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utils.c
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utils.c
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/*
* lxc: linux Container library
*
* (C) Copyright IBM Corp. 2007, 2008
*
* Authors:
* Daniel Lezcano <daniel.lezcano at free.fr>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif
#define __STDC_FORMAT_MACROS /* Required for PRIu64 to work. */
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <inttypes.h>
#include <libgen.h>
#include <pthread.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "config.h"
#include "log.h"
#include "lxclock.h"
#include "namespace.h"
#include "parse.h"
#include "raw_syscalls.h"
#include "syscall_wrappers.h"
#include "utils.h"
#ifndef HAVE_STRLCPY
#include "include/strlcpy.h"
#endif
#ifndef HAVE_STRLCAT
#include "include/strlcat.h"
#endif
#ifndef O_PATH
#define O_PATH 010000000
#endif
#ifndef O_NOFOLLOW
#define O_NOFOLLOW 00400000
#endif
lxc_log_define(utils, lxc);
/*
* if path is btrfs, tries to remove it and any subvolumes beneath it
*/
extern bool btrfs_try_remove_subvol(const char *path);
static int _recursive_rmdir(const char *dirname, dev_t pdev,
const char *exclude, int level, bool onedev)
{
struct dirent *direntp;
DIR *dir;
int ret, failed = 0;
char pathname[PATH_MAX];
bool hadexclude = false;
dir = opendir(dirname);
if (!dir) {
ERROR("Failed to open \"%s\"", dirname);
return -1;
}
while ((direntp = readdir(dir))) {
struct stat mystat;
int rc;
if (!strcmp(direntp->d_name, ".") ||
!strcmp(direntp->d_name, ".."))
continue;
rc = snprintf(pathname, PATH_MAX, "%s/%s", dirname, direntp->d_name);
if (rc < 0 || rc >= PATH_MAX) {
ERROR("The name of path is too long");
failed=1;
continue;
}
if (!level && exclude && !strcmp(direntp->d_name, exclude)) {
ret = rmdir(pathname);
if (ret < 0) {
switch(errno) {
case ENOTEMPTY:
INFO("Not deleting snapshot \"%s\"", pathname);
hadexclude = true;
break;
case ENOTDIR:
ret = unlink(pathname);
if (ret)
INFO("Failed to remove \"%s\"", pathname);
break;
default:
SYSERROR("Failed to rmdir \"%s\"", pathname);
failed = 1;
break;
}
}
continue;
}
ret = lstat(pathname, &mystat);
if (ret) {
SYSERROR("Failed to stat \"%s\"", pathname);
failed = 1;
continue;
}
if (onedev && mystat.st_dev != pdev) {
/* TODO should we be checking /proc/self/mountinfo for
* pathname and not doing this if found? */
if (btrfs_try_remove_subvol(pathname))
INFO("Removed btrfs subvolume at \"%s\"", pathname);
continue;
}
if (S_ISDIR(mystat.st_mode)) {
if (_recursive_rmdir(pathname, pdev, exclude, level+1, onedev) < 0)
failed=1;
} else {
if (unlink(pathname) < 0) {
SYSERROR("Failed to delete \"%s\"", pathname);
failed=1;
}
}
}
if (rmdir(dirname) < 0 && !btrfs_try_remove_subvol(dirname) && !hadexclude) {
SYSERROR("Failed to delete \"%s\"", dirname);
failed=1;
}
ret = closedir(dir);
if (ret) {
SYSERROR("Failed to close directory \"%s\"", dirname);
failed=1;
}
return failed ? -1 : 0;
}
/* In overlayfs, st_dev is unreliable. So on overlayfs we don't do the
* lxc_rmdir_onedev()
*/
static bool is_native_overlayfs(const char *path)
{
if (has_fs_type(path, OVERLAY_SUPER_MAGIC) ||
has_fs_type(path, OVERLAYFS_SUPER_MAGIC))
return true;
return false;
}
/* returns 0 on success, -1 if there were any failures */
extern int lxc_rmdir_onedev(const char *path, const char *exclude)
{
struct stat mystat;
bool onedev = true;
if (is_native_overlayfs(path))
onedev = false;
if (lstat(path, &mystat) < 0) {
if (errno == ENOENT)
return 0;
SYSERROR("Failed to stat \"%s\"", path);
return -1;
}
return _recursive_rmdir(path, mystat.st_dev, exclude, 0, onedev);
}
/* borrowed from iproute2 */
extern int get_u16(unsigned short *val, const char *arg, int base)
{
unsigned long res;
char *ptr;
if (!arg || !*arg)
return -1;
errno = 0;
res = strtoul(arg, &ptr, base);
if (!ptr || ptr == arg || *ptr || res > 0xFFFF || errno != 0)
return -1;
*val = res;
return 0;
}
int mkdir_p(const char *dir, mode_t mode)
{
const char *tmp = dir;
const char *orig = dir;
do {
int ret;
char *makeme;
dir = tmp + strspn(tmp, "/");
tmp = dir + strcspn(dir, "/");
errno = ENOMEM;
makeme = strndup(orig, dir - orig);
if (!makeme)
return -1;
ret = mkdir(makeme, mode);
if (ret < 0 && errno != EEXIST) {
SYSERROR("Failed to create directory \"%s\"", makeme);
free(makeme);
return -1;
}
free(makeme);
} while (tmp != dir);
return 0;
}
char *get_rundir()
{
char *rundir;
const char *homedir;
struct stat sb;
if (stat(RUNTIME_PATH, &sb) < 0)
return NULL;
if (geteuid() == sb.st_uid || getegid() == sb.st_gid) {
rundir = strdup(RUNTIME_PATH);
return rundir;
}
rundir = getenv("XDG_RUNTIME_DIR");
if (rundir) {
rundir = strdup(rundir);
return rundir;
}
INFO("XDG_RUNTIME_DIR isn't set in the environment");
homedir = getenv("HOME");
if (!homedir) {
ERROR("HOME isn't set in the environment");
return NULL;
}
rundir = malloc(sizeof(char) * (17 + strlen(homedir)));
if (!rundir)
return NULL;
sprintf(rundir, "%s/.cache/lxc/run/", homedir);
return rundir;
}
int wait_for_pid(pid_t pid)
{
int status, ret;
again:
ret = waitpid(pid, &status, 0);
if (ret == -1) {
if (errno == EINTR)
goto again;
return -1;
}
if (ret != pid)
goto again;
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
return -1;
return 0;
}
int lxc_wait_for_pid_status(pid_t pid)
{
int status, ret;
again:
ret = waitpid(pid, &status, 0);
if (ret == -1) {
if (errno == EINTR)
goto again;
return -1;
}
if (ret != pid)
goto again;
return status;
}
#if HAVE_LIBGNUTLS
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>
__attribute__((constructor))
static void gnutls_lxc_init(void)
{
gnutls_global_init();
}
int sha1sum_file(char *fnam, unsigned char *digest)
{
char *buf;
int ret;
FILE *f;
long flen;
if (!fnam)
return -1;
f = fopen_cloexec(fnam, "r");
if (!f) {
SYSERROR("Failed to open template \"%s\"", fnam);
return -1;
}
if (fseek(f, 0, SEEK_END) < 0) {
SYSERROR("Failed to seek to end of template");
fclose(f);
return -1;
}
if ((flen = ftell(f)) < 0) {
SYSERROR("Failed to tell size of template");
fclose(f);
return -1;
}
if (fseek(f, 0, SEEK_SET) < 0) {
SYSERROR("Failed to seek to start of template");
fclose(f);
return -1;
}
if ((buf = malloc(flen+1)) == NULL) {
SYSERROR("Out of memory");
fclose(f);
return -1;
}
if (fread(buf, 1, flen, f) != flen) {
SYSERROR("Failed to read template");
free(buf);
fclose(f);
return -1;
}
if (fclose(f) < 0) {
SYSERROR("Failed to close template");
free(buf);
return -1;
}
buf[flen] = '\0';
ret = gnutls_hash_fast(GNUTLS_DIG_SHA1, buf, flen, (void *)digest);
free(buf);
return ret;
}
#endif
struct lxc_popen_FILE *lxc_popen(const char *command)
{
int ret;
int pipe_fds[2];
pid_t child_pid;
struct lxc_popen_FILE *fp = NULL;
ret = pipe2(pipe_fds, O_CLOEXEC);
if (ret < 0)
return NULL;
child_pid = fork();
if (child_pid < 0)
goto on_error;
if (!child_pid) {
sigset_t mask;
close(pipe_fds[0]);
/* duplicate stdout */
if (pipe_fds[1] != STDOUT_FILENO)
ret = dup2(pipe_fds[1], STDOUT_FILENO);
else
ret = fcntl(pipe_fds[1], F_SETFD, 0);
if (ret < 0) {
close(pipe_fds[1]);
_exit(EXIT_FAILURE);
}
/* duplicate stderr */
if (pipe_fds[1] != STDERR_FILENO)
ret = dup2(pipe_fds[1], STDERR_FILENO);
else
ret = fcntl(pipe_fds[1], F_SETFD, 0);
close(pipe_fds[1]);
if (ret < 0)
_exit(EXIT_FAILURE);
/* unblock all signals */
ret = sigfillset(&mask);
if (ret < 0)
_exit(EXIT_FAILURE);
ret = pthread_sigmask(SIG_UNBLOCK, &mask, NULL);
if (ret < 0)
_exit(EXIT_FAILURE);
execl("/bin/sh", "sh", "-c", command, (char *)NULL);
_exit(127);
}
close(pipe_fds[1]);
pipe_fds[1] = -1;
fp = malloc(sizeof(*fp));
if (!fp)
goto on_error;
memset(fp, 0, sizeof(*fp));
fp->child_pid = child_pid;
fp->pipe = pipe_fds[0];
/* From now on, closing fp->f will also close fp->pipe. So only ever
* call fclose(fp->f).
*/
fp->f = fdopen(pipe_fds[0], "r");
if (!fp->f)
goto on_error;
return fp;
on_error:
/* We can only close pipe_fds[0] if fdopen() didn't succeed or wasn't
* called yet. Otherwise the fd belongs to the file opened by fdopen()
* since it isn't dup()ed.
*/
if (fp && !fp->f && pipe_fds[0] >= 0)
close(pipe_fds[0]);
if (pipe_fds[1] >= 0)
close(pipe_fds[1]);
if (fp && fp->f)
fclose(fp->f);
if (fp)
free(fp);
return NULL;
}
int lxc_pclose(struct lxc_popen_FILE *fp)
{
pid_t wait_pid;
int wstatus = 0;
if (!fp)
return -1;
do {
wait_pid = waitpid(fp->child_pid, &wstatus, 0);
} while (wait_pid < 0 && errno == EINTR);
fclose(fp->f);
free(fp);
if (wait_pid < 0)
return -1;
return wstatus;
}
int randseed(bool srand_it)
{
FILE *f;
/*
* srand pre-seed function based on /dev/urandom
*/
unsigned int seed = time(NULL) + getpid();
f = fopen("/dev/urandom", "r");
if (f) {
int ret = fread(&seed, sizeof(seed), 1, f);
if (ret != 1)
SYSDEBUG("Unable to fread /dev/urandom, fallback to time+pid rand seed");
fclose(f);
}
if (srand_it)
srand(seed);
return seed;
}
uid_t get_ns_uid(uid_t orig)
{
char *line = NULL;
size_t sz = 0;
uid_t nsid, hostid, range;
FILE *f;
f = fopen("/proc/self/uid_map", "r");
if (!f) {
SYSERROR("Failed to open uid_map");
return 0;
}
while (getline(&line, &sz, f) != -1) {
if (sscanf(line, "%u %u %u", &nsid, &hostid, &range) != 3)
continue;
if (hostid <= orig && hostid + range > orig) {
nsid += orig - hostid;
goto found;
}
}
nsid = LXC_INVALID_UID;
found:
fclose(f);
free(line);
return nsid;
}
gid_t get_ns_gid(gid_t orig)
{
char *line = NULL;
size_t sz = 0;
gid_t nsid, hostid, range;
FILE *f;
f = fopen("/proc/self/gid_map", "r");
if (!f) {
SYSERROR("Failed to open gid_map");
return 0;
}
while (getline(&line, &sz, f) != -1) {
if (sscanf(line, "%u %u %u", &nsid, &hostid, &range) != 3)
continue;
if (hostid <= orig && hostid + range > orig) {
nsid += orig - hostid;
goto found;
}
}
nsid = LXC_INVALID_GID;
found:
fclose(f);
free(line);
return nsid;
}
bool dir_exists(const char *path)
{
struct stat sb;
int ret;
ret = stat(path, &sb);
if (ret < 0)
/* Could be something other than eexist, just say "no". */
return false;
return S_ISDIR(sb.st_mode);
}
/* Note we don't use SHA-1 here as we don't want to depend on HAVE_GNUTLS.
* FNV has good anti collision properties and we're not worried
* about pre-image resistance or one-way-ness, we're just trying to make
* the name unique in the 108 bytes of space we have.
*/
uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval)
{
unsigned char *bp;
for(bp = buf; bp < (unsigned char *)buf + len; bp++) {
/* xor the bottom with the current octet */
hval ^= (uint64_t)*bp;
/* gcc optimised:
* multiply by the 64 bit FNV magic prime mod 2^64
*/
hval += (hval << 1) + (hval << 4) + (hval << 5) +
(hval << 7) + (hval << 8) + (hval << 40);
}
return hval;
}
/*
* Detect whether / is mounted MS_SHARED. The only way I know of to
* check that is through /proc/self/mountinfo.
* I'm only checking for /. If the container rootfs or mount location
* is MS_SHARED, but not '/', then you're out of luck - figuring that
* out would be too much work to be worth it.
*/
int detect_shared_rootfs(void)
{
char buf[LXC_LINELEN], *p;
FILE *f;
int i;
char *p2;
f = fopen("/proc/self/mountinfo", "r");
if (!f)
return 0;
while (fgets(buf, LXC_LINELEN, f)) {
for (p = buf, i = 0; p && i < 4; i++)
p = strchr(p + 1, ' ');
if (!p)
continue;
p2 = strchr(p + 1, ' ');
if (!p2)
continue;
*p2 = '\0';
if (strcmp(p + 1, "/") == 0) {
/* This is '/'. Is it shared? */
p = strchr(p2 + 1, ' ');
if (p && strstr(p, "shared:")) {
fclose(f);
return 1;
}
}
}
fclose(f);
return 0;
}
bool switch_to_ns(pid_t pid, const char *ns)
{
int fd, ret;
char nspath[PATH_MAX];
/* Switch to new ns */
ret = snprintf(nspath, PATH_MAX, "/proc/%d/ns/%s", pid, ns);
if (ret < 0 || ret >= PATH_MAX)
return false;
fd = open(nspath, O_RDONLY);
if (fd < 0) {
SYSERROR("Failed to open \"%s\"", nspath);
return false;
}
ret = setns(fd, 0);
if (ret) {
SYSERROR("Failed to set process %d to \"%s\" of %d.", pid, ns, fd);
close(fd);
return false;
}
close(fd);
return true;
}
/*
* looking at fs/proc_namespace.c, it appears we can
* actually expect the rootfs entry to very specifically contain
* " - rootfs rootfs "
* IIUC, so long as we've chrooted so that rootfs is not our root,
* the rootfs entry should always be skipped in mountinfo contents.
*/
bool detect_ramfs_rootfs(void)
{
FILE *f;
char *p, *p2;
char *line = NULL;
size_t len = 0;
int i;
f = fopen("/proc/self/mountinfo", "r");
if (!f) {
SYSERROR("Failed to open mountinfo");
return false;
}
while (getline(&line, &len, f) != -1) {
for (p = line, i = 0; p && i < 4; i++)
p = strchr(p + 1, ' ');
if (!p)
continue;
p2 = strchr(p + 1, ' ');
if (!p2)
continue;
*p2 = '\0';
if (strcmp(p + 1, "/") == 0) {
/* This is '/'. Is it the ramfs? */
p = strchr(p2 + 1, '-');
if (p && strncmp(p, "- rootfs rootfs ", 16) == 0) {
free(line);
fclose(f);
INFO("Rootfs is located on ramfs");
return true;
}
}
}
free(line);
fclose(f);
return false;
}
char *on_path(const char *cmd, const char *rootfs)
{
char *entry = NULL, *path = NULL;
char cmdpath[PATH_MAX];
int ret;
path = getenv("PATH");
if (!path)
return NULL;
path = strdup(path);
if (!path)
return NULL;
lxc_iterate_parts (entry, path, ":") {
if (rootfs)
ret = snprintf(cmdpath, PATH_MAX, "%s/%s/%s", rootfs,
entry, cmd);
else
ret = snprintf(cmdpath, PATH_MAX, "%s/%s", entry, cmd);
if (ret < 0 || ret >= PATH_MAX)
continue;
if (access(cmdpath, X_OK) == 0) {
free(path);
return strdup(cmdpath);
}
}
free(path);
return NULL;
}
bool cgns_supported(void)
{
return file_exists("/proc/self/ns/cgroup");
}
/* historically lxc-init has been under /usr/lib/lxc and under
* /usr/lib/$ARCH/lxc. It now lives as $prefix/sbin/init.lxc.
*/
char *choose_init(const char *rootfs)
{
char *retv = NULL;
const char *empty = "",
*tmp;
int ret, env_set = 0;
if (!getenv("PATH")) {
if (setenv("PATH", "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", 0))
SYSERROR("Failed to setenv");
env_set = 1;
}
retv = on_path("init.lxc", rootfs);
if (env_set)
if (unsetenv("PATH"))
SYSERROR("Failed to unsetenv");
if (retv)
return retv;
retv = malloc(PATH_MAX);
if (!retv)
return NULL;
if (rootfs)
tmp = rootfs;
else
tmp = empty;
ret = snprintf(retv, PATH_MAX, "%s/%s/%s", tmp, SBINDIR, "/init.lxc");
if (ret < 0 || ret >= PATH_MAX) {
ERROR("The name of path is too long");
goto out1;
}
if (access(retv, X_OK) == 0)
return retv;
ret = snprintf(retv, PATH_MAX, "%s/%s/%s", tmp, LXCINITDIR, "/lxc/lxc-init");
if (ret < 0 || ret >= PATH_MAX) {
ERROR("The name of path is too long");
goto out1;
}
if (access(retv, X_OK) == 0)
return retv;
ret = snprintf(retv, PATH_MAX, "%s/usr/lib/lxc/lxc-init", tmp);
if (ret < 0 || ret >= PATH_MAX) {
ERROR("The name of path is too long");
goto out1;
}
if (access(retv, X_OK) == 0)
return retv;
ret = snprintf(retv, PATH_MAX, "%s/sbin/lxc-init", tmp);
if (ret < 0 || ret >= PATH_MAX) {
ERROR("The name of path is too long");
goto out1;
}
if (access(retv, X_OK) == 0)
return retv;
/*
* Last resort, look for the statically compiled init.lxc which we
* hopefully bind-mounted in.
* If we are called during container setup, and we get to this point,
* then the init.lxc.static from the host will need to be bind-mounted
* in. So we return NULL here to indicate that.
*/
if (rootfs)
goto out1;
ret = snprintf(retv, PATH_MAX, "/init.lxc.static");
if (ret < 0 || ret >= PATH_MAX) {
WARN("Nonsense - name /lxc.init.static too long");
goto out1;
}
if (access(retv, X_OK) == 0)
return retv;
out1:
free(retv);
return NULL;
}
/*
* Given the '-t' template option to lxc-create, figure out what to
* do. If the template is a full executable path, use that. If it
* is something like 'sshd', then return $templatepath/lxc-sshd.
* On success return the template, on error return NULL.
*/
char *get_template_path(const char *t)
{
int ret, len;
char *tpath;
if (t[0] == '/' && access(t, X_OK) == 0) {
tpath = strdup(t);
return tpath;
}
len = strlen(LXCTEMPLATEDIR) + strlen(t) + strlen("/lxc-") + 1;
tpath = malloc(len);
if (!tpath)
return NULL;
ret = snprintf(tpath, len, "%s/lxc-%s", LXCTEMPLATEDIR, t);
if (ret < 0 || ret >= len) {
free(tpath);
return NULL;
}
if (access(tpath, X_OK) < 0) {
SYSERROR("bad template: %s", t);
free(tpath);
return NULL;
}
return tpath;
}
/*
* @path: a pathname where / replaced with '\0'.
* @offsetp: pointer to int showing which path segment was last seen.
* Updated on return to reflect the next segment.
* @fulllen: full original path length.
* Returns a pointer to the next path segment, or NULL if done.
*/
static char *get_nextpath(char *path, int *offsetp, int fulllen)
{
int offset = *offsetp;
if (offset >= fulllen)
return NULL;
while (offset < fulllen && path[offset] != '\0')
offset++;
while (offset < fulllen && path[offset] == '\0')
offset++;
*offsetp = offset;
return (offset < fulllen) ? &path[offset] : NULL;
}
/*
* Check that @subdir is a subdir of @dir. @len is the length of
* @dir (to avoid having to recalculate it).
*/
static bool is_subdir(const char *subdir, const char *dir, size_t len)
{
size_t subdirlen = strlen(subdir);
if (subdirlen < len)
return false;
if (strncmp(subdir, dir, len) != 0)
return false;
if (dir[len-1] == '/')
return true;
if (subdir[len] == '/' || subdirlen == len)
return true;
return false;
}
/*
* Check if the open fd is a symlink. Return -ELOOP if it is. Return
* -ENOENT if we couldn't fstat. Return 0 if the fd is ok.
*/
static int check_symlink(int fd)
{
struct stat sb;
int ret;
ret = fstat(fd, &sb);
if (ret < 0)
return -ENOENT;
if (S_ISLNK(sb.st_mode))
return -ELOOP;
return 0;
}
/*
* Open a file or directory, provided that it contains no symlinks.
*
* CAVEAT: This function must not be used for other purposes than container
* setup before executing the container's init
*/
static int open_if_safe(int dirfd, const char *nextpath)
{