On 7/14/24 10:51 AM, Amery Hung wrote:
+static const struct bpf_func_proto *
+bpf_qdisc_get_func_proto(enum bpf_func_id func_id,
+ const struct bpf_prog *prog)
+{
+ switch (func_id) {
Instead of an empty switch, it should be useful to provide the skb->data related
helper. It can start with read only dynptr first, the BPF_FUNC_dynptr_read
helper here.
Also, the kfuncs: bpf_dynptr_slice and bpf_dynptr_from_skb_rdonly.
+ default:
+ return bpf_base_func_proto(func_id, prog);
[ ... ]
+ }
+}
+
+BTF_ID_LIST_SINGLE(bpf_sk_buff_ids, struct, sk_buff)
+BTF_ID_LIST_SINGLE(bpf_sk_buff_ptr_ids, struct, bpf_sk_buff_ptr)
+
+static bool bpf_qdisc_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ struct btf *btf = prog->aux->attach_btf;
+ u32 arg;
+
+ arg = get_ctx_arg_idx(btf, prog->aux->attach_func_proto, off);
+ if (!strcmp(prog->aux->attach_func_name, "enqueue")) {
+ if (arg == 2) {
+ info->reg_type = PTR_TO_BTF_ID | PTR_TRUSTED;
+ info->btf = btf;
+ info->btf_id = bpf_sk_buff_ptr_ids[0];
+ return true;
This will allow type == BPF_WRITE to ctx which should be rejected. The below
bpf_tracing_btf_ctx_access() could have rejected it.
+ }
+ }
+
+ return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
+}
+
[ ... ]
+
+static bool is_unsupported(u32 member_offset)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) {
+ if (member_offset == unsupported_ops[i])
+ return true;
+ }
+
+ return false;
+}
+
+static int bpf_qdisc_check_member(const struct btf_type *t,
+ const struct btf_member *member,
+ const struct bpf_prog *prog)
+{
+ if (is_unsupported(__btf_member_bit_offset(t, member) / 8))
Note that the ".check_member" and the "is_unsupported" can be removed as you
also noticed on the recent unsupported ops cleanup patches.
+ return -ENOTSUPP;
+ return 0;
+}
[ ... ]
+static struct Qdisc_ops __bpf_ops_qdisc_ops = {
+ .enqueue = Qdisc_ops__enqueue,
+ .dequeue = Qdisc_ops__dequeue,
+ .peek = Qdisc_ops__peek,
+ .init = Qdisc_ops__init,
+ .reset = Qdisc_ops__reset,
+ .destroy = Qdisc_ops__destroy,
+ .change = Qdisc_ops__change,
+ .attach = Qdisc_ops__attach,
+ .change_tx_queue_len = Qdisc_ops__change_tx_queue_len,
+ .change_real_num_tx = Qdisc_ops__change_real_num_tx,
+ .dump = Qdisc_ops__dump,
+ .dump_stats = Qdisc_ops__dump_stats,
Similar to the above is_unsupported comment. The unsupported ops should be
removed from the cfi_stubs.
+ .ingress_block_set = Qdisc_ops__ingress_block_set,
+ .egress_block_set = Qdisc_ops__egress_block_set,
+ .ingress_block_get = Qdisc_ops__ingress_block_get,
+ .egress_block_get = Qdisc_ops__egress_block_get,
+};
+
+static struct bpf_struct_ops bpf_Qdisc_ops = {
+ .verifier_ops = &bpf_qdisc_verifier_ops,
+ .reg = bpf_qdisc_reg,
+ .unreg = bpf_qdisc_unreg,
+ .check_member = bpf_qdisc_check_member,
+ .init_member = bpf_qdisc_init_member,
+ .init = bpf_qdisc_init,
+ .validate = bpf_qdisc_validate,
".validate" is optional. The empty "bpf_qdisc_validate" can be removed.
+ .name = "Qdisc_ops",
+ .cfi_stubs = &__bpf_ops_qdisc_ops,
+ .owner = THIS_MODULE,
+};
