lkml.org 
[lkml]   [2006]   [Feb]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC][PATCH 0/20] Multiple instances of the process id namespace
From
Date
Hubertus Franke <frankeh@watson.ibm.com> writes:

> Eric W. Biederman wrote:
>> Hubertus Franke <frankeh@watson.ibm.com> writes:
>>
>>
>>>find_task_by_pid( pid ) { return find_task_pidspace_by_pid ( current->pspace,
>>>pid ); }
>>>
>>>and then only deal with the exceptional cases using find_task_pidspace_by_pid
>>>when the pidspace is different..
>> That is a possibility. However I want to break some eggs so that the
>> users are updated appropriately. It is only by a strenuous act of
>> will that I don't change the type of pid,tgid,pgrp,session.
>> The size of the changes is much less important than being clear.
>> So for I want find_task_by_pid to be an absolute interface.
>>
>
> Fair enough, valid answers .. I checked the patch and it would only take
> 19/33 instances out .. so not the end of the world.
>
>>
>>>> Does the use of clone to create a new namespace instance look
>>>> like the sane approach?
>>>>
>>>
>>>At he surface it looks OK .. how does this work in a multi-threaded
>>>process which does cloen ( CLONE_NPSPACE ) ?
>>>We discussed at some point that exec is the right place to do it,
>>>but what I get is that because this is the container_init task
>>>we are OK !
>>>A bit clarification would help here ...
>> Well the parent doesn't much matter. But the child must have a fresh
>> start on all the groups of processes. As all other groupings known by
>> a pid are per pspace, so they can't cross that line.
>>
>
> Now, on which kernel does this compile/work ?

2.6.latest plus a few patches I have already sent off to Andrew.

> Do you have a "helper" program you can share that starts/exec's an
> app under a new container (uhmm, namespace). No point for us to
> actually write that..

Ok here is my little helper/tester program. Not beautiful but
it should work.

Eric


/* gcc -Wall -O2 -g chpid.c -o chpid */
#define _XOPEN_SOURCE
#define _XOPEN_SOURCE_EXTENDED
#define _SVID_SOURCE
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/mount.h>
#include <sys/vfs.h>
#include <fcntl.h>
#include <unistd.h>
#include <sched.h>
#include <stdarg.h>
#include <dirent.h>

#ifndef MNT_FORCE
#define MNT_FORCE 0x00000001 /* Attempt to forcibily umount */
#endif /* MNT_FORCE */
#ifndef MNT_DETACH
#define MNT_DETACH 0x00000002 /* Just detach from the tree */
#endif /* MNT_DETACH */
#ifndef MNT_EXPIRE
#define MNT_EXPIRE 0x00000004 /* Mark for expiry */
#endif /* MNT_EXPIRE */

#ifndef MS_MOVE
#define MS_MOVE 8192
#endif
#ifndef MS_REC
#define MS_REC 16384
#endif

#ifndef CLONE_NPSPACE
#define CLONE_NPSPACE 0x04000000 /* New process space */
#endif


#ifndef PROC_SUPER_MAGIC
#define PROC_SUPER_MAGIC 0x9fa0
#endif /* PROC_SUPER_MAGIC */

struct user_desc;
static pid_t raw_clone(int flags, void *child_stack,
int *parent_tidptr, struct user_desc *newtls, int *child_tidptr)
{
return syscall(__NR_clone, flags, child_stack, parent_tidptr, newtls, child_tidptr);
}

static int raw_pivot_root(const char *new_root, const char *old_root)
{
return syscall(__NR_pivot_root, new_root, old_root);
}

static void (*my_exit)(int status) = exit;

static void die(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
fflush(stderr);
fflush(stdout);
my_exit(1);
}

static void *xmalloc(size_t size)
{
void *ptr;
ptr = malloc(size);
if (!ptr) die("malloc of %d bytes failed: %s\n", size, strerror(errno));
return ptr;
}

int main(int argc, char **argv, char **envp)
{
pid_t pid;
int status;
struct rlimit rlim;
int clone_flags;
char **cmd_argv, *shell_argv[2];
char *root = "/", *old = "/mnt";
int i;
int tty, tty_force;

tty = 0;
tty_force = 0;
clone_flags = CLONE_NPSPACE | SIGCHLD;

for (i = 1; (i < argc) && (argv[i][0] == '-'); i++) {
if (strcmp(argv[i], "--") == 0) {
break;
}
else if (((argc - i) >= 2) && (strcmp(argv[i], "-r") == 0)) {
clone_flags |= CLONE_NEWNS;
root = argv[i + 1];
i++;
}
else if (((argc - i) >= 2) && (strcmp(argv[i], "-o") == 0)) {
old = argv[i + 1];
i++;
}
else if (strcmp(argv[i], "-n") == 0) {
clone_flags |= CLONE_NEWNS;
}
else if (strcmp(argv[i], "--tty") == 0) {
tty = 1;
}
else if (strcmp(argv[i], "--tty-force") == 0) {
tty = 1; tty_force = 1;
}
else {
die("Bad argument %s\n", argv[i]);
}
}
cmd_argv = argv + i;
if (cmd_argv[0] == NULL) {
cmd_argv = shell_argv;
shell_argv[0] = getenv("SHELL");
shell_argv[1] = NULL;
}
if (cmd_argv[0] == NULL) {
die("No command specified\n");
}
#if 1
fprintf(stderr, "cmd_argv: %s\n", cmd_argv[0]);
#endif
if (root[0] != '/') {
die("root path: '%s' not absolute\n", root);
}
if (old[0] != '/') {
die("old path: '%s' not absolute\n", old);
}

pid = raw_clone(clone_flags, NULL, NULL, NULL, NULL);
if (pid < 0) {
fprintf(stderr, "clone_failed: pid: %d %d:%s\n",
pid, errno, strerror(errno));
exit(2);
}
if (pid == 0) {
/* In the child */
int result;
my_exit = _exit;

/* FIXME allocate a process inside for controlling the new process space */

fprintf(stderr, "pid: %d, ppid: %d pgrp: %d sid: %d\n",
getpid(), getppid(), getpgid(0), getsid(0));
/* If CLONE_NPSPACE isn't implemented exit */
if (getpid() != 1)
die("CLONE_NPSPACE not implemented\n");
if (clone_flags & CLONE_NEWNS) {
struct statfs stfs;
if (strcmp(root, "/") != 0) {
char put_old[PATH_MAX];
result = snprintf(put_old, sizeof(put_old), "%s%s", root, old);
if (result >= sizeof(put_old))
die("path name to long\n");
if (result < 0)
die("snprintf failed: %d:%s\n",
errno, strerror(errno));

/* Ensure I have a mount point at the directory I want to export */
result = mount(root, root, NULL, MS_BIND | MS_REC, NULL);
if (result < 0)
die("bind of '%s' failed: %d:%s\n",
root, errno, strerror(errno));

/* Switch the mount points */
result = raw_pivot_root(root, put_old);
if (result < 0)
die("pivot_root('%s', '%s') failed: %d:%s\n",
root, put_old, errno, strerror(errno));

/* Unmount all of the old mounts */
result = umount2(old, MNT_DETACH);
if (result < 0)
die("umount2 of '%s' failed: %d:%s\n",
put_old, errno, strerror(errno));
}

result = statfs("/proc", &stfs);
if ((result == 0) && (stfs.f_type == PROC_SUPER_MAGIC)) {
/* Unmount and remount proc so it reflects the new pid space */
result = umount2("/proc", 0);
if (result < 0)
die("umount failed: %d:%s\n", errno, strerror(errno));

result = mount("proc", "/proc", "proc", 0, NULL);
if (result < 0)
die("mount failed: %d:%s\n",
errno, strerror(errno));
}
}
if (tty) {
pid_t sid, pgrp;
sid = setsid();
if (sid < 0)
die("setsid failed: %d:%s\n",
errno, strerror(errno));
fprintf(stderr, "pid: %d, ppid: %d pgrp: %d sid: %d\n",
getpid(), getppid(), getpgid(0), getsid(0));

result = ioctl(STDIN_FILENO, TIOCSCTTY, tty_force);
if (result < 0)
die("tiocsctty failed: %d:%s\n",
errno, strerror(errno));

pgrp = tcgetpgrp(STDIN_FILENO);

fprintf(stderr, "pgrp: %d\n", pgrp);

fprintf(stderr, "pid: %d, ppid: %d pgrp: %d sid: %d\n",
getpid(), getppid(), getpgid(0), getsid(0));

}
result = execve(cmd_argv[0], cmd_argv, envp);
die("execve of %s failed: %d:%s\n",
cmd_argv[0], errno, strerror(errno));
}
/* In the parent */
fprintf(stderr, "child pid: %d\n", pid);
pid = waitpid(pid, &status, 0);
fprintf(stderr, "pid: %d exited status: %d\n",
pid, status);
if (pid < 0) {
fprintf(stderr, "waitpid failed: %d %s\n",
errno, strerror(errno));
exit(9);
}
if (pid == 0) {
fprintf(stderr, "waitpid returned no pid!\n");
exit(10);
}
if (WIFEXITED(status)) {
fprintf(stderr, "pid: %d exited: %d\n",
pid, WEXITSTATUS(status));
}
if (WIFSIGNALED(status)) {
fprintf(stderr, "pid: %d exited with a uncaught signal: %d %s\n",
pid, WTERMSIG(status), strsignal(WTERMSIG(status)));
}
if (WIFSTOPPED(status)) {
fprintf(stderr, "pid: %d stopped with signal: %d\n",
pid, WSTOPSIG(status));
}
return 0;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-02-06 23:02    [W:0.133 / U:0.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site