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Message-Id: <20211121003149.28397-2-keescook@chromium.org>
Date: Sat, 20 Nov 2021 16:31:48 -0800
From: Kees Cook <keescook@...omium.org>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
"David S. Miller" <davem@...emloft.net>,
Jonathan Lemon <jonathan.lemon@...il.com>,
Alexander Lobakin <alobakin@...me>,
Jakub Sitnicki <jakub@...udflare.com>,
Marco Elver <elver@...gle.com>,
Willem de Bruijn <willemb@...gle.com>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
"Jason A. Donenfeld" <Jason@...c4.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Cong Wang <cong.wang@...edance.com>,
Paolo Abeni <pabeni@...hat.com>,
Talal Ahmad <talalahmad@...gle.com>,
Kevin Hao <haokexin@...il.com>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>,
Vasily Averin <vvs@...tuozzo.com>,
linux-kernel@...r.kernel.org, wireguard@...ts.zx2c4.com,
netdev@...r.kernel.org, bpf@...r.kernel.org, llvm@...ts.linux.dev,
linux-hardening@...r.kernel.org
Subject: [PATCH v2 net-next 1/2] skbuff: Move conditional preprocessor directives out of struct sk_buff
In preparation for using the struct_group() macro in struct sk_buff,
move the conditional preprocessor directives out of the region of struct
sk_buff that will be enclosed by struct_group(). While GCC and Clang are
happy with conditional preprocessor directives here, sparse is not, even
under -Wno-directive-within-macro[1], as would be seen under a C=1 build:
net/core/filter.c: note: in included file (through include/linux/netlink.h, include/linux/sock_diag.h):
./include/linux/skbuff.h:820:1: warning: directive in macro's argument list
./include/linux/skbuff.h:822:1: warning: directive in macro's argument list
./include/linux/skbuff.h:846:1: warning: directive in macro's argument list
./include/linux/skbuff.h:848:1: warning: directive in macro's argument list
Additionally remove empty macro argument definitions and usage.
"objdump -d" shows no object code differences.
[1] https://www.spinics.net/lists/linux-sparse/msg10857.html
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/linux/skbuff.h | 36 +++++++++++++++++++-----------------
net/core/filter.c | 10 +++++-----
2 files changed, 24 insertions(+), 22 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 686a666d073d..0bce88ac799a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -792,7 +792,7 @@ struct sk_buff {
#else
#define CLONED_MASK 1
#endif
-#define CLONED_OFFSET() offsetof(struct sk_buff, __cloned_offset)
+#define CLONED_OFFSET offsetof(struct sk_buff, __cloned_offset)
/* private: */
__u8 __cloned_offset[0];
@@ -815,18 +815,10 @@ struct sk_buff {
__u32 headers_start[0];
/* public: */
-/* if you move pkt_type around you also must adapt those constants */
-#ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_TYPE_MAX (7 << 5)
-#else
-#define PKT_TYPE_MAX 7
-#endif
-#define PKT_TYPE_OFFSET() offsetof(struct sk_buff, __pkt_type_offset)
-
/* private: */
__u8 __pkt_type_offset[0];
/* public: */
- __u8 pkt_type:3;
+ __u8 pkt_type:3; /* see PKT_TYPE_MAX */
__u8 ignore_df:1;
__u8 nf_trace:1;
__u8 ip_summed:2;
@@ -842,16 +834,10 @@ struct sk_buff {
__u8 encap_hdr_csum:1;
__u8 csum_valid:1;
-#ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_VLAN_PRESENT_BIT 7
-#else
-#define PKT_VLAN_PRESENT_BIT 0
-#endif
-#define PKT_VLAN_PRESENT_OFFSET() offsetof(struct sk_buff, __pkt_vlan_present_offset)
/* private: */
__u8 __pkt_vlan_present_offset[0];
/* public: */
- __u8 vlan_present:1;
+ __u8 vlan_present:1; /* See PKT_VLAN_PRESENT_BIT */
__u8 csum_complete_sw:1;
__u8 csum_level:2;
__u8 csum_not_inet:1;
@@ -950,6 +936,22 @@ struct sk_buff {
#endif
};
+/* if you move pkt_type around you also must adapt those constants */
+#ifdef __BIG_ENDIAN_BITFIELD
+#define PKT_TYPE_MAX (7 << 5)
+#else
+#define PKT_TYPE_MAX 7
+#endif
+#define PKT_TYPE_OFFSET offsetof(struct sk_buff, __pkt_type_offset)
+
+/* if you move pkt_vlan_present around you also must adapt these constants */
+#ifdef __BIG_ENDIAN_BITFIELD
+#define PKT_VLAN_PRESENT_BIT 7
+#else
+#define PKT_VLAN_PRESENT_BIT 0
+#endif
+#define PKT_VLAN_PRESENT_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset)
+
#ifdef __KERNEL__
/*
* Handling routines are only of interest to the kernel
diff --git a/net/core/filter.c b/net/core/filter.c
index e471c9b09670..0bf912a44099 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -301,7 +301,7 @@ static u32 convert_skb_access(int skb_field, int dst_reg, int src_reg,
break;
case SKF_AD_PKTTYPE:
- *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, PKT_TYPE_OFFSET());
+ *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, PKT_TYPE_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, PKT_TYPE_MAX);
#ifdef __BIG_ENDIAN_BITFIELD
*insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 5);
@@ -323,7 +323,7 @@ static u32 convert_skb_access(int skb_field, int dst_reg, int src_reg,
offsetof(struct sk_buff, vlan_tci));
break;
case SKF_AD_VLAN_TAG_PRESENT:
- *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, PKT_VLAN_PRESENT_OFFSET());
+ *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, PKT_VLAN_PRESENT_OFFSET);
if (PKT_VLAN_PRESENT_BIT)
*insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, PKT_VLAN_PRESENT_BIT);
if (PKT_VLAN_PRESENT_BIT < 7)
@@ -8027,7 +8027,7 @@ static int bpf_unclone_prologue(struct bpf_insn *insn_buf, bool direct_write,
* (Fast-path, otherwise approximation that we might be
* a clone, do the rest in helper.)
*/
- *insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_6, BPF_REG_1, CLONED_OFFSET());
+ *insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_6, BPF_REG_1, CLONED_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_6, CLONED_MASK);
*insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 7);
@@ -8615,7 +8615,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
case offsetof(struct __sk_buff, pkt_type):
*target_size = 1;
*insn++ = BPF_LDX_MEM(BPF_B, si->dst_reg, si->src_reg,
- PKT_TYPE_OFFSET());
+ PKT_TYPE_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, PKT_TYPE_MAX);
#ifdef __BIG_ENDIAN_BITFIELD
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, 5);
@@ -8640,7 +8640,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
case offsetof(struct __sk_buff, vlan_present):
*target_size = 1;
*insn++ = BPF_LDX_MEM(BPF_B, si->dst_reg, si->src_reg,
- PKT_VLAN_PRESENT_OFFSET());
+ PKT_VLAN_PRESENT_OFFSET);
if (PKT_VLAN_PRESENT_BIT)
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, PKT_VLAN_PRESENT_BIT);
if (PKT_VLAN_PRESENT_BIT < 7)
--
2.30.2
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