From b7b7013cac55d794940bd9cb7b7c55c9dececac4 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Sat, 24 Sep 2016 02:05:02 +0530 Subject: [PATCH] powerpc/bpf: Add support for bpf constant blinding In line with similar support for other architectures by Daniel Borkmann. 'MOD Default X' from test_bpf without constant blinding: 84 bytes emitted from JIT compiler (pass:3, flen:7) d0000000058a4688 + : 0: nop 4: nop 8: std r27,-40(r1) c: std r28,-32(r1) 10: xor r8,r8,r8 14: xor r28,r28,r28 18: mr r27,r3 1c: li r8,66 20: cmpwi r28,0 24: bne 0x0000000000000030 28: li r8,0 2c: b 0x0000000000000044 30: divwu r9,r8,r28 34: mullw r9,r28,r9 38: subf r8,r9,r8 3c: rotlwi r8,r8,0 40: li r8,66 44: ld r27,-40(r1) 48: ld r28,-32(r1) 4c: mr r3,r8 50: blr ... and with constant blinding: 140 bytes emitted from JIT compiler (pass:3, flen:11) d00000000bd6ab24 + : 0: nop 4: nop 8: std r27,-40(r1) c: std r28,-32(r1) 10: xor r8,r8,r8 14: xor r28,r28,r28 18: mr r27,r3 1c: lis r2,-22834 20: ori r2,r2,36083 24: rotlwi r2,r2,0 28: xori r2,r2,36017 2c: xoris r2,r2,42702 30: rotlwi r2,r2,0 34: mr r8,r2 38: rotlwi r8,r8,0 3c: cmpwi r28,0 40: bne 0x000000000000004c 44: li r8,0 48: b 0x000000000000007c 4c: divwu r9,r8,r28 50: mullw r9,r28,r9 54: subf r8,r9,r8 58: rotlwi r8,r8,0 5c: lis r2,-17137 60: ori r2,r2,39065 64: rotlwi r2,r2,0 68: xori r2,r2,39131 6c: xoris r2,r2,48399 70: rotlwi r2,r2,0 74: mr r8,r2 78: rotlwi r8,r8,0 7c: ld r27,-40(r1) 80: ld r28,-32(r1) 84: mr r3,r8 88: blr Signed-off-by: Naveen N. Rao Acked-by: Daniel Borkmann Signed-off-by: Michael Ellerman --- arch/powerpc/net/bpf_jit64.h | 9 ++++---- arch/powerpc/net/bpf_jit_comp64.c | 36 +++++++++++++++++++++++++------ 2 files changed, 34 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/net/bpf_jit64.h b/arch/powerpc/net/bpf_jit64.h index 038e00bf2b77..62fa7589db2b 100644 --- a/arch/powerpc/net/bpf_jit64.h +++ b/arch/powerpc/net/bpf_jit64.h @@ -39,10 +39,10 @@ #ifndef __ASSEMBLY__ /* BPF register usage */ -#define SKB_HLEN_REG (MAX_BPF_REG + 0) -#define SKB_DATA_REG (MAX_BPF_REG + 1) -#define TMP_REG_1 (MAX_BPF_REG + 2) -#define TMP_REG_2 (MAX_BPF_REG + 3) +#define SKB_HLEN_REG (MAX_BPF_JIT_REG + 0) +#define SKB_DATA_REG (MAX_BPF_JIT_REG + 1) +#define TMP_REG_1 (MAX_BPF_JIT_REG + 2) +#define TMP_REG_2 (MAX_BPF_JIT_REG + 3) /* BPF to ppc register mappings */ static const int b2p[] = { @@ -62,6 +62,7 @@ static const int b2p[] = { /* frame pointer aka BPF_REG_10 */ [BPF_REG_FP] = 31, /* eBPF jit internal registers */ + [BPF_REG_AX] = 2, [SKB_HLEN_REG] = 25, [SKB_DATA_REG] = 26, [TMP_REG_1] = 9, diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 3ec29d6fba60..0fe98a567125 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -974,21 +974,37 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) int pass; int flen; struct bpf_binary_header *bpf_hdr; + struct bpf_prog *org_fp = fp; + struct bpf_prog *tmp_fp; + bool bpf_blinded = false; if (!bpf_jit_enable) - return fp; + return org_fp; + + tmp_fp = bpf_jit_blind_constants(org_fp); + if (IS_ERR(tmp_fp)) + return org_fp; + + if (tmp_fp != org_fp) { + bpf_blinded = true; + fp = tmp_fp; + } flen = fp->len; addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL); - if (addrs == NULL) - return fp; + if (addrs == NULL) { + fp = org_fp; + goto out; + } + + memset(&cgctx, 0, sizeof(struct codegen_context)); - cgctx.idx = 0; - cgctx.seen = 0; /* Scouting faux-generate pass 0 */ - if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) + if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) { /* We hit something illegal or unsupported. */ + fp = org_fp; goto out; + } /* * Pretend to build prologue, given the features we've seen. This will @@ -1003,8 +1019,10 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns); - if (!bpf_hdr) + if (!bpf_hdr) { + fp = org_fp; goto out; + } code_base = (u32 *)(image + FUNCTION_DESCR_SIZE); @@ -1041,6 +1059,10 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) out: kfree(addrs); + + if (bpf_blinded) + bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp); + return fp; } -- GitLab