Make the verifier sanitize LDX insns in jited BPF programs, a little more complicated than STX/ST. The dst_reg and AX are free here, different insns that backup R0&R1 are inserted before calling the checking functions based on their relationships with dst_reg and src_reg, the checking funcs are then inserted, and finally regs are restored. Signed-off-by: Hao Sun <sunhao.th@xxxxxxxxx> --- arch/x86/net/bpf_jit_comp.c | 4 +- include/linux/bpf.h | 5 +++ kernel/bpf/verifier.c | 88 +++++++++++++++++++++++++++++++++++++ 3 files changed, 96 insertions(+), 1 deletion(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index ceaef69adc49..0fc67383ffa8 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -343,7 +343,9 @@ static int emit_call(u8 **pprog, void *func, void *ip) u8 *prog = *pprog; bool is_sanitize = func == bpf_asan_store8 || func == bpf_asan_store16 || - func == bpf_asan_store32 || func == bpf_asan_store64; + func == bpf_asan_store32 || func == bpf_asan_store64 || + func == bpf_asan_load8 || func == bpf_asan_load16 || + func == bpf_asan_load32 || func == bpf_asan_load64; if (!is_sanitize) return emit_patch(pprog, func, ip, 0xE8); diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a7eb99928fee..350d890a39ac 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2842,6 +2842,11 @@ u64 bpf_asan_store16(u16 *addr); u64 bpf_asan_store32(u32 *addr); u64 bpf_asan_store64(u64 *addr); +u64 bpf_asan_load8(u8 *addr); +u64 bpf_asan_load16(u16 *addr); +u64 bpf_asan_load32(u32 *addr); +u64 bpf_asan_load64(u64 *addr); + #endif /* CONFIG_BPF_PROG_KASAN */ #endif /* _LINUX_BPF_H */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index af214f0191e0..c0c11d24dc7b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15238,6 +15238,17 @@ BPF_ASAN_STORE(16); BPF_ASAN_STORE(32); BPF_ASAN_STORE(64); +#define BPF_ASAN_LOAD(n) \ + notrace u64 bpf_asan_load##n(u##n *addr) \ + { \ + return *addr; \ + } + +BPF_ASAN_LOAD(8); +BPF_ASAN_LOAD(16); +BPF_ASAN_LOAD(32); +BPF_ASAN_LOAD(64); + #endif /* Do various post-verification rewrites in a single program pass. @@ -15454,6 +15465,83 @@ static int do_misc_fixups(struct bpf_verifier_env *env) insn = new_prog->insnsi + i + delta; continue; } + + /* Sanitize LDX operation*/ + if (BPF_CLASS(insn->code) == BPF_LDX) { + struct bpf_insn sanitize_fn; + struct bpf_insn *patch = &insn_buf[0]; + bool dst_is_r0 = insn->dst_reg == BPF_REG_0; + bool dst_is_r1 = insn->dst_reg == BPF_REG_1; + + if (in_patch_use_ax || insn->src_reg == BPF_REG_10) + continue; + + switch (BPF_SIZE(insn->code)) { + case BPF_B: + sanitize_fn = BPF_EMIT_CALL(bpf_asan_load8); + break; + case BPF_H: + sanitize_fn = BPF_EMIT_CALL(bpf_asan_load16); + break; + case BPF_W: + sanitize_fn = BPF_EMIT_CALL(bpf_asan_load32); + break; + case BPF_DW: + sanitize_fn = BPF_EMIT_CALL(bpf_asan_load64); + break; + } + + /* Backup R0 and R1, REG_AX and dst_reg are free. */ + if (insn->src_reg == BPF_REG_1) { + if (!dst_is_r0) + *patch++ = BPF_MOV64_REG(BPF_REG_AX, BPF_REG_0); + } else if (insn->src_reg == BPF_REG_0) { + if (!dst_is_r1) + *patch++ = BPF_MOV64_REG(BPF_REG_AX, BPF_REG_1); + *patch++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_0); + } else if (!dst_is_r1) { + *patch++ = BPF_MOV64_REG(BPF_REG_AX, BPF_REG_1); + *patch++ = BPF_MOV64_REG(BPF_REG_1, insn->src_reg); + if (!dst_is_r0) + *patch++ = BPF_MOV64_REG(insn->dst_reg, BPF_REG_0); + } else { + *patch++ = BPF_MOV64_REG(BPF_REG_1, insn->src_reg); + *patch++ = BPF_MOV64_REG(BPF_REG_AX, BPF_REG_0); + } + if (insn->off != 0) + *patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, insn->off); + /* Invoke sanitize fn, R1~R5 are stored to stack during jit. */ + *patch++ = sanitize_fn; + if (insn->off != 0) + *patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -insn->off); + if (insn->src_reg == BPF_REG_1) { + if (!dst_is_r0) + *patch++ = BPF_MOV64_REG(BPF_REG_0, BPF_REG_AX); + } else if (insn->src_reg == BPF_REG_0) { + *patch++ = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1); + if (!dst_is_r1) + *patch++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_AX); + } else if (!dst_is_r1) { + if (!dst_is_r0) + *patch++ = BPF_MOV64_REG(BPF_REG_0, insn->dst_reg); + if (insn->src_reg == insn->dst_reg) + *patch++ = BPF_MOV64_REG(insn->src_reg, BPF_REG_1); + *patch++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_AX); + } else { + *patch++ = BPF_MOV64_REG(BPF_REG_0, BPF_REG_AX); + } + *patch++ = *insn; + cnt = patch - insn_buf; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } #endif if (insn->code != (BPF_JMP | BPF_CALL)) -- 2.38.1