| Message ID | 20210414195147.1624932-2-jolsa@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | [PATCHv5,bpf-next,1/7] bpf: Allow trampoline re-attach for tracing and lsm programs | expand |
On Wed, Apr 14, 2021 at 5:44 PM Jiri Olsa <jolsa@kernel.org> wrote: > > Currently we don't allow re-attaching of trampolines. Once > it's detached, it can't be re-attach even when the program > is still loaded. > > Adding the possibility to re-attach the loaded tracing and > lsm programs. > > Fixing missing unlock with proper cleanup goto jump reported > by Julia. > > Reported-by: kernel test robot <lkp@intel.com> > Reported-by: Julia Lawall <julia.lawall@lip6.fr> > Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- Acked-by: Andrii Nakryiko <andrii@kernel.org> > kernel/bpf/syscall.c | 23 +++++++++++++++++------ > kernel/bpf/trampoline.c | 4 ++-- > 2 files changed, 19 insertions(+), 8 deletions(-) > [...]
On Fri, Apr 16, 2021 at 1:22 AM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Wed, Apr 14, 2021 at 5:44 PM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Currently we don't allow re-attaching of trampolines. Once > > it's detached, it can't be re-attach even when the program > > is still loaded. > > > > Adding the possibility to re-attach the loaded tracing and > > lsm programs. > > > > Fixing missing unlock with proper cleanup goto jump reported > > by Julia. > > > > Reported-by: kernel test robot <lkp@intel.com> > > Reported-by: Julia Lawall <julia.lawall@lip6.fr> > > Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > Acked-by: Andrii Nakryiko <andrii@kernel.org> Thanks! Acked-by: KP Singh <kpsingh@kernel.org>
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index fd495190115e..941ca06d9dfa 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2648,14 +2648,25 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * target_btf_id using the link_create API. * * - if tgt_prog == NULL when this function was called using the old - * raw_tracepoint_open API, and we need a target from prog->aux - * - * The combination of no saved target in prog->aux, and no target - * specified on load is illegal, and we reject that here. + * raw_tracepoint_open API, and we need a target from prog->aux + * + * - if prog->aux->dst_trampoline and tgt_prog is NULL, the program + * was detached and is going for re-attachment. */ if (!prog->aux->dst_trampoline && !tgt_prog) { - err = -ENOENT; - goto out_unlock; + /* + * Allow re-attach for TRACING and LSM programs. If it's + * currently linked, bpf_trampoline_link_prog will fail. + * EXT programs need to specify tgt_prog_fd, so they + * re-attach in separate code path. + */ + if (prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM) { + err = -EINVAL; + goto out_unlock; + } + btf_id = prog->aux->attach_btf_id; + key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id); } if (!prog->aux->dst_trampoline || diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 1f3a4be4b175..205c2cc36ad7 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -414,7 +414,7 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) tr->progs_cnt[kind]++; err = bpf_trampoline_update(tr); if (err) { - hlist_del(&prog->aux->tramp_hlist); + hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; } out: @@ -437,7 +437,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) tr->extension_prog = NULL; goto out; } - hlist_del(&prog->aux->tramp_hlist); + hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; err = bpf_trampoline_update(tr); out: