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/*
* Copyright (C) 2008 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.
*/
/*
** mountd process killer
*/
#include "mountd.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <dirent.h>
#include <ctype.h>
#include <pwd.h>
#include <stdlib.h>
#include <poll.h>
#include <sys/stat.h>
static boolean ReadSymLink(const char* path, char* link)
{
struct stat s;
int length;
if (lstat(path, &s) < 0)
return false;
if ((s.st_mode & S_IFMT) != S_IFLNK)
return false;
// we have a symlink
length = readlink(path, link, PATH_MAX - 1);
if (length <= 0)
return false;
link[length] = 0;
return true;
}
static boolean PathMatchesMountPoint(const char* path, const char* mountPoint)
{
int length = strlen(mountPoint);
if (length > 1 && strncmp(path, mountPoint, length) == 0)
{
// we need to do extra checking if mountPoint does not end in a '/'
if (mountPoint[length - 1] == '/')
return true;
// if mountPoint does not have a trailing slash, we need to make sure
// there is one in the path to avoid partial matches.
return (path[length] == 0 || path[length] == '/');
}
return false;
}
static void GetProcessName(int pid, char buffer[PATH_MAX])
{
int fd;
sprintf(buffer, "/proc/%d/cmdline", pid);
fd = open(buffer, O_RDONLY);
if (fd < 0) {
strcpy(buffer, "???");
} else {
int length = read(fd, buffer, PATH_MAX - 1);
buffer[length] = 0;
close(fd);
}
}
static boolean CheckFileDescriptorSymLinks(int pid, const char* mountPoint)
{
DIR* dir;
struct dirent* de;
boolean fileOpen = false;
char path[PATH_MAX];
char link[PATH_MAX];
int parent_length;
// compute path to process's directory of open files
sprintf(path, "/proc/%d/fd", pid);
dir = opendir(path);
if (!dir)
return false;
// remember length of the path
parent_length = strlen(path);
// append a trailing '/'
path[parent_length++] = '/';
while ((de = readdir(dir)) != 0 && !fileOpen) {
if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
continue;
// append the file name, after truncating to parent directory
path[parent_length] = 0;
strcat(path, de->d_name);
if (ReadSymLink(path, link) && PathMatchesMountPoint(link, mountPoint))
{
char name[PATH_MAX];
GetProcessName(pid, name);
LOG_ERROR("process %s (%d) has open file %s\n", name, pid, link);
fileOpen = true;
}
}
closedir(dir);
return fileOpen;
}
static boolean CheckFileMaps(int pid, const char* mountPoint)
{
FILE* file;
char buffer[PATH_MAX + 100];
boolean mapOpen = false;
sprintf(buffer, "/proc/%d/maps", pid);
file = fopen(buffer, "r");
if (!file)
return false;
while (!mapOpen && fgets(buffer, sizeof(buffer), file))
{
// skip to the path
const char* path = strchr(buffer, '/');
if (path && PathMatchesMountPoint(path, mountPoint))
{
char name[PATH_MAX];
GetProcessName(pid, name);
LOG_ERROR("process %s (%d) has open file map for %s\n", name, pid, path);
mapOpen = true;
}
}
fclose(file);
return mapOpen;
}
static boolean CheckSymLink(int pid, const char* mountPoint, const char* name, const char* message)
{
char path[PATH_MAX];
char link[PATH_MAX];
sprintf(path, "/proc/%d/%s", pid, name);
if (ReadSymLink(path, link) && PathMatchesMountPoint(link, mountPoint))
{
char name[PATH_MAX];
GetProcessName(pid, name);
LOG_ERROR("process %s (%d) has %s in %s\n", name, pid, message, mountPoint);
return true;
}
else
return false;
}
static int get_pid(const char* s)
{
int result = 0;
while (*s) {
if (!isdigit(*s)) return -1;
result = 10 * result + (*s++ - '0');
}
return result;
}
// hunt down and kill processes that have files open on the given mount point
void KillProcessesWithOpenFiles(const char* mountPoint, boolean sigkill, int *excluded, int num_excluded)
{
DIR* dir;
struct dirent* de;
LOG_ERROR("KillProcessesWithOpenFiles %s\n", mountPoint);
dir = opendir("/proc");
if (!dir) return;
while ((de = readdir(dir)) != 0)
{
boolean killed = false;
// does the name look like a process ID?
int pid = get_pid(de->d_name);
if (pid == -1) continue;
if (CheckFileDescriptorSymLinks(pid, mountPoint) // check for open files
|| CheckFileMaps(pid, mountPoint) // check for mmap()
|| CheckSymLink(pid, mountPoint, "cwd", "working directory") // check working directory
|| CheckSymLink(pid, mountPoint, "root", "chroot") // check for chroot()
|| CheckSymLink(pid, mountPoint, "exe", "executable path") // check executable path
)
{
int i;
boolean hit = false;
for (i = 0; i < num_excluded; i++) {
if (pid == excluded[i]) {
LOG_ERROR("I just need a little more TIME captain!\n");
hit = true;
break;
}
}
if (!hit) {
LOG_ERROR("Killing process %d\n", pid);
kill(pid, (sigkill ? SIGKILL : SIGTERM));
}
}
}
closedir(dir);
}
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