diff options
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 121 |
1 files changed, 95 insertions, 26 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 5997887..fc2b522 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -830,6 +830,10 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + /* Don't allow unprivileged users to reveal what is under a mount */ + if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire)) + mnt->mnt.mnt_flags |= MNT_LOCKED; + atomic_inc(&sb->s_active); mnt->mnt.mnt_sb = sb; mnt->mnt.mnt_root = dget(root); @@ -1326,6 +1330,8 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags) goto dput_and_out; if (!check_mnt(mnt)) goto dput_and_out; + if (mnt->mnt.mnt_flags & MNT_LOCKED) + goto dput_and_out; retval = do_umount(mnt, flags); dput_and_out: @@ -1348,14 +1354,11 @@ SYSCALL_DEFINE1(oldumount, char __user *, name) #endif -static bool mnt_ns_loop(struct path *path) +static bool is_mnt_ns_file(struct dentry *dentry) { - /* Could bind mounting the mount namespace inode cause a - * mount namespace loop? - */ - struct inode *inode = path->dentry->d_inode; + /* Is this a proxy for a mount namespace? */ + struct inode *inode = dentry->d_inode; struct proc_ns *ei; - struct mnt_namespace *mnt_ns; if (!proc_ns_inode(inode)) return false; @@ -1364,7 +1367,19 @@ static bool mnt_ns_loop(struct path *path) if (ei->ns_ops != &mntns_operations) return false; - mnt_ns = ei->ns; + return true; +} + +static bool mnt_ns_loop(struct dentry *dentry) +{ + /* Could bind mounting the mount namespace inode cause a + * mount namespace loop? + */ + struct mnt_namespace *mnt_ns; + if (!is_mnt_ns_file(dentry)) + return false; + + mnt_ns = get_proc_ns(dentry->d_inode)->ns; return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; } @@ -1373,13 +1388,17 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, { struct mount *res, *p, *q, *r, *parent; - if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) + if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) + return ERR_PTR(-EINVAL); + + if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) return ERR_PTR(-EINVAL); res = q = clone_mnt(mnt, dentry, flag); if (IS_ERR(q)) return q; + q->mnt.mnt_flags &= ~MNT_LOCKED; q->mnt_mountpoint = mnt->mnt_mountpoint; p = mnt; @@ -1389,7 +1408,13 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, continue; for (s = r; s; s = next_mnt(s, r)) { - if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { + if (!(flag & CL_COPY_UNBINDABLE) && + IS_MNT_UNBINDABLE(s)) { + s = skip_mnt_tree(s); + continue; + } + if (!(flag & CL_COPY_MNT_NS_FILE) && + is_mnt_ns_file(s->mnt.mnt_root)) { s = skip_mnt_tree(s); continue; } @@ -1695,6 +1720,19 @@ static int do_change_type(struct path *path, int flag) return err; } +static bool has_locked_children(struct mount *mnt, struct dentry *dentry) +{ + struct mount *child; + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + if (!is_subdir(child->mnt_mountpoint, dentry)) + continue; + + if (child->mnt.mnt_flags & MNT_LOCKED) + return true; + } + return false; +} + /* * do loopback mount. */ @@ -1712,7 +1750,7 @@ static int do_loopback(struct path *path, const char *old_name, return err; err = -EINVAL; - if (mnt_ns_loop(&old_path)) + if (mnt_ns_loop(old_path.dentry)) goto out; mp = lock_mount(path); @@ -1730,8 +1768,11 @@ static int do_loopback(struct path *path, const char *old_name, if (!check_mnt(parent) || !check_mnt(old)) goto out2; + if (!recurse && has_locked_children(old, old_path.dentry)) + goto out2; + if (recurse) - mnt = copy_tree(old, old_path.dentry, 0); + mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE); else mnt = clone_mnt(old, old_path.dentry, 0); @@ -1740,6 +1781,8 @@ static int do_loopback(struct path *path, const char *old_name, goto out2; } + mnt->mnt.mnt_flags &= ~MNT_LOCKED; + err = graft_tree(mnt, parent, mp); if (err) { br_write_lock(&vfsmount_lock); @@ -1852,6 +1895,9 @@ static int do_move_mount(struct path *path, const char *old_name) if (!check_mnt(p) || !check_mnt(old)) goto out1; + if (old->mnt.mnt_flags & MNT_LOCKED) + goto out1; + err = -EINVAL; if (old_path.dentry != old_path.mnt->mnt_root) goto out1; @@ -2388,7 +2434,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, namespace_lock(); /* First pass: copy the tree topology */ - copy_flags = CL_COPY_ALL | CL_EXPIRE; + copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; if (user_ns != mnt_ns->user_ns) copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED; new = copy_tree(old, old->mnt.mnt_root, copy_flags); @@ -2423,6 +2469,10 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, } p = next_mnt(p, old); q = next_mnt(q, new); + if (!q) + break; + while (p->mnt.mnt_root != q->mnt.mnt_root) + p = next_mnt(p, old); } namespace_unlock(); @@ -2629,6 +2679,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, goto out4; if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) goto out4; + if (new_mnt->mnt.mnt_flags & MNT_LOCKED) + goto out4; error = -ENOENT; if (d_unlinked(new.dentry)) goto out4; @@ -2652,6 +2704,10 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, br_write_lock(&vfsmount_lock); detach_mnt(new_mnt, &parent_path); detach_mnt(root_mnt, &root_parent); + if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { + new_mnt->mnt.mnt_flags |= MNT_LOCKED; + root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; + } /* mount old root on put_old */ attach_mnt(root_mnt, old_mnt, old_mp); /* mount new_root on / */ @@ -2810,25 +2866,38 @@ bool current_chrooted(void) return chrooted; } -void update_mnt_policy(struct user_namespace *userns) +bool fs_fully_visible(struct file_system_type *type) { struct mnt_namespace *ns = current->nsproxy->mnt_ns; struct mount *mnt; + bool visible = false; - down_read(&namespace_sem); + if (unlikely(!ns)) + return false; + + namespace_lock(); 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; + struct mount *child; + if (mnt->mnt.mnt_sb->s_type != type) + continue; + + /* This mount is not fully visible if there are any child mounts + * that cover anything except for empty directories. + */ + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + struct inode *inode = child->mnt_mountpoint->d_inode; + if (!S_ISDIR(inode->i_mode)) + goto next; + if (inode->i_nlink != 2) + goto next; } - if (userns->may_mount_sysfs && userns->may_mount_proc) - break; + visible = true; + goto found; + next: ; } - up_read(&namespace_sem); +found: + namespace_unlock(); + return visible; } static void *mntns_get(struct task_struct *task) @@ -2859,8 +2928,8 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns) struct path root; if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || - !nsown_capable(CAP_SYS_CHROOT) || - !nsown_capable(CAP_SYS_ADMIN)) + !ns_capable(current_user_ns(), CAP_SYS_CHROOT) || + !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) return -EPERM; if (fs->users != 1) |