Merge branch 'enable-bpf_skc-cast-for-networking-progs'

Martin KaFai Lau says:

====================
This set allows networking prog type to directly read fields from
the in-kernel socket type, e.g. "struct tcp_sock".

Patch 2 has the details on the use case.

v3:
- Pass arg_btf_id instead of fn into check_reg_type() in Patch 1 (Lorenz)
- Move arg_btf_id from func_proto to struct bpf_reg_types in Patch 2 (Lorenz)
- Remove test_sock_fields from .gitignore in Patch 8 (Andrii)
- Add tests to have better coverage on the modified helpers (Alexei)
  Patch 13 is added.
- Use "void *sk" as the helper argument in UAPI bpf.h

v3:
- ARG_PTR_TO_SOCK_COMMON_OR_NULL was attempted in v2.  The _OR_NULL was
  needed because the PTR_TO_BTF_ID could be NULL but note that a could be NULL
  PTR_TO_BTF_ID is not a scalar NULL to the verifier.  "_OR_NULL" implicitly
  gives an expectation that the helper can take a scalar NULL which does
  not make sense in most (except one) helpers.  Passing scalar NULL
  should be rejected at the verification time.

  Thus, this patch uses ARG_PTR_TO_BTF_ID_SOCK_COMMON to specify that the
  helper can take both the btf-id ptr or the legacy PTR_TO_SOCK_COMMON but
  not scalar NULL.  It requires the func_proto to explicitly specify the
  arg_btf_id such that there is a very clear expectation that the helper
  can handle a NULL PTR_TO_BTF_ID.

v2:
- Add ARG_PTR_TO_SOCK_COMMON_OR_NULL (Lorenz)
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 65 insertions, 33 deletions

diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index 9cd1428c7199..78ea8a7bd27f 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c
@@ -56,9 +56,9 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_inode_storage_delete:
 		return &bpf_inode_storage_delete_proto;
 	case BPF_FUNC_sk_storage_get:
-		return &sk_storage_get_btf_proto;
+		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
-		return &sk_storage_delete_btf_proto;
+		return &bpf_sk_storage_delete_proto;
 	default:
 		return tracing_prog_func_proto(func_id, prog);
 	}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 42dee5dcbc74..d4ba29fb17a6 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -486,7 +486,12 @@ static bool is_acquire_function(enum bpf_func_id func_id,
 static bool is_ptr_cast_function(enum bpf_func_id func_id)
 {
 	return func_id == BPF_FUNC_tcp_sock ||
-		func_id == BPF_FUNC_sk_fullsock;
+		func_id == BPF_FUNC_sk_fullsock ||
+		func_id == BPF_FUNC_skc_to_tcp_sock ||
+		func_id == BPF_FUNC_skc_to_tcp6_sock ||
+		func_id == BPF_FUNC_skc_to_udp6_sock ||
+		func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
+		func_id == BPF_FUNC_skc_to_tcp_request_sock;
 }
 
 /* string representation of 'enum bpf_reg_type' */
@@ -3953,6 +3958,7 @@ static int resolve_map_arg_type(struct bpf_verifier_env *env,
 
 struct bpf_reg_types {
 	const enum bpf_reg_type types[10];
+	u32 *btf_id;
 };
 
 static const struct bpf_reg_types map_key_value_types = {
@@ -3973,6 +3979,17 @@ static const struct bpf_reg_types sock_types = {
 	},
 };
 
+static const struct bpf_reg_types btf_id_sock_common_types = {
+	.types = {
+		PTR_TO_SOCK_COMMON,
+		PTR_TO_SOCKET,
+		PTR_TO_TCP_SOCK,
+		PTR_TO_XDP_SOCK,
+		PTR_TO_BTF_ID,
+	},
+	.btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
+};
+
 static const struct bpf_reg_types mem_types = {
 	.types = {
 		PTR_TO_STACK,
@@ -4014,6 +4031,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_PTR_TO_CTX]		= &context_types,
 	[ARG_PTR_TO_CTX_OR_NULL]	= &context_types,
 	[ARG_PTR_TO_SOCK_COMMON]	= &sock_types,
+	[ARG_PTR_TO_BTF_ID_SOCK_COMMON]	= &btf_id_sock_common_types,
 	[ARG_PTR_TO_SOCKET]		= &fullsock_types,
 	[ARG_PTR_TO_SOCKET_OR_NULL]	= &fullsock_types,
 	[ARG_PTR_TO_BTF_ID]		= &btf_ptr_types,
@@ -4028,19 +4046,27 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 };
 
 static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
-			  const struct bpf_reg_types *compatible)
+			  enum bpf_arg_type arg_type,
+			  const u32 *arg_btf_id)
 {
 	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
 	enum bpf_reg_type expected, type = reg->type;
+	const struct bpf_reg_types *compatible;
 	int i, j;
 
+	compatible = compatible_reg_types[arg_type];
+	if (!compatible) {
+		verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
+		return -EFAULT;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
 		expected = compatible->types[i];
 		if (expected == NOT_INIT)
 			break;
 
 		if (type == expected)
-			return 0;
+			goto found;
 	}
 
 	verbose(env, "R%d type=%s expected=", regno, reg_type_str[type]);
@@ -4048,6 +4074,33 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
 		verbose(env, "%s, ", reg_type_str[compatible->types[j]]);
 	verbose(env, "%s\n", reg_type_str[compatible->types[j]]);
 	return -EACCES;
+
+found:
+	if (type == PTR_TO_BTF_ID) {
+		if (!arg_btf_id) {
+			if (!compatible->btf_id) {
+				verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
+				return -EFAULT;
+			}
+			arg_btf_id = compatible->btf_id;
+		}
+
+		if (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id,
+					  *arg_btf_id)) {
+			verbose(env, "R%d is of type %s but %s is expected\n",
+				regno, kernel_type_name(reg->btf_id),
+				kernel_type_name(*arg_btf_id));
+			return -EACCES;
+		}
+
+		if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
+			verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n",
+				regno);
+			return -EACCES;
+		}
+	}
+
+	return 0;
 }
 
 static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
@@ -4057,7 +4110,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 	u32 regno = BPF_REG_1 + arg;
 	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
 	enum bpf_arg_type arg_type = fn->arg_type[arg];
-	const struct bpf_reg_types *compatible;
 	enum bpf_reg_type type = reg->type;
 	int err = 0;
 
@@ -4097,35 +4149,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		 */
 		goto skip_type_check;
 
-	compatible = compatible_reg_types[arg_type];
-	if (!compatible) {
-		verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
-		return -EFAULT;
-	}
-
-	err = check_reg_type(env, regno, compatible);
+	err = check_reg_type(env, regno, arg_type, fn->arg_btf_id[arg]);
 	if (err)
 		return err;
 
-	if (type == PTR_TO_BTF_ID) {
-		const u32 *btf_id = fn->arg_btf_id[arg];
-
-		if (!btf_id) {
-			verbose(env, "verifier internal error: missing BTF ID\n");
-			return -EFAULT;
-		}
-
-		if (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id, *btf_id)) {
-			verbose(env, "R%d is of type %s but %s is expected\n",
-				regno, kernel_type_name(reg->btf_id), kernel_type_name(*btf_id));
-			return -EACCES;
-		}
-		if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
-			verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n",
-				regno);
-			return -EACCES;
-		}
-	} else if (type == PTR_TO_CTX) {
+	if (type == PTR_TO_CTX) {
 		err = check_ctx_reg(env, reg, regno);
 		if (err < 0)
 			return err;
@@ -4573,10 +4601,14 @@ static bool check_btf_id_ok(const struct bpf_func_proto *fn)
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++)
+	for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
 		if (fn->arg_type[i] == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i])
 			return false;
 
+		if (fn->arg_type[i] != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i])
+			return false;
+	}
+
 	return true;
 }