On Fri, Oct 1, 2021 at 2:16 PM Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> wrote: > > Add checks to ensure that we never emit branch instructions with > truncated branch offsets. > > Suggested-by: Michael Ellerman <m...@ellerman.id.au> > Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
Acked-by: Song Liu <songliubrav...@fb.com> > --- > 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 935ea95b66359e..7e9b978b768ed9 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 53aefee3fe70be..fcbf7a917c566e 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 beb12cbc8c2994..a74d52204f8da2 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 b87a63dba9c8fb..f06c62089b1457 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 >