| Message ID | 20250331094745.336010-2-chen.dylane@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [bpf-next,1/2] bpf: Check link_create parameter for multi_kprobe | expand |
On Mon, Mar 31, 2025 at 05:47:45PM +0800, Tao Chen wrote: > The target_fd and flags in link_create no used in multi_uprobe > , return -EINVAL if they assigned, keep it same as other link > attach apis. > > Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") > Signed-off-by: Tao Chen <chen.dylane@linux.dev> > --- > kernel/trace/bpf_trace.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 2f206a2a2..f7ebf17e3 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -3385,6 +3385,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > if (sizeof(u64) != sizeof(void *)) > return -EOPNOTSUPP; > > + if (attr->link_create.target_fd || attr->link_create.flags) > + return -EINVAL; I think the CI is failing because usdt code does uprobe multi detection with target_fd = -1 and it fails and perf-uprobe fallback will fail on not having enough file descriptors but I think at this stage we will brake some user apps by introducing this check, link ebpf go library, which passes 0 jirka > + > if (!is_uprobe_multi(prog)) > return -EINVAL; > > -- > 2.43.0 >
在 2025/4/1 19:03, Jiri Olsa 写道: > On Mon, Mar 31, 2025 at 05:47:45PM +0800, Tao Chen wrote: >> The target_fd and flags in link_create no used in multi_uprobe >> , return -EINVAL if they assigned, keep it same as other link >> attach apis. >> >> Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") >> Signed-off-by: Tao Chen <chen.dylane@linux.dev> >> --- >> kernel/trace/bpf_trace.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c >> index 2f206a2a2..f7ebf17e3 100644 >> --- a/kernel/trace/bpf_trace.c >> +++ b/kernel/trace/bpf_trace.c >> @@ -3385,6 +3385,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr >> if (sizeof(u64) != sizeof(void *)) >> return -EOPNOTSUPP; >> >> + if (attr->link_create.target_fd || attr->link_create.flags) >> + return -EINVAL; > > I think the CI is failing because usdt code does uprobe multi detection > with target_fd = -1 and it fails and perf-uprobe fallback will fail on > not having enough file descriptors > Hi jiri As you said, i found it, thanks. static int probe_uprobe_multi_link(int token_fd) { LIBBPF_OPTS(bpf_prog_load_opts, load_opts, .expected_attach_type = BPF_TRACE_UPROBE_MULTI, .token_fd = token_fd, .prog_flags = token_fd ? BPF_F_TOKEN_FD : 0, ); LIBBPF_OPTS(bpf_link_create_opts, link_opts); struct bpf_insn insns[] = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; int prog_fd, link_fd, err; unsigned long offset = 0; prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, ARRAY_SIZE(insns), &load_opts); if (prog_fd < 0) return -errno; /* Creating uprobe in '/' binary should fail with -EBADF. */ link_opts.uprobe_multi.path = "/"; link_opts.uprobe_multi.offsets = &offset; link_opts.uprobe_multi.cnt = 1; link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); > but I think at this stage we will brake some user apps by introducing > this check, link ebpf go library, which passes 0 > So is it ok just check the flags? > jirka > > >> + >> if (!is_uprobe_multi(prog)) >> return -EINVAL; >> >> -- >> 2.43.0 >>
On Tue, Apr 1, 2025 at 5:40 AM Tao Chen <chen.dylane@linux.dev> wrote: > > 在 2025/4/1 19:03, Jiri Olsa 写道: > > On Mon, Mar 31, 2025 at 05:47:45PM +0800, Tao Chen wrote: > >> The target_fd and flags in link_create no used in multi_uprobe > >> , return -EINVAL if they assigned, keep it same as other link > >> attach apis. > >> > >> Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") > >> Signed-off-by: Tao Chen <chen.dylane@linux.dev> > >> --- > >> kernel/trace/bpf_trace.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > >> index 2f206a2a2..f7ebf17e3 100644 > >> --- a/kernel/trace/bpf_trace.c > >> +++ b/kernel/trace/bpf_trace.c > >> @@ -3385,6 +3385,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > >> if (sizeof(u64) != sizeof(void *)) > >> return -EOPNOTSUPP; > >> > >> + if (attr->link_create.target_fd || attr->link_create.flags) > >> + return -EINVAL; > > > > I think the CI is failing because usdt code does uprobe multi detection > > with target_fd = -1 and it fails and perf-uprobe fallback will fail on > > not having enough file descriptors > > > > Hi jiri > > As you said, i found it, thanks. > > static int probe_uprobe_multi_link(int token_fd) > { > LIBBPF_OPTS(bpf_prog_load_opts, load_opts, > .expected_attach_type = BPF_TRACE_UPROBE_MULTI, > .token_fd = token_fd, > .prog_flags = token_fd ? BPF_F_TOKEN_FD : 0, > ); > LIBBPF_OPTS(bpf_link_create_opts, link_opts); > struct bpf_insn insns[] = { > BPF_MOV64_IMM(BPF_REG_0, 0), > BPF_EXIT_INSN(), > }; > int prog_fd, link_fd, err; > unsigned long offset = 0; > > prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", > insns, ARRAY_SIZE(insns), &load_opts); > if (prog_fd < 0) > return -errno; > > /* Creating uprobe in '/' binary should fail with -EBADF. */ > link_opts.uprobe_multi.path = "/"; > link_opts.uprobe_multi.offsets = &offset; > link_opts.uprobe_multi.cnt = 1; > > link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, > &link_opts); > > > but I think at this stage we will brake some user apps by introducing > > this check, link ebpf go library, which passes 0 > > > > So is it ok just check the flags? good catch, Jiri! Yep, let's validate just flags? pw-bot: cr > > > jirka > > > > > >> + > >> if (!is_uprobe_multi(prog)) > >> return -EINVAL; > >> > >> -- > >> 2.43.0 > >> > > > -- > Best Regards > Tao Chen >
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 2f206a2a2..f7ebf17e3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3385,6 +3385,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr if (sizeof(u64) != sizeof(void *)) return -EOPNOTSUPP; + if (attr->link_create.target_fd || attr->link_create.flags) + return -EINVAL; + if (!is_uprobe_multi(prog)) return -EINVAL;
The target_fd and flags in link_create no used in multi_uprobe , return -EINVAL if they assigned, keep it same as other link attach apis. Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") Signed-off-by: Tao Chen <chen.dylane@linux.dev> --- kernel/trace/bpf_trace.c | 3 +++ 1 file changed, 3 insertions(+)