Merge branch 'allow-bpf_map_sum_elem_count-for-all-program-types'

Anton Protopopov says:

====================
allow bpf_map_sum_elem_count for all program types

This series is a follow up to the recent change [1] which added
per-cpu insert/delete statistics for maps. The bpf_map_sum_elem_count
kfunc presented in the original series was only available to tracing
programs, so let's make it available to all.

The first patch makes types listed in the reg2btf_ids[] array to be
considered trusted by kfuncs.

The second patch allows to treat CONST_PTR_TO_MAP as trusted pointers from
kfunc's point of view by adding it to the reg2btf_ids[] array.

The third patch adds missing const to the map argument of the
bpf_map_sum_elem_count kfunc.

The fourth patch registers the bpf_map_sum_elem_count for all programs,
and patches selftests correspondingly.

  [1] https://lore.kernel.org/bpf/20230705160139.19967-1-aspsk@isovalent.com/

v1 -> v2:
  * treat the whole reg2btf_ids array as trusted (Alexei)
====================

Link: https://lore.kernel.org/r/20230719092952.41202-1-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/btf_ids.h

@@ -267,5 +267,6 @@ MAX_BTF_TRACING_TYPE,
 extern u32 btf_tracing_ids[];
 extern u32 bpf_cgroup_btf_id[];
 extern u32 bpf_local_storage_map_btf_id[];
+extern u32 btf_bpf_map_id[];
 
 #endif

kernel/bpf/map_iter.c

@@ -78,8 +78,7 @@ static const struct seq_operations bpf_map_seq_ops = {
 	.show	= bpf_map_seq_show,
 };
 
-BTF_ID_LIST(btf_bpf_map_id)
-BTF_ID(struct, bpf_map)
+BTF_ID_LIST_GLOBAL_SINGLE(btf_bpf_map_id, struct, bpf_map)
 
 static const struct bpf_iter_seq_info bpf_map_seq_info = {
 	.seq_ops		= &bpf_map_seq_ops,
@@ -198,7 +197,7 @@ __diag_push();
 __diag_ignore_all("-Wmissing-prototypes",
 		  "Global functions as their definitions will be in vmlinux BTF");
 
-__bpf_kfunc s64 bpf_map_sum_elem_count(struct bpf_map *map)
+__bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map)
 {
 	s64 *pcount;
 	s64 ret = 0;
@@ -227,6 +226,6 @@ static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
 
 static int init_subsystem(void)
 {
-	return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_map_iter_kfunc_set);
+	return register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &bpf_map_iter_kfunc_set);
 }
 late_initcall(init_subsystem);

kernel/bpf/verifier.c

@@ -5413,12 +5413,25 @@ static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
 	return reg->type == PTR_TO_FLOW_KEYS;
 }
 
+static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
+#ifdef CONFIG_NET
+	[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
+	[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
+	[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
+#endif
+	[CONST_PTR_TO_MAP] = btf_bpf_map_id,
+};
+
 static bool is_trusted_reg(const struct bpf_reg_state *reg)
 {
 	/* A referenced register is always trusted. */
 	if (reg->ref_obj_id)
 		return true;
 
+	/* Types listed in the reg2btf_ids are always trusted */
+	if (reg2btf_ids[base_type(reg->type)])
+		return true;
+
 	/* If a register is not referenced, it is trusted if it has the
 	 * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the
 	 * other type modifiers may be safe, but we elect to take an opt-in
@@ -10052,15 +10065,6 @@ static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env,
 	return true;
 }
 
-
-static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
-#ifdef CONFIG_NET
-	[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
-	[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
-	[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
-#endif
-};
-
 enum kfunc_ptr_arg_type {
 	KF_ARG_PTR_TO_CTX,
 	KF_ARG_PTR_TO_ALLOC_BTF_ID,    /* Allocated object */

tools/testing/selftests/bpf/progs/map_ptr_kern.c

@@ -103,6 +103,8 @@ struct {
 	__type(value, __u32);
 } m_hash SEC(".maps");
 
+__s64 bpf_map_sum_elem_count(struct bpf_map *map) __ksym;
+
 static inline int check_hash(void)
 {
 	struct bpf_htab *hash = (struct bpf_htab *)&m_hash;
@@ -115,6 +117,8 @@ static inline int check_hash(void)
 	VERIFY(hash->elem_size == 64);
 
 	VERIFY(hash->count.counter == 0);
+	VERIFY(bpf_map_sum_elem_count(map) == 0);
+
 	for (i = 0; i < HALF_ENTRIES; ++i) {
 		const __u32 key = i;
 		const __u32 val = 1;
@@ -123,6 +127,7 @@ static inline int check_hash(void)
 			return 0;
 	}
 	VERIFY(hash->count.counter == HALF_ENTRIES);
+	VERIFY(bpf_map_sum_elem_count(map) == HALF_ENTRIES);
 
 	return 1;
 }