Merge changes from topic "libprocessgroup_rc"

* changes:
  CgroupSetupCgroups -> CgroupSetup
  Add libcgrouprc to ld.config.*.txt.
  libprocessgroup: use libcgrouprc to read cgroup.rc
  libprocessgroup_setup: use libcgrouprc_format
  libprocessgroup: Move CgroupSetupCgroups() to libprocessgroup_setup
  libprocessgroup: Add libcgrouprc
  libprocessgroup: Add libcgrouprc_format

1 files changed, 334 insertions, 0 deletions

diff --git a/libprocessgroup/setup/cgroup_map_write.cpp b/libprocessgroup/setup/cgroup_map_write.cpp
new file mode 100644
index 000000000..26703eea7
--- /dev/null
+++ b/libprocessgroup/setup/cgroup_map_write.cpp
@@ -0,0 +1,334 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "libprocessgroup"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <pwd.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <regex>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/stringprintf.h>
+#include <android-base/unique_fd.h>
+#include <json/reader.h>
+#include <json/value.h>
+#include <processgroup/format/cgroup_file.h>
+#include <processgroup/processgroup.h>
+#include <processgroup/setup.h>
+
+#include "cgroup_descriptor.h"
+
+using android::base::GetBoolProperty;
+using android::base::StringPrintf;
+using android::base::unique_fd;
+
+namespace android {
+namespace cgrouprc {
+
+static constexpr const char* CGROUPS_DESC_FILE = "/etc/cgroups.json";
+static constexpr const char* CGROUPS_DESC_VENDOR_FILE = "/vendor/etc/cgroups.json";
+
+static bool Mkdir(const std::string& path, mode_t mode, const std::string& uid,
+                  const std::string& gid) {
+    if (mode == 0) {
+        mode = 0755;
+    }
+
+    if (mkdir(path.c_str(), mode) != 0) {
+        /* chmod in case the directory already exists */
+        if (errno == EEXIST) {
+            if (fchmodat(AT_FDCWD, path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
+                // /acct is a special case when the directory already exists
+                // TODO: check if file mode is already what we want instead of using EROFS
+                if (errno != EROFS) {
+                    PLOG(ERROR) << "fchmodat() failed for " << path;
+                    return false;
+                }
+            }
+        } else {
+            PLOG(ERROR) << "mkdir() failed for " << path;
+            return false;
+        }
+    }
+
+    if (uid.empty()) {
+        return true;
+    }
+
+    passwd* uid_pwd = getpwnam(uid.c_str());
+    if (!uid_pwd) {
+        PLOG(ERROR) << "Unable to decode UID for '" << uid << "'";
+        return false;
+    }
+
+    uid_t pw_uid = uid_pwd->pw_uid;
+    gid_t gr_gid = -1;
+    if (!gid.empty()) {
+        group* gid_pwd = getgrnam(gid.c_str());
+        if (!gid_pwd) {
+            PLOG(ERROR) << "Unable to decode GID for '" << gid << "'";
+            return false;
+        }
+        gr_gid = gid_pwd->gr_gid;
+    }
+
+    if (lchown(path.c_str(), pw_uid, gr_gid) < 0) {
+        PLOG(ERROR) << "lchown() failed for " << path;
+        return false;
+    }
+
+    /* chown may have cleared S_ISUID and S_ISGID, chmod again */
+    if (mode & (S_ISUID | S_ISGID)) {
+        if (fchmodat(AT_FDCWD, path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
+            PLOG(ERROR) << "fchmodat() failed for " << path;
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static bool ReadDescriptorsFromFile(const std::string& file_name,
+                                    std::map<std::string, CgroupDescriptor>* descriptors) {
+    std::vector<CgroupDescriptor> result;
+    std::string json_doc;
+
+    if (!android::base::ReadFileToString(file_name, &json_doc)) {
+        PLOG(ERROR) << "Failed to read task profiles from " << file_name;
+        return false;
+    }
+
+    Json::Reader reader;
+    Json::Value root;
+    if (!reader.parse(json_doc, root)) {
+        LOG(ERROR) << "Failed to parse cgroups description: " << reader.getFormattedErrorMessages();
+        return false;
+    }
+
+    if (root.isMember("Cgroups")) {
+        const Json::Value& cgroups = root["Cgroups"];
+        for (Json::Value::ArrayIndex i = 0; i < cgroups.size(); ++i) {
+            std::string name = cgroups[i]["Controller"].asString();
+            auto iter = descriptors->find(name);
+            if (iter == descriptors->end()) {
+                descriptors->emplace(
+                        name, CgroupDescriptor(
+                                      1, name, cgroups[i]["Path"].asString(),
+                                      std::strtoul(cgroups[i]["Mode"].asString().c_str(), 0, 8),
+                                      cgroups[i]["UID"].asString(), cgroups[i]["GID"].asString()));
+            } else {
+                iter->second = CgroupDescriptor(
+                        1, name, cgroups[i]["Path"].asString(),
+                        std::strtoul(cgroups[i]["Mode"].asString().c_str(), 0, 8),
+                        cgroups[i]["UID"].asString(), cgroups[i]["GID"].asString());
+            }
+        }
+    }
+
+    if (root.isMember("Cgroups2")) {
+        const Json::Value& cgroups2 = root["Cgroups2"];
+        auto iter = descriptors->find(CGROUPV2_CONTROLLER_NAME);
+        if (iter == descriptors->end()) {
+            descriptors->emplace(
+                    CGROUPV2_CONTROLLER_NAME,
+                    CgroupDescriptor(2, CGROUPV2_CONTROLLER_NAME, cgroups2["Path"].asString(),
+                                     std::strtoul(cgroups2["Mode"].asString().c_str(), 0, 8),
+                                     cgroups2["UID"].asString(), cgroups2["GID"].asString()));
+        } else {
+            iter->second =
+                    CgroupDescriptor(2, CGROUPV2_CONTROLLER_NAME, cgroups2["Path"].asString(),
+                                     std::strtoul(cgroups2["Mode"].asString().c_str(), 0, 8),
+                                     cgroups2["UID"].asString(), cgroups2["GID"].asString());
+        }
+    }
+
+    return true;
+}
+
+static bool ReadDescriptors(std::map<std::string, CgroupDescriptor>* descriptors) {
+    // load system cgroup descriptors
+    if (!ReadDescriptorsFromFile(CGROUPS_DESC_FILE, descriptors)) {
+        return false;
+    }
+
+    // load vendor cgroup descriptors if the file exists
+    if (!access(CGROUPS_DESC_VENDOR_FILE, F_OK) &&
+        !ReadDescriptorsFromFile(CGROUPS_DESC_VENDOR_FILE, descriptors)) {
+        return false;
+    }
+
+    return true;
+}
+
+// To avoid issues in sdk_mac build
+#if defined(__ANDROID__)
+
+static bool SetupCgroup(const CgroupDescriptor& descriptor) {
+    const format::CgroupController* controller = descriptor.controller();
+
+    // mkdir <path> [mode] [owner] [group]
+    if (!Mkdir(controller->path(), descriptor.mode(), descriptor.uid(), descriptor.gid())) {
+        LOG(ERROR) << "Failed to create directory for " << controller->name() << " cgroup";
+        return false;
+    }
+
+    int result;
+    if (controller->version() == 2) {
+        result = mount("none", controller->path(), "cgroup2", MS_NODEV | MS_NOEXEC | MS_NOSUID,
+                       nullptr);
+    } else {
+        // Unfortunately historically cpuset controller was mounted using a mount command
+        // different from all other controllers. This results in controller attributes not
+        // to be prepended with controller name. For example this way instead of
+        // /dev/cpuset/cpuset.cpus the attribute becomes /dev/cpuset/cpus which is what
+        // the system currently expects.
+        if (!strcmp(controller->name(), "cpuset")) {
+            // mount cpuset none /dev/cpuset nodev noexec nosuid
+            result = mount("none", controller->path(), controller->name(),
+                           MS_NODEV | MS_NOEXEC | MS_NOSUID, nullptr);
+        } else {
+            // mount cgroup none <path> nodev noexec nosuid <controller>
+            result = mount("none", controller->path(), "cgroup", MS_NODEV | MS_NOEXEC | MS_NOSUID,
+                           controller->name());
+        }
+    }
+
+    if (result < 0) {
+        PLOG(ERROR) << "Failed to mount " << controller->name() << " cgroup";
+        return false;
+    }
+
+    return true;
+}
+
+#else
+
+// Stubs for non-Android targets.
+static bool SetupCgroup(const CgroupDescriptor&) {
+    return false;
+}
+
+#endif
+
+// WARNING: This function should be called only from SetupCgroups and only once.
+// It intentionally leaks an FD, so additional invocation will result in additional leak.
+static bool WriteRcFile(const std::map<std::string, CgroupDescriptor>& descriptors) {
+    // WARNING: We are intentionally leaking the FD to keep the file open forever.
+    // Let init keep the FD open to prevent file mappings from becoming invalid in
+    // case the file gets deleted somehow.
+    int fd = TEMP_FAILURE_RETRY(open(CGROUPS_RC_PATH, O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC,
+                                     S_IRUSR | S_IRGRP | S_IROTH));
+    if (fd < 0) {
+        PLOG(ERROR) << "open() failed for " << CGROUPS_RC_PATH;
+        return false;
+    }
+
+    format::CgroupFile fl;
+    fl.version_ = format::CgroupFile::FILE_CURR_VERSION;
+    fl.controller_count_ = descriptors.size();
+    int ret = TEMP_FAILURE_RETRY(write(fd, &fl, sizeof(fl)));
+    if (ret < 0) {
+        PLOG(ERROR) << "write() failed for " << CGROUPS_RC_PATH;
+        return false;
+    }
+
+    for (const auto& [name, descriptor] : descriptors) {
+        ret = TEMP_FAILURE_RETRY(
+                write(fd, descriptor.controller(), sizeof(format::CgroupController)));
+        if (ret < 0) {
+            PLOG(ERROR) << "write() failed for " << CGROUPS_RC_PATH;
+            return false;
+        }
+    }
+
+    return true;
+}
+
+CgroupDescriptor::CgroupDescriptor(uint32_t version, const std::string& name,
+                                   const std::string& path, mode_t mode, const std::string& uid,
+                                   const std::string& gid)
+    : controller_(version, name, path), mode_(mode), uid_(uid), gid_(gid) {}
+
+}  // namespace cgrouprc
+}  // namespace android
+
+bool CgroupSetup() {
+    using namespace android::cgrouprc;
+
+    std::map<std::string, CgroupDescriptor> descriptors;
+
+    if (getpid() != 1) {
+        LOG(ERROR) << "Cgroup setup can be done only by init process";
+        return false;
+    }
+
+    // Make sure we do this only one time. No need for std::call_once because
+    // init is a single-threaded process
+    if (access(CGROUPS_RC_PATH, F_OK) == 0) {
+        LOG(WARNING) << "Attempt to call SetupCgroups more than once";
+        return true;
+    }
+
+    // load cgroups.json file
+    if (!ReadDescriptors(&descriptors)) {
+        LOG(ERROR) << "Failed to load cgroup description file";
+        return false;
+    }
+
+    // setup cgroups
+    for (const auto& [name, descriptor] : descriptors) {
+        if (!SetupCgroup(descriptor)) {
+            // issue a warning and proceed with the next cgroup
+            // TODO: mark the descriptor as invalid and skip it in WriteRcFile()
+            LOG(WARNING) << "Failed to setup " << name << " cgroup";
+        }
+    }
+
+    // mkdir <CGROUPS_RC_DIR> 0711 system system
+    if (!Mkdir(android::base::Dirname(CGROUPS_RC_PATH), 0711, "system", "system")) {
+        LOG(ERROR) << "Failed to create directory for " << CGROUPS_RC_PATH << " file";
+        return false;
+    }
+
+    // Generate <CGROUPS_RC_FILE> file which can be directly mmapped into
+    // process memory. This optimizes performance, memory usage
+    // and limits infrormation shared with unprivileged processes
+    // to the minimum subset of information from cgroups.json
+    if (!WriteRcFile(descriptors)) {
+        LOG(ERROR) << "Failed to write " << CGROUPS_RC_PATH << " file";
+        return false;
+    }
+
+    // chmod 0644 <CGROUPS_RC_PATH>
+    if (fchmodat(AT_FDCWD, CGROUPS_RC_PATH, 0644, AT_SYMLINK_NOFOLLOW) < 0) {
+        PLOG(ERROR) << "fchmodat() failed";
+        return false;
+    }
+
+    return true;
+}