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![Christian Brauner](/assets/img/avatar_default.png)
Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
158 lines
3.2 KiB
C
158 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2007 Red Hat. All rights reserved.
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*/
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/xattr.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/posix_acl.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/slab.h>
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#include "ctree.h"
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#include "btrfs_inode.h"
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#include "xattr.h"
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struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
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{
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int size;
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const char *name;
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char *value = NULL;
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struct posix_acl *acl;
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switch (type) {
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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return ERR_PTR(-EINVAL);
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}
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size = btrfs_getxattr(inode, name, NULL, 0);
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if (size > 0) {
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value = kzalloc(size, GFP_KERNEL);
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if (!value)
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return ERR_PTR(-ENOMEM);
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size = btrfs_getxattr(inode, name, value, size);
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}
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if (size > 0)
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acl = posix_acl_from_xattr(&init_user_ns, value, size);
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else if (size == -ENODATA || size == 0)
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acl = NULL;
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else
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acl = ERR_PTR(size);
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kfree(value);
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return acl;
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}
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static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
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struct inode *inode, struct posix_acl *acl, int type)
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{
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int ret, size = 0;
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const char *name;
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char *value = NULL;
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switch (type) {
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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if (!S_ISDIR(inode->i_mode))
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return acl ? -EINVAL : 0;
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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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return -EINVAL;
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}
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if (acl) {
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unsigned int nofs_flag;
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size = posix_acl_xattr_size(acl->a_count);
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/*
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* We're holding a transaction handle, so use a NOFS memory
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* allocation context to avoid deadlock if reclaim happens.
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*/
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nofs_flag = memalloc_nofs_save();
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value = kmalloc(size, GFP_KERNEL);
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memalloc_nofs_restore(nofs_flag);
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if (!value) {
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ret = -ENOMEM;
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goto out;
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}
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ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
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if (ret < 0)
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goto out;
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}
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if (trans)
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ret = btrfs_setxattr(trans, inode, name, value, size, 0);
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else
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ret = btrfs_setxattr_trans(inode, name, value, size, 0);
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out:
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kfree(value);
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if (!ret)
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set_cached_acl(inode, type, acl);
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return ret;
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}
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int btrfs_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
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struct posix_acl *acl, int type)
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{
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int ret;
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umode_t old_mode = inode->i_mode;
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if (type == ACL_TYPE_ACCESS && acl) {
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ret = posix_acl_update_mode(&init_user_ns, inode,
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&inode->i_mode, &acl);
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if (ret)
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return ret;
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}
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ret = __btrfs_set_acl(NULL, inode, acl, type);
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if (ret)
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inode->i_mode = old_mode;
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return ret;
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}
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int btrfs_init_acl(struct btrfs_trans_handle *trans,
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struct inode *inode, struct inode *dir)
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{
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struct posix_acl *default_acl, *acl;
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int ret = 0;
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/* this happens with subvols */
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if (!dir)
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return 0;
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ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
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if (ret)
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return ret;
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if (default_acl) {
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ret = __btrfs_set_acl(trans, inode, default_acl,
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ACL_TYPE_DEFAULT);
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posix_acl_release(default_acl);
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}
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if (acl) {
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if (!ret)
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ret = __btrfs_set_acl(trans, inode, acl,
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ACL_TYPE_ACCESS);
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posix_acl_release(acl);
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}
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if (!default_acl && !acl)
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cache_no_acl(inode);
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return ret;
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}
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