diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 78 |
1 files changed, 34 insertions, 44 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6ea2adcb233b..6f820a044079 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) { @@ -761,7 +747,9 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, 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 }; + struct bpf_insn_access_aux info = { + .reg_type = *reg_type, + }; /* for analyzer ctx accesses are already validated and converted */ if (env->analyzer_ops) @@ -769,25 +757,14 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, if (env->prog->aux->ops->is_valid_access && env->prog->aux->ops->is_valid_access(off, size, t, &info)) { - /* a non zero info.ctx_field_size indicates: - * . For this field, the prog type specific ctx conversion algorithm - * only supports whole field access. - * . This ctx access is a candiate for later verifier transformation - * to load the whole field and then apply a mask to get correct result. - * a non zero info.converted_op_size indicates perceived actual converted - * value width in convert_ctx_access. + /* 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. */ - if ((info.ctx_field_size && !info.converted_op_size) || - (!info.ctx_field_size && info.converted_op_size)) { - verbose("verifier bug in is_valid_access prog type=%u off=%d size=%d\n", - env->prog->type, off, size); - return -EACCES; - } - - if (info.ctx_field_size) { - env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; - env->insn_aux_data[insn_idx].converted_op_size = info.converted_op_size; - } + 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 */ @@ -3401,11 +3378,13 @@ 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, off, size, ctx_field_size, converted_op_size, is_narrower_load, delta = 0; + bool is_narrower_load; + u32 target_size; if (ops->gen_prologue) { cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, @@ -3445,39 +3424,50 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) continue; - off = insn->off; - size = bpf_size_to_bytes(BPF_SIZE(insn->code)); ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; - converted_op_size = env->insn_aux_data[i + delta].converted_op_size; - is_narrower_load = type == BPF_READ && size < 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) { - int size_code = BPF_H; + 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; } - cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog); - if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { + + 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 < converted_op_size) { + + 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); + (1 << size * 8) - 1); else insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, - (1 << size * 8) - 1); + (1 << size * 8) - 1); } new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); |