diff options
Diffstat (limited to 'kernel/bpf/syscall.c')
| -rw-r--r-- | kernel/bpf/syscall.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 1bf9805ee185..a1f18681721c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2738,6 +2738,22 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) goto free_prog_sec; } + /* + * Bookkeeping for managing the program attachment chain. + * + * It might be tempting to set attach_tracing_prog flag at the attachment + * time, but this will not prevent from loading bunch of tracing prog + * first, then attach them one to another. + * + * The flag attach_tracing_prog is set for the whole program lifecycle, and + * doesn't have to be cleared in bpf_tracing_link_release, since tracing + * programs cannot change attachment target. + */ + if (type == BPF_PROG_TYPE_TRACING && dst_prog && + dst_prog->type == BPF_PROG_TYPE_TRACING) { + prog->aux->attach_tracing_prog = true; + } + /* find program type: socket_filter vs tracing_filter */ err = find_prog_type(type, prog); if (err < 0) @@ -3171,7 +3187,12 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, } if (tgt_prog_fd) { - /* For now we only allow new targets for BPF_PROG_TYPE_EXT */ + /* + * For now we only allow new targets for BPF_PROG_TYPE_EXT. If this + * part would be changed to implement the same for + * BPF_PROG_TYPE_TRACING, do not forget to update the way how + * attach_tracing_prog flag is set. + */ if (prog->type != BPF_PROG_TYPE_EXT) { err = -EINVAL; goto out_put_prog; @@ -3216,6 +3237,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * * - 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 is NULL and tgt_prog and prog->aux->attach_btf + * are NULL, then program was already attached and user did not provide + * tgt_prog_fd so we have no way to find out or create trampoline */ if (!prog->aux->dst_trampoline && !tgt_prog) { /* @@ -3229,6 +3254,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, err = -EINVAL; goto out_unlock; } + /* We can allow re-attach only if we have valid attach_btf. */ + if (!prog->aux->attach_btf) { + err = -EINVAL; + goto out_unlock; + } btf_id = prog->aux->attach_btf_id; key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id); } |