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Merge "crash_reporter: Support crashes from arbitrary users"

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This commit is contained in:
Steve Fung 2015-10-08 22:11:13 +00:00 • committed by Gerrit Code Review
commit 23fe7be8d6
2 changed files with 76 additions and 5 deletions
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7
crash_reporter/crash_reporter.rc
View file

@ -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

74
crash_reporter/user_collector.cc
View file

@ -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);