diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r-- | kernel/bpf/verifier.c | 194 |
1 files changed, 155 insertions, 39 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 339c8a1371de..6a86723c5b64 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -546,20 +546,6 @@ static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, return 0; } -static int bpf_size_to_bytes(int bpf_size) -{ - if (bpf_size == BPF_W) - return 4; - else if (bpf_size == BPF_H) - return 2; - else if (bpf_size == BPF_B) - return 1; - else if (bpf_size == BPF_DW) - return 8; - else - return -EINVAL; -} - static bool is_spillable_regtype(enum bpf_reg_type type) { switch (type) { @@ -758,15 +744,29 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, } /* check access to 'struct bpf_context' fields */ -static int check_ctx_access(struct bpf_verifier_env *env, int off, int size, +static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, enum bpf_access_type t, enum bpf_reg_type *reg_type) { + struct bpf_insn_access_aux info = { + .reg_type = *reg_type, + }; + /* for analyzer ctx accesses are already validated and converted */ if (env->analyzer_ops) return 0; if (env->prog->aux->ops->is_valid_access && - env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { + env->prog->aux->ops->is_valid_access(off, size, t, &info)) { + /* A non zero info.ctx_field_size indicates that this field is a + * candidate for later verifier transformation to load the whole + * field and then apply a mask when accessed with a narrower + * access than actual ctx access size. A zero info.ctx_field_size + * will only allow for whole field access and rejects any other + * type of narrower access. + */ + env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + *reg_type = info.reg_type; + /* remember the offset of last byte accessed in ctx */ if (env->prog->aux->max_ctx_offset < off + size) env->prog->aux->max_ctx_offset = off + size; @@ -868,7 +868,7 @@ static int check_ptr_alignment(struct bpf_verifier_env *env, * if t==write && value_regno==-1, some unknown value is stored into memory * if t==read && value_regno==-1, don't care what we read from memory */ -static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, +static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, int bpf_size, enum bpf_access_type t, int value_regno) { @@ -911,7 +911,7 @@ static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, verbose("R%d leaks addr into ctx\n", value_regno); return -EACCES; } - err = check_ctx_access(env, off, size, t, ®_type); + err = check_ctx_access(env, insn_idx, off, size, t, ®_type); if (!err && t == BPF_READ && value_regno >= 0) { mark_reg_unknown_value_and_range(state->regs, value_regno); @@ -926,6 +926,10 @@ static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, verbose("invalid stack off=%d size=%d\n", off, size); return -EACCES; } + + if (env->prog->aux->stack_depth < -off) + env->prog->aux->stack_depth = -off; + if (t == BPF_WRITE) { if (!env->allow_ptr_leaks && state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && @@ -968,7 +972,7 @@ static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, return err; } -static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn) +static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) { struct bpf_reg_state *regs = env->cur_state.regs; int err; @@ -989,14 +993,19 @@ static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn) if (err) return err; + if (is_pointer_value(env, insn->src_reg)) { + verbose("R%d leaks addr into mem\n", insn->src_reg); + return -EACCES; + } + /* check whether atomic_add can read the memory */ - err = check_mem_access(env, insn->dst_reg, insn->off, + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, -1); if (err) return err; /* check whether atomic_add can write into the same memory */ - return check_mem_access(env, insn->dst_reg, insn->off, + return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1); } @@ -1032,6 +1041,9 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, return -EACCES; } + if (env->prog->aux->stack_depth < -off) + env->prog->aux->stack_depth = -off; + if (meta && meta->raw_mode) { meta->access_size = access_size; meta->regno = regno; @@ -1339,8 +1351,8 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env) if (reg->type != PTR_TO_PACKET && reg->type != PTR_TO_PACKET_END) continue; - reg->type = UNKNOWN_VALUE; - reg->imm = 0; + __mark_reg_unknown_value(state->spilled_regs, + i / BPF_REG_SIZE); } } @@ -1409,7 +1421,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) * is inferred from register state. */ for (i = 0; i < meta.access_size; i++) { - err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); + err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); if (err) return err; } @@ -1645,6 +1657,65 @@ static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) return 0; } +static int evaluate_reg_imm_alu_unknown(struct bpf_verifier_env *env, + struct bpf_insn *insn) +{ + struct bpf_reg_state *regs = env->cur_state.regs; + struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; + struct bpf_reg_state *src_reg = ®s[insn->src_reg]; + u8 opcode = BPF_OP(insn->code); + s64 imm_log2 = __ilog2_u64((long long)dst_reg->imm); + + /* BPF_X code with src_reg->type UNKNOWN_VALUE here. */ + if (src_reg->imm > 0 && dst_reg->imm) { + switch (opcode) { + case BPF_ADD: + /* dreg += sreg + * where both have zero upper bits. Adding them + * can only result making one more bit non-zero + * in the larger value. + * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) + * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) + */ + dst_reg->imm = min(src_reg->imm, 63 - imm_log2); + dst_reg->imm--; + break; + case BPF_AND: + /* dreg &= sreg + * AND can not extend zero bits only shrink + * Ex. 0x00..00ffffff + * & 0x0f..ffffffff + * ---------------- + * 0x00..00ffffff + */ + dst_reg->imm = max(src_reg->imm, 63 - imm_log2); + break; + case BPF_OR: + /* dreg |= sreg + * OR can only extend zero bits + * Ex. 0x00..00ffffff + * | 0x0f..ffffffff + * ---------------- + * 0x0f..00ffffff + */ + dst_reg->imm = min(src_reg->imm, 63 - imm_log2); + break; + case BPF_SUB: + case BPF_MUL: + case BPF_RSH: + case BPF_LSH: + /* These may be flushed out later */ + default: + mark_reg_unknown_value(regs, insn->dst_reg); + } + } else { + mark_reg_unknown_value(regs, insn->dst_reg); + } + + dst_reg->type = UNKNOWN_VALUE; + return 0; +} + static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) { @@ -1654,6 +1725,9 @@ static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, u8 opcode = BPF_OP(insn->code); u64 dst_imm = dst_reg->imm; + if (BPF_SRC(insn->code) == BPF_X && src_reg->type == UNKNOWN_VALUE) + return evaluate_reg_imm_alu_unknown(env, insn); + /* dst_reg->type == CONST_IMM here. Simulate execution of insns * containing ALU ops. Don't care about overflow or negative * values, just add/sub/... them; registers are in u64. @@ -1945,6 +2019,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) */ regs[insn->dst_reg].type = CONST_IMM; regs[insn->dst_reg].imm = insn->imm; + regs[insn->dst_reg].id = 0; regs[insn->dst_reg].max_value = insn->imm; regs[insn->dst_reg].min_value = insn->imm; regs[insn->dst_reg].min_align = calc_align(insn->imm); @@ -2402,6 +2477,7 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) regs[insn->dst_reg].type = CONST_IMM; regs[insn->dst_reg].imm = imm; + regs[insn->dst_reg].id = 0; return 0; } @@ -2821,6 +2897,8 @@ static bool states_equal(struct bpf_verifier_env *env, return false; if (i % BPF_REG_SIZE) continue; + if (old->stack_slot_type[i] != STACK_SPILL) + continue; if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], &cur->spilled_regs[i / BPF_REG_SIZE], sizeof(old->spilled_regs[0]))) @@ -2982,18 +3060,12 @@ static int do_check(struct bpf_verifier_env *env) /* check that memory (src_reg + off) is readable, * the state of dst_reg will be updated by this func */ - err = check_mem_access(env, insn->src_reg, insn->off, + err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, insn->dst_reg); if (err) return err; - if (BPF_SIZE(insn->code) != BPF_W && - BPF_SIZE(insn->code) != BPF_DW) { - insn_idx++; - continue; - } - prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; if (*prev_src_type == NOT_INIT) { @@ -3021,7 +3093,7 @@ static int do_check(struct bpf_verifier_env *env) enum bpf_reg_type *prev_dst_type, dst_reg_type; if (BPF_MODE(insn->code) == BPF_XADD) { - err = check_xadd(env, insn); + err = check_xadd(env, insn_idx, insn); if (err) return err; insn_idx++; @@ -3040,7 +3112,7 @@ static int do_check(struct bpf_verifier_env *env) dst_reg_type = regs[insn->dst_reg].type; /* check that memory (dst_reg + off) is writeable */ - err = check_mem_access(env, insn->dst_reg, insn->off, + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, insn->src_reg); if (err) @@ -3069,7 +3141,7 @@ static int do_check(struct bpf_verifier_env *env) return err; /* check that memory (dst_reg + off) is writeable */ - err = check_mem_access(env, insn->dst_reg, insn->off, + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1); if (err) @@ -3167,7 +3239,8 @@ process_bpf_exit: insn_idx++; } - verbose("processed %d insns\n", insn_processed); + verbose("processed %d insns, stack depth %d\n", + insn_processed, env->prog->aux->stack_depth); return 0; } @@ -3367,11 +3440,13 @@ static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of static int convert_ctx_accesses(struct bpf_verifier_env *env) { const struct bpf_verifier_ops *ops = env->prog->aux->ops; + int i, cnt, size, ctx_field_size, delta = 0; const int insn_cnt = env->prog->len; struct bpf_insn insn_buf[16], *insn; struct bpf_prog *new_prog; enum bpf_access_type type; - int i, cnt, delta = 0; + bool is_narrower_load; + u32 target_size; if (ops->gen_prologue) { cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, @@ -3411,12 +3486,52 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) continue; - cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog); - if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { + ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; + size = BPF_LDST_BYTES(insn); + + /* If the read access is a narrower load of the field, + * convert to a 4/8-byte load, to minimum program type specific + * convert_ctx_access changes. If conversion is successful, + * we will apply proper mask to the result. + */ + is_narrower_load = size < ctx_field_size; + if (is_narrower_load) { + u32 off = insn->off; + u8 size_code; + + if (type == BPF_WRITE) { + verbose("bpf verifier narrow ctx access misconfigured\n"); + return -EINVAL; + } + + size_code = BPF_H; + if (ctx_field_size == 4) + size_code = BPF_W; + else if (ctx_field_size == 8) + size_code = BPF_DW; + + insn->off = off & ~(ctx_field_size - 1); + insn->code = BPF_LDX | BPF_MEM | size_code; + } + + target_size = 0; + cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog, + &target_size); + if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || + (ctx_field_size && !target_size)) { verbose("bpf verifier is misconfigured\n"); return -EINVAL; } + if (is_narrower_load && size < target_size) { + if (ctx_field_size <= 4) + insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, + (1 << size * 8) - 1); + else + insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, + (1 << size * 8) - 1); + } + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; @@ -3462,6 +3577,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) * the program array. */ prog->cb_access = 1; + env->prog->aux->stack_depth = MAX_BPF_STACK; /* mark bpf_tail_call as different opcode to avoid * conditional branch in the interpeter for every normal @@ -3469,7 +3585,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) * that doesn't support bpf_tail_call yet */ insn->imm = 0; - insn->code |= BPF_X; + insn->code = BPF_JMP | BPF_TAIL_CALL; continue; } |