src/lxc/storage/dir.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #ifndef _GNU_SOURCE
   4 #define _GNU_SOURCE 1
   5 #endif
   6 #include <stdint.h>
   7 #include <stdio.h>
   8 #include <string.h>
   9
  10 #include "config.h"
  11 #include "log.h"
  12 #include "macro.h"
  13 #include "memory_utils.h"
  14 #include "mount_utils.h"
  15 #include "storage.h"
  16 #include "utils.h"
  17
  18 lxc_log_define(dir, lxc);
  19
  20 /*
  21  * For a simple directory bind mount, we substitute the old container name and
  22  * paths for the new.
  23  */
  24 int dir_clonepaths(struct lxc_storage *orig, struct lxc_storage *new,
  25                    const char *oldname, const char *cname, const char *oldpath,
  26                    const char *lxcpath, int snap, uint64_t newsize,
  27                    struct lxc_conf *conf)
  28 {
  29         const char *src_no_prefix;
  30         int ret;
  31         size_t len;
  32
  33         if (snap)
  34                 return log_error_errno(-EINVAL, EINVAL, "Directories cannot be snapshotted");
  35
  36         if (!orig->dest || !orig->src)
  37                 return ret_errno(EINVAL);
  38
  39         len = STRLITERALLEN("dir:") + strlen(lxcpath) + STRLITERALLEN("/") +
  40               strlen(cname) + STRLITERALLEN("/rootfs") + 1;
  41         new->src = malloc(len);
  42         if (!new->src)
  43                 return ret_errno(ENOMEM);
  44
  45         ret = snprintf(new->src, len, "dir:%s/%s/rootfs", lxcpath, cname);
  46         if (ret < 0 || (size_t)ret >= len)
  47                 return ret_errno(EIO);
  48
  49         src_no_prefix = lxc_storage_get_path(new->src, new->type);
  50         new->dest = strdup(src_no_prefix);
  51         if (!new->dest)
  52                 return log_error_errno(-ENOMEM, ENOMEM, "Failed to duplicate string \"%s\"", new->src);
  53
  54         TRACE("Created new path \"%s\" for dir storage driver", new->dest);
  55         return 0;
  56 }
  57
  58 int dir_create(struct lxc_storage *bdev, const char *dest, const char *n,
  59                struct bdev_specs *specs, const struct lxc_conf *conf)
  60 {
  61         __do_free char *bdev_src = NULL, *bdev_dest = NULL;
  62         int ret;
  63         const char *src;
  64         size_t len;
  65
  66         len = STRLITERALLEN("dir:");
  67         if (specs && specs->dir)
  68                 src = specs->dir;
  69         else
  70                 src = dest;
  71
  72         len += strlen(src) + 1;
  73         bdev_src = malloc(len);
  74         if (!bdev_src)
  75                 return ret_errno(ENOMEM);
  76
  77         ret = snprintf(bdev_src, len, "dir:%s", src);
  78         if (ret < 0 || (size_t)ret >= len)
  79                 return ret_errno(EIO);
  80
  81         bdev_dest = strdup(dest);
  82         if (!bdev_dest)
  83                 return ret_errno(ENOMEM);
  84
  85         ret = mkdir_p(dest, 0755);
  86         if (ret < 0)
  87                 return log_error_errno(-errno, errno, "Failed to create directory \"%s\"", dest);
  88
  89         TRACE("Created directory \"%s\"", dest);
  90         bdev->src = move_ptr(bdev_src);
  91         bdev->dest = move_ptr(bdev_dest);
  92
  93         return 0;
  94 }
  95
  96 int dir_destroy(struct lxc_storage *orig)
  97 {
  98         int ret;
  99         const char *src;
 100
 101         src = lxc_storage_get_path(orig->src, orig->src);
 102
 103         ret = lxc_rmdir_onedev(src, NULL);
 104         if (ret < 0)
 105                 return log_error_errno(ret, errno, "Failed to delete \"%s\"", src);
 106
 107         return 0;
 108 }
 109
 110 bool dir_detect(const char *path)
 111 {
 112         struct stat statbuf;
 113         int ret;
 114
 115         if (!strncmp(path, "dir:", 4))
 116                 return true;
 117
 118         ret = stat(path, &statbuf);
 119         if (ret == -1 && errno == EPERM)
 120                 return log_error_errno(false, errno, "dir_detect: failed to look at \"%s\"", path);
 121
 122         if (ret == 0 && S_ISDIR(statbuf.st_mode))
 123                 return true;
 124
 125         return false;
 126 }
 127
 128 int dir_mount(struct lxc_storage *bdev)
 129 {
 130         struct lxc_rootfs *rootfs = bdev->rootfs;
 131         struct lxc_mount_options *mnt_opts = &rootfs->mnt_opts;
 132         int ret;
 133         const char *source, *target;
 134
 135         if (!strequal(bdev->type, "dir"))
 136                 return syserror_set(-EINVAL, "Invalid storage driver");
 137
 138         if (is_empty_string(bdev->src))
 139                 return syserror_set(-EINVAL, "Missing rootfs path");
 140
 141         if (is_empty_string(bdev->dest))
 142                 return syserror_set(-EINVAL, "Missing target mountpoint");
 143
 144         if (rootfs->dfd_idmapped >= 0 && !can_use_bind_mounts())
 145                 return syserror_set(-EOPNOTSUPP, "Idmapped mount requested but kernel doesn't support new mount API");
 146
 147         source = lxc_storage_get_path(bdev->src, bdev->type);
 148         target = bdev->dest;
 149
 150         if (can_use_bind_mounts()) {
 151                 __do_close int fd_source = -EBADF, fd_target = -EBADF;
 152
 153                 fd_target = open_at(-EBADF, target, PROTECT_OPATH_DIRECTORY, 0, 0);
 154                 if (fd_target < 0)
 155                         return syserror("Failed to open \"%s\"", target);
 156
 157                 if (rootfs->dfd_idmapped >= 0) {
 158                         ret = move_detached_mount(rootfs->dfd_idmapped, fd_target, "",
 159                                                   PROTECT_OPATH_DIRECTORY,
 160                                                   PROTECT_LOOKUP_BENEATH);
 161                 } else {
 162                         fd_source = open_at(-EBADF, source, PROTECT_OPATH_DIRECTORY, 0, 0);
 163                         if (fd_source < 0)
 164                                 return syserror("Failed to open \"%s\"", source);
 165
 166                         ret = fd_bind_mount(fd_source, "",
 167                                             PROTECT_OPATH_DIRECTORY,
 168                                             PROTECT_LOOKUP_BENEATH, fd_target,
 169                                             "", PROTECT_OPATH_DIRECTORY,
 170                                             PROTECT_LOOKUP_BENEATH, 0, true);
 171                 }
 172         } else {
 173                 ret = mount(source, target, "bind", MS_BIND | MS_REC | mnt_opts->mnt_flags | mnt_opts->prop_flags, mnt_opts->data);
 174                 if (!ret && (mnt_opts->mnt_flags & MS_RDONLY)) {
 175                         unsigned long mflags;
 176
 177                         mflags = add_required_remount_flags(source, target,
 178                                                             MS_BIND |
 179                                                             MS_REC |
 180                                                             mnt_opts->mnt_flags |
 181                                                             MS_REMOUNT);
 182
 183                         ret = mount(source, target, "bind", mflags, mnt_opts->data);
 184                         if (ret)
 185                                 SYSERROR("Failed to remount \"%s\" on \"%s\" read-only", source, target);
 186                         else
 187                                 TRACE("Remounted \"%s\" on \"%s\" read-only", source, target);
 188                 }
 189         }
 190         if (ret < 0)
 191                 return syserror_set(ret, "Failed to mount \"%s\" onto \"%s\"", source, target);
 192
 193         TRACE("Mounted \"%s\" onto \"%s\"", source, target);
 194         return 0;
 195 }
 196
 197 int dir_umount(struct lxc_storage *bdev)
 198 {
 199         if (strcmp(bdev->type, "dir"))
 200                 return ret_errno(EINVAL);
 201
 202         if (!bdev->src || !bdev->dest)
 203                 return ret_errno(EINVAL);
 204
 205         return umount2(bdev->dest, MNT_DETACH);
 206 }