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96 lines
2.4 KiB
96 lines
2.4 KiB
4 months ago
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/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common/libs/utils/users.h"
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#include <cerrno>
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#include <cstring>
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#include <sys/types.h>
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#include <unistd.h>
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#include <grp.h>
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#include <algorithm>
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#include <vector>
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#include <android-base/logging.h>
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namespace cuttlefish {
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namespace {
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gid_t GroupIdFromName(const std::string& group_name) {
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struct group grp{};
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struct group* grp_p{};
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std::vector<char> buffer(100);
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int result = 0;
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while(true) {
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result = getgrnam_r(group_name.c_str(), &grp, buffer.data(), buffer.size(),
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&grp_p);
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if (result != ERANGE) {
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break;
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}
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buffer.resize(2*buffer.size());
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}
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if (result == 0) {
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if (grp_p != nullptr) {
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return grp.gr_gid;
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} else {
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// Caller may be checking with non-existent group name
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return -1;
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}
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} else {
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LOG(ERROR) << "Unable to get group id for group " << group_name << ": "
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<< std::strerror(result);
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return -1;
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}
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}
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std::vector<gid_t> GetSuplementaryGroups() {
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int num_groups = getgroups(0, nullptr);
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if (num_groups < 0) {
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LOG(ERROR) << "Unable to get number of suplementary groups: "
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<< std::strerror(errno);
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return {};
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}
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std::vector<gid_t> groups(num_groups + 1);
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int retval = getgroups(groups.size(), groups.data());
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if (retval < 0) {
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LOG(ERROR) << "Error obtaining list of suplementary groups (list size: "
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<< groups.size() << "): " << std::strerror(errno);
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return {};
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}
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return groups;
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}
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} // namespace
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bool InGroup(const std::string& group) {
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auto gid = GroupIdFromName(group);
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if (gid == static_cast<gid_t>(-1)) {
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return false;
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}
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if (gid == getegid()) {
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return true;
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}
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auto groups = GetSuplementaryGroups();
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if (std::find(groups.cbegin(), groups.cend(), gid) != groups.cend()) {
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return true;
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}
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return false;
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}
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} // namespace cuttlefish
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