diff options
Diffstat (limited to 'kernel/bpf')
-rw-r--r-- | kernel/bpf/verifier.c | 102 |
1 files changed, 34 insertions, 68 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 86dfe6b5c243..04b24876cd23 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1890,29 +1890,25 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, if (BPF_CLASS(insn->code) != BPF_ALU64) { /* 32-bit ALU ops on pointers produce (meaningless) scalars */ - if (!env->allow_ptr_leaks) - verbose(env, - "R%d 32-bit pointer arithmetic prohibited\n", - dst); + verbose(env, + "R%d 32-bit pointer arithmetic prohibited\n", + dst); return -EACCES; } if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { - if (!env->allow_ptr_leaks) - verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n", - dst); + verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n", + dst); return -EACCES; } if (ptr_reg->type == CONST_PTR_TO_MAP) { - if (!env->allow_ptr_leaks) - verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n", - dst); + verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n", + dst); return -EACCES; } if (ptr_reg->type == PTR_TO_PACKET_END) { - if (!env->allow_ptr_leaks) - verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n", - dst); + verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n", + dst); return -EACCES; } @@ -1979,9 +1975,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, case BPF_SUB: if (dst_reg == off_reg) { /* scalar -= pointer. Creates an unknown scalar */ - if (!env->allow_ptr_leaks) - verbose(env, "R%d tried to subtract pointer from scalar\n", - dst); + verbose(env, "R%d tried to subtract pointer from scalar\n", + dst); return -EACCES; } /* We don't allow subtraction from FP, because (according to @@ -1989,9 +1984,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, * be able to deal with it. */ if (ptr_reg->type == PTR_TO_STACK) { - if (!env->allow_ptr_leaks) - verbose(env, "R%d subtraction from stack pointer prohibited\n", - dst); + verbose(env, "R%d subtraction from stack pointer prohibited\n", + dst); return -EACCES; } if (known && (ptr_reg->off - smin_val == @@ -2040,19 +2034,14 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, case BPF_AND: case BPF_OR: case BPF_XOR: - /* bitwise ops on pointers are troublesome, prohibit for now. - * (However, in principle we could allow some cases, e.g. - * ptr &= ~3 which would reduce min_value by 3.) - */ - if (!env->allow_ptr_leaks) - verbose(env, "R%d bitwise operator %s on pointer prohibited\n", - dst, bpf_alu_string[opcode >> 4]); + /* bitwise ops on pointers are troublesome, prohibit. */ + verbose(env, "R%d bitwise operator %s on pointer prohibited\n", + dst, bpf_alu_string[opcode >> 4]); return -EACCES; default: /* other operators (e.g. MUL,LSH) produce non-pointer results */ - if (!env->allow_ptr_leaks) - verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", - dst, bpf_alu_string[opcode >> 4]); + verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", + dst, bpf_alu_string[opcode >> 4]); return -EACCES; } @@ -2308,7 +2297,6 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, struct bpf_reg_state *regs = cur_regs(env), *dst_reg, *src_reg; struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; u8 opcode = BPF_OP(insn->code); - int rc; dst_reg = ®s[insn->dst_reg]; src_reg = NULL; @@ -2319,43 +2307,29 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, if (src_reg->type != SCALAR_VALUE) { if (dst_reg->type != SCALAR_VALUE) { /* Combining two pointers by any ALU op yields - * an arbitrary scalar. + * an arbitrary scalar. Disallow all math except + * pointer subtraction */ - if (!env->allow_ptr_leaks) { - verbose(env, "R%d pointer %s pointer prohibited\n", - insn->dst_reg, - bpf_alu_string[opcode >> 4]); - return -EACCES; + if (opcode == BPF_SUB){ + mark_reg_unknown(env, regs, insn->dst_reg); + return 0; } - mark_reg_unknown(env, regs, insn->dst_reg); - return 0; + verbose(env, "R%d pointer %s pointer prohibited\n", + insn->dst_reg, + bpf_alu_string[opcode >> 4]); + return -EACCES; } else { /* scalar += pointer * This is legal, but we have to reverse our * src/dest handling in computing the range */ - rc = adjust_ptr_min_max_vals(env, insn, - src_reg, dst_reg); - if (rc == -EACCES && env->allow_ptr_leaks) { - /* scalar += unknown scalar */ - __mark_reg_unknown(&off_reg); - return adjust_scalar_min_max_vals( - env, insn, - dst_reg, off_reg); - } - return rc; + return adjust_ptr_min_max_vals(env, insn, + src_reg, dst_reg); } } else if (ptr_reg) { /* pointer += scalar */ - rc = adjust_ptr_min_max_vals(env, insn, - dst_reg, src_reg); - if (rc == -EACCES && env->allow_ptr_leaks) { - /* unknown scalar += scalar */ - __mark_reg_unknown(dst_reg); - return adjust_scalar_min_max_vals( - env, insn, dst_reg, *src_reg); - } - return rc; + return adjust_ptr_min_max_vals(env, insn, + dst_reg, src_reg); } } else { /* Pretend the src is a reg with a known value, since we only @@ -2364,17 +2338,9 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, off_reg.type = SCALAR_VALUE; __mark_reg_known(&off_reg, insn->imm); src_reg = &off_reg; - if (ptr_reg) { /* pointer += K */ - rc = adjust_ptr_min_max_vals(env, insn, - ptr_reg, src_reg); - if (rc == -EACCES && env->allow_ptr_leaks) { - /* unknown scalar += K */ - __mark_reg_unknown(dst_reg); - return adjust_scalar_min_max_vals( - env, insn, dst_reg, off_reg); - } - return rc; - } + if (ptr_reg) /* pointer += K */ + return adjust_ptr_min_max_vals(env, insn, + ptr_reg, src_reg); } /* Got here implies adding two SCALAR_VALUEs */ |