diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 67 |
1 files changed, 48 insertions, 19 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d1c009e8c57f..4161b6c406bc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1494,6 +1494,9 @@ static int check_subprogs(struct bpf_verifier_env *env) insn[i].imm == BPF_FUNC_tail_call && insn[i].src_reg != BPF_PSEUDO_CALL) subprog[cur_subprog].has_tail_call = true; + if (BPF_CLASS(code) == BPF_LD && + (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) + subprog[cur_subprog].has_ld_abs = true; if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) goto next; if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL) @@ -7514,18 +7517,6 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) return -EINVAL; } - if (env->subprog_cnt > 1) { - /* when program has LD_ABS insn JITs and interpreter assume - * that r1 == ctx == skb which is not the case for callees - * that can have arbitrary arguments. It's problematic - * for main prog as well since JITs would need to analyze - * all functions in order to make proper register save/restore - * decisions in the main prog. Hence disallow LD_ABS with calls - */ - verbose(env, "BPF_LD_[ABS|IND] instructions cannot be mixed with bpf-to-bpf calls\n"); - return -EINVAL; - } - if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || BPF_SIZE(insn->code) == BPF_DW || (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { @@ -7936,6 +7927,23 @@ err_free: return ret; } +static int check_abnormal_return(struct bpf_verifier_env *env) +{ + int i; + + for (i = 1; i < env->subprog_cnt; i++) { + if (env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + if (env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + } + return 0; +} + /* The minimum supported BTF func info size */ #define MIN_BPF_FUNCINFO_SIZE 8 #define MAX_FUNCINFO_REC_SIZE 252 @@ -7944,20 +7952,24 @@ static int check_btf_func(struct bpf_verifier_env *env, const union bpf_attr *attr, union bpf_attr __user *uattr) { + const struct btf_type *type, *func_proto, *ret_type; u32 i, nfuncs, urec_size, min_size; u32 krec_size = sizeof(struct bpf_func_info); struct bpf_func_info *krecord; struct bpf_func_info_aux *info_aux = NULL; - const struct btf_type *type; struct bpf_prog *prog; const struct btf *btf; void __user *urecord; u32 prev_offset = 0; + bool scalar_return; int ret = -ENOMEM; nfuncs = attr->func_info_cnt; - if (!nfuncs) + if (!nfuncs) { + if (check_abnormal_return(env)) + return -EINVAL; return 0; + } if (nfuncs != env->subprog_cnt) { verbose(env, "number of funcs in func_info doesn't match number of subprogs\n"); @@ -8005,25 +8017,23 @@ static int check_btf_func(struct bpf_verifier_env *env, } /* check insn_off */ + ret = -EINVAL; if (i == 0) { if (krecord[i].insn_off) { verbose(env, "nonzero insn_off %u for the first func info record", krecord[i].insn_off); - ret = -EINVAL; goto err_free; } } else if (krecord[i].insn_off <= prev_offset) { verbose(env, "same or smaller insn offset (%u) than previous func info record (%u)", krecord[i].insn_off, prev_offset); - ret = -EINVAL; goto err_free; } if (env->subprog_info[i].start != krecord[i].insn_off) { verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n"); - ret = -EINVAL; goto err_free; } @@ -8032,10 +8042,26 @@ static int check_btf_func(struct bpf_verifier_env *env, if (!type || !btf_type_is_func(type)) { verbose(env, "invalid type id %d in func info", krecord[i].type_id); - ret = -EINVAL; goto err_free; } info_aux[i].linkage = BTF_INFO_VLEN(type->info); + + func_proto = btf_type_by_id(btf, type->type); + if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto))) + /* btf_func_check() already verified it during BTF load */ + goto err_free; + ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL); + scalar_return = + btf_type_is_small_int(ret_type) || btf_type_is_enum(ret_type); + if (i && !scalar_return && env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n"); + goto err_free; + } + if (i && !scalar_return && env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is only allowed in functions that return 'int'.\n"); + goto err_free; + } + prev_offset = krecord[i].insn_off; urecord += urec_size; } @@ -8196,8 +8222,11 @@ static int check_btf_info(struct bpf_verifier_env *env, struct btf *btf; int err; - if (!attr->func_info_cnt && !attr->line_info_cnt) + if (!attr->func_info_cnt && !attr->line_info_cnt) { + if (check_abnormal_return(env)) + return -EINVAL; return 0; + } btf = btf_get_by_fd(attr->prog_btf_fd); if (IS_ERR(btf)) |