[PATCH AUTOSEL 5.14 14/17] powerpc/bpf: Validate branch ranges
From: Sasha Levin <sashal@kernel.org>
Date: 2021-10-13 00:55:38
Also in:
bpf, linuxppc-dev, lkml, stable
Subsystem:
bpf jit for powerpc (32-bit and 64-bit), bpf [general] (safe dynamic programs and tools), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Hari Bathini, Christophe Leroy, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
From: "Naveen N. Rao" <redacted> [ Upstream commit 3832ba4e283d7052b783dab8311df7e3590fed93 ] Add checks to ensure that we never emit branch instructions with truncated branch offsets. Suggested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Naveen N. Rao <redacted> Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Reviewed-by: Christophe Leroy <redacted> Acked-by: Song Liu <redacted> Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/71d33a6b7603ec1013c9734dd8bdd4ff5e929142.1633464148.git.naveen.n.rao@linux.vnet.ibm.com (local) Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/powerpc/net/bpf_jit.h | 26 ++++++++++++++++++++------ arch/powerpc/net/bpf_jit_comp.c | 6 +++++- arch/powerpc/net/bpf_jit_comp32.c | 8 ++++++-- arch/powerpc/net/bpf_jit_comp64.c | 8 ++++++-- 4 files changed, 37 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 935ea95b6635..7e9b978b768e 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h@@ -24,16 +24,30 @@ #define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr) /* Long jump; (unconditional 'branch') */ -#define PPC_JMP(dest) EMIT(PPC_INST_BRANCH | \ - (((dest) - (ctx->idx * 4)) & 0x03fffffc)) +#define PPC_JMP(dest) \ + do { \ + long offset = (long)(dest) - (ctx->idx * 4); \ + if (!is_offset_in_branch_range(offset)) { \ + pr_err_ratelimited("Branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \ + return -ERANGE; \ + } \ + EMIT(PPC_INST_BRANCH | (offset & 0x03fffffc)); \ + } while (0) + /* blr; (unconditional 'branch' with link) to absolute address */ #define PPC_BL_ABS(dest) EMIT(PPC_INST_BL | \ (((dest) - (unsigned long)(image + ctx->idx)) & 0x03fffffc)) /* "cond" here covers BO:BI fields. */ -#define PPC_BCC_SHORT(cond, dest) EMIT(PPC_INST_BRANCH_COND | \ - (((cond) & 0x3ff) << 16) | \ - (((dest) - (ctx->idx * 4)) & \ - 0xfffc)) +#define PPC_BCC_SHORT(cond, dest) \ + do { \ + long offset = (long)(dest) - (ctx->idx * 4); \ + if (!is_offset_in_cond_branch_range(offset)) { \ + pr_err_ratelimited("Conditional branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \ + return -ERANGE; \ + } \ + EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc)); \ + } while (0) + /* Sign-extended 32-bit immediate load */ #define PPC_LI32(d, i) do { \ if ((int)(uintptr_t)(i) >= -32768 && \
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 53aefee3fe70..fcbf7a917c56 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c@@ -210,7 +210,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) /* Now build the prologue, body code & epilogue for real. */ cgctx.idx = 0; bpf_jit_build_prologue(code_base, &cgctx); - bpf_jit_build_body(fp, code_base, &cgctx, addrs, extra_pass); + if (bpf_jit_build_body(fp, code_base, &cgctx, addrs, extra_pass)) { + bpf_jit_binary_free(bpf_hdr); + fp = org_fp; + goto out_addrs; + } bpf_jit_build_epilogue(code_base, &cgctx); if (bpf_jit_enable > 1)
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index beb12cbc8c29..a74d52204f8d 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c@@ -200,7 +200,7 @@ void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 fun } } -static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) { /* * By now, the eBPF program has already setup parameters in r3-r6
@@ -261,7 +261,9 @@ static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 bpf_jit_emit_common_epilogue(image, ctx); EMIT(PPC_RAW_BCTR()); + /* out: */ + return 0; } /* Assemble the body code between the prologue & epilogue */
@@ -1090,7 +1092,9 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * */ case BPF_JMP | BPF_TAIL_CALL: ctx->seen |= SEEN_TAILCALL; - bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + if (ret < 0) + return ret; break; default:
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index b87a63dba9c8..f06c62089b14 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c@@ -206,7 +206,7 @@ void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 fun EMIT(PPC_RAW_BCTRL()); } -static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) { /* * By now, the eBPF program has already setup parameters in r3, r4 and r5
@@ -267,7 +267,9 @@ static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 bpf_jit_emit_common_epilogue(image, ctx); EMIT(PPC_RAW_BCTR()); + /* out: */ + return 0; } /* Assemble the body code between the prologue & epilogue */
@@ -993,7 +995,9 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * */ case BPF_JMP | BPF_TAIL_CALL: ctx->seen |= SEEN_TAILCALL; - bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + if (ret < 0) + return ret; break; default:
--
2.33.0