diff options
| -rw-r--r-- | include/linux/btf.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/btf.c | 13 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 10 |
3 files changed, 20 insertions, 4 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h index f9e56fd12a9f..56d91daacdba 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -531,6 +531,7 @@ s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id); int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, struct module *owner); struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id); +bool btf_is_projection_of(const char *pname, const char *tname); bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, enum bpf_prog_type prog_type, int arg); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 7928d920056f..ce4707968217 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5820,6 +5820,15 @@ static int find_kern_ctx_type_id(enum bpf_prog_type prog_type) return ctx_type->type; } +bool btf_is_projection_of(const char *pname, const char *tname) +{ + if (strcmp(pname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0) + return true; + if (strcmp(pname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0) + return true; + return false; +} + bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, enum bpf_prog_type prog_type, int arg) @@ -5882,9 +5891,7 @@ again: * int socket_filter_bpf_prog(struct __sk_buff *skb) * { // no fields of skb are ever used } */ - if (strcmp(ctx_tname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0) - return true; - if (strcmp(ctx_tname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0) + if (btf_is_projection_of(ctx_tname, tname)) return true; if (strcmp(ctx_tname, tname)) { /* bpf_user_pt_regs_t is a typedef, so resolve it to diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 20ac9cfd54dd..dcac6119d810 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11265,6 +11265,8 @@ static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, bool strict_type_match = false; const struct btf *reg_btf; const char *reg_ref_tname; + bool taking_projection; + bool struct_same; u32 reg_ref_id; if (base_type(reg->type) == PTR_TO_BTF_ID) { @@ -11308,7 +11310,13 @@ static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, ®_ref_id); reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); - if (!btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match)) { + struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match); + /* If kfunc is accepting a projection type (ie. __sk_buff), it cannot + * actually use it -- it must cast to the underlying type. So we allow + * caller to pass in the underlying type. + */ + taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname); + if (!taking_projection && !struct_same) { verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n", meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1, btf_type_str(reg_ref_t), reg_ref_tname); |