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Merge branch 'skbuff-struct-group'

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Kees Cook says:

====================
skbuff: Switch structure bounds to struct_group()

This is a pair of patches to add struct_group() to struct sk_buff. The
first is needed to work around sparse-specific complaints, and is new
for v2. The second patch is the same as originally sent as v1.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2021-11-22 15:13:54 +00:00
parent cb902b332f 03f61041c1
commit 8ba71dbb7f
4 changed files with 33 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/net/wireguard/queueing.h
View File

@@ -79,9 +79,7 @@ static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating)
u8 sw_hash = skb->sw_hash;
u32 hash = skb->hash;
skb_scrub_packet(skb, true);
memset(&skb->headers_start, 0,
offsetof(struct sk_buff, headers_end) -
offsetof(struct sk_buff, headers_start));
memset(&skb->headers, 0, sizeof(skb->headers));
if (encapsulating) {
skb->l4_hash = l4_hash;
skb->sw_hash = sw_hash;

46
include/linux/skbuff.h
View File

@@ -795,7 +795,7 @@ 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];
@@ -811,25 +811,15 @@ struct sk_buff {
__u8 active_extensions;
#endif
/* fields enclosed in headers_start/headers_end are copied
/* Fields enclosed in headers group are copied
* using a single memcpy() in __copy_skb_header()
*/
/* private: */
__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)
struct_group(headers,
/* 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;
@@ -845,16 +835,10 @@ 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;
@@ -935,9 +919,7 @@ struct sk_buff {
u64 kcov_handle;
#endif
/* private: */
__u32 headers_end[0];
/* public: */
); /* end headers group */
/* These elements must be at the end, see alloc_skb() for details. */
sk_buff_data_t tail;
@@ -953,6 +935,22 @@ 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

10
net/core/filter.c
View File

@@ -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)
@@ -8029,7 +8029,7 @@ 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);
@@ -8617,7 +8617,7 @@ 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);
@@ -8642,7 +8642,7 @@ 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)

14
net/core/skbuff.c
View File

@@ -992,12 +992,10 @@ void napi_consume_skb(struct sk_buff *skb, int budget)
}
EXPORT_SYMBOL(napi_consume_skb);
/* Make sure a field is enclosed inside headers_start/headers_end section */
/* Make sure a field is contained by headers group */
#define CHECK_SKB_FIELD(field) \
BUILD_BUG_ON(offsetof(struct sk_buff, field) < \
offsetof(struct sk_buff, headers_start)); \
BUILD_BUG_ON(offsetof(struct sk_buff, field) > \
offsetof(struct sk_buff, headers_end)); \
BUILD_BUG_ON(offsetof(struct sk_buff, field) != \
offsetof(struct sk_buff, headers.field)); \
static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
@@ -1009,14 +1007,12 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
__skb_ext_copy(new, old);
__nf_copy(new, old, false);
/* Note : this field could be in headers_start/headers_end section
/* Note : this field could be in the headers group.
* It is not yet because we do not want to have a 16 bit hole
*/
new->queue_mapping = old->queue_mapping;
memcpy(&new->headers_start, &old->headers_start,
offsetof(struct sk_buff, headers_end) -
offsetof(struct sk_buff, headers_start));
memcpy(&new->headers, &old->headers, sizeof(new->headers));
CHECK_SKB_FIELD(protocol);
CHECK_SKB_FIELD(csum);
CHECK_SKB_FIELD(hash);