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-rw-r--r--fs/namespace.c54
1 files changed, 53 insertions, 1 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 50ca17d..d581e45 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -798,6 +798,10 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
}
mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
+ /* Don't allow unprivileged users to change mount flags */
+ if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY))
+ mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+
atomic_inc(&sb->s_active);
mnt->mnt.mnt_sb = sb;
mnt->mnt.mnt_root = dget(root);
@@ -1713,6 +1717,9 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
if (readonly_request == __mnt_is_readonly(mnt))
return 0;
+ if (mnt->mnt_flags & MNT_LOCK_READONLY)
+ return -EPERM;
+
if (readonly_request)
error = mnt_make_readonly(real_mount(mnt));
else
@@ -2339,7 +2346,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
/* First pass: copy the tree topology */
copy_flags = CL_COPY_ALL | CL_EXPIRE;
if (user_ns != mnt_ns->user_ns)
- copy_flags |= CL_SHARED_TO_SLAVE;
+ copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED;
new = copy_tree(old, old->mnt.mnt_root, copy_flags);
if (IS_ERR(new)) {
up_write(&namespace_sem);
@@ -2732,6 +2739,51 @@ bool our_mnt(struct vfsmount *mnt)
return check_mnt(real_mount(mnt));
}
+bool current_chrooted(void)
+{
+ /* Does the current process have a non-standard root */
+ struct path ns_root;
+ struct path fs_root;
+ bool chrooted;
+
+ /* Find the namespace root */
+ ns_root.mnt = &current->nsproxy->mnt_ns->root->mnt;
+ ns_root.dentry = ns_root.mnt->mnt_root;
+ path_get(&ns_root);
+ while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
+ ;
+
+ get_fs_root(current->fs, &fs_root);
+
+ chrooted = !path_equal(&fs_root, &ns_root);
+
+ path_put(&fs_root);
+ path_put(&ns_root);
+
+ return chrooted;
+}
+
+void update_mnt_policy(struct user_namespace *userns)
+{
+ struct mnt_namespace *ns = current->nsproxy->mnt_ns;
+ struct mount *mnt;
+
+ down_read(&namespace_sem);
+ list_for_each_entry(mnt, &ns->list, mnt_list) {
+ switch (mnt->mnt.mnt_sb->s_magic) {
+ case SYSFS_MAGIC:
+ userns->may_mount_sysfs = true;
+ break;
+ case PROC_SUPER_MAGIC:
+ userns->may_mount_proc = true;
+ break;
+ }
+ if (userns->may_mount_sysfs && userns->may_mount_proc)
+ break;
+ }
+ up_read(&namespace_sem);
+}
+
static void *mntns_get(struct task_struct *task)
{
struct mnt_namespace *ns = NULL;
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