Adds a function to utils library to check group membership
Bug: 110476897
Test: local
Change-Id: I6d259fa36798dd4797a512543b12e84f5d2644e5
Merged-In: I6d259fa36798dd4797a512543b12e84f5d2644e5
(cherry picked from commit e23e695c5ab40e2ff54ef3bd9ac0d999d27f74d9)
diff --git a/common/libs/utils/Android.bp b/common/libs/utils/Android.bp
index 56c18e3..98c16c7 100644
--- a/common/libs/utils/Android.bp
+++ b/common/libs/utils/Android.bp
@@ -20,6 +20,7 @@
"environment.cpp",
"size_utils.cpp",
"files.cpp",
+ "users.cpp",
],
header_libs: [
"cuttlefish_glog",
diff --git a/common/libs/utils/users.cpp b/common/libs/utils/users.cpp
new file mode 100644
index 0000000..0ec92c2
--- /dev/null
+++ b/common/libs/utils/users.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "common/libs/utils/users.h"
+
+#include <cerrno>
+#include <cstring>
+#include <sys/types.h>
+#include <unistd.h>
+#include <grp.h>
+
+#include <algorithm>
+#include <vector>
+
+#include <glog/logging.h>
+
+namespace {
+gid_t GroupIdFromName(const std::string& group_name) {
+ struct group grp{};
+ struct group* grp_p{};
+ std::vector<char> buffer(100);
+ int result = 0;
+ while(true) {
+ result = getgrnam_r(group_name.c_str(), &grp, buffer.data(), buffer.size(),
+ &grp_p);
+ if (result != ERANGE) {
+ break;
+ }
+ buffer.resize(2*buffer.size());
+ }
+ if (result == 0) {
+ if (grp_p != nullptr) {
+ return grp.gr_gid;
+ } else {
+ LOG(ERROR) << "Group " << group_name << " does not exist";
+ return -1;
+ }
+ } else {
+ LOG(ERROR) << "Unable to get group id for group " << group_name << ": "
+ << std::strerror(result);
+ return -1;
+ }
+}
+
+std::vector<gid_t> GetSuplementaryGroups() {
+ int num_groups = getgroups(0, nullptr);
+ if (num_groups < 0) {
+ LOG(ERROR) << "Unable to get number of suplementary groups: "
+ << std::strerror(errno);
+ return {};
+ }
+ std::vector<gid_t> groups(num_groups + 1);
+ int retval = getgroups(groups.size(), groups.data());
+ if (retval < 0) {
+ LOG(ERROR) << "Error obtaining list of suplementary groups (list size: "
+ << groups.size() << "): " << std::strerror(errno);
+ return {};
+ }
+ return groups;
+}
+} // namespace
+
+bool cvd::InGroup(const std::string& group) {
+ auto gid = GroupIdFromName(group);
+ if (gid == static_cast<gid_t>(-1)) {
+ return false;
+ }
+
+ if (gid == getegid()) {
+ return true;
+ }
+
+ auto groups = GetSuplementaryGroups();
+
+ if (std::find(groups.cbegin(), groups.cend(), gid) != groups.cend()) {
+ return true;
+ }
+ return false;
+}
\ No newline at end of file
diff --git a/common/libs/utils/users.h b/common/libs/utils/users.h
new file mode 100644
index 0000000..2fbbdd4
--- /dev/null
+++ b/common/libs/utils/users.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <string>
+
+namespace cvd {
+
+bool InGroup(const std::string& group);
+
+} // namespace cvd
