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Date: Tue, 26 Mar 2019 18:05:28 +0000
From: Jiong Wang <jiong.wang@...ronome.com>
To: alexei.starovoitov@...il.com, daniel@...earbox.net
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
oss-drivers@...ronome.com, Jiong Wang <jiong.wang@...ronome.com>
Subject: [PATCH/RFC bpf-next 05/16] bpf: reduce false alarm by refining "enum bpf_arg_type"
Unlike BPF to BPF function call, BPF helper call is calls to native insns
that verifier can't walk. So, verifier needs helper proto type descriptions
for data-flow purpose.
There is such information already, but it is not differentiate sub-register
read with full register read.
This patch split "enum bpf_arg_type" for sub-register read, and updated
descriptions for several functions that shown frequent usage in one Cilium
benchmark.
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
---
include/linux/bpf.h | 3 +++
kernel/bpf/core.c | 2 +-
kernel/bpf/helpers.c | 2 +-
kernel/bpf/verifier.c | 19 +++++++++++++------
net/core/filter.c | 28 ++++++++++++++--------------
5 files changed, 32 insertions(+), 22 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f628971..5616a58 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -190,9 +190,12 @@ enum bpf_arg_type {
ARG_CONST_SIZE, /* number of bytes accessed from memory */
ARG_CONST_SIZE_OR_ZERO, /* number of bytes accessed from memory or 0 */
+ ARG_CONST_SIZE32, /* Likewise, but size fits into 32-bit */
+ ARG_CONST_SIZE32_OR_ZERO, /* Ditto */
ARG_PTR_TO_CTX, /* pointer to context */
ARG_ANYTHING, /* any (initialized) argument is ok */
+ ARG_ANYTHING32, /* Likewise, but it is a 32-bit argument */
ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */
ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */
};
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ff09d32..8834d80 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2065,7 +2065,7 @@ const struct bpf_func_proto bpf_tail_call_proto = {
.ret_type = RET_VOID,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
- .arg3_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING32,
};
/* Stub for JITs that only support cBPF. eBPF programs are interpreted.
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a411fc1..6b7453e 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -218,7 +218,7 @@ const struct bpf_func_proto bpf_get_current_comm_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
- .arg2_type = ARG_CONST_SIZE,
+ .arg2_type = ARG_CONST_SIZE32,
};
#if defined(CONFIG_QUEUED_SPINLOCKS) || defined(CONFIG_BPF_ARCH_SPINLOCK)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 66e5e65..83448bb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2398,7 +2398,9 @@ static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
return type == ARG_CONST_SIZE ||
- type == ARG_CONST_SIZE_OR_ZERO;
+ type == ARG_CONST_SIZE_OR_ZERO ||
+ type == ARG_CONST_SIZE32 ||
+ type == ARG_CONST_SIZE32_OR_ZERO;
}
static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
@@ -2416,10 +2418,12 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
if (err)
return err;
- /* arg_type doesn't differentiate 32 and 64-bit arg, always zext. */
- mark_insn_zext(env, cur_func(env), regno);
+ if (arg_type != ARG_ANYTHING32 &&
+ arg_type != ARG_CONST_SIZE32 &&
+ arg_type != ARG_CONST_SIZE32_OR_ZERO)
+ mark_insn_zext(env, cur_func(env), regno);
- if (arg_type == ARG_ANYTHING) {
+ if (arg_type == ARG_ANYTHING || arg_type == ARG_ANYTHING32) {
if (is_pointer_value(env, regno)) {
verbose(env, "R%d leaks addr into helper function\n",
regno);
@@ -2442,7 +2446,9 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
type != expected_type)
goto err_type;
} else if (arg_type == ARG_CONST_SIZE ||
- arg_type == ARG_CONST_SIZE_OR_ZERO) {
+ arg_type == ARG_CONST_SIZE_OR_ZERO ||
+ arg_type == ARG_CONST_SIZE32 ||
+ arg_type == ARG_CONST_SIZE32_OR_ZERO) {
expected_type = SCALAR_VALUE;
if (type != expected_type)
goto err_type;
@@ -2536,7 +2542,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
meta->map_ptr->value_size, false,
meta);
} else if (arg_type_is_mem_size(arg_type)) {
- bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
+ bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO ||
+ arg_type == ARG_CONST_SIZE32_OR_ZERO);
/* remember the mem_size which may be used later
* to refine return values.
diff --git a/net/core/filter.c b/net/core/filter.c
index 22eb2ed..3f6d8af 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1693,9 +1693,9 @@ static const struct bpf_func_proto bpf_skb_store_bytes_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_PTR_TO_MEM,
- .arg4_type = ARG_CONST_SIZE,
+ .arg4_type = ARG_CONST_SIZE32,
.arg5_type = ARG_ANYTHING,
};
@@ -1724,9 +1724,9 @@ static const struct bpf_func_proto bpf_skb_load_bytes_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_PTR_TO_UNINIT_MEM,
- .arg4_type = ARG_CONST_SIZE,
+ .arg4_type = ARG_CONST_SIZE32,
};
BPF_CALL_5(bpf_skb_load_bytes_relative, const struct sk_buff *, skb,
@@ -1875,7 +1875,7 @@ static const struct bpf_func_proto bpf_l3_csum_replace_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_ANYTHING,
.arg5_type = ARG_ANYTHING,
@@ -1928,7 +1928,7 @@ static const struct bpf_func_proto bpf_l4_csum_replace_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_ANYTHING,
.arg5_type = ARG_ANYTHING,
@@ -1967,9 +1967,9 @@ static const struct bpf_func_proto bpf_csum_diff_proto = {
.pkt_access = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM_OR_NULL,
- .arg2_type = ARG_CONST_SIZE_OR_ZERO,
+ .arg2_type = ARG_CONST_SIZE32_OR_ZERO,
.arg3_type = ARG_PTR_TO_MEM_OR_NULL,
- .arg4_type = ARG_CONST_SIZE_OR_ZERO,
+ .arg4_type = ARG_CONST_SIZE32_OR_ZERO,
.arg5_type = ARG_ANYTHING,
};
@@ -2150,7 +2150,7 @@ static const struct bpf_func_proto bpf_redirect_proto = {
.func = bpf_redirect,
.gpl_only = false,
.ret_type = RET_INTEGER,
- .arg1_type = ARG_ANYTHING,
+ .arg1_type = ARG_ANYTHING32,
.arg2_type = ARG_ANYTHING,
};
@@ -2928,7 +2928,7 @@ static const struct bpf_func_proto bpf_skb_change_proto_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_ANYTHING,
};
@@ -2948,7 +2948,7 @@ static const struct bpf_func_proto bpf_skb_change_type_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
};
static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
@@ -3236,7 +3236,7 @@ static const struct bpf_func_proto bpf_skb_change_tail_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
- .arg2_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING32,
.arg3_type = ARG_ANYTHING,
};
@@ -3832,7 +3832,7 @@ static const struct bpf_func_proto bpf_skb_get_tunnel_key_proto = {
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
- .arg3_type = ARG_CONST_SIZE,
+ .arg3_type = ARG_CONST_SIZE32,
.arg4_type = ARG_ANYTHING,
};
@@ -3941,7 +3941,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_key_proto = {
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_MEM,
- .arg3_type = ARG_CONST_SIZE,
+ .arg3_type = ARG_CONST_SIZE32,
.arg4_type = ARG_ANYTHING,
};
--
2.7.4
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