| Message ID | 20240311093526.1010158-6-dongmenglong.8@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | bpf: make tracing program support multi-link | expand |
On Mon, Mar 11, 2024 at 2:35 AM Menglong Dong <dongmenglong.8@bytedance.com> wrote: > > Add target btf to the function args of bpf_check_attach_target(), then > the caller can specify the btf to check. > > Signed-off-by: Menglong Dong <dongmenglong.8@bytedance.com> > --- > include/linux/bpf_verifier.h | 1 + > kernel/bpf/syscall.c | 6 ++++-- > kernel/bpf/trampoline.c | 1 + > kernel/bpf/verifier.c | 8 +++++--- > 4 files changed, 11 insertions(+), 5 deletions(-) > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h > index 4b0f6600e499..6cb20efcfac3 100644 > --- a/include/linux/bpf_verifier.h > +++ b/include/linux/bpf_verifier.h > @@ -811,6 +811,7 @@ static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id) > int bpf_check_attach_target(struct bpf_verifier_log *log, > const struct bpf_prog *prog, > const struct bpf_prog *tgt_prog, > + struct btf *btf, > u32 btf_id, > struct bpf_attach_target_info *tgt_info); > void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index d1cd645ef9ac..6128c3131141 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -3401,9 +3401,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, > * need a new trampoline and a check for compatibility > */ > struct bpf_attach_target_info tgt_info = {}; > + struct btf *btf; > > - err = bpf_check_attach_target(NULL, prog, tgt_prog, btf_id, > - &tgt_info); > + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; I think it's better to keep this bit inside bpf_check_attach_target(), since a lot of other code in there is working with if (tgt_prog) ... so if the caller messes up passing tgt_prog->aux->btf with tgt_prog the bug will be difficult to debug. > + err = bpf_check_attach_target(NULL, prog, tgt_prog, btf, > + btf_id, &tgt_info);
On Tue, Mar 12, 2024 at 9:51 AM Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > > On Mon, Mar 11, 2024 at 2:35 AM Menglong Dong > <dongmenglong.8@bytedance.com> wrote: > > > > Add target btf to the function args of bpf_check_attach_target(), then > > the caller can specify the btf to check. > > > > Signed-off-by: Menglong Dong <dongmenglong.8@bytedance.com> > > --- > > include/linux/bpf_verifier.h | 1 + > > kernel/bpf/syscall.c | 6 ++++-- > > kernel/bpf/trampoline.c | 1 + > > kernel/bpf/verifier.c | 8 +++++--- > > 4 files changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h > > index 4b0f6600e499..6cb20efcfac3 100644 > > --- a/include/linux/bpf_verifier.h > > +++ b/include/linux/bpf_verifier.h > > @@ -811,6 +811,7 @@ static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id) > > int bpf_check_attach_target(struct bpf_verifier_log *log, > > const struct bpf_prog *prog, > > const struct bpf_prog *tgt_prog, > > + struct btf *btf, > > u32 btf_id, > > struct bpf_attach_target_info *tgt_info); > > void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index d1cd645ef9ac..6128c3131141 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -3401,9 +3401,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, > > * need a new trampoline and a check for compatibility > > */ > > struct bpf_attach_target_info tgt_info = {}; > > + struct btf *btf; > > > > - err = bpf_check_attach_target(NULL, prog, tgt_prog, btf_id, > > - &tgt_info); > > + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; > > I think it's better to keep this bit inside bpf_check_attach_target(), > since a lot of other code in there is working with if (tgt_prog) ... > so if the caller messes up passing tgt_prog->aux->btf with tgt_prog > the bug will be difficult to debug. In the previous version, I pass the attach_btf with the following way: + origin_btf = prog->aux->attach_btf; + /* use the new attach_btf to check the target */ + prog->aux->attach_btf = attach_btf; err = bpf_check_attach_target(NULL, prog, tgt_prog, btf_id, &tgt_info); + prog->aux->attach_btf = origin_btf; And Jiri suggested to add the attach_btf to the function args of bpf_check_attach_target(). Ennn....Should I convert to the old way? Thanks! Menglong Dong > > > + err = bpf_check_attach_target(NULL, prog, tgt_prog, btf, > > + btf_id, &tgt_info);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 4b0f6600e499..6cb20efcfac3 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -811,6 +811,7 @@ static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id) int bpf_check_attach_target(struct bpf_verifier_log *log, const struct bpf_prog *prog, const struct bpf_prog *tgt_prog, + struct btf *btf, u32 btf_id, struct bpf_attach_target_info *tgt_info); void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d1cd645ef9ac..6128c3131141 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3401,9 +3401,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * need a new trampoline and a check for compatibility */ struct bpf_attach_target_info tgt_info = {}; + struct btf *btf; - err = bpf_check_attach_target(NULL, prog, tgt_prog, btf_id, - &tgt_info); + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; + err = bpf_check_attach_target(NULL, prog, tgt_prog, btf, + btf_id, &tgt_info); if (err) goto out_unlock; diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 2167aa3fe583..b00d53af8fcb 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -747,6 +747,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, int err; err = bpf_check_attach_target(NULL, prog, NULL, + prog->aux->attach_btf, prog->aux->attach_btf_id, &tgt_info); if (err) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bf084c693507..4493ecc23597 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20613,6 +20613,7 @@ static int check_non_sleepable_error_inject(u32 btf_id) int bpf_check_attach_target(struct bpf_verifier_log *log, const struct bpf_prog *prog, const struct bpf_prog *tgt_prog, + struct btf *btf, u32 btf_id, struct bpf_attach_target_info *tgt_info) { @@ -20623,7 +20624,6 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, const struct btf_type *t; bool conservative = true; const char *tname; - struct btf *btf; long addr = 0; struct module *mod = NULL; @@ -20631,7 +20631,6 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, bpf_log(log, "Tracing programs must provide btf_id\n"); return -EINVAL; } - btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; if (!btf) { bpf_log(log, "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); @@ -20940,6 +20939,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) struct bpf_attach_target_info tgt_info = {}; u32 btf_id = prog->aux->attach_btf_id; struct bpf_trampoline *tr; + struct btf *btf; int ret; u64 key; @@ -20964,7 +20964,9 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) prog->type != BPF_PROG_TYPE_EXT) return 0; - ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info); + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; + ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf, + btf_id, &tgt_info); if (ret) return ret;
Add target btf to the function args of bpf_check_attach_target(), then the caller can specify the btf to check. Signed-off-by: Menglong Dong <dongmenglong.8@bytedance.com> --- include/linux/bpf_verifier.h | 1 + kernel/bpf/syscall.c | 6 ++++-- kernel/bpf/trampoline.c | 1 + kernel/bpf/verifier.c | 8 +++++--- 4 files changed, 11 insertions(+), 5 deletions(-)