Allow non-privileged user to call subvolume show (-r or -u cannot be used)
if new ioctls (BTRFS_IOC_GET_SUBVOL_INFO etc.) are available.
The behavior for root user is the same as before.
There are some output differences between root and user:
root ... subvolume path is from top-level subvolume
list all snapshots in the fs (inc. non-accessible ones)
user ... subvolume path is from mount point
list snapshots under the mountpoint
(to which the user has appropriate privileges)
Signed-off-by: Tomohiro Misono <misono.tomoh...@jp.fujitsu.com>
---
cmds-subvolume.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 78 insertions(+), 12 deletions(-)
diff --git a/cmds-subvolume.c b/cmds-subvolume.c
index c3952172..d88d5d76 100644
--- a/cmds-subvolume.c
+++ b/cmds-subvolume.c
@@ -1883,8 +1883,8 @@ static int cmd_subvol_find_new(int argc, char **argv)
static const char * const cmd_subvol_show_usage[] = {
"btrfs subvolume show [options] <subvol-path>|<mnt>",
"Show more information about the subvolume",
- "-r|--rootid rootid of the subvolume",
- "-u|--uuid uuid of the subvolume",
+ "-r|--rootid rootid of the subvolume (require root privileges)",
+ "-u|--uuid uuid of the subvolume (require root privileges)",
"",
"If no option is specified, <subvol-path> will be shown, otherwise",
"the rootid or uuid are resolved relative to the <mnt> path.",
@@ -1897,8 +1897,10 @@ static int cmd_subvol_show(int argc, char **argv)
char uuidparse[BTRFS_UUID_UNPARSED_SIZE];
char *fullpath = NULL;
int fd = -1;
+ int fd_mnt = -1;
int ret = 1;
DIR *dirstream1 = NULL;
+ DIR *dirstream_mnt = NULL;
int by_rootid = 0;
int by_uuid = 0;
u64 rootid_arg = 0;
@@ -1906,6 +1908,8 @@ static int cmd_subvol_show(int argc, char **argv)
struct btrfs_util_subvolume_iterator *iter;
struct btrfs_util_subvolume_info subvol;
char *subvol_path = NULL;
+ char *subvol_name = NULL;
+ char *mount_point = NULL;
enum btrfs_util_error err;
while (1) {
@@ -1943,6 +1947,11 @@ static int cmd_subvol_show(int argc, char **argv)
usage(cmd_subvol_show_usage);
}
+ if (!is_root() && (by_rootid || by_uuid)) {
+ error("Only root can use -r or -u options");
+ return -1;
+ }
+
fullpath = realpath(argv[optind], NULL);
if (!fullpath) {
error("cannot find real path for '%s': %m", argv[optind]);
@@ -1997,19 +2006,65 @@ static int cmd_subvol_show(int argc, char **argv)
goto out;
}
- err = btrfs_util_subvolume_path_fd(fd, subvol.id, &subvol_path);
- if (err) {
- error_btrfs_util(err);
- goto out;
+ if (is_root()) {
+ /* Construct path from top-level subvolume */
+ err = btrfs_util_subvolume_path_fd(fd, subvol.id,
+ &subvol_path);
+ if (err) {
+ error_btrfs_util(err);
+ goto out;
+ }
+ subvol_name = strdup(basename(subvol_path));
+ } else {
+ /* Construct path from mount point */
+ ret = find_mount_root(fullpath, &mount_point);
+ if (ret < 0) {
+ error("cannot get mount point");
+ goto out;
+ }
+
+ fd_mnt = open_file_or_dir(mount_point, &dirstream_mnt);
+ if (fd_mnt < 0) {
+ error("cannot open mount point");
+ goto out;
+ }
+
+ if (strlen(fullpath) == strlen(mount_point)) {
+ /* Get real name at mount point */
+ struct btrfs_ioctl_get_subvol_info_args arg;
+
+ ret = ioctl(fd_mnt, BTRFS_IOC_GET_SUBVOL_INFO,
+ &arg);
+ if (ret < 0) {
+ error("cannot get subvolume info");
+ goto out;
+ }
+ subvol_path = strdup("./");
+ subvol_name = strdup(arg.name);
+ } else {
+ subvol_path = malloc(strlen(fullpath) -
+ strlen(mount_point) + 1);
+ if (!subvol_path) {
+ error("not enough memory");
+ ret = 1;
+ goto out;
+ }
+ subvol_path[0] = '.';
+ memcpy(subvol_path + 1,
+ fullpath + strlen(mount_point),
+ strlen(fullpath) - strlen(mount_point));
+ subvol_name = strdup(basename(subvol_path));
+ }
}
}
/* print the info */
- printf("%s\n", subvol.id == BTRFS_FS_TREE_OBJECTID ? "/" : subvol_path);
+ printf("%s\n", subvol.id == BTRFS_FS_TREE_OBJECTID ?
+ (is_root() ? "/" : "./") : subvol_path);
printf("\tName: \t\t\t%s\n",
- (subvol.id == BTRFS_FS_TREE_OBJECTID ? "<FS_TREE>" :
- basename(subvol_path)));
+ (subvol.id == BTRFS_FS_TREE_OBJECTID ? "<FS_TREE>" :
+ subvol_name));
if (uuid_is_null(subvol.uuid))
strcpy(uuidparse, "-");
@@ -2052,9 +2107,18 @@ static int cmd_subvol_show(int argc, char **argv)
/* print the snapshots of the given subvol if any*/
printf("\tSnapshot(s):\n");
- err = btrfs_util_create_subvolume_iterator_fd(fd,
- BTRFS_FS_TREE_OBJECTID, 0,
- &iter);
+ /*
+ * For root, show all snapshots in the filesystem.
+ * For non-privileged user, show all snapshots under mount point.
+ */
+ if (is_root())
+ err = btrfs_util_create_subvolume_iterator_fd(fd,
+ BTRFS_FS_TREE_OBJECTID, 0,
+ &iter);
+ else
+ err = btrfs_util_create_subvolume_iterator_fd(fd_mnt,
+ 0, 0,
+ &iter);
for (;;) {
struct btrfs_util_subvolume_info subvol2;
@@ -2080,7 +2144,9 @@ static int cmd_subvol_show(int argc, char **argv)
out:
free(subvol_path);
close_file_or_dir(fd, dirstream1);
+ close_file_or_dir(fd_mnt, dirstream_mnt);
free(fullpath);
+ free(mount_point);
return !!ret;
}
--
2.14.3
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