diff mbox series

[PATCHv2,bpf] bpf: Force kprobe multi expected_attach_type for kprobe_multi link

Message ID 20230618131414.75649-1-jolsa@kernel.org (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series [PATCHv2,bpf] bpf: Force kprobe multi expected_attach_type for kprobe_multi link | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for bpf
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 10 this patch: 10
netdev/cc_maintainers warning 3 maintainers not CCed: kpsingh@kernel.org martin.lau@linux.dev song@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 10 this patch: 10
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 11 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-PR fail PR summary
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Commit Message

Jiri Olsa June 18, 2023, 1:14 p.m. UTC 
We currently allow to create perf link for program with
expected_attach_type == BPF_TRACE_KPROBE_MULTI.

This will cause crash when we call helpers like get_attach_cookie or
get_func_ip in such program, because it will call the kprobe_multi's
version (current->bpf_ctx context setup) of those helpers while it
expects perf_link's current->bpf_ctx context setup.

Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
only for programs attaching through kprobe_multi link.

Fixes: ca74823c6e16 ("bpf: Add cookie support to programs attached with kprobe multi link")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/syscall.c | 5 +++++
 1 file changed, 5 insertions(+)

 v2 changes:
 - moved the check to bpf_prog_attach_check_attach_type [Andrii]

Comments

Andrii Nakryiko June 20, 2023, 5:20 p.m. UTC | #1 
On Sun, Jun 18, 2023 at 6:14 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> We currently allow to create perf link for program with
> expected_attach_type == BPF_TRACE_KPROBE_MULTI.
>
> This will cause crash when we call helpers like get_attach_cookie or
> get_func_ip in such program, because it will call the kprobe_multi's
> version (current->bpf_ctx context setup) of those helpers while it
> expects perf_link's current->bpf_ctx context setup.
>
> Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
> only for programs attaching through kprobe_multi link.
>
> Fixes: ca74823c6e16 ("bpf: Add cookie support to programs attached with kprobe multi link")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  kernel/bpf/syscall.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
>  v2 changes:
>  - moved the check to bpf_prog_attach_check_attach_type [Andrii]
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 0c21d0d8efe4..129cc5c276c0 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -3440,6 +3440,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
>                 return prog->enforce_expected_attach_type &&
>                         prog->expected_attach_type != attach_type ?
>                         -EINVAL : 0;
> +       case BPF_PROG_TYPE_KPROBE:
> +               if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
> +                   attach_type != BPF_TRACE_KPROBE_MULTI)
> +                       return -EINVAL;
> +               fallthrough;

there is no point in falling through (other branches return without
falling through as well), so I replaced this with `return 0;` and
applied to bpf tree, thanks.


>         default:
>                 return 0;
>         }
> --
> 2.41.0
>
diff mbox series

Patch

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0c21d0d8efe4..129cc5c276c0 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3440,6 +3440,11 @@  static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
 		return prog->enforce_expected_attach_type &&
 			prog->expected_attach_type != attach_type ?
 			-EINVAL : 0;
+	case BPF_PROG_TYPE_KPROBE:
+		if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
+		    attach_type != BPF_TRACE_KPROBE_MULTI)
+			return -EINVAL;
+		fallthrough;
 	default:
 		return 0;
 	}