+++ /dev/null
-/*-*- Mode: C; c-basic-offset: 8 -*-*/
-
-/***
- This file is part of systemd.
-
- Copyright 2010 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- systemd 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
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include <errno.h>
-#include <sys/mount.h>
-#include <string.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <sched.h>
-#include <sys/syscall.h>
-#include <limits.h>
-#include <linux/fs.h>
-
-#include "strv.h"
-#include "util.h"
-#include "namespace.h"
-#include "missing.h"
-
-typedef enum PathMode {
- /* This is ordered by priority! */
- INACCESSIBLE,
- READONLY,
- PRIVATE,
- READWRITE
-} PathMode;
-
-typedef struct Path {
- const char *path;
- PathMode mode;
-} Path;
-
-static int append_paths(Path **p, char **strv, PathMode mode) {
- char **i;
-
- STRV_FOREACH(i, strv) {
-
- if (!path_is_absolute(*i))
- return -EINVAL;
-
- (*p)->path = *i;
- (*p)->mode = mode;
- (*p)++;
- }
-
- return 0;
-}
-
-static int path_compare(const void *a, const void *b) {
- const Path *p = a, *q = b;
-
- if (path_equal(p->path, q->path)) {
-
- /* If the paths are equal, check the mode */
- if (p->mode < q->mode)
- return -1;
-
- if (p->mode > q->mode)
- return 1;
-
- return 0;
- }
-
- /* If the paths are not equal, then order prefixes first */
- if (path_startswith(p->path, q->path))
- return 1;
-
- if (path_startswith(q->path, p->path))
- return -1;
-
- return 0;
-}
-
-static void drop_duplicates(Path *p, unsigned *n, bool *need_inaccessible, bool *need_private) {
- Path *f, *t, *previous;
-
- assert(p);
- assert(n);
- assert(need_inaccessible);
- assert(need_private);
-
- for (f = p, t = p, previous = NULL; f < p+*n; f++) {
-
- if (previous && path_equal(f->path, previous->path))
- continue;
-
- t->path = f->path;
- t->mode = f->mode;
-
- if (t->mode == PRIVATE)
- *need_private = true;
-
- if (t->mode == INACCESSIBLE)
- *need_inaccessible = true;
-
- previous = t;
-
- t++;
- }
-
- *n = t - p;
-}
-
-static int apply_mount(Path *p, const char *root_dir, const char *inaccessible_dir, const char *private_dir, unsigned long flags) {
- const char *what;
- char *where;
- int r;
-
- assert(p);
- assert(root_dir);
- assert(inaccessible_dir);
- assert(private_dir);
-
- if (!(where = strappend(root_dir, p->path)))
- return -ENOMEM;
-
- switch (p->mode) {
-
- case INACCESSIBLE:
- what = inaccessible_dir;
- flags |= MS_RDONLY;
- break;
-
- case READONLY:
- flags |= MS_RDONLY;
- /* Fall through */
-
- case READWRITE:
- what = p->path;
- break;
-
- case PRIVATE:
- what = private_dir;
- break;
- }
-
- if ((r = mount(what, where, NULL, MS_BIND|MS_REC, NULL)) >= 0) {
- log_debug("Successfully mounted %s to %s", what, where);
-
- /* The bind mount will always inherit the original
- * flags. If we want to set any flag we need
- * to do so in a second indepdant step. */
- if (flags)
- r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|MS_REC|flags, NULL);
-
- /* Avoid expontial growth of trees */
- if (r >= 0 && path_equal(p->path, "/"))
- r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|MS_UNBINDABLE|flags, NULL);
-
- if (r < 0) {
- r = -errno;
- umount2(where, MNT_DETACH);
- }
- }
-
- free(where);
- return r;
-}
-
-int setup_namespace(
- char **writable,
- char **readable,
- char **inaccessible,
- bool private_tmp,
- unsigned long flags) {
-
- char
- tmp_dir[] = "/tmp/systemd-namespace-XXXXXX",
- root_dir[] = "/tmp/systemd-namespace-XXXXXX/root",
- old_root_dir[] = "/tmp/systemd-namespace-XXXXXX/root/tmp/old-root-XXXXXX",
- inaccessible_dir[] = "/tmp/systemd-namespace-XXXXXX/inaccessible",
- private_dir[] = "/tmp/systemd-namespace-XXXXXX/private";
-
- Path *paths, *p;
- unsigned n;
- bool need_private = false, need_inaccessible = false;
- bool remove_tmp = false, remove_root = false, remove_old_root = false, remove_inaccessible = false, remove_private = false;
- int r;
- const char *t;
-
- n =
- strv_length(writable) +
- strv_length(readable) +
- strv_length(inaccessible) +
- (private_tmp ? 2 : 1);
-
- if (!(paths = new(Path, n)))
- return -ENOMEM;
-
- p = paths;
- if ((r = append_paths(&p, writable, READWRITE)) < 0 ||
- (r = append_paths(&p, readable, READONLY)) < 0 ||
- (r = append_paths(&p, inaccessible, INACCESSIBLE)) < 0)
- goto fail;
-
- if (private_tmp) {
- p->path = "/tmp";
- p->mode = PRIVATE;
- p++;
- }
-
- p->path = "/";
- p->mode = READWRITE;
- p++;
-
- assert(paths + n == p);
-
- qsort(paths, n, sizeof(Path), path_compare);
- drop_duplicates(paths, &n, &need_inaccessible, &need_private);
-
- if (!mkdtemp(tmp_dir)) {
- r = -errno;
- goto fail;
- }
- remove_tmp = true;
-
- memcpy(root_dir, tmp_dir, sizeof(tmp_dir)-1);
- if (mkdir(root_dir, 0777) < 0) {
- r = -errno;
- goto fail;
- }
- remove_root = true;
-
- if (need_inaccessible) {
- memcpy(inaccessible_dir, tmp_dir, sizeof(tmp_dir)-1);
- if (mkdir(inaccessible_dir, 0) < 0) {
- r = -errno;
- goto fail;
- }
- remove_inaccessible = true;
- }
-
- if (need_private) {
- memcpy(private_dir, tmp_dir, sizeof(tmp_dir)-1);
- if (mkdir(private_dir, 0777 + S_ISVTX) < 0) {
- r = -errno;
- goto fail;
- }
- remove_private = true;
- }
-
- if (unshare(CLONE_NEWNS) < 0) {
- r = -errno;
- goto fail;
- }
-
- /* We assume that by default mount events from us won't be
- * propagated to the root namespace. */
-
- for (p = paths; p < paths + n; p++)
- if ((r = apply_mount(p, root_dir, inaccessible_dir, private_dir, flags)) < 0)
- goto undo_mounts;
-
- memcpy(old_root_dir, tmp_dir, sizeof(tmp_dir)-1);
- if (!mkdtemp(old_root_dir)) {
- r = -errno;
- goto undo_mounts;
- }
- remove_old_root = true;
-
- if (chdir(root_dir) < 0) {
- r = -errno;
- goto undo_mounts;
- }
-
- if (pivot_root(root_dir, old_root_dir) < 0) {
- r = -errno;
- goto undo_mounts;
- }
-
- t = old_root_dir + sizeof(root_dir) - 1;
- if (umount2(t, MNT_DETACH) < 0)
- /* At this point it's too late to turn anything back,
- * since we are already in the new root. */
- return -errno;
-
- if (rmdir(t) < 0)
- return -errno;
-
- return 0;
-
-undo_mounts:
-
- for (p--; p >= paths; p--) {
- char full_path[PATH_MAX];
-
- snprintf(full_path, sizeof(full_path), "%s%s", root_dir, p->path);
- char_array_0(full_path);
-
- umount2(full_path, MNT_DETACH);
- }
-
-fail:
- if (remove_old_root)
- rmdir(old_root_dir);
-
- if (remove_inaccessible)
- rmdir(inaccessible_dir);
-
- if (remove_private)
- rmdir(private_dir);
-
- if (remove_root)
- rmdir(root_dir);
-
- if (remove_tmp)
- rmdir(tmp_dir);
-
- free(paths);
-
- return r;
-}
~ianmdlvl / elogind.git / blobdiff