libbpf: Add bpf_cookie support to bpf_link_create() API
Add ability to specify bpf_cookie value when creating BPF perf link with bpf_link_create() low-level API. Given BPF_LINK_CREATE command is growing and keeps getting new fields that are specific to the type of BPF_LINK, extend libbpf side of bpf_link_create() API and corresponding OPTS struct to accomodate such changes. Add extra checks to prevent using incompatible/unexpected combinations of fields. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210815070609.987780-11-andrii@kernel.org
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@ -684,8 +684,13 @@ int bpf_link_create(int prog_fd, int target_fd,
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iter_info_len = OPTS_GET(opts, iter_info_len, 0);
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target_btf_id = OPTS_GET(opts, target_btf_id, 0);
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if (iter_info_len && target_btf_id)
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return libbpf_err(-EINVAL);
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/* validate we don't have unexpected combinations of non-zero fields */
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if (iter_info_len || target_btf_id) {
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if (iter_info_len && target_btf_id)
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return libbpf_err(-EINVAL);
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if (!OPTS_ZEROED(opts, target_btf_id))
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return libbpf_err(-EINVAL);
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}
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memset(&attr, 0, sizeof(attr));
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attr.link_create.prog_fd = prog_fd;
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@ -693,14 +698,27 @@ int bpf_link_create(int prog_fd, int target_fd,
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attr.link_create.attach_type = attach_type;
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attr.link_create.flags = OPTS_GET(opts, flags, 0);
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if (iter_info_len) {
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attr.link_create.iter_info =
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ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
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attr.link_create.iter_info_len = iter_info_len;
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} else if (target_btf_id) {
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if (target_btf_id) {
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attr.link_create.target_btf_id = target_btf_id;
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goto proceed;
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}
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switch (attach_type) {
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case BPF_TRACE_ITER:
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attr.link_create.iter_info = ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
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attr.link_create.iter_info_len = iter_info_len;
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break;
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case BPF_PERF_EVENT:
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attr.link_create.perf_event.bpf_cookie = OPTS_GET(opts, perf_event.bpf_cookie, 0);
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if (!OPTS_ZEROED(opts, perf_event))
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return libbpf_err(-EINVAL);
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break;
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default:
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if (!OPTS_ZEROED(opts, flags))
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return libbpf_err(-EINVAL);
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break;
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}
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proceed:
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fd = sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
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return libbpf_err_errno(fd);
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}
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@ -177,8 +177,14 @@ struct bpf_link_create_opts {
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union bpf_iter_link_info *iter_info;
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__u32 iter_info_len;
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__u32 target_btf_id;
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union {
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struct {
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__u64 bpf_cookie;
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} perf_event;
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};
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size_t :0;
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};
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#define bpf_link_create_opts__last_field target_btf_id
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#define bpf_link_create_opts__last_field perf_event
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LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
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enum bpf_attach_type attach_type,
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@ -196,6 +196,17 @@ void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
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size_t cur_cnt, size_t max_cnt, size_t add_cnt);
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int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
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static inline bool libbpf_is_mem_zeroed(const char *p, ssize_t len)
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{
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while (len > 0) {
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if (*p)
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return false;
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p++;
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len--;
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}
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return true;
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}
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static inline bool libbpf_validate_opts(const char *opts,
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size_t opts_sz, size_t user_sz,
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const char *type_name)
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@ -204,16 +215,9 @@ static inline bool libbpf_validate_opts(const char *opts,
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pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
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return false;
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}
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if (user_sz > opts_sz) {
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size_t i;
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for (i = opts_sz; i < user_sz; i++) {
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if (opts[i]) {
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pr_warn("%s has non-zero extra bytes\n",
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type_name);
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return false;
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}
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}
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if (!libbpf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
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pr_warn("%s has non-zero extra bytes\n", type_name);
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return false;
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}
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return true;
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}
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@ -233,6 +237,14 @@ static inline bool libbpf_validate_opts(const char *opts,
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(opts)->field = value; \
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} while (0)
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#define OPTS_ZEROED(opts, last_nonzero_field) \
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({ \
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ssize_t __off = offsetofend(typeof(*(opts)), last_nonzero_field); \
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!(opts) || libbpf_is_mem_zeroed((const void *)opts + __off, \
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(opts)->sz - __off); \
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})
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int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
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int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
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int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
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