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@xxxxxxxxxx>
---
tools/lib/bpf/bpf.c | 32 +++++++++++++++++++++++++-------
tools/lib/bpf/bpf.h | 8 +++++++-
tools/lib/bpf/libbpf_internal.h | 32 ++++++++++++++++++++++----------
3 files changed, 54 insertions(+), 18 deletions(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 86dcac44f32f..2401fad090c5 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -684,8 +684,13 @@ int bpf_link_create(int prog_fd, int target_fd,
iter_info_len = OPTS_GET(opts, iter_info_len, 0);
target_btf_id = OPTS_GET(opts, target_btf_id, 0);
- if (iter_info_len && target_btf_id)
- return libbpf_err(-EINVAL);
+ /* validate we don't have unexpected combinations of non-zero fields */
+ if (iter_info_len || target_btf_id) {
+ if (iter_info_len && target_btf_id)
+ return libbpf_err(-EINVAL);
+ if (!OPTS_ZEROED(opts, target_btf_id))
+ return libbpf_err(-EINVAL);
+ }
memset(&attr, 0, sizeof(attr));
attr.link_create.prog_fd = prog_fd;
@@ -693,14 +698,27 @@ int bpf_link_create(int prog_fd, int target_fd,
attr.link_create.attach_type = attach_type;
attr.link_create.flags = OPTS_GET(opts, flags, 0);
- if (iter_info_len) {
- attr.link_create.iter_info =
- ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
- attr.link_create.iter_info_len = iter_info_len;
- } else if (target_btf_id) {
+ if (target_btf_id) {
attr.link_create.target_btf_id = target_btf_id;
+ goto proceed;
}
+ switch (attach_type) {
+ case BPF_TRACE_ITER:
+ attr.link_create.iter_info = ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
+ attr.link_create.iter_info_len = iter_info_len;
+ break;
+ case BPF_PERF_EVENT:
+ attr.link_create.perf_event.bpf_cookie = OPTS_GET(opts, perf_event.bpf_cookie, 0);
+ if (!OPTS_ZEROED(opts, perf_event))
+ return libbpf_err(-EINVAL);
+ break;
+ default:
+ if (!OPTS_ZEROED(opts, flags))
+ return libbpf_err(-EINVAL);
+ break;
+ }
+proceed:
fd = sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
return libbpf_err_errno(fd);
}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 4f758f8f50cd..6fffb3cdf39b 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -177,8 +177,14 @@ struct bpf_link_create_opts {
union bpf_iter_link_info *iter_info;
__u32 iter_info_len;
__u32 target_btf_id;
+ union {
+ struct {
+ __u64 bpf_cookie;
+ } perf_event;
+ };
+ size_t :0;
};
-#define bpf_link_create_opts__last_field target_btf_id
+#define bpf_link_create_opts__last_field perf_event
LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f7b691d5f9eb..533b0211f40a 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -196,6 +196,17 @@ void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
size_t cur_cnt, size_t max_cnt, size_t add_cnt);
int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
+static inline bool libbpf_is_mem_zeroed(const char *p, ssize_t len)
+{
+ while (len > 0) {
+ if (*p)
+ return false;
+ p++;
+ len--;
+ }
+ return true;
+}
+
static inline bool libbpf_validate_opts(const char *opts,
size_t opts_sz, size_t user_sz,
const char *type_name)
@@ -204,16 +215,9 @@ static inline bool libbpf_validate_opts(const char *opts,
pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
return false;
}
- if (user_sz > opts_sz) {
- size_t i;
-
- for (i = opts_sz; i < user_sz; i++) {
- if (opts[i]) {
- pr_warn("%s has non-zero extra bytes\n",
- type_name);
- return false;
- }
- }
+ if (!libbpf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
+ pr_warn("%s has non-zero extra bytes\n", type_name);
+ return false;
}
return true;
}
@@ -233,6 +237,14 @@ static inline bool libbpf_validate_opts(const char *opts,
(opts)->field = value; \
} while (0)
+#define OPTS_ZEROED(opts, last_nonzero_field) \
+({ \
+ ssize_t __off = offsetofend(typeof(*(opts)), last_nonzero_field); \
+ !(opts) || libbpf_is_mem_zeroed((const void *)opts + __off, \
+ (opts)->sz - __off); \
+})
+
+
int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
--
2.30.2
