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652f887144
libvirt/src/lxc/lxc_container.c
Daniel P. Berrange 652f887144 Allow passing of command line args to LXC container 
When booting a virtual machine with a kernel/initrd it is possible
to pass command line arguments using the <cmdline>...args...</cmdline>
element in the guest XML. These appear to the kernel / init process
in /proc/cmdline.

When booting a container we do not have a custom /proc/cmdline,
but we can easily set an environment variable for it. Ideally
we could pass individual arguments to the init process as a
regular set of 'char *argv[]' parameters, but that would involve
libvirt parsing the <cmdline> XML text. This can easily be added
later, even if we add the env variable now

* docs/drvlxc.html.in: Document env variables passed to LXC
* src/conf/domain_conf.c: Add <cmdline> to be parsed for
  guests of type='exe'
* src/lxc/lxc_container.c: Set LIBVIRT_LXC_CMDLINE env var
2011-10-04 14:15:09 +01:00

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/*
* Copyright (C) 2008-2011 Red Hat, Inc.
* Copyright (C) 2008 IBM Corp.
*
* lxc_container.c: file description
*
* Authors:
* David L. Leskovec <dlesko at linux.vnet.ibm.com>
* Daniel P. Berrange <berrange@redhat.com>
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <config.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <unistd.h>
#include <mntent.h>
#include <dirent.h>
/* Yes, we want linux private one, for _syscall2() macro */
#include <linux/unistd.h>
/* For MS_MOVE */
#include <linux/fs.h>
#if HAVE_CAPNG
# include <cap-ng.h>
#endif
#include "virterror_internal.h"
#include "logging.h"
#include "lxc_container.h"
#include "util.h"
#include "memory.h"
#include "veth.h"
#include "uuid.h"
#include "virfile.h"
#include "command.h"
#define VIR_FROM_THIS VIR_FROM_LXC
/*
* GLibc headers are behind the kernel, so we define these
* constants if they're not present already.
*/
#ifndef CLONE_NEWPID
# define CLONE_NEWPID 0x20000000
#endif
#ifndef CLONE_NEWUTS
# define CLONE_NEWUTS 0x04000000
#endif
#ifndef CLONE_NEWUSER
# define CLONE_NEWUSER 0x10000000
#endif
#ifndef CLONE_NEWIPC
# define CLONE_NEWIPC 0x08000000
#endif
#ifndef CLONE_NEWNET
# define CLONE_NEWNET 0x40000000 /* New network namespace */
#endif
/* messages between parent and container */
typedef char lxc_message_t;
#define LXC_CONTINUE_MSG 'c'
typedef struct __lxc_child_argv lxc_child_argv_t;
struct __lxc_child_argv {
virDomainDefPtr config;
unsigned int nveths;
char **veths;
int monitor;
char *ttyPath;
int handshakefd;
};
/**
* lxcContainerBuildInitCmd:
* @vmDef: pointer to vm definition structure
*
* Build a virCommandPtr for launching the container 'init' process
*
* Returns a virCommandPtr
*/
static virCommandPtr lxcContainerBuildInitCmd(virDomainDefPtr vmDef)
{
char uuidstr[VIR_UUID_STRING_BUFLEN];
virCommandPtr cmd;
virUUIDFormat(vmDef->uuid, uuidstr);
cmd = virCommandNew(vmDef->os.init);
virCommandAddEnvString(cmd, "PATH=/bin:/sbin");
virCommandAddEnvString(cmd, "TERM=linux");
virCommandAddEnvPair(cmd, "LIBVIRT_LXC_UUID", uuidstr);
virCommandAddEnvPair(cmd, "LIBVIRT_LXC_NAME", vmDef->name);
if (vmDef->os.cmdline)
virCommandAddEnvPair(cmd, "LIBVIRT_LXC_CMDLINE", vmDef->os.cmdline);
return cmd;
}
/**
* lxcContainerSetStdio:
* @control: control FD from parent
* @ttyfd: FD of tty to set as the container console
*
* Sets the given tty as the primary conosole for the container as well as
* stdout, stdin and stderr.
*
* Returns 0 on success or -1 in case of error
*/
static int lxcContainerSetStdio(int control, int ttyfd, int handshakefd)
{
int rc = -1;
int open_max, i;
if (setsid() < 0) {
virReportSystemError(errno, "%s",
_("setsid failed"));
goto cleanup;
}
if (ioctl(ttyfd, TIOCSCTTY, NULL) < 0) {
virReportSystemError(errno, "%s",
_("ioctl(TIOCSTTY) failed"));
goto cleanup;
}
/* Just in case someone forget to set FD_CLOEXEC, explicitly
* close all FDs before executing the container */
open_max = sysconf (_SC_OPEN_MAX);
for (i = 0; i < open_max; i++)
if (i != ttyfd && i != control && i != handshakefd) {
int tmpfd = i;
VIR_FORCE_CLOSE(tmpfd);
}
if (dup2(ttyfd, 0) < 0) {
virReportSystemError(errno, "%s",
_("dup2(stdin) failed"));
goto cleanup;
}
if (dup2(ttyfd, 1) < 0) {
virReportSystemError(errno, "%s",
_("dup2(stdout) failed"));
goto cleanup;
}
if (dup2(ttyfd, 2) < 0) {
virReportSystemError(errno, "%s",
_("dup2(stderr) failed"));
goto cleanup;
}
rc = 0;
cleanup:
VIR_DEBUG("rc=%d", rc);
return rc;
}
/**
* lxcContainerSendContinue:
* @control: control FD to child
*
* Sends the continue message via the socket pair stored in the vm
* structure.
*
* Returns 0 on success or -1 in case of error
*/
int lxcContainerSendContinue(int control)
{
int rc = -1;
lxc_message_t msg = LXC_CONTINUE_MSG;
int writeCount = 0;
writeCount = safewrite(control, &msg, sizeof(msg));
if (writeCount != sizeof(msg)) {
goto error_out;
}
rc = 0;
error_out:
return rc;
}
/**
* lxcContainerWaitForContinue:
* @control: Control FD from parent
*
* This function will wait for the container continue message from the
* parent process. It will send this message on the socket pair stored in
* the vm structure once it has completed the post clone container setup.
*
* Returns 0 on success or -1 in case of error
*/
int lxcContainerWaitForContinue(int control)
{
lxc_message_t msg;
int readLen;
readLen = saferead(control, &msg, sizeof(msg));
if (readLen != sizeof(msg) ||
msg != LXC_CONTINUE_MSG) {
return -1;
}
return 0;
}
/**
* lxcContainerRenameAndEnableInterfaces:
* @nveths: number of interfaces
* @veths: interface names
*
* This function will rename the interfaces to ethN
* with id ascending order from zero and enable the
* renamed interfaces for this container.
*
* Returns 0 on success or nonzero in case of error
*/
static int lxcContainerRenameAndEnableInterfaces(unsigned int nveths,
char **veths)
{
int rc = 0;
unsigned int i;
char *newname = NULL;
for (i = 0 ; i < nveths ; i++) {
if (virAsprintf(&newname, "eth%d", i) < 0) {
virReportOOMError();
rc = -1;
goto error_out;
}
VIR_DEBUG("Renaming %s to %s", veths[i], newname);
rc = setInterfaceName(veths[i], newname);
if (rc < 0)
goto error_out;
VIR_DEBUG("Enabling %s", newname);
rc = vethInterfaceUpOrDown(newname, 1);
if (rc < 0)
goto error_out;
VIR_FREE(newname);
}
/* enable lo device only if there were other net devices */
if (veths)
rc = vethInterfaceUpOrDown("lo", 1);
error_out:
VIR_FREE(newname);
return rc;
}
/*_syscall2(int, pivot_root, char *, newroot, const char *, oldroot)*/
extern int pivot_root(const char * new_root,const char * put_old);
static int lxcContainerChildMountSort(const void *a, const void *b)
{
const char **sa = (const char**)a;
const char **sb = (const char**)b;
/* Deliberately reversed args - we need to unmount deepest
children first */
return strcmp(*sb, *sa);
}
#ifndef MS_REC
# define MS_REC 16384
#endif
#ifndef MNT_DETACH
# define MNT_DETACH 0x00000002
#endif
#ifndef MS_PRIVATE
# define MS_PRIVATE (1<<18)
#endif
#ifndef MS_SLAVE
# define MS_SLAVE (1<<19)
#endif
static int lxcContainerPivotRoot(virDomainFSDefPtr root)
{
int ret;
char *oldroot = NULL, *newroot = NULL;
ret = -1;
/* root->parent must be private, so make / private. */
if (mount("", "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) {
virReportSystemError(errno, "%s",
_("Failed to make root private"));
goto err;
}
if (virAsprintf(&oldroot, "%s/.oldroot", root->src) < 0) {
virReportOOMError();
goto err;
}
if (virFileMakePath(oldroot) < 0) {
virReportSystemError(errno,
_("Failed to create %s"),
oldroot);
goto err;
}
/* Create a tmpfs root since old and new roots must be
* on separate filesystems */
if (mount("tmprootfs", oldroot, "tmpfs", 0, NULL) < 0) {
virReportSystemError(errno,
_("Failed to mount empty tmpfs at %s"),
oldroot);
goto err;
}
/* Create a directory called 'new' in tmpfs */
if (virAsprintf(&newroot, "%s/new", oldroot) < 0) {
virReportOOMError();
goto err;
}
if (virFileMakePath(newroot) < 0) {
virReportSystemError(errno,
_("Failed to create %s"),
newroot);
goto err;
}
/* ... and mount our root onto it */
if (mount(root->src, newroot, NULL, MS_BIND|MS_REC, NULL) < 0) {
virReportSystemError(errno,
_("Failed to bind new root %s into tmpfs"),
root->src);
goto err;
}
if (root->readonly) {
if (mount(root->src, newroot, NULL, MS_BIND|MS_REC|MS_RDONLY|MS_REMOUNT, NULL) < 0) {
virReportSystemError(errno,
_("Failed to make new root %s readonly"),
root->src);
goto err;
}
}
/* Now we chroot into the tmpfs, then pivot into the
* root->src bind-mounted onto '/new' */
if (chdir(newroot) < 0) {
virReportSystemError(errno,
_("Failed to chroot into %s"), newroot);
goto err;
}
/* The old root directory will live at /.oldroot after
* this and will soon be unmounted completely */
if (pivot_root(".", ".oldroot") < 0) {
virReportSystemError(errno, "%s",
_("Failed to pivot root"));
goto err;
}
/* CWD is undefined after pivot_root, so go to / */
if (chdir("/") < 0)
goto err;
ret = 0;
err:
VIR_FREE(oldroot);
VIR_FREE(newroot);
return ret;
}
static int lxcContainerMountBasicFS(const char *srcprefix, bool pivotRoot)
{
const struct {
bool onlyPivotRoot;
bool needPrefix;
const char *src;
const char *dst;
const char *type;
const char *opts;
int mflags;
} mnts[] = {
/* When we want to make a bind mount readonly, for unknown reasons,
* it is currently neccessary to bind it once, and then remount the
* bind with the readonly flag. If this is not done, then the original
* mount point in the main OS becomes readonly too which is not what
* we want. Hence some things have two entries here.
*/
{ true, false, "devfs", "/dev", "tmpfs", "mode=755", MS_NOSUID },
{ false, false, "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV },
{ false, false, "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND },
{ false, false, "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY },
{ false, true, "/sys", "/sys", NULL, NULL, MS_BIND },
{ false, true, "/sys", "/sys", NULL, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY },
{ false, true, "/selinux", "/selinux", NULL, NULL, MS_BIND },
{ false, true, "/selinux", "/selinux", NULL, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY },
};
int i, rc = -1;
VIR_DEBUG("Mounting basic filesystems %s pivotRoot=%d", NULLSTR(srcprefix), pivotRoot);
for (i = 0 ; i < ARRAY_CARDINALITY(mnts) ; i++) {
char *src = NULL;
const char *srcpath = NULL;
VIR_DEBUG("Consider %s onlyPivotRoot=%d",
mnts[i].src, mnts[i].onlyPivotRoot);
if (mnts[i].onlyPivotRoot && !pivotRoot)
continue;
if (virFileMakePath(mnts[i].dst) < 0) {
virReportSystemError(errno,
_("Failed to mkdir %s"),
mnts[i].src);
goto cleanup;
}
if (mnts[i].needPrefix && srcprefix) {
if (virAsprintf(&src, "%s%s", srcprefix, mnts[i].src) < 0) {
virReportOOMError();
goto cleanup;
}
srcpath = src;
} else {
srcpath = mnts[i].src;
}
/* Skip if mount doesn't exist in source */
if ((srcpath[0] == '/') &&
(access(srcpath, R_OK) < 0))
continue;
VIR_DEBUG("Mount %s on %s type=%s flags=%x, opts=%s",
srcpath, mnts[i].dst, mnts[i].type, mnts[i].mflags, mnts[i].opts);
if (mount(srcpath, mnts[i].dst, mnts[i].type, mnts[i].mflags, mnts[i].opts) < 0) {
VIR_FREE(src);
virReportSystemError(errno,
_("Failed to mount %s on %s type %s"),
mnts[i].src, mnts[i].dst, NULLSTR(mnts[i].type));
goto cleanup;
}
VIR_FREE(src);
}
rc = 0;
cleanup:
VIR_DEBUG("rc=%d", rc);
return rc;
}
static int lxcContainerMountDevFS(virDomainFSDefPtr root)
{
char *devpts = NULL;
int rc = -1;
if (virAsprintf(&devpts, "/.oldroot%s/dev/pts", root->src) < 0) {
virReportOOMError();
goto cleanup;
}
if (virFileMakePath("/dev/pts") < 0) {
virReportSystemError(errno, "%s",
_("Cannot create /dev/pts"));
goto cleanup;
}
VIR_DEBUG("Trying to move %s to %s", devpts, "/dev/pts");
if ((rc = mount(devpts, "/dev/pts", NULL, MS_MOVE, NULL)) < 0) {
virReportSystemError(errno, "%s",
_("Failed to mount /dev/pts in container"));
goto cleanup;
}
rc = 0;
cleanup:
VIR_FREE(devpts);
return rc;
}
static int lxcContainerPopulateDevices(void)
{
int i;
const struct {
int maj;
int min;
mode_t mode;
const char *path;
} devs[] = {
{ LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_NULL, 0666, "/dev/null" },
{ LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_ZERO, 0666, "/dev/zero" },
{ LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_FULL, 0666, "/dev/full" },
{ LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_RANDOM, 0666, "/dev/random" },
{ LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_URANDOM, 0666, "/dev/urandom" },
};
/* Populate /dev/ with a few important bits */
for (i = 0 ; i < ARRAY_CARDINALITY(devs) ; i++) {
dev_t dev = makedev(devs[i].maj, devs[i].min);
if (mknod(devs[i].path, S_IFCHR, dev) < 0 ||
chmod(devs[i].path, devs[i].mode)) {
virReportSystemError(errno,
_("Failed to make device %s"),
devs[i].path);
return -1;
}
}
dev_t dev = makedev(LXC_DEV_MAJ_TTY, LXC_DEV_MIN_PTMX);
if (mknod("/dev/ptmx", S_IFCHR, dev) < 0 ||
chmod("/dev/ptmx", 0666)) {
virReportSystemError(errno, "%s",
_("Failed to make device /dev/ptmx"));
return -1;
}
if (access("/dev/pts/ptmx", W_OK) == 0) {
if (mount("/dev/pts/ptmx", "/dev/ptmx", "ptmx", MS_BIND, NULL) < 0) {
virReportSystemError(errno, "%s",
_("Failed to bind-mount /dev/ptmx to /dev/pts/ptmx"));
return -1;
}
}
/* XXX we should allow multiple consoles per container
* for tty2, tty3, etc, but the domain XML does not
* handle this yet
*/
if (symlink("/dev/pts/0", "/dev/tty1") < 0) {
virReportSystemError(errno, "%s",
_("Failed to symlink /dev/pts/0 to /dev/tty1"));
return -1;
}
if (symlink("/dev/pts/0", "/dev/console") < 0) {
virReportSystemError(errno, "%s",
_("Failed to symlink /dev/pts/0 to /dev/console"));
return -1;
}
return 0;
}
static int lxcContainerMountFSBind(virDomainFSDefPtr fs,
const char *srcprefix)
{
char *src = NULL;
int ret = -1;
if (virAsprintf(&src, "%s%s", srcprefix, fs->src) < 0) {
virReportOOMError();
goto cleanup;
}
if (virFileMakePath(fs->dst) < 0) {
virReportSystemError(errno,
_("Failed to create %s"),
fs->dst);
goto cleanup;
}
if (mount(src, fs->dst, NULL, MS_BIND, NULL) < 0) {
virReportSystemError(errno,
_("Failed to bind mount directory %s to %s"),
src, fs->dst);
goto cleanup;
}
if (fs->readonly) {
VIR_DEBUG("Binding %s readonly", fs->dst);
if (mount(fs->dst, fs->dst, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
virReportSystemError(errno,
_("Failed to make directory %s readonly"),
fs->dst);
}
}
ret = 0;
cleanup:
VIR_FREE(src);
return ret;
}
/*
* This functions attempts to do automatic detection of filesystem
* type following the same rules as the util-linux 'mount' binary.
*
* The main difference is that we don't (currently) try to use
* libblkid to detect the format first. We go straight to using
* /etc/filesystems, and then /proc/filesystems
*/
static int lxcContainerMountFSBlockAuto(virDomainFSDefPtr fs,
int fsflags,
const char *src,
const char *srcprefix)
{
FILE *fp = NULL;
int ret = -1;
bool tryProc = false;
bool gotStar = false;
char *fslist = NULL;
char *line = NULL;
const char *type;
VIR_DEBUG("src=%s srcprefix=%s dst=%s", src, srcprefix, fs->dst);
/* First time around we use /etc/filesystems */
retry:
if (virAsprintf(&fslist, "%s%s",
srcprefix, tryProc ? "/proc/filesystems" : "/etc/filesystems") < 0) {
virReportOOMError();
goto cleanup;
}
VIR_DEBUG("Open fslist %s", fslist);
if (!(fp = fopen(fslist, "r"))) {
/* If /etc/filesystems does not exist, then we need to retry
* with /proc/filesystems next
*/
if (errno == ENOENT &&
!tryProc) {
tryProc = true;
VIR_FREE(fslist);
goto retry;
}
virReportSystemError(errno,
_("Unable to read %s"),
fslist);
goto cleanup;
}
while (!feof(fp)) {
size_t n;
VIR_FREE(line);
if (getline(&line, &n, fp) <= 0) {
if (feof(fp))
break;
goto cleanup;
}
if (strstr(line, "nodev"))
continue;
type = strchr(line, '\n');
if (type)
line[type-line] = '\0';
type = line;
virSkipSpaces(&type);
/*
* /etc/filesystems is only allowed to contain '*' on the last line
*/
if (gotStar) {
lxcError(VIR_ERR_INTERNAL_ERROR,
_("%s has unexpected '*' before last line"),
fslist);
goto cleanup;
}
/* An '*' on the last line in /etc/filesystems
* means try /proc/filesystems next. We don't
* jump immediately though, since we need to see
* if any more lines follow
*/
if (!tryProc &&
STREQ(type, "*"))
gotStar = true;
VIR_DEBUG("Trying mount %s with %s", src, type);
if (mount(src, fs->dst, type, fsflags, NULL) < 0) {
/* These errnos indicate a bogus filesystem type for
* the image we have, so skip to the next type
*/
if (errno == EINVAL || errno == ENODEV)
continue;
virReportSystemError(errno,
_("Failed to bind mount directory %s to %s"),
src, fs->dst);
goto cleanup;
}
ret = 0;
break;
}
/* We've got to the end of /etc/filesystems and saw
* a '*', so we must try /proc/filesystems next
*/
if (ret != 0 &&
!tryProc &&
gotStar) {
tryProc = true;
VIR_FREE(fslist);
VIR_FORCE_FCLOSE(fp);
goto retry;
}
VIR_DEBUG("Done mounting filesystem ret=%d tryProc=%d", ret, tryProc);
cleanup:
VIR_FREE(line);
VIR_FORCE_FCLOSE(fp);
return ret;
}
/*
* Mount a block device 'src' on fs->dst, automatically
* probing for filesystem type
*/
static int lxcContainerMountFSBlockHelper(virDomainFSDefPtr fs,
const char *src,
const char *srcprefix)
{
int fsflags = 0;
int ret = -1;
if (fs->readonly)
fsflags |= MS_RDONLY;
if (virFileMakePath(fs->dst) < 0) {
virReportSystemError(errno,
_("Failed to create %s"),
fs->dst);
goto cleanup;
}
ret = lxcContainerMountFSBlockAuto(fs, fsflags, src, srcprefix);
cleanup:
return ret;
}
static int lxcContainerMountFSBlock(virDomainFSDefPtr fs,
const char *srcprefix)
{
char *src = NULL;
int ret = -1;
if (virAsprintf(&src, "%s%s", srcprefix, fs->src) < 0) {
virReportOOMError();
goto cleanup;
}
ret = lxcContainerMountFSBlockHelper(fs, src, srcprefix);
VIR_DEBUG("Done mounting filesystem ret=%d", ret);
cleanup:
VIR_FREE(src);
return ret;
}
static int lxcContainerMountFS(virDomainFSDefPtr fs,
const char *srcprefix)
{
switch (fs->type) {
case VIR_DOMAIN_FS_TYPE_MOUNT:
if (lxcContainerMountFSBind(fs, srcprefix) < 0)
return -1;
break;
case VIR_DOMAIN_FS_TYPE_BLOCK:
if (lxcContainerMountFSBlock(fs, srcprefix) < 0)
return -1;
break;
case VIR_DOMAIN_FS_TYPE_FILE:
lxcError(VIR_ERR_INTERNAL_ERROR,
_("Unexpected filesystem type %s"),
virDomainFSTypeToString(fs->type));
break;
default:
lxcError(VIR_ERR_CONFIG_UNSUPPORTED,
_("Cannot mount filesystem type %s"),
virDomainFSTypeToString(fs->type));
break;
}
return 0;
}
static int lxcContainerMountAllFS(virDomainDefPtr vmDef,
const char *dstprefix,
bool skipRoot)
{
size_t i;
VIR_DEBUG("Mounting %s %d", dstprefix, skipRoot);
/* Pull in rest of container's mounts */
for (i = 0 ; i < vmDef->nfss ; i++) {
if (skipRoot &&
STREQ(vmDef->fss[i]->dst, "/"))
continue;
if (lxcContainerMountFS(vmDef->fss[i], dstprefix) < 0)
return -1;
}
VIR_DEBUG("Mounted all filesystems");
return 0;
}
static int lxcContainerUnmountOldFS(void)
{
struct mntent mntent;
char **mounts = NULL;
int nmounts = 0;
FILE *procmnt;
int i;
char mntbuf[1024];
if (!(procmnt = setmntent("/proc/mounts", "r"))) {
virReportSystemError(errno, "%s",
_("Failed to read /proc/mounts"));
return -1;
}
while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) {
VIR_DEBUG("Got %s", mntent.mnt_dir);
if (!STRPREFIX(mntent.mnt_dir, "/.oldroot"))
continue;
if (VIR_REALLOC_N(mounts, nmounts+1) < 0) {
endmntent(procmnt);
virReportOOMError();
return -1;
}
if (!(mounts[nmounts++] = strdup(mntent.mnt_dir))) {
endmntent(procmnt);
virReportOOMError();
return -1;
}
}
endmntent(procmnt);
if (mounts)
qsort(mounts, nmounts, sizeof(mounts[0]),
lxcContainerChildMountSort);
for (i = 0 ; i < nmounts ; i++) {
VIR_DEBUG("Umount %s", mounts[i]);
if (umount(mounts[i]) < 0) {
virReportSystemError(errno,
_("Failed to unmount '%s'"),
mounts[i]);
return -1;
}
VIR_FREE(mounts[i]);
}
VIR_FREE(mounts);
return 0;
}
/* Got a FS mapped to /, we're going the pivot_root
* approach to do a better-chroot-than-chroot
* this is based on this thread http://lkml.org/lkml/2008/3/5/29
*/
static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
virDomainFSDefPtr root)
{
/* Gives us a private root, leaving all parent OS mounts on /.oldroot */
if (lxcContainerPivotRoot(root) < 0)
return -1;
/* Mounts the core /proc, /sys, etc filesystems */
if (lxcContainerMountBasicFS("/.oldroot", true) < 0)
return -1;
/* Mounts /dev and /dev/pts */
if (lxcContainerMountDevFS(root) < 0)
return -1;
/* Populates device nodes in /dev/ */
if (lxcContainerPopulateDevices() < 0)
return -1;
/* Sets up any non-root mounts from guest config */
if (lxcContainerMountAllFS(vmDef, "/.oldroot", true) < 0)
return -1;
/* Gets rid of all remaining mounts from host OS, including /.oldroot itself */
if (lxcContainerUnmountOldFS() < 0)
return -1;
return 0;
}
/* Nothing mapped to /, we're using the main root,
but with extra stuff mapped in */
static int lxcContainerSetupExtraMounts(virDomainDefPtr vmDef)
{
VIR_DEBUG("def=%p", vmDef);
/*
* This makes sure that any new filesystems in the
* host OS propagate to the container, but any
* changes in the container are private
*/
if (mount("", "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
virReportSystemError(errno, "%s",
_("Failed to make / slave"));
return -1;
}
VIR_DEBUG("Mounting config FS");
if (lxcContainerMountAllFS(vmDef, "", false) < 0)
return -1;
/* Mounts the core /proc, /sys, etc filesystems */
if (lxcContainerMountBasicFS(NULL, false) < 0)
return -1;
VIR_DEBUG("Mounting completed");
return 0;
}
static int lxcContainerSetupMounts(virDomainDefPtr vmDef,
virDomainFSDefPtr root)
{
if (root)
return lxcContainerSetupPivotRoot(vmDef, root);
else
return lxcContainerSetupExtraMounts(vmDef);
}
/*
* This is running as the 'init' process insid the container.
* It removes some capabilities that could be dangerous to
* host system, since they are not currently "containerized"
*/
static int lxcContainerDropCapabilities(void)
{
#if HAVE_CAPNG
int ret;
capng_get_caps_process();
if ((ret = capng_updatev(CAPNG_DROP,
CAPNG_EFFECTIVE | CAPNG_PERMITTED |
CAPNG_INHERITABLE | CAPNG_BOUNDING_SET,
CAP_SYS_BOOT, /* No use of reboot */
CAP_SYS_MODULE, /* No kernel module loading */
CAP_SYS_TIME, /* No changing the clock */
CAP_AUDIT_CONTROL, /* No messing with auditing status */
CAP_MAC_ADMIN, /* No messing with LSM config */
-1 /* sentinal */)) < 0) {
lxcError(VIR_ERR_INTERNAL_ERROR,
_("Failed to remove capabilities: %d"), ret);
return -1;
}
if ((ret = capng_apply(CAPNG_SELECT_BOTH)) < 0) {
lxcError(VIR_ERR_INTERNAL_ERROR,
_("Failed to apply capabilities: %d"), ret);
return -1;
}
/* We do not need to call capng_lock() in this case. The bounding
* set restriction will prevent them reacquiring sys_boot/module/time,
* etc which is all that matters for the container. Once inside the
* container it is fine for SECURE_NOROOT / SECURE_NO_SETUID_FIXUP to
* be unmasked - they can never escape the bounding set. */
#else
VIR_WARN("libcap-ng support not compiled in, unable to clear capabilities");
#endif
return 0;
}
/**
* lxcContainerChild:
* @data: pointer to container arguments
*
* This function is run in the process clone()'d in lxcStartContainer.
* Perform a number of container setup tasks:
* Setup container file system
* mount container /proca
* Then exec's the container init
*
* Returns 0 on success or -1 in case of error
*/
static int lxcContainerChild( void *data )
{
lxc_child_argv_t *argv = data;
virDomainDefPtr vmDef = argv->config;
int ttyfd = -1;
int ret = -1;
char *ttyPath = NULL;
virDomainFSDefPtr root;
virCommandPtr cmd = NULL;
if (NULL == vmDef) {
lxcError(VIR_ERR_INTERNAL_ERROR,
"%s", _("lxcChild() passed invalid vm definition"));
goto cleanup;
}
cmd = lxcContainerBuildInitCmd(vmDef);
virCommandWriteArgLog(cmd, 1);
root = virDomainGetRootFilesystem(vmDef);
if (root) {
if (virAsprintf(&ttyPath, "%s%s", root->src, argv->ttyPath) < 0) {
virReportOOMError();
goto cleanup;
}
} else {
if (!(ttyPath = strdup(argv->ttyPath))) {
virReportOOMError();
goto cleanup;
}
}
VIR_DEBUG("Container TTY path: %s", ttyPath);
ttyfd = open(ttyPath, O_RDWR|O_NOCTTY);
if (ttyfd < 0) {
virReportSystemError(errno,
_("Failed to open tty %s"),
ttyPath);
goto cleanup;
}
if (lxcContainerSetupMounts(vmDef, root) < 0)
goto cleanup;
if (!virFileExists(vmDef->os.init)) {
virReportSystemError(errno,
_("cannot find init path '%s' relative to container root"),
vmDef->os.init);
goto cleanup;
}
/* Wait for interface devices to show up */
if (lxcContainerWaitForContinue(argv->monitor) < 0) {
virReportSystemError(errno, "%s",
_("Failed to read the container continue message"));
goto cleanup;
}
VIR_DEBUG("Received container continue message");
/* rename and enable interfaces */
if (lxcContainerRenameAndEnableInterfaces(argv->nveths,
argv->veths) < 0) {
goto cleanup;
}
/* drop a set of root capabilities */
if (lxcContainerDropCapabilities() < 0)
goto cleanup;
if (lxcContainerSendContinue(argv->handshakefd) < 0) {
virReportSystemError(errno, "%s",
_("failed to send continue signal to controller"));
goto cleanup;
}
if (lxcContainerSetStdio(argv->monitor, ttyfd, argv->handshakefd) < 0) {
goto cleanup;
}
ret = 0;
cleanup:
VIR_FREE(ttyPath);
VIR_FORCE_CLOSE(ttyfd);
VIR_FORCE_CLOSE(argv->monitor);
VIR_FORCE_CLOSE(argv->handshakefd);
if (ret == 0) {
/* this function will only return if an error occured */
ret = virCommandExec(cmd);
}
virCommandFree(cmd);
return ret;
}
static int userns_supported(void)
{
#if 1
/*
* put off using userns until uid mapping is implemented
*/
return 0;
#else
return lxcContainerAvailable(LXC_CONTAINER_FEATURE_USER) == 0;
#endif
}
const char *lxcContainerGetAlt32bitArch(const char *arch)
{
/* Any Linux 64bit arch which has a 32bit
* personality available should be listed here */
if (STREQ(arch, "x86_64"))
return "i686";
if (STREQ(arch, "s390x"))
return "s390";
if (STREQ(arch, "ppc64"))
return "ppc";
if (STREQ(arch, "parisc64"))
return "parisc";
if (STREQ(arch, "sparc64"))
return "sparc";
if (STREQ(arch, "mips64"))
return "mips";
return NULL;
}
/**
* lxcContainerStart:
* @def: pointer to virtual machine structure
* @nveths: number of interfaces
* @veths: interface names
* @control: control FD to the container
* @ttyPath: path of tty to set as the container console
*
* Starts a container process by calling clone() with the namespace flags
*
* Returns PID of container on success or -1 in case of error
*/
int lxcContainerStart(virDomainDefPtr def,
unsigned int nveths,
char **veths,
int control,
int handshakefd,
char *ttyPath)
{
pid_t pid;
int cflags;
int stacksize = getpagesize() * 4;
char *stack, *stacktop;
lxc_child_argv_t args = { def, nveths, veths, control, ttyPath,
handshakefd};
/* allocate a stack for the container */
if (VIR_ALLOC_N(stack, stacksize) < 0) {
virReportOOMError();
return -1;
}
stacktop = stack + stacksize;
cflags = CLONE_NEWPID|CLONE_NEWNS|CLONE_NEWUTS|CLONE_NEWIPC|SIGCHLD;
if (userns_supported()) {
VIR_DEBUG("Enable user namespaces");
cflags |= CLONE_NEWUSER;
}
if (def->nets != NULL) {
VIR_DEBUG("Enable network namespaces");
cflags |= CLONE_NEWNET;
}
pid = clone(lxcContainerChild, stacktop, cflags, &args);
VIR_FREE(stack);
VIR_DEBUG("clone() completed, new container PID is %d", pid);
if (pid < 0) {
virReportSystemError(errno, "%s",
_("Failed to run clone container"));
return -1;
}
return pid;
}
ATTRIBUTE_NORETURN static int
lxcContainerDummyChild(void *argv ATTRIBUTE_UNUSED)
{
_exit(0);
}
int lxcContainerAvailable(int features)
{
int flags = CLONE_NEWPID|CLONE_NEWNS|CLONE_NEWUTS|
CLONE_NEWIPC|SIGCHLD;
int cpid;
char *childStack;
char *stack;
int childStatus;
if (features & LXC_CONTAINER_FEATURE_USER)
flags |= CLONE_NEWUSER;
if (features & LXC_CONTAINER_FEATURE_NET)
flags |= CLONE_NEWNET;
if (VIR_ALLOC_N(stack, getpagesize() * 4) < 0) {
VIR_DEBUG("Unable to allocate stack");
return -1;
}
childStack = stack + (getpagesize() * 4);
cpid = clone(lxcContainerDummyChild, childStack, flags, NULL);
VIR_FREE(stack);
if (cpid < 0) {
char ebuf[1024] ATTRIBUTE_UNUSED;
VIR_DEBUG("clone call returned %s, container support is not enabled",
virStrerror(errno, ebuf, sizeof ebuf));
return -1;
} else {
waitpid(cpid, &childStatus, 0);
}
VIR_DEBUG("Mounted all filesystems");
return 0;
}
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