[PATCHv5 bpf-next 04/28] bpf: Add cookies support for uprobe_multi link

Jiri Olsa
2023-07-30T13:43:09Z

Adding support to specify cookies array for uprobe_multi link.

The cookies array share indexes and length with other uprobe_multi
arrays (offsets/ref_ctr_offsets).

The cookies[i] value defines cookie for i-the uprobe and will be
returned by bpf_get_attach_cookie helper when called from ebpf
program hooked to that specific uprobe.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/uapi/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 2 +-
kernel/trace/bpf_trace.c | 45 +++++++++++++++++++++++++++++++---
tools/include/uapi/linux/bpf.h | 1 +
4 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f112a0b948f3..2b6cd7d1c165 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1639,6 +1639,7 @@ union bpf_attr {
__aligned_u64 path;
__aligned_u64 offsets;
__aligned_u64 ref_ctr_offsets;
+ __aligned_u64 cookies;
__u32 cnt;
__u32 flags;
} uprobe_multi;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 75c83300339e..98459fb34ff7 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4883,7 +4883,7 @@ static int bpf_map_do_batch(const union bpf_attr *attr,
return err;
}

-#define BPF_LINK_CREATE_LAST_FIELD link_create.kprobe_multi.cookies
+#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.flags
static int link_create(union bpf_attr *attr, bpfptr_t uattr)
{
struct bpf_prog *prog;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 10284fd46f98..d73a47bd2bbd 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -87,6 +87,8 @@ static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx);
static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx);

+static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx);
+
/**
* trace_call_bpf - invoke BPF program
* @call: tracepoint event
@@ -1099,6 +1101,18 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto_kmulti = {
.arg1_type = ARG_PTR_TO_CTX,
};

+BPF_CALL_1(bpf_get_attach_cookie_uprobe_multi, struct pt_regs *, regs)
+{
+ return bpf_uprobe_multi_cookie(current->bpf_ctx);
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_umulti = {
+ .func = bpf_get_attach_cookie_uprobe_multi,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
{
struct bpf_trace_run_ctx *run_ctx;
@@ -1545,9 +1559,11 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
&bpf_get_func_ip_proto_kprobe_multi :
&bpf_get_func_ip_proto_kprobe;
case BPF_FUNC_get_attach_cookie:
- return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
- &bpf_get_attach_cookie_proto_kmulti :
- &bpf_get_attach_cookie_proto_trace;
+ if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI)
+ return &bpf_get_attach_cookie_proto_kmulti;
+ if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI)
+ return &bpf_get_attach_cookie_proto_umulti;
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -2973,6 +2989,7 @@ struct bpf_uprobe_multi_link;
struct bpf_uprobe {
struct bpf_uprobe_multi_link *link;
loff_t offset;
+ u64 cookie;
struct uprobe_consumer consumer;
};

@@ -2986,6 +3003,7 @@ struct bpf_uprobe_multi_link {
struct bpf_uprobe_multi_run_ctx {
struct bpf_run_ctx run_ctx;
unsigned long entry_ip;
+ struct bpf_uprobe *uprobe;
};

static void bpf_uprobe_unregister(struct path *path, struct bpf_uprobe *uprobes,
@@ -3029,6 +3047,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
struct bpf_uprobe_multi_link *link = uprobe->link;
struct bpf_uprobe_multi_run_ctx run_ctx = {
.entry_ip = entry_ip,
+ .uprobe = uprobe,
};
struct bpf_prog *prog = link->link.prog;
bool sleepable = prog->aux->sleepable;
@@ -3075,6 +3094,14 @@ uprobe_multi_link_ret_handler(struct uprobe_consumer *con, unsigned long func, s
return uprobe_prog_run(uprobe, func, regs);
}

+static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
+{
+ struct bpf_uprobe_multi_run_ctx *run_ctx;
+
+ run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx, run_ctx);
+ return run_ctx->uprobe->cookie;
+}
+
int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
struct bpf_uprobe_multi_link *link = NULL;
@@ -3083,6 +3110,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
struct bpf_link_primer link_primer;
struct bpf_uprobe *uprobes = NULL;
unsigned long __user *uoffsets;
+ u64 __user *ucookies;
void __user *upath;
u32 flags, cnt, i;
struct path path;
@@ -3102,7 +3130,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr

/*
* path, offsets and cnt are mandatory,
- * ref_ctr_offsets is optional
+ * ref_ctr_offsets and cookies are optional
*/
upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
@@ -3112,6 +3140,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
return -EINVAL;

uref_ctr_offsets = u64_to_user_ptr(attr->link_create.uprobe_multi.ref_ctr_offsets);
+ ucookies = u64_to_user_ptr(attr->link_create.uprobe_multi.cookies);

name = strndup_user(upath, PATH_MAX);
if (IS_ERR(name)) {
@@ -3144,6 +3173,10 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
}

for (i = 0; i < cnt; i++) {
+ if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) {
+ err = -EFAULT;
+ goto error_free;
+ }
if (uref_ctr_offsets && __get_user(ref_ctr_offsets[i], uref_ctr_offsets + i)) {
err = -EFAULT;
goto error_free;
@@ -3201,4 +3234,8 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
{
return -EOPNOTSUPP;
}
+static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
+{
+ return 0;
+}
#endif /* CONFIG_UPROBES */
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index f112a0b948f3..2b6cd7d1c165 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1639,6 +1639,7 @@ union bpf_attr {
__aligned_u64 path;
__aligned_u64 offsets;
__aligned_u64 ref_ctr_offsets;
+ __aligned_u64 cookies;
__u32 cnt;
__u32 flags;
} uprobe_multi;
--
2.41.0