From f035a51536af9802f55d8c79bd87f184ebffb093 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 9 Sep 2016 02:45:29 +0200 Subject: [PATCH] bpf: add BPF_SIZEOF and BPF_FIELD_SIZEOF macros 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 Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- 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; -- 2.7.4