diff options
| -rw-r--r-- | fs/namespace.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 8e7edaf60fe1..63b9806235e6 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2332,7 +2332,7 @@ unlock: return err; } -static bool fs_fully_visible(struct file_system_type *fs_type); +static bool fs_fully_visible(struct file_system_type *fs_type, int *new_mnt_flags); /* * create a new mount for userspace and request it to be added into the @@ -2366,7 +2366,7 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } if (type->fs_flags & FS_USERNS_VISIBLE) { - if (!fs_fully_visible(type)) + if (!fs_fully_visible(type, &mnt_flags)) return -EPERM; } } @@ -3170,9 +3170,10 @@ bool current_chrooted(void) return chrooted; } -static bool fs_fully_visible(struct file_system_type *type) +static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) { struct mnt_namespace *ns = current->nsproxy->mnt_ns; + int new_flags = *new_mnt_flags; struct mount *mnt; bool visible = false; @@ -3191,6 +3192,19 @@ static bool fs_fully_visible(struct file_system_type *type) if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) continue; + /* Verify the mount flags are equal to or more permissive + * than the proposed new mount. + */ + if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && + !(new_flags & MNT_READONLY)) + continue; + if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && + !(new_flags & MNT_NODEV)) + continue; + if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && + ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) + continue; + /* This mount is not fully visible if there are any child mounts * that cover anything except for empty directories. */ @@ -3201,6 +3215,10 @@ static bool fs_fully_visible(struct file_system_type *type) if (inode->i_nlink > 2) goto next; } + /* Preserve the locked attributes */ + *new_mnt_flags |= mnt->mnt.mnt_flags & (MNT_LOCK_READONLY | \ + MNT_LOCK_NODEV | \ + MNT_LOCK_ATIME); visible = true; goto found; next: ; |