Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit
which otherwise often result in overly long bytes_to_bpf_size(sizeof())
and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro
helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF())
check in convert_bpf_extensions(), but we should rather make that generic
as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF()
users to detect any rewriter size issues at compile time. Note, there are
currently none, but we want to assert that it stays this way.
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
include/linux/filter.h | 14 ++++++++++++++
kernel/trace/bpf_trace.c | 12 ++++++------
net/core/filter.c | 15 +++++++--------
3 files changed, 27 insertions(+), 14 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index a16439b..7fabad8 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -314,6 +314,20 @@ struct bpf_prog_aux;
bpf_size; \
})
+#define BPF_SIZEOF(type) \
+ ({ \
+ const int __size = bytes_to_bpf_size(sizeof(type)); \
+ BUILD_BUG_ON(__size < 0); \
+ __size; \
+ })
+
+#define BPF_FIELD_SIZEOF(type, field) \
+ ({ \
+ const int __size = bytes_to_bpf_size(FIELD_SIZEOF(type,
field)); \
+ BUILD_BUG_ON(__size < 0); \
+ __size; \
+ })
+
#ifdef CONFIG_COMPAT
/* A struct sock_filter is architecture independent. */
struct compat_sock_fprog {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d3869b0..e63d7d4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -583,18 +583,18 @@ static u32 pe_prog_convert_ctx_access(enum
bpf_access_type type, int dst_reg,
switch (ctx_off) {
case offsetof(struct bpf_perf_event_data, sample_period):
BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) !=
sizeof(u64));
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
bpf_perf_event_data_kern, data)),
- dst_reg, src_reg,
+
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct
bpf_perf_event_data_kern,
+ data), dst_reg, src_reg,
offsetof(struct bpf_perf_event_data_kern,
data));
*insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg,
offsetof(struct perf_sample_data,
period));
break;
default:
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
bpf_perf_event_data_kern, regs)),
- dst_reg, src_reg,
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct
bpf_perf_event_data_kern,
+ regs), dst_reg, src_reg,
offsetof(struct bpf_perf_event_data_kern,
regs));
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(long)),
- dst_reg, dst_reg, ctx_off);
+ *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), dst_reg, dst_reg,
ctx_off);
break;
}
diff --git a/net/core/filter.c b/net/core/filter.c
index 628ed8c..120c813 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -233,9 +233,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
case SKF_AD_OFF + SKF_AD_HATYPE:
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
- BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff,
dev)) < 0);
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
sk_buff, dev)),
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, dev),
BPF_REG_TMP, BPF_REG_CTX,
offsetof(struct sk_buff, dev));
/* if (tmp != 0) goto pc + 1 */
@@ -2685,7 +2684,7 @@ static u32 bpf_net_convert_ctx_access(enum
bpf_access_type type, int dst_reg,
case offsetof(struct __sk_buff, ifindex):
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
sk_buff, dev)),
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, dev),
dst_reg, src_reg,
offsetof(struct sk_buff, dev));
*insn++ = BPF_JMP_IMM(BPF_JEQ, dst_reg, 0, 1);
@@ -2750,7 +2749,7 @@ static u32 bpf_net_convert_ctx_access(enum
bpf_access_type type, int dst_reg,
break;
case offsetof(struct __sk_buff, data):
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
sk_buff, data)),
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data),
dst_reg, src_reg,
offsetof(struct sk_buff, data));
break;
@@ -2759,8 +2758,8 @@ static u32 bpf_net_convert_ctx_access(enum
bpf_access_type type, int dst_reg,
ctx_off -= offsetof(struct __sk_buff, data_end);
ctx_off += offsetof(struct sk_buff, cb);
ctx_off += offsetof(struct bpf_skb_data_end, data_end);
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(void *)),
- dst_reg, src_reg, ctx_off);
+ *insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), dst_reg, src_reg,
+ ctx_off);
break;
case offsetof(struct __sk_buff, tc_index):
@@ -2795,12 +2794,12 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type
type, int dst_reg,
switch (ctx_off) {
case offsetof(struct xdp_md, data):
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
xdp_buff, data)),
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, data),
dst_reg, src_reg,
offsetof(struct xdp_buff, data));
break;
case offsetof(struct xdp_md, data_end):
- *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
xdp_buff, data_end)),
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff,
data_end),
dst_reg, src_reg,
offsetof(struct xdp_buff, data_end));
break;
--
1.9.3
