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bpf, arm64: add support for constant blinding

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This patch adds recently added constant blinding helpers into the
arm64 eBPF JIT. In the bpf_int_jit_compile() path, requirements are
to utilize bpf_jit_blind_constants()/bpf_jit_prog_release_other()
pair for rewriting the program into a blinded one, and to map the
BPF_REG_AX register to a CPU register. The mapping is on x9.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Yang Shi <yang.shi@linaro.org>
Tested-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2016-05-13 19:08:34 +02:00 committed by David S. Miller
parent 959a757916
commit 26eb042ee4
1 changed files with 40 additions and 12 deletions
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52
arch/arm64/net/bpf_jit_comp.c
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@ -31,8 +31,8 @@
int bpf_jit_enable __read_mostly;
#define TMP_REG_1 (MAX_BPF_REG + 0)
#define TMP_REG_2 (MAX_BPF_REG + 1)
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
/* Map BPF registers to A64 registers */
static const int bpf2a64[] = {
@ -54,6 +54,8 @@ static const int bpf2a64[] = {
/* temporary register for internal BPF JIT */
[TMP_REG_1] = A64_R(23),
[TMP_REG_2] = A64_R(24),
/* temporary register for blinding constants */
[BPF_REG_AX] = A64_R(9),
};
struct jit_ctx {
@ -764,26 +766,43 @@ void bpf_jit_compile(struct bpf_prog *prog)
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
struct bpf_prog *tmp, *orig_prog = prog;
struct bpf_binary_header *header;
bool tmp_blinded = false;
struct jit_ctx ctx;
int image_size;
u8 *image_ptr;
if (!bpf_jit_enable)
return prog;
return orig_prog;
tmp = bpf_jit_blind_constants(prog);
/* If blinding was requested and we failed during blinding,
* we must fall back to the interpreter.
*/
if (IS_ERR(tmp))
return orig_prog;
if (tmp != prog) {
tmp_blinded = true;
prog = tmp;
}
memset(&ctx, 0, sizeof(ctx));
ctx.prog = prog;
ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
if (ctx.offset == NULL)
return prog;
if (ctx.offset == NULL) {
prog = orig_prog;
goto out;
}
/* 1. Initial fake pass to compute ctx->idx. */
/* Fake pass to fill in ctx->offset and ctx->tmp_used. */
if (build_body(&ctx))
goto out;
if (build_body(&ctx)) {
prog = orig_prog;
goto out_off;
}
build_prologue(&ctx);
@ -794,8 +813,10 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
image_size = sizeof(u32) * ctx.idx;
header = bpf_jit_binary_alloc(image_size, &image_ptr,
sizeof(u32), jit_fill_hole);
if (header == NULL)
goto out;
if (header == NULL) {
prog = orig_prog;
goto out_off;
}
/* 2. Now, the actual pass. */
@ -806,7 +827,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
if (build_body(&ctx)) {
bpf_jit_binary_free(header);
goto out;
prog = orig_prog;
goto out_off;
}
build_epilogue(&ctx);
@ -814,7 +836,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
/* 3. Extra pass to validate JITed code. */
if (validate_code(&ctx)) {
bpf_jit_binary_free(header);
goto out;
prog = orig_prog;
goto out_off;
}
/* And we're done. */
@ -826,8 +849,13 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
set_memory_ro((unsigned long)header, header->pages);
prog->bpf_func = (void *)ctx.image;
prog->jited = 1;
out:
out_off:
kfree(ctx.offset);
out:
if (tmp_blinded)
bpf_jit_prog_release_other(prog, prog == orig_prog ?
tmp : orig_prog);
return prog;
}