linux/tools/lib/bpf/libbpf.map, branch v5.14

libbpf: Move few APIs from 0.4 to 0.5 version

2021-06-03T13:50:05Z

Official libbpf 0.4 release doesn't include three APIs that were tentatively put into 0.4 section. Fix libbpf.map and move these three APIs: - bpf_map__initial_value; - bpf_map_lookup_and_delete_elem_flags; - bpf_object__gen_loader. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210603004026.2698513-2-andrii@kernel.org

libbpf: Add libbpf_set_strict_mode() API to turn on libbpf 1.0 behaviors

2021-05-26T00:32:34Z

Add libbpf_set_strict_mode() API that allows application to simulate libbpf 1.0 breaking changes before libbpf 1.0 is released. This will help users migrate gradually and with confidence. For now only ALL or NONE options are available, subsequent patches will add more flags. This patch is preliminary for selftests/bpf changes. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210525035935.1461796-2-andrii@kernel.org

bpf: Extend libbpf with bpf_map_lookup_and_delete_elem_flags

2021-05-24T20:30:51Z

Add bpf_map_lookup_and_delete_elem_flags() libbpf API in order to use the BPF_F_LOCK flag with the map_lookup_and_delete_elem() function. Signed-off-by: Denis Salopek Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/15b05dafe46c7e0750d110f233977372029d1f62.1620763117.git.denis.salopek@sartura.hr

libbpf: Introduce bpf_map__initial_value().

2021-05-18T22:40:56Z

Introduce bpf_map__initial_value() to read initial contents of mmaped data/rodata/bss maps. Note that bpf_map__set_initial_value() doesn't allow modifying kconfig map while bpf_map__initial_value() allows reading its values. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210514003623.28033-17-alexei.starovoitov@gmail.com

libbpf: Generate loader program out of BPF ELF file.

2021-05-18T22:39:40Z

The BPF program loading process performed by libbpf is quite complex and consists of the following steps: "open" phase: - parse elf file and remember relocations, sections - collect externs and ksyms including their btf_ids in prog's BTF - patch BTF datasec (since llvm couldn't do it) - init maps (old style map_def, BTF based, global data map, kconfig map) - collect relocations against progs and maps "load" phase: - probe kernel features - load vmlinux BTF - resolve externs (kconfig and ksym) - load program BTF - init struct_ops - create maps - apply CO-RE relocations - patch ld_imm64 insns with src_reg=PSEUDO_MAP, PSEUDO_MAP_VALUE, PSEUDO_BTF_ID - reposition subprograms and adjust call insns - sanitize and load progs During this process libbpf does sys_bpf() calls to load BTF, create maps, populate maps and finally load programs. Instead of actually doing the syscalls generate a trace of what libbpf would have done and represent it as the "loader program". The "loader program" consists of single map with: - union bpf_attr(s) - BTF bytes - map value bytes - insns bytes and single bpf program that passes bpf_attr(s) and data into bpf_sys_bpf() helper. Executing such "loader program" via bpf_prog_test_run() command will replay the sequence of syscalls that libbpf would have done which will result the same maps created and programs loaded as specified in the elf file. The "loader program" removes libelf and majority of libbpf dependency from program loading process. kconfig, typeless ksym, struct_ops and CO-RE are not supported yet. The order of relocate_data and relocate_calls had to change, so that bpf_gen__prog_load() can see all relocations for a given program with correct insn_idx-es. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210514003623.28033-15-alexei.starovoitov@gmail.com

libbpf: Add low level TC-BPF management API

2021-05-17T15:48:45Z

This adds functions that wrap the netlink API used for adding, manipulating, and removing traffic control filters. The API summary: A bpf_tc_hook represents a location where a TC-BPF filter can be attached. This means that creating a hook leads to creation of the backing qdisc, while destruction either removes all filters attached to a hook, or destroys qdisc if requested explicitly (as discussed below). The TC-BPF API functions operate on this bpf_tc_hook to attach, replace, query, and detach tc filters. All functions return 0 on success, and a negative error code on failure. bpf_tc_hook_create - Create a hook Parameters: @hook - Cannot be NULL, ifindex > 0, attach_point must be set to proper enum constant. Note that parent must be unset when attach_point is one of BPF_TC_INGRESS or BPF_TC_EGRESS. Note that as an exception BPF_TC_INGRESS|BPF_TC_EGRESS is also a valid value for attach_point. Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM. bpf_tc_hook_destroy - Destroy a hook Parameters: @hook - Cannot be NULL. The behaviour depends on value of attach_point. If BPF_TC_INGRESS, all filters attached to the ingress hook will be detached. If BPF_TC_EGRESS, all filters attached to the egress hook will be detached. If BPF_TC_INGRESS|BPF_TC_EGRESS, the clsact qdisc will be deleted, also detaching all filters. As before, parent must be unset for these attach_points, and set for BPF_TC_CUSTOM. It is advised that if the qdisc is operated on by many programs, then the program at least check that there are no other existing filters before deleting the clsact qdisc. An example is shown below: DECLARE_LIBBPF_OPTS(bpf_tc_hook, .ifindex = if_nametoindex("lo"), .attach_point = BPF_TC_INGRESS); /* set opts as NULL, as we're not really interested in * getting any info for a particular filter, but just * detecting its presence. */ r = bpf_tc_query(&hook, NULL); if (r == -ENOENT) { /* no filters */ hook.attach_point = BPF_TC_INGRESS|BPF_TC_EGREESS; return bpf_tc_hook_destroy(&hook); } else { /* failed or r == 0, the latter means filters do exist */ return r; } Note that there is a small race between checking for no filters and deleting the qdisc. This is currently unavoidable. Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM. bpf_tc_attach - Attach a filter to a hook Parameters: @hook - Cannot be NULL. Represents the hook the filter will be attached to. Requirements for ifindex and attach_point are same as described in bpf_tc_hook_create, but BPF_TC_CUSTOM is also supported. In that case, parent must be set to the handle where the filter will be attached (using BPF_TC_PARENT). E.g. to set parent to 1:16 like in tc command line, the equivalent would be BPF_TC_PARENT(1, 16). @opts - Cannot be NULL. The following opts are optional: * handle - The handle of the filter * priority - The priority of the filter Must be >= 0 and <= UINT16_MAX Note that when left unset, they will be auto-allocated by the kernel. The following opts must be set: * prog_fd - The fd of the loaded SCHED_CLS prog The following opts must be unset: * prog_id - The ID of the BPF prog The following opts are optional: * flags - Currently only BPF_TC_F_REPLACE is allowed. It allows replacing an existing filter instead of failing with -EEXIST. The following opts will be filled by bpf_tc_attach on a successful attach operation if they are unset: * handle - The handle of the attached filter * priority - The priority of the attached filter * prog_id - The ID of the attached SCHED_CLS prog This way, the user can know what the auto allocated values for optional opts like handle and priority are for the newly attached filter, if they were unset. Note that some other attributes are set to fixed default values listed below (this holds for all bpf_tc_* APIs): protocol as ETH_P_ALL, direct action mode, chain index of 0, and class ID of 0 (this can be set by writing to the skb->tc_classid field from the BPF program). bpf_tc_detach Parameters: @hook - Cannot be NULL. Represents the hook the filter will be detached from. Requirements are same as described above in bpf_tc_attach. @opts - Cannot be NULL. The following opts must be set: * handle, priority The following opts must be unset: * prog_fd, prog_id, flags bpf_tc_query Parameters: @hook - Cannot be NULL. Represents the hook where the filter lookup will be performed. Requirements are same as described above in bpf_tc_attach(). @opts - Cannot be NULL. The following opts must be set: * handle, priority The following opts must be unset: * prog_fd, prog_id, flags The following fields will be filled by bpf_tc_query upon a successful lookup: * prog_id Some usage examples (using BPF skeleton infrastructure): BPF program (test_tc_bpf.c): #include #include SEC("classifier") int cls(struct __sk_buff *skb) { return 0; } Userspace loader: struct test_tc_bpf *skel = NULL; int fd, r; skel = test_tc_bpf__open_and_load(); if (!skel) return -ENOMEM; fd = bpf_program__fd(skel->progs.cls); DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex = if_nametoindex("lo"), .attach_point = BPF_TC_INGRESS); /* Create clsact qdisc */ r = bpf_tc_hook_create(&hook); if (r < 0) goto end; DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts, .prog_fd = fd); r = bpf_tc_attach(&hook, &opts); if (r < 0) goto end; /* Print the auto allocated handle and priority */ printf("Handle=%u", opts.handle); printf("Priority=%u", opts.priority); opts.prog_fd = opts.prog_id = 0; bpf_tc_detach(&hook, &opts); end: test_tc_bpf__destroy(skel); This is equivalent to doing the following using tc command line: # tc qdisc add dev lo clsact # tc filter add dev lo ingress bpf obj foo.o sec classifier da # tc filter del dev lo ingress handle prio

bpf ... where the handle and priority can be found using: # tc filter show dev lo ingress Another example replacing a filter (extending prior example): /* We can also choose both (or one), let's try replacing an * existing filter. */ DECLARE_LIBBPF_OPTS(bpf_tc_opts, replace_opts, .handle = opts.handle, .priority = opts.priority, .prog_fd = fd); r = bpf_tc_attach(&hook, &replace_opts); if (r == -EEXIST) { /* Expected, now use BPF_TC_F_REPLACE to replace it */ replace_opts.flags = BPF_TC_F_REPLACE; return bpf_tc_attach(&hook, &replace_opts); } else if (r < 0) { return r; } /* There must be no existing filter with these * attributes, so cleanup and return an error. */ replace_opts.prog_fd = replace_opts.prog_id = 0; bpf_tc_detach(&hook, &replace_opts); return -1; To obtain info of a particular filter: /* Find info for filter with handle 1 and priority 50 */ DECLARE_LIBBPF_OPTS(bpf_tc_opts, info_opts, .handle = 1, .priority = 50); r = bpf_tc_query(&hook, &info_opts); if (r == -ENOENT) printf("Filter not found"); else if (r < 0) return r; printf("Prog ID: %u", info_opts.prog_id); return 0; Signed-off-by: Kumar Kartikeya Dwivedi Co-developed-by: Daniel Borkmann # libbpf API design [ Daniel: also did major patch cleanup ] Signed-off-by: Daniel Borkmann Reviewed-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210512103451.989420-3-memxor@gmail.com

libbpf: Add bpf_map__inner_map API

2021-04-09T06:54:48Z

The API gives access to inner map for map in map types (array or hash of map). It will be used to dynamically set max_entries in it. Signed-off-by: Yauheni Kaliuta Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210408061310.95877-7-yauheni.kaliuta@redhat.com

libbpf: Add bpf object kern_version attribute setter

2021-03-26T02:23:27Z

Unfortunately some distros don't have their kernel version defined accurately in due to different long term support reasons. It is important to have a way to override the bpf kern_version attribute during runtime: some old kernels might still check for kern_version attribute during bpf_prog_load(). Signed-off-by: Rafael David Tinoco Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20210323040952.2118241-1-rafaeldtinoco@ubuntu.com

libbpf: Add BPF static linker APIs

2021-03-18T23:14:22Z

Introduce BPF static linker APIs to libbpf. BPF static linker allows to perform static linking of multiple BPF object files into a single combined resulting object file, preserving all the BPF programs, maps, global variables, etc. Data sections (.bss, .data, .rodata, .maps, maps, etc) with the same name are concatenated together. Similarly, code sections are also concatenated. All the symbols and ELF relocations are also concatenated in their respective ELF sections and are adjusted accordingly to the new object file layout. Static variables and functions are handled correctly as well, adjusting BPF instructions offsets to reflect new variable/function offset within the combined ELF section. Such relocations are referencing STT_SECTION symbols and that stays intact. Data sections in different files can have different alignment requirements, so that is taken care of as well, adjusting sizes and offsets as necessary to satisfy both old and new alignment requirements. DWARF data sections are stripped out, currently. As well as LLLVM_ADDRSIG section, which is ignored by libbpf in bpf_object__open() anyways. So, in a way, BPF static linker is an analogue to `llvm-strip -g`, which is a pretty nice property, especially if resulting .o file is then used to generate BPF skeleton. Original string sections are ignored and instead we construct our own set of unique strings using libbpf-internal `struct strset` API. To reduce the size of the patch, all the .BTF and .BTF.ext processing was moved into a separate patch. The high-level API consists of just 4 functions: - bpf_linker__new() creates an instance of BPF static linker. It accepts output filename and (currently empty) options struct; - bpf_linker__add_file() takes input filename and appends it to the already processed ELF data; it can be called multiple times, one for each BPF ELF object file that needs to be linked in; - bpf_linker__finalize() needs to be called to dump final ELF contents into the output file, specified when bpf_linker was created; after bpf_linker__finalize() is called, no more bpf_linker__add_file() and bpf_linker__finalize() calls are allowed, they will return error; - regardless of whether bpf_linker__finalize() was called or not, bpf_linker__free() will free up all the used resources. Currently, BPF static linker doesn't resolve cross-object file references (extern variables and/or functions). This will be added in the follow up patch set. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210318194036.3521577-7-andrii@kernel.org

libbpf: Add generic BTF type shallow copy API

2021-03-18T23:14:22Z

Add btf__add_type() API that performs shallow copy of a given BTF type from the source BTF into the destination BTF. All the information and type IDs are preserved, but all the strings encountered are added into the destination BTF and corresponding offsets are rewritten. BTF type IDs are assumed to be correct or such that will be (somehow) modified afterwards. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210318194036.3521577-6-andrii@kernel.org