diff options
Diffstat (limited to 'src/basic')
| -rw-r--r-- | src/basic/fd-util.c | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/src/basic/fd-util.c b/src/basic/fd-util.c index 7125e28e1b..974a7aac65 100644 --- a/src/basic/fd-util.c +++ b/src/basic/fd-util.c @@ -911,10 +911,23 @@ int dir_fd_is_root(int dir_fd) { if (!statx_inode_same(&st.sx, &pst.sx)) return false; + /* Even if the parent directory has the same inode, the fd may not point to the root directory "/", + * and we also need to check that the mount ids are the same. Otherwise, a construct like the + * following could be used to trick us: + * + * $ mkdir /tmp/x /tmp/x/y + * $ mount --bind /tmp/x /tmp/x/y + * + * Note, statx() does not provide the mount ID and path_get_mnt_id_at() does not work when an old + * kernel is used without /proc mounted. In that case, let's assume that we do not have such spurious + * mount points in an early boot stage, and silently skip the following check. */ + if (!FLAGS_SET(st.nsx.stx_mask, STATX_MNT_ID)) { int mntid; r = path_get_mnt_id_at(dir_fd, "", &mntid); + if (r == -ENOSYS) + return true; /* skip the mount ID check */ if (r < 0) return r; assert(mntid >= 0); @@ -927,6 +940,8 @@ int dir_fd_is_root(int dir_fd) { int mntid; r = path_get_mnt_id_at(dir_fd, "..", &mntid); + if (r == -ENOSYS) + return true; /* skip the mount ID check */ if (r < 0) return r; assert(mntid >= 0); @@ -935,13 +950,6 @@ int dir_fd_is_root(int dir_fd) { pst.nsx.stx_mask |= STATX_MNT_ID; } - /* Even if the parent directory has the same inode, the fd may not point to the root directory "/", - * and we also need to check that the mount ids are the same. Otherwise, a construct like the - * following could be used to trick us: - * - * $ mkdir /tmp/x /tmp/x/y - * $ mount --bind /tmp/x /tmp/x/y - */ return statx_mount_same(&st.nsx, &pst.nsx); } |