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Date: Mon, 21 Sep 2020 13:12:27 +0100
From: Lorenz Bauer <lmb@...udflare.com>
To: ast@...nel.org, daniel@...earbox.net
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
Lorenz Bauer <lmb@...udflare.com>,
Martin KaFai Lau <kafai@...com>
Subject: [PATCH bpf-next v4 11/11] bpf: use a table to drive helper arg type checks
The mapping between bpf_arg_type and bpf_reg_type is encoded in a big
hairy if statement that is hard to follow. The debug output also leaves
to be desired: if a reg_type doesn't match we only print one of the
options, instead printing all the valid ones.
Convert the if statement into a table which is then used to drive type
checking. If none of the reg_types match we print all options, e.g.:
R2 type=rdonly_buf expected=fp, pkt, pkt_meta, map_value
Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
Acked-by: Martin KaFai Lau <kafai@...com>
---
include/linux/bpf.h | 1 +
kernel/bpf/verifier.c | 183 +++++++++++++++++++++++++-----------------
2 files changed, 110 insertions(+), 74 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 732e2f144b6d..4ca817a9195c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -292,6 +292,7 @@ enum bpf_arg_type {
ARG_PTR_TO_ALLOC_MEM, /* pointer to dynamically allocated memory */
ARG_PTR_TO_ALLOC_MEM_OR_NULL, /* pointer to dynamically allocated memory or NULL */
ARG_CONST_ALLOC_SIZE_OR_ZERO, /* number of allocated bytes requested */
+ __BPF_ARG_TYPE_MAX,
};
/* type of values returned from helper functions */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d64ac79982ad..b5c00d08f9c0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3856,12 +3856,6 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type)
type == ARG_CONST_SIZE_OR_ZERO;
}
-static bool arg_type_is_alloc_mem_ptr(enum bpf_arg_type type)
-{
- return type == ARG_PTR_TO_ALLOC_MEM ||
- type == ARG_PTR_TO_ALLOC_MEM_OR_NULL;
-}
-
static bool arg_type_is_alloc_size(enum bpf_arg_type type)
{
return type == ARG_CONST_ALLOC_SIZE_OR_ZERO;
@@ -3910,14 +3904,115 @@ static int resolve_map_arg_type(struct bpf_verifier_env *env,
return 0;
}
+struct bpf_reg_types {
+ const enum bpf_reg_type types[10];
+};
+
+static const struct bpf_reg_types map_key_value_types = {
+ .types = {
+ PTR_TO_STACK,
+ PTR_TO_PACKET,
+ PTR_TO_PACKET_META,
+ PTR_TO_MAP_VALUE,
+ },
+};
+
+static const struct bpf_reg_types sock_types = {
+ .types = {
+ PTR_TO_SOCK_COMMON,
+ PTR_TO_SOCKET,
+ PTR_TO_TCP_SOCK,
+ PTR_TO_XDP_SOCK,
+ },
+};
+
+static const struct bpf_reg_types mem_types = {
+ .types = {
+ PTR_TO_STACK,
+ PTR_TO_PACKET,
+ PTR_TO_PACKET_META,
+ PTR_TO_MAP_VALUE,
+ PTR_TO_MEM,
+ PTR_TO_RDONLY_BUF,
+ PTR_TO_RDWR_BUF,
+ },
+};
+
+static const struct bpf_reg_types int_ptr_types = {
+ .types = {
+ PTR_TO_STACK,
+ PTR_TO_PACKET,
+ PTR_TO_PACKET_META,
+ PTR_TO_MAP_VALUE,
+ },
+};
+
+static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
+static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
+static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
+static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM } };
+static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
+static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
+static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
+
+static const struct bpf_reg_types *compatible_reg_types[] = {
+ [ARG_PTR_TO_MAP_KEY] = &map_key_value_types,
+ [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types,
+ [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types,
+ [ARG_PTR_TO_MAP_VALUE_OR_NULL] = &map_key_value_types,
+ [ARG_CONST_SIZE] = &scalar_types,
+ [ARG_CONST_SIZE_OR_ZERO] = &scalar_types,
+ [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types,
+ [ARG_CONST_MAP_PTR] = &const_map_ptr_types,
+ [ARG_PTR_TO_CTX] = &context_types,
+ [ARG_PTR_TO_CTX_OR_NULL] = &context_types,
+ [ARG_PTR_TO_SOCK_COMMON] = &sock_types,
+ [ARG_PTR_TO_SOCKET] = &fullsock_types,
+ [ARG_PTR_TO_SOCKET_OR_NULL] = &fullsock_types,
+ [ARG_PTR_TO_BTF_ID] = &btf_ptr_types,
+ [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types,
+ [ARG_PTR_TO_MEM] = &mem_types,
+ [ARG_PTR_TO_MEM_OR_NULL] = &mem_types,
+ [ARG_PTR_TO_UNINIT_MEM] = &mem_types,
+ [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types,
+ [ARG_PTR_TO_ALLOC_MEM_OR_NULL] = &alloc_mem_types,
+ [ARG_PTR_TO_INT] = &int_ptr_types,
+ [ARG_PTR_TO_LONG] = &int_ptr_types,
+ [__BPF_ARG_TYPE_MAX] = NULL,
+};
+
+static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
+ const struct bpf_reg_types *compatible)
+{
+ struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
+ enum bpf_reg_type expected, type = reg->type;
+ int i, j;
+
+ for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
+ expected = compatible->types[i];
+ if (expected == NOT_INIT)
+ break;
+
+ if (type == expected)
+ return 0;
+ }
+
+ verbose(env, "R%d type=%s expected=", regno, reg_type_str[type]);
+ for (j = 0; j + 1 < i; j++)
+ verbose(env, "%s, ", reg_type_str[compatible->types[j]]);
+ verbose(env, "%s\n", reg_type_str[compatible->types[j]]);
+ return -EACCES;
+}
+
static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
struct bpf_call_arg_meta *meta,
const struct bpf_func_proto *fn)
{
u32 regno = BPF_REG_1 + arg;
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- enum bpf_reg_type expected_type, type = reg->type;
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;
if (arg_type == ARG_DONTCARE)
@@ -3956,72 +4051,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
*/
goto skip_type_check;
- if (arg_type == ARG_PTR_TO_MAP_KEY ||
- arg_type == ARG_PTR_TO_MAP_VALUE ||
- arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE ||
- arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) {
- expected_type = PTR_TO_STACK;
- if (!type_is_pkt_pointer(type) &&
- type != PTR_TO_MAP_VALUE &&
- type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_CONST_SIZE ||
- arg_type == ARG_CONST_SIZE_OR_ZERO ||
- arg_type == ARG_CONST_ALLOC_SIZE_OR_ZERO) {
- expected_type = SCALAR_VALUE;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_CONST_MAP_PTR) {
- expected_type = CONST_PTR_TO_MAP;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_PTR_TO_CTX ||
- arg_type == ARG_PTR_TO_CTX_OR_NULL) {
- expected_type = PTR_TO_CTX;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_PTR_TO_SOCK_COMMON) {
- expected_type = PTR_TO_SOCK_COMMON;
- /* Any sk pointer can be ARG_PTR_TO_SOCK_COMMON */
- if (!type_is_sk_pointer(type))
- goto err_type;
- } else if (arg_type == ARG_PTR_TO_SOCKET ||
- arg_type == ARG_PTR_TO_SOCKET_OR_NULL) {
- expected_type = PTR_TO_SOCKET;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_PTR_TO_BTF_ID) {
- expected_type = PTR_TO_BTF_ID;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
- expected_type = PTR_TO_MAP_VALUE;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type_is_mem_ptr(arg_type)) {
- expected_type = PTR_TO_STACK;
- if (!type_is_pkt_pointer(type) &&
- type != PTR_TO_MAP_VALUE &&
- type != PTR_TO_MEM &&
- type != PTR_TO_RDONLY_BUF &&
- type != PTR_TO_RDWR_BUF &&
- type != expected_type)
- goto err_type;
- } else if (arg_type_is_alloc_mem_ptr(arg_type)) {
- expected_type = PTR_TO_MEM;
- if (type != expected_type)
- goto err_type;
- } else if (arg_type_is_int_ptr(arg_type)) {
- expected_type = PTR_TO_STACK;
- if (!type_is_pkt_pointer(type) &&
- type != PTR_TO_MAP_VALUE &&
- type != expected_type)
- goto err_type;
- } else {
- verbose(env, "unsupported arg_type %d\n", arg_type);
+ 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);
+ if (err)
+ return err;
+
if (type == PTR_TO_BTF_ID) {
const u32 *btf_id = fn->arg_btf_id[arg];
@@ -4174,10 +4213,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
}
return err;
-err_type:
- verbose(env, "R%d type=%s expected=%s\n", regno,
- reg_type_str[type], reg_type_str[expected_type]);
- return -EACCES;
}
static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
--
2.25.1
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