionality, introducing getter/setter for this field. `bpf_object__(attach|detach)_skeleton` is extended with attaching/detaching struct_ops maps logic. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240605175135.117127-1-yatsenko@meta.com

libbpf: Configure log verbosity with env variable

2024-05-28T23:25:06Z

Configure logging verbosity by setting LIBBPF_LOG_LEVEL environment variable, which is applied only to default logger. Once user set their custom logging callback, it is up to them to handle filtering. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240524131840.114289-1-yatsenko@meta.com

libbpf: Add support for kprobe session attach

2024-04-30T16:45:53Z

Adding support to attach program in kprobe session mode with bpf_program__attach_kprobe_multi_opts function. Adding session bool to bpf_kprobe_multi_opts struct that allows to load and attach the bpf program via kprobe session. the attachment to create kprobe multi session. Also adding new program loader section that allows: SEC("kprobe.session/bpf_fentry_test*") and loads/attaches kprobe program as kprobe session. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240430112830.1184228-5-jolsa@kernel.org

libbpf: Add bpf_link support for BPF_PROG_TYPE_SOCKMAP

2024-04-11T02:52:25Z

Introduce a libbpf API function bpf_program__attach_sockmap() which allow user to get a bpf_link for their corresponding programs. Acked-by: Andrii Nakryiko Acked-by: Eduard Zingerman Reviewed-by: John Fastabend Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20240410043532.3737722-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov

libbpf: Add ring__consume_n / ring_buffer__consume_n

2024-04-06T16:11:55Z

Introduce a new API to consume items from a ring buffer, limited to a specified amount, and return to the caller the actual number of items consumed. Signed-off-by: Andrea Righi Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/lkml/20240310154726.734289-1-andrea.righi@canonical.com/T Link: https://lore.kernel.org/bpf/20240406092005.92399-4-andrea.righi@canonical.com

libbpf: add support for BPF cookie for raw_tp/tp_btf programs

2024-03-20T06:05:34Z

Wire up BPF cookie passing or raw_tp and tp_btf programs, both in low-level and high-level APIs. Acked-by: Stanislav Fomichev Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Message-ID: <20240319233852.1977493-5-andrii@kernel.org> Signed-off-by: Alexei Starovoitov

libbpf: Recognize __arena global variables.

2024-03-11T22:43:35Z

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

libbpf: Support BPF token path setting through LIBBPF_BPF_TOKEN_PATH envvar

2024-01-25T00:21:03Z

To allow external admin authority to override default BPF FS location (/sys/fs/bpf) for implicit BPF token creation, teach libbpf to recognize LIBBPF_BPF_TOKEN_PATH envvar. If it is specified and user application didn't explicitly specify bpf_token_path option, it will be treated exactly like bpf_token_path option, overriding default /sys/fs/bpf location and making BPF token mandatory. Suggested-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20240124022127.2379740-29-andrii@kernel.org

libbpf: Wire up BPF token support at BPF object level

2024-01-25T00:21:02Z

Add BPF token support to BPF object-level functionality. BPF token is supported by BPF object logic either as an explicitly provided BPF token from outside (through BPF FS path), or implicitly (unless prevented through bpf_object_open_opts). Implicit mode is assumed to be the most common one for user namespaced unprivileged workloads. The assumption is that privileged container manager sets up default BPF FS mount point at /sys/fs/bpf with BPF token delegation options (delegate_{cmds,maps,progs,attachs} mount options). BPF object during loading will attempt to create BPF token from /sys/fs/bpf location, and pass it for all relevant operations (currently, map creation, BTF load, and program load). In this implicit mode, if BPF token creation fails due to whatever reason (BPF FS is not mounted, or kernel doesn't support BPF token, etc), this is not considered an error. BPF object loading sequence will proceed with no BPF token. In explicit BPF token mode, user provides explicitly custom BPF FS mount point path. In such case, BPF object will attempt to create BPF token from provided BPF FS location. If BPF token creation fails, that is considered a critical error and BPF object load fails with an error. Libbpf provides a way to disable implicit BPF token creation, if it causes any troubles (BPF token is designed to be completely optional and shouldn't cause any problems even if provided, but in the world of BPF LSM, custom security logic can be installed that might change outcome depending on the presence of BPF token). To disable libbpf's default BPF token creation behavior user should provide either invalid BPF token FD (negative), or empty bpf_token_path option. BPF token presence can influence libbpf's feature probing, so if BPF object has associated BPF token, feature probing is instructed to use BPF object-specific feature detection cache and token FD. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20240124022127.2379740-26-andrii@kernel.org

libbpf: Add link-based API for netkit

2023-10-24T23:06:58Z

This adds bpf_program__attach_netkit() API to libbpf. Overall it is very similar to tcx. The API looks as following: LIBBPF_API struct bpf_link * bpf_program__attach_netkit(const struct bpf_program *prog, int ifindex, const struct bpf_netkit_opts *opts); The struct bpf_netkit_opts is done in similar way as struct bpf_tcx_opts for supporting bpf_mprog control parameters. The attach location for the primary and peer device is derived from the program section "netkit/primary" and "netkit/peer", respectively. Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20231024214904.29825-4-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau