diff options
author | Yonghong Song <yhs@fb.com> | 2020-05-09 19:59:00 +0200 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-10 02:05:26 +0200 |
commit | 15d83c4d7cef5c067a8b075ce59e97df4f60706e (patch) | |
tree | b6baafd12655fe3a8d53f8db5d87fcfb95de4559 /kernel/bpf | |
parent | bpf: Implement an interface to register bpf_iter targets (diff) | |
download | linux-15d83c4d7cef5c067a8b075ce59e97df4f60706e.tar.xz linux-15d83c4d7cef5c067a8b075ce59e97df4f60706e.zip |
bpf: Allow loading of a bpf_iter program
A bpf_iter program is a tracing program with attach type
BPF_TRACE_ITER. The load attribute
attach_btf_id
is used by the verifier against a particular kernel function,
which represents a target, e.g., __bpf_iter__bpf_map
for target bpf_map which is implemented later.
The program return value must be 0 or 1 for now.
0 : successful, except potential seq_file buffer overflow
which is handled by seq_file reader.
1 : request to restart the same object
In the future, other return values may be used for filtering or
teminating the iterator.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175900.2474947-1-yhs@fb.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r-- | kernel/bpf/bpf_iter.c | 36 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 21 |
2 files changed, 57 insertions, 0 deletions
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index 5a8119d17d14..dec182d8395a 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -12,6 +12,7 @@ struct bpf_iter_target_info { bpf_iter_init_seq_priv_t init_seq_private; bpf_iter_fini_seq_priv_t fini_seq_private; u32 seq_priv_size; + u32 btf_id; /* cached value */ }; static struct list_head targets = LIST_HEAD_INIT(targets); @@ -57,3 +58,38 @@ void bpf_iter_unreg_target(const char *target) WARN_ON(found == false); } + +static void cache_btf_id(struct bpf_iter_target_info *tinfo, + struct bpf_prog *prog) +{ + tinfo->btf_id = prog->aux->attach_btf_id; +} + +bool bpf_iter_prog_supported(struct bpf_prog *prog) +{ + const char *attach_fname = prog->aux->attach_func_name; + u32 prog_btf_id = prog->aux->attach_btf_id; + const char *prefix = BPF_ITER_FUNC_PREFIX; + struct bpf_iter_target_info *tinfo; + int prefix_len = strlen(prefix); + bool supported = false; + + if (strncmp(attach_fname, prefix, prefix_len)) + return false; + + mutex_lock(&targets_mutex); + list_for_each_entry(tinfo, &targets, list) { + if (tinfo->btf_id && tinfo->btf_id == prog_btf_id) { + supported = true; + break; + } + if (!strcmp(attach_fname + prefix_len, tinfo->target)) { + cache_btf_id(tinfo, prog); + supported = true; + break; + } + } + mutex_unlock(&targets_mutex); + + return supported; +} diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 70ad009577f8..d725ff7d11db 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7101,6 +7101,10 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; range = tnum_const(0); break; + case BPF_PROG_TYPE_TRACING: + if (env->prog->expected_attach_type != BPF_TRACE_ITER) + return 0; + break; default: return 0; } @@ -10481,6 +10485,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) struct bpf_prog *tgt_prog = prog->aux->linked_prog; u32 btf_id = prog->aux->attach_btf_id; const char prefix[] = "btf_trace_"; + struct btf_func_model fmodel; int ret = 0, subprog = -1, i; struct bpf_trampoline *tr; const struct btf_type *t; @@ -10622,6 +10627,22 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) prog->aux->attach_func_proto = t; prog->aux->attach_btf_trace = true; return 0; + case BPF_TRACE_ITER: + if (!btf_type_is_func(t)) { + verbose(env, "attach_btf_id %u is not a function\n", + btf_id); + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + return -EINVAL; + prog->aux->attach_func_name = tname; + prog->aux->attach_func_proto = t; + if (!bpf_iter_prog_supported(prog)) + return -EINVAL; + ret = btf_distill_func_proto(&env->log, btf, t, + tname, &fmodel); + return ret; default: if (!prog_extension) return -EINVAL; |