diff options
author | Yonghong Song <yhs@fb.com> | 2020-06-24 02:08:09 +0300 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-06-25 04:37:59 +0300 |
commit | af7ec13833619e17f03aa73a785a2f871da6d66b (patch) | |
tree | 80a186e36a8007eeebb720adca3d59654d31fe86 /kernel | |
parent | 72e2b2b66f9c1225e51fc4a1c1e8512959195b76 (diff) | |
download | linux-af7ec13833619e17f03aa73a785a2f871da6d66b.tar.xz |
bpf: Add bpf_skc_to_tcp6_sock() helper
The helper is used in tracing programs to cast a socket
pointer to a tcp6_sock pointer.
The return value could be NULL if the casting is illegal.
A new helper return type RET_PTR_TO_BTF_ID_OR_NULL is added
so the verifier is able to deduce proper return types for the helper.
Different from the previous BTF_ID based helpers,
the bpf_skc_to_tcp6_sock() argument can be several possible
btf_ids. More specifically, all possible socket data structures
with sock_common appearing in the first in the memory layout.
This patch only added socket types related to tcp and udp.
All possible argument btf_id and return value btf_id
for helper bpf_skc_to_tcp6_sock() are pre-calculcated and
cached. In the future, it is even possible to precompute
these btf_id's at kernel build time.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200623230809.3988195-1-yhs@fb.com
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/bpf/btf.c | 1 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 43 | ||||
-rw-r--r-- | kernel/trace/bpf_trace.c | 2 |
3 files changed, 36 insertions, 10 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e377d1981730..4c3007f428b1 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3674,6 +3674,7 @@ struct btf *btf_parse_vmlinux(void) goto errout; bpf_struct_ops_init(btf, log); + init_btf_sock_ids(btf); btf_verifier_env_free(env); refcount_set(&btf->refcnt, 1); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7460f967cb75..7de98906ddf4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3800,12 +3800,14 @@ static int int_ptr_type_to_size(enum bpf_arg_type type) return -EINVAL; } -static int check_func_arg(struct bpf_verifier_env *env, u32 regno, - enum bpf_arg_type arg_type, - struct bpf_call_arg_meta *meta) +static int check_func_arg(struct bpf_verifier_env *env, u32 arg, + struct bpf_call_arg_meta *meta, + const struct bpf_func_proto *fn) { + u32 regno = BPF_REG_1 + arg; struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; enum bpf_reg_type expected_type, type = reg->type; + enum bpf_arg_type arg_type = fn->arg_type[arg]; int err = 0; if (arg_type == ARG_DONTCARE) @@ -3885,9 +3887,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, expected_type = PTR_TO_BTF_ID; if (type != expected_type) goto err_type; - if (reg->btf_id != meta->btf_id) { - verbose(env, "Helper has type %s got %s in R%d\n", - kernel_type_name(meta->btf_id), + if (!fn->check_btf_id) { + if (reg->btf_id != meta->btf_id) { + verbose(env, "Helper has type %s got %s in R%d\n", + kernel_type_name(meta->btf_id), + kernel_type_name(reg->btf_id), regno); + + return -EACCES; + } + } else if (!fn->check_btf_id(reg->btf_id, arg)) { + verbose(env, "Helper does not support %s in R%d\n", kernel_type_name(reg->btf_id), regno); return -EACCES; @@ -4709,10 +4718,12 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn meta.func_id = func_id; /* check args */ for (i = 0; i < 5; i++) { - err = btf_resolve_helper_id(&env->log, fn, i); - if (err > 0) - meta.btf_id = err; - err = check_func_arg(env, BPF_REG_1 + i, fn->arg_type[i], &meta); + if (!fn->check_btf_id) { + err = btf_resolve_helper_id(&env->log, fn, i); + if (err > 0) + meta.btf_id = err; + } + err = check_func_arg(env, i, &meta, fn); if (err) return err; } @@ -4815,6 +4826,18 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn regs[BPF_REG_0].type = PTR_TO_MEM_OR_NULL; regs[BPF_REG_0].id = ++env->id_gen; regs[BPF_REG_0].mem_size = meta.mem_size; + } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) { + int ret_btf_id; + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL; + ret_btf_id = *fn->ret_btf_id; + if (ret_btf_id == 0) { + verbose(env, "invalid return type %d of func %s#%d\n", + fn->ret_type, func_id_name(func_id), func_id); + return -EINVAL; + } + regs[BPF_REG_0].btf_id = ret_btf_id; } else { verbose(env, "unknown return type %d of func %s#%d\n", fn->ret_type, func_id_name(func_id), func_id); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0159f12d2af5..2a97a268f533 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1515,6 +1515,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skb_output_proto; case BPF_FUNC_xdp_output: return &bpf_xdp_output_proto; + case BPF_FUNC_skc_to_tcp6_sock: + return &bpf_skc_to_tcp6_sock_proto; #endif case BPF_FUNC_seq_printf: return prog->expected_attach_type == BPF_TRACE_ITER ? |