From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH v2 bpf-next 10/14] libbpf: add user_ctx support to bpf_link_create() API
Date: Mon, 26 Jul 2021 09:12:07 -0700 [thread overview]
Message-ID: <20210726161211.925206-11-andrii@kernel.org> (raw)
In-Reply-To: <20210726161211.925206-1-andrii@kernel.org>
Add ability to specify user_ctx 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>
---
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..8dcbee80ced7 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.user_ctx = OPTS_GET(opts, perf_event.user_ctx, 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..49d5d08c3832 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 user_ctx;
+ } 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 016ca7cb4f8a..e371188c8f87 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -195,6 +195,17 @@ 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)
@@ -203,16 +214,9 @@ 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;
}
@@ -232,6 +236,14 @@ 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
next prev parent reply other threads:[~2021-07-26 16:13 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 16:11 [PATCH v2 bpf-next 00/14] BPF perf link and user-provided context value Andrii Nakryiko
2021-07-26 16:11 ` [PATCH v2 bpf-next 01/14] bpf: refactor BPF_PROG_RUN into a function Andrii Nakryiko
2021-07-29 16:49 ` Yonghong Song
2021-07-30 4:05 ` Andrii Nakryiko
2021-07-26 16:11 ` [PATCH v2 bpf-next 02/14] bpf: refactor BPF_PROG_RUN_ARRAY family of macros into functions Andrii Nakryiko
2021-07-29 17:04 ` Yonghong Song
2021-07-26 16:12 ` [PATCH v2 bpf-next 03/14] bpf: refactor perf_event_set_bpf_prog() to use struct bpf_prog input Andrii Nakryiko
2021-07-27 8:48 ` Peter Zijlstra
2021-07-29 17:09 ` Yonghong Song
2021-07-26 16:12 ` [PATCH v2 bpf-next 04/14] bpf: implement minimal BPF perf link Andrii Nakryiko
2021-07-27 9:04 ` Peter Zijlstra
2021-07-30 4:23 ` Andrii Nakryiko
2021-07-27 9:12 ` Peter Zijlstra
2021-07-27 20:56 ` Andrii Nakryiko
2021-07-27 15:40 ` Jiri Olsa
2021-07-27 20:56 ` Andrii Nakryiko
2021-07-29 17:35 ` Yonghong Song
2021-07-30 4:16 ` Andrii Nakryiko
2021-07-30 5:42 ` Yonghong Song
2021-07-26 16:12 ` [PATCH v2 bpf-next 05/14] bpf: allow to specify user-provided context value for BPF perf links Andrii Nakryiko
2021-07-27 9:11 ` Peter Zijlstra
2021-07-27 21:09 ` Andrii Nakryiko
2021-07-28 8:58 ` Peter Zijlstra
2021-07-29 18:00 ` Yonghong Song
2021-07-30 4:31 ` Andrii Nakryiko
2021-07-30 5:49 ` Yonghong Song
2021-07-30 17:48 ` Andrii Nakryiko
2021-07-30 21:34 ` Yonghong Song
2021-07-30 22:06 ` Andrii Nakryiko
2021-07-30 22:28 ` Yonghong Song
2021-07-26 16:12 ` [PATCH v2 bpf-next 06/14] bpf: add bpf_get_user_ctx() BPF helper to access user_ctx value Andrii Nakryiko
2021-07-29 18:17 ` Yonghong Song
2021-07-30 4:49 ` Andrii Nakryiko
2021-07-30 5:53 ` Yonghong Song
2021-07-26 16:12 ` [PATCH v2 bpf-next 07/14] libbpf: re-build libbpf.so when libbpf.map changes Andrii Nakryiko
2021-07-26 16:12 ` [PATCH v2 bpf-next 08/14] libbpf: remove unused bpf_link's destroy operation, but add dealloc Andrii Nakryiko
2021-07-26 16:12 ` [PATCH v2 bpf-next 09/14] libbpf: use BPF perf link when supported by kernel Andrii Nakryiko
2021-07-26 16:12 ` Andrii Nakryiko [this message]
2021-07-26 16:12 ` [PATCH v2 bpf-next 11/14] libbpf: add user_ctx to perf_event, kprobe, uprobe, and tp attach APIs Andrii Nakryiko
2021-07-30 1:11 ` Rafael David Tinoco
2021-07-26 16:12 ` [PATCH v2 bpf-next 12/14] selftests/bpf: test low-level perf BPF link API Andrii Nakryiko
2021-07-26 16:12 ` [PATCH v2 bpf-next 13/14] selftests/bpf: extract uprobe-related helpers into trace_helpers.{c,h} Andrii Nakryiko
2021-07-26 16:12 ` [PATCH v2 bpf-next 14/14] selftests/bpf: add user_ctx selftests for high-level APIs Andrii Nakryiko
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