Netdev Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Lorenz Bauer <lmb@cloudflare.com>
To: ast@kernel.org, daniel@iogearbox.net
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org,
Lorenz Bauer <lmb@cloudflare.com>,
Martin KaFai Lau <kafai@fb.com>
Subject: [PATCH bpf-next v4 11/11] bpf: use a table to drive helper arg type checks
Date: Mon, 21 Sep 2020 13:12:27 +0100 [thread overview]
Message-ID: <20200921121227.255763-12-lmb@cloudflare.com> (raw)
In-Reply-To: <20200921121227.255763-1-lmb@cloudflare.com>
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@cloudflare.com>
Acked-by: Martin KaFai Lau <kafai@fb.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
next prev parent reply other threads:[~2020-09-21 12:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 12:12 [PATCH RESEND bpf-next v4 00/11] Make check_func_arg type checks table driven Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 01/11] btf: make btf_set_contains take a const pointer Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 02/11] bpf: check scalar or invalid register in check_helper_mem_access Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 03/11] btf: Add BTF_ID_LIST_SINGLE macro Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 04/11] bpf: allow specifying a BTF ID per argument in function protos Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 05/11] bpf: make BTF pointer type checking generic Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 06/11] bpf: make reference tracking generic Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 07/11] bpf: make context access check generic Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 08/11] bpf: set meta->raw_mode for pointers close to use Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 09/11] bpf: check ARG_PTR_TO_SPINLOCK register type in check_func_arg Lorenz Bauer
2020-09-21 12:12 ` [PATCH bpf-next v4 10/11] bpf: hoist type checking for nullable arg types Lorenz Bauer
2020-09-21 12:12 ` Lorenz Bauer [this message]
2020-09-21 22:23 ` [PATCH bpf-next v4 11/11] bpf: use a table to drive helper arg type checks Alexei Starovoitov
2020-09-22 8:20 ` Lorenz Bauer
2020-09-22 20:07 ` Alexei Starovoitov
2020-09-23 9:45 ` Lorenz Bauer
2020-09-23 15:24 ` Alexei Starovoitov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200921121227.255763-12-lmb@cloudflare.com \
--to=lmb@cloudflare.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=netdev@vger.kernel.org \
--subject='Re: [PATCH bpf-next v4 11/11] bpf: use a table to drive helper arg type checks' \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).