bpf: prepare btf_prepare_func_args() for multiple tags per argument

Add btf_arg_tag flags enum to be able to record multiple tags per
argument. Also streamline pointer argument processing some more.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240105000909.2818934-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index dbe7a590f565a1ab8580105966255d0a5b50cbff..1636b574a63d54709990765705567bb59da4f01e 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6946,6 +6946,11 @@ static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t)
        return false;
 }
 
+enum btf_arg_tag {
+       ARG_TAG_CTX = 0x1,
+       ARG_TAG_NONNULL = 0x2,
+};
+
 /* Process BTF of a function to produce high-level expectation of function
  * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information
  * is cached in subprog info for reuse.
@@ -7027,10 +7032,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
         * Only PTR_TO_CTX and SCALAR are supported atm.
         */
        for (i = 0; i < nargs; i++) {
-               bool is_nonnull = false;
                const char *tag;
-
-               t = btf_type_by_id(btf, args[i].type);
+               u32 tags = 0;
 
                tag = btf_find_decl_tag_value(btf, fn_t, i, "arg:");
                if (IS_ERR(tag) && PTR_ERR(tag) == -ENOENT) {
@@ -7048,43 +7051,61 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
                                bpf_log(log, "arg#%d type tag is not supported in static functions\n", i);
                                return -EOPNOTSUPP;
                        }
+
                        if (strcmp(tag, "ctx") == 0) {
-                               sub->args[i].arg_type = ARG_PTR_TO_CTX;
-                               continue;
+                               tags |= ARG_TAG_CTX;
+                       } else if (strcmp(tag, "nonnull") == 0) {
+                               tags |= ARG_TAG_NONNULL;
+                       } else {
+                               bpf_log(log, "arg#%d has unsupported set of tags\n", i);
+                               return -EOPNOTSUPP;
                        }
-                       if (strcmp(tag, "nonnull") == 0)
-                               is_nonnull = true;
                }
 
+               t = btf_type_by_id(btf, args[i].type);
                while (btf_type_is_modifier(t))
                        t = btf_type_by_id(btf, t->type);
-               if (btf_type_is_ptr(t) && btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
+               if (!btf_type_is_ptr(t))
+                       goto skip_pointer;
+
+               if ((tags & ARG_TAG_CTX) || btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
+                       if (tags & ~ARG_TAG_CTX) {
+                               bpf_log(log, "arg#%d has invalid combination of tags\n", i);
+                               return -EINVAL;
+                       }
                        sub->args[i].arg_type = ARG_PTR_TO_CTX;
                        continue;
                }
-               if (btf_type_is_ptr(t) && btf_is_dynptr_ptr(btf, t)) {
+               if (btf_is_dynptr_ptr(btf, t)) {
+                       if (tags) {
+                               bpf_log(log, "arg#%d has invalid combination of tags\n", i);
+                               return -EINVAL;
+                       }
                        sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY;
                        continue;
                }
-               if (is_global && btf_type_is_ptr(t)) {
+               if (is_global) { /* generic user data pointer */
                        u32 mem_size;
 
                        t = btf_type_skip_modifiers(btf, t->type, NULL);
                        ref_t = btf_resolve_size(btf, t, &mem_size);
                        if (IS_ERR(ref_t)) {
-                               bpf_log(log,
-                                   "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
-                                   i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
+                               bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
+                                       i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
                                        PTR_ERR(ref_t));
                                return -EINVAL;
                        }
 
-                       sub->args[i].arg_type = is_nonnull ? ARG_PTR_TO_MEM : ARG_PTR_TO_MEM_OR_NULL;
+                       sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
+                       if (tags & ARG_TAG_NONNULL)
+                               sub->args[i].arg_type &= ~PTR_MAYBE_NULL;
                        sub->args[i].mem_size = mem_size;
                        continue;
                }
-               if (is_nonnull) {
-                       bpf_log(log, "arg#%d marked as non-null, but is not a pointer type\n", i);
+
+skip_pointer:
+               if (tags) {
+                       bpf_log(log, "arg#%d has pointer tag, but is not a pointer type\n", i);
                        return -EINVAL;
                }
                if (btf_type_is_int(t) || btf_is_any_enum(t)) {

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5b33d65eef7bef3aabadb9aee1ea116499d24dfc..27ad463b3bddcbc0f39eac1662174f9fe81e770c 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20058,7 +20058,6 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
        state->first_insn_idx = env->subprog_info[subprog].start;
        state->last_insn_idx = -1;
 
-
        regs = state->frame[state->curframe]->regs;
        if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
                const char *sub_name = subprog_name(env, subprog);