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powerpc/bpf: Validate branch ranges

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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 <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Song Liu <songliubraving@fb.com>
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
This commit is contained in:
Naveen N. Rao 2021-10-06 01:55:21 +05:30 committed by Michael Ellerman
parent 4549c3ea31
commit 3832ba4e28
4 changed files with 37 additions and 11 deletions
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26
arch/powerpc/net/bpf_jit.h
View File

@ -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 && \

6
arch/powerpc/net/bpf_jit_comp.c
View File

@ -210,7 +210,11 @@ skip_init_ctx:
/* 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)

8
arch/powerpc/net/bpf_jit_comp32.c
View File

@ -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 @@ cond_branch:
*/
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:

8
arch/powerpc/net/bpf_jit_comp64.c
View File

@ -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 @@ cond_branch:
*/
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: