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-rw-r--r--kernel/bpf/core.c203
1 files changed, 203 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 70f0821aca47..f1e8a0def99b 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -243,6 +243,209 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr)
{
module_memfree(hdr);
}
+
+int bpf_jit_harden __read_mostly;
+
+static int bpf_jit_blind_insn(const struct bpf_insn *from,
+ const struct bpf_insn *aux,
+ struct bpf_insn *to_buff)
+{
+ struct bpf_insn *to = to_buff;
+ u32 imm_rnd = prandom_u32();
+ s16 off;
+
+ BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG);
+ BUILD_BUG_ON(MAX_BPF_REG + 1 != MAX_BPF_JIT_REG);
+
+ if (from->imm == 0 &&
+ (from->code == (BPF_ALU | BPF_MOV | BPF_K) ||
+ from->code == (BPF_ALU64 | BPF_MOV | BPF_K))) {
+ *to++ = BPF_ALU64_REG(BPF_XOR, from->dst_reg, from->dst_reg);
+ goto out;
+ }
+
+ switch (from->code) {
+ case BPF_ALU | BPF_ADD | BPF_K:
+ case BPF_ALU | BPF_SUB | BPF_K:
+ case BPF_ALU | BPF_AND | BPF_K:
+ case BPF_ALU | BPF_OR | BPF_K:
+ case BPF_ALU | BPF_XOR | BPF_K:
+ case BPF_ALU | BPF_MUL | BPF_K:
+ case BPF_ALU | BPF_MOV | BPF_K:
+ case BPF_ALU | BPF_DIV | BPF_K:
+ case BPF_ALU | BPF_MOD | BPF_K:
+ *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_ALU32_REG(from->code, from->dst_reg, BPF_REG_AX);
+ break;
+
+ case BPF_ALU64 | BPF_ADD | BPF_K:
+ case BPF_ALU64 | BPF_SUB | BPF_K:
+ case BPF_ALU64 | BPF_AND | BPF_K:
+ case BPF_ALU64 | BPF_OR | BPF_K:
+ case BPF_ALU64 | BPF_XOR | BPF_K:
+ case BPF_ALU64 | BPF_MUL | BPF_K:
+ case BPF_ALU64 | BPF_MOV | BPF_K:
+ case BPF_ALU64 | BPF_DIV | BPF_K:
+ case BPF_ALU64 | BPF_MOD | BPF_K:
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_ALU64_REG(from->code, from->dst_reg, BPF_REG_AX);
+ break;
+
+ case BPF_JMP | BPF_JEQ | BPF_K:
+ case BPF_JMP | BPF_JNE | BPF_K:
+ case BPF_JMP | BPF_JGT | BPF_K:
+ case BPF_JMP | BPF_JGE | BPF_K:
+ case BPF_JMP | BPF_JSGT | BPF_K:
+ case BPF_JMP | BPF_JSGE | BPF_K:
+ case BPF_JMP | BPF_JSET | BPF_K:
+ /* Accommodate for extra offset in case of a backjump. */
+ off = from->off;
+ if (off < 0)
+ off -= 2;
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_JMP_REG(from->code, from->dst_reg, BPF_REG_AX, off);
+ break;
+
+ case BPF_LD | BPF_ABS | BPF_W:
+ case BPF_LD | BPF_ABS | BPF_H:
+ case BPF_LD | BPF_ABS | BPF_B:
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_LD_IND(from->code, BPF_REG_AX, 0);
+ break;
+
+ case BPF_LD | BPF_IND | BPF_W:
+ case BPF_LD | BPF_IND | BPF_H:
+ case BPF_LD | BPF_IND | BPF_B:
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_ALU32_REG(BPF_ADD, BPF_REG_AX, from->src_reg);
+ *to++ = BPF_LD_IND(from->code, BPF_REG_AX, 0);
+ break;
+
+ case BPF_LD | BPF_IMM | BPF_DW:
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[1].imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
+ *to++ = BPF_ALU64_REG(BPF_MOV, aux[0].dst_reg, BPF_REG_AX);
+ break;
+ case 0: /* Part 2 of BPF_LD | BPF_IMM | BPF_DW. */
+ *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[0].imm);
+ *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_ALU64_REG(BPF_OR, aux[0].dst_reg, BPF_REG_AX);
+ break;
+
+ case BPF_ST | BPF_MEM | BPF_DW:
+ case BPF_ST | BPF_MEM | BPF_W:
+ case BPF_ST | BPF_MEM | BPF_H:
+ case BPF_ST | BPF_MEM | BPF_B:
+ *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+ *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+ *to++ = BPF_STX_MEM(from->code, from->dst_reg, BPF_REG_AX, from->off);
+ break;
+ }
+out:
+ return to - to_buff;
+}
+
+static struct bpf_prog *bpf_prog_clone_create(struct bpf_prog *fp_other,
+ gfp_t gfp_extra_flags)
+{
+ gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO |
+ gfp_extra_flags;
+ struct bpf_prog *fp;
+
+ fp = __vmalloc(fp_other->pages * PAGE_SIZE, gfp_flags, PAGE_KERNEL);
+ if (fp != NULL) {
+ kmemcheck_annotate_bitfield(fp, meta);
+
+ /* aux->prog still points to the fp_other one, so
+ * when promoting the clone to the real program,
+ * this still needs to be adapted.
+ */
+ memcpy(fp, fp_other, fp_other->pages * PAGE_SIZE);
+ }
+
+ return fp;
+}
+
+static void bpf_prog_clone_free(struct bpf_prog *fp)
+{
+ /* aux was stolen by the other clone, so we cannot free
+ * it from this path! It will be freed eventually by the
+ * other program on release.
+ *
+ * At this point, we don't need a deferred release since
+ * clone is guaranteed to not be locked.
+ */
+ fp->aux = NULL;
+ __bpf_prog_free(fp);
+}
+
+void bpf_jit_prog_release_other(struct bpf_prog *fp, struct bpf_prog *fp_other)
+{
+ /* We have to repoint aux->prog to self, as we don't
+ * know whether fp here is the clone or the original.
+ */
+ fp->aux->prog = fp;
+ bpf_prog_clone_free(fp_other);
+}
+
+struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog)
+{
+ struct bpf_insn insn_buff[16], aux[2];
+ struct bpf_prog *clone, *tmp;
+ int insn_delta, insn_cnt;
+ struct bpf_insn *insn;
+ int i, rewritten;
+
+ if (!bpf_jit_blinding_enabled())
+ return prog;
+
+ clone = bpf_prog_clone_create(prog, GFP_USER);
+ if (!clone)
+ return ERR_PTR(-ENOMEM);
+
+ insn_cnt = clone->len;
+ insn = clone->insnsi;
+
+ for (i = 0; i < insn_cnt; i++, insn++) {
+ /* We temporarily need to hold the original ld64 insn
+ * so that we can still access the first part in the
+ * second blinding run.
+ */
+ if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW) &&
+ insn[1].code == 0)
+ memcpy(aux, insn, sizeof(aux));
+
+ rewritten = bpf_jit_blind_insn(insn, aux, insn_buff);
+ if (!rewritten)
+ continue;
+
+ tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten);
+ if (!tmp) {
+ /* Patching may have repointed aux->prog during
+ * realloc from the original one, so we need to
+ * fix it up here on error.
+ */
+ bpf_jit_prog_release_other(prog, clone);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ clone = tmp;
+ insn_delta = rewritten - 1;
+
+ /* Walk new program and skip insns we just inserted. */
+ insn = clone->insnsi + i + insn_delta;
+ insn_cnt += insn_delta;
+ i += insn_delta;
+ }
+
+ return clone;
+}
#endif /* CONFIG_BPF_JIT */
/* Base function for offset calculation. Needs to go into .text section,