crash_reporter: Support crashes from arbitrary users (6db7cd78) · Commits · e / os / android_system_core

crash_reporter/crash_reporter.rc

+5 −2

Original line number	Diff line number	Diff line
		@@ -14,11 +14,14 @@ on boot
		rmdir /data/misc/crash_reporter/lock/crash_sender

		# Create crash directories.
		mkdir /data/misc/crash_reporter 0700 root root
		# These directories are group-writable by root so that crash_reporter can
		# still access them when it switches users.
		mkdir /data/misc/crash_reporter 0770 root root
		mkdir /data/misc/crash_reporter/crash 0770 root root
		mkdir /data/misc/crash_reporter/lock 0700 root root
		mkdir /data/misc/crash_reporter/log 0700 root root
		mkdir /data/misc/crash_reporter/run 0700 root root
		mkdir /data/misc/crash_reporter/tmp 0700 root root
		mkdir /data/misc/crash_reporter/tmp 0770 root root

		service crash_reporter /system/bin/crash_reporter --init
		class late_start

crash_reporter/user_collector.cc

+71 −3

Original line number	Diff line number	Diff line
		@@ -23,9 +23,11 @@
		#include <pwd.h> // For struct passwd.
		#include <stdint.h>
		#include <sys/cdefs.h> // For __WORDSIZE
		#include <sys/fsuid.h>
		#include <sys/types.h> // For getpwuid_r, getgrnam_r, WEXITSTATUS.
		#include <unistd.h> // For setgroups

		#include <iostream> // For std::oct
		#include <string>
		#include <vector>

		@@ -87,9 +89,9 @@ void UserCollector::Initialize(
		directory_failure_ = directory_failure;
		filter_in_ = filter_in;

		gid_t groups[] = { AID_SYSTEM, AID_DBUS };
		gid_t groups[] = { AID_ROOT, AID_SYSTEM, AID_DBUS };
		if (setgroups(arraysize(groups), groups) != 0) {
		PLOG(FATAL) << "Unable to set groups to system and dbus";
		PLOG(FATAL) << "Unable to set groups to root, system, and dbus";
		}
		}

		@@ -227,7 +229,19 @@ void UserCollector::EnqueueCollectionErrorLog(pid_t pid,
		bool UserCollector::CopyOffProcFiles(pid_t pid,
		const FilePath &container_dir) {
		if (!base::CreateDirectory(container_dir)) {
		PLOG(ERROR) << "Could not create " << container_dir.value().c_str();
		PLOG(ERROR) << "Could not create " << container_dir.value();
		return false;
		}
		int dir_mask = base::FILE_PERMISSION_READ_BY_USER
		\| base::FILE_PERMISSION_WRITE_BY_USER
		\| base::FILE_PERMISSION_EXECUTE_BY_USER
		\| base::FILE_PERMISSION_READ_BY_GROUP
		\| base::FILE_PERMISSION_WRITE_BY_GROUP;
		if (!base::SetPosixFilePermissions(container_dir,
		base::FILE_PERMISSION_MASK & dir_mask)) {
		PLOG(ERROR) << "Could not set permissions for " << container_dir.value()
		<< " to " << std::oct
		<< (base::FILE_PERMISSION_MASK & dir_mask);
		return false;
		}
		FilePath process_path = GetProcessPath(pid);
		@@ -410,6 +424,43 @@ UserCollector::ErrorType UserCollector::ConvertCoreToMinidump(
		bool proc_files_usable =
		CopyOffProcFiles(pid, container_dir) && ValidateProcFiles(container_dir);

		// Switch back to the original UID/GID.
		gid_t rgid, egid, sgid;
		if (getresgid(&rgid, &egid, &sgid) != 0) {
		PLOG(FATAL) << "Unable to read saved gid";
		}
		if (setresgid(sgid, sgid, -1) != 0) {
		PLOG(FATAL) << "Unable to set real group ID back to saved gid";
		} else {
		if (getresgid(&rgid, &egid, &sgid) != 0) {
		// If the groups cannot be read at this point, the rgid variable will
		// contain the previously read group ID from before changing it. This
		// will cause the chown call below to set the incorrect group for
		// non-root crashes. But do not treat this as a fatal error, so that
		// the rest of the collection will continue for potential manual
		// collection by a developer.
		PLOG(ERROR) << "Unable to read real group ID after setting it";
		}
		}

		uid_t ruid, euid, suid;
		if (getresuid(&ruid, &euid, &suid) != 0) {
		PLOG(FATAL) << "Unable to read saved uid";
		}
		if (setresuid(suid, suid, -1) != 0) {
		PLOG(FATAL) << "Unable to set real user ID back to saved uid";
		} else {
		if (getresuid(&ruid, &euid, &suid) != 0) {
		// If the user ID cannot be read at this point, the ruid variable will
		// contain the previously read user ID from before changing it. This
		// will cause the chown call below to set the incorrect user for
		// non-root crashes. But do not treat this as a fatal error, so that
		// the rest of the collection will continue for potential manual
		// collection by a developer.
		PLOG(ERROR) << "Unable to read real user ID after setting it";
		}
		}

		if (!CopyStdinToCoreFile(core_path)) {
		return kErrorReadCoreData;
		}
		@@ -425,6 +476,13 @@ UserCollector::ErrorType UserCollector::ConvertCoreToMinidump(
		return error;
		}

		// Chown the temp container directory back to the original user/group that
		// crash_reporter is run as, so that additional files can be written to
		// the temp folder.
		if (chown(container_dir.value().c_str(), ruid, rgid) < 0) {
		PLOG(ERROR) << "Could not set owner for " << container_dir.value();
		}

		if (!RunCoreToMinidump(core_path,
		container_dir, // procfs directory
		minidump_path,
		@@ -545,6 +603,16 @@ bool UserCollector::HandleCrash(const std::string &crash_attributes,
		return false;
		}

		// Switch to the group and user that ran the crashing binary in order to
		// access their /proc files. Do not set suid/sgid, so that we can switch
		// back after copying the necessary files.
		if (setresgid(supplied_ruid, supplied_ruid, -1) != 0) {
		PLOG(FATAL) << "Unable to set real group ID to access process files";
		}
		if (setresuid(supplied_ruid, supplied_ruid, -1) != 0) {
		PLOG(FATAL) << "Unable to set real user ID to access process files";
		}

		std::string exec;
		if (force_exec) {
		exec.assign(force_exec);