From: Andrii Nakryiko <andrii@kernel.org>
Date: Sun, 15 Aug 2021 00:05:59 -0700
Subject: bpf: Add bpf_get_attach_cookie() BPF helper to access bpf_cookie
value
Patch-mainline: v5.15-rc1
Git-commit: 7adfc6c9b315e174cf8743b21b7b691c8766791b
References: jsc#PED-1377
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs
to get access to a user-provided bpf_cookie value, specified during BPF
program attachment (BPF link creation) time.
Naming is hard, though. With the concept being named "BPF cookie", I've
considered calling the helper:
- bpf_get_cookie() -- seems too unspecific and easily mistaken with socket
cookie;
- bpf_get_bpf_cookie() -- too much tautology;
- bpf_get_link_cookie() -- would be ok, but while we create a BPF link to
attach BPF program to BPF hook, it's still an "attachment" and the
bpf_cookie is associated with BPF program attachment to a hook, not a BPF
link itself. Technically, we could support bpf_cookie with old-style
cgroup programs.So I ultimately rejected it in favor of
bpf_get_attach_cookie().
Currently all perf_event-backed BPF program types support
bpf_get_attach_cookie() helper. Follow-up patches will add support for
fentry/fexit programs as well.
While at it, mark bpf_tracing_func_proto() as static to make it obvious that
it's only used from within the kernel/trace/bpf_trace.c.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
include/linux/bpf.h | 3 ---
include/uapi/linux/bpf.h | 16 ++++++++++++++++
kernel/trace/bpf_trace.c | 35 ++++++++++++++++++++++++++++++++++-
tools/include/uapi/linux/bpf.h | 16 ++++++++++++++++
4 files changed, 66 insertions(+), 4 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2102,9 +2102,6 @@ extern const struct bpf_func_proto bpf_b
extern const struct bpf_func_proto bpf_sk_setsockopt_proto;
extern const struct bpf_func_proto bpf_sk_getsockopt_proto;
-const struct bpf_func_proto *bpf_tracing_func_proto(
- enum bpf_func_id func_id, const struct bpf_prog *prog);
-
const struct bpf_func_proto *tracing_prog_func_proto(
enum bpf_func_id func_id, const struct bpf_prog *prog);
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4856,6 +4856,21 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
+ *
+ * u64 bpf_get_attach_cookie(void *ctx)
+ * Description
+ * Get bpf_cookie value provided (optionally) during the program
+ * attachment. It might be different for each individual
+ * attachment, even if BPF program itself is the same.
+ * Expects BPF program context *ctx* as a first argument.
+ *
+ * Supported for the following program types:
+ * - kprobe/uprobe;
+ * - tracepoint;
+ * - perf_event.
+ * Return
+ * Value specified by user at BPF link creation/attachment time
+ * or 0, if it was not specified.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5032,6 +5047,7 @@ union bpf_attr {
FN(timer_start), \
FN(timer_cancel), \
FN(get_func_ip), \
+ FN(get_attach_cookie), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -975,7 +975,34 @@ static const struct bpf_func_proto bpf_g
.arg1_type = ARG_PTR_TO_CTX,
};
-const struct bpf_func_proto *
+BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
+{
+ struct bpf_trace_run_ctx *run_ctx;
+
+ run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
+ return run_ctx->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_trace = {
+ .func = bpf_get_attach_cookie_trace,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_get_attach_cookie_pe, struct bpf_perf_event_data_kern *, ctx)
+{
+ return ctx->event->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = {
+ .func = bpf_get_attach_cookie_pe,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
@@ -1109,6 +1136,8 @@ kprobe_prog_func_proto(enum bpf_func_id
#endif
case BPF_FUNC_get_func_ip:
return &bpf_get_func_ip_proto_kprobe;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1219,6 +1248,8 @@ tp_prog_func_proto(enum bpf_func_id func
return &bpf_get_stackid_proto_tp;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1326,6 +1357,8 @@ pe_prog_func_proto(enum bpf_func_id func
return &bpf_perf_prog_read_value_proto;
case BPF_FUNC_read_branch_records:
return &bpf_read_branch_records_proto;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_pe;
default:
return bpf_tracing_func_proto(func_id, prog);
}
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4859,6 +4859,21 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
+ *
+ * u64 bpf_get_attach_cookie(void *ctx)
+ * Description
+ * Get bpf_cookie value provided (optionally) during the program
+ * attachment. It might be different for each individual
+ * attachment, even if BPF program itself is the same.
+ * Expects BPF program context *ctx* as a first argument.
+ *
+ * Supported for the following program types:
+ * - kprobe/uprobe;
+ * - tracepoint;
+ * - perf_event.
+ * Return
+ * Value specified by user at BPF link creation/attachment time
+ * or 0, if it was not specified.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5035,6 +5050,7 @@ union bpf_attr {
FN(timer_start), \
FN(timer_cancel), \
FN(get_func_ip), \
+ FN(get_attach_cookie), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper