In this commit, we add the 'accessed_args' field to struct bpf_prog_aux,
which is used to record the accessed index of the function args in
btf_ctx_access().
Meanwhile, we add the function btf_check_func_part_match() to compare the
accessed function args of two function prototype. This function will be
used in the following commit.
Signed-off-by: Menglong Dong <dongmenglong.8@xxxxxxxxxxxxx>
---
include/linux/bpf.h | 4 ++
kernel/bpf/btf.c | 121 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 125 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c7aa99b44dbd..0225b8dbdd9d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1464,6 +1464,7 @@ struct bpf_prog_aux {
const struct btf_type *attach_func_proto;
/* function name for valid attach_btf_id */
const char *attach_func_name;
+ u64 accessed_args;
struct bpf_prog **func;
void *jit_data; /* JIT specific data. arch dependent */
struct bpf_jit_poke_descriptor *poke_tab;
@@ -2566,6 +2567,9 @@ struct bpf_reg_state;
int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog);
int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
struct btf *btf, const struct btf_type *t);
+int btf_check_func_part_match(struct btf *btf1, const struct btf_type *t1,
+ struct btf *btf2, const struct btf_type *t2,
+ u64 func_args);
const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt,
int comp_idx, const char *tag_key);
int btf_find_next_decl_tag(const struct btf *btf, const struct btf_type *pt,
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6ff0bd1a91d5..3a6931402fe4 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6203,6 +6203,9 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
/* skip first 'void *__data' argument in btf_trace_##name typedef */
args++;
nr_args--;
+ prog->aux->accessed_args |= (1 << (arg + 1));
+ } else {
+ prog->aux->accessed_args |= (1 << arg);
}
if (arg > nr_args) {
@@ -7010,6 +7013,124 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr
return btf_check_func_type_match(log, btf1, t1, btf2, t2);
}
+static u32 get_ctx_arg_total_size(struct btf *btf, const struct btf_type *t)
+{
+ const struct btf_param *args;
+ u32 size = 0, nr_args;
+ int i;
+
+ nr_args = btf_type_vlen(t);
+ args = (const struct btf_param *)(t + 1);
+ for (i = 0; i < nr_args; i++) {
+ t = btf_type_skip_modifiers(btf, args[i].type, NULL);
+ size += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
+ }
+
+ return size;
+}
+
+static int get_ctx_arg_idx_aligned(struct btf *btf, const struct btf_type *t,
+ int off)
+{
+ const struct btf_param *args;
+ u32 offset = 0, nr_args;
+ int i;
+
+ nr_args = btf_type_vlen(t);
+ args = (const struct btf_param *)(t + 1);
+ for (i = 0; i < nr_args; i++) {
+ if (offset == off)
+ return i;
+
+ t = btf_type_skip_modifiers(btf, args[i].type, NULL);
+ offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
+ if (offset > off)
+ return -1;
+ }
+ return -1;
+}
+
+/* This function is similar to btf_check_func_type_match(), except that it
+ * only compare some function args of the function prototype t1 and t2.
+ */
+int btf_check_func_part_match(struct btf *btf1, const struct btf_type *func1,
+ struct btf *btf2, const struct btf_type *func2,
+ u64 func_args)
+{
+ const struct btf_param *args1, *args2;
+ u32 nargs1, i, offset = 0;
+ const char *s1, *s2;
+
+ if (!btf_type_is_func_proto(func1) || !btf_type_is_func_proto(func2))
+ return -EINVAL;
+
+ args1 = (const struct btf_param *)(func1 + 1);
+ args2 = (const struct btf_param *)(func2 + 1);
+ nargs1 = btf_type_vlen(func1);
+
+ for (i = 0; i <= nargs1; i++) {
+ const struct btf_type *t1, *t2;
+
+ if (!(func_args & (1 << i)))
+ goto next;
+
+ if (i < nargs1) {
+ int t2_index;
+
+ /* get the index of the arg corresponding to args1[i]
+ * by the offset.
+ */
+ t2_index = get_ctx_arg_idx_aligned(btf2, func2,
+ offset);
+ if (t2_index < 0)
+ return -EINVAL;
+
+ t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
+ t2 = btf_type_skip_modifiers(btf2, args2[t2_index].type,
+ NULL);
+ } else {
+ /* i == nargs1, this is the index of return value of t1 */
+ if (get_ctx_arg_total_size(btf1, func1) !=
+ get_ctx_arg_total_size(btf2, func2))
+ return -EINVAL;
+
+ /* check the return type of t1 and t2 */
+ t1 = btf_type_skip_modifiers(btf1, func1->type, NULL);
+ t2 = btf_type_skip_modifiers(btf2, func2->type, NULL);
+ }
+
+ if (t1->info != t2->info ||
+ (btf_type_has_size(t1) && t1->size != t2->size))
+ return -EINVAL;
+ if (btf_type_is_int(t1) || btf_is_any_enum(t1))
+ goto next;
+
+ if (btf_type_is_struct(t1))
+ goto on_struct;
+
+ if (!btf_type_is_ptr(t1))
+ return -EINVAL;
+
+ t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
+ t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
+ if (!btf_type_is_struct(t1) || !btf_type_is_struct(t2))
+ return -EINVAL;
+
+on_struct:
+ s1 = btf_name_by_offset(btf1, t1->name_off);
+ s2 = btf_name_by_offset(btf2, t2->name_off);
+ if (strcmp(s1, s2))
+ return -EINVAL;
+next:
+ if (i < nargs1) {
+ t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
+ offset += btf_type_is_ptr(t1) ? 8 : roundup(t1->size, 8);
+ }
+ }
+
+ return 0;
+}
+
static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t)
{
const char *name;
--
2.39.2
