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The posix acl permission checking helpers determine whether a caller is privileged over an inode according to the acls associated with the inode. Add helpers that make it possible to handle acls on idmapped mounts. The vfs and the filesystems targeted by this first iteration make use of posix_acl_fix_xattr_from_user() and posix_acl_fix_xattr_to_user() to translate basic posix access and default permissions such as the ACL_USER and ACL_GROUP type according to the initial user namespace (or the superblock's user namespace) to and from the caller's current user namespace. Adapt these two helpers to handle idmapped mounts whereby we either map from or into the mount's user namespace depending on in which direction we're translating. Similarly, cap_convert_nscap() is used by the vfs to translate user namespace and non-user namespace aware filesystem capabilities from the superblock's user namespace to the caller's user namespace. Enable it to handle idmapped mounts by accounting for the mount's user namespace. In addition the fileystems targeted in the first iteration of this patch series make use of the posix_acl_chmod() and, posix_acl_update_mode() helpers. Both helpers perform permission checks on the target inode. Let them handle idmapped mounts. These two helpers are called when posix acls are set by the respective filesystems to handle this case we extend the ->set() method to take an additional user namespace argument to pass the mount's user namespace down. Link: https://lore.kernel.org/r/20210121131959.646623-9-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>
154 lines
3.1 KiB
C
154 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) International Business Machines Corp., 2002-2004
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* Copyright (C) Andreas Gruenbacher, 2001
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* Copyright (C) Linus Torvalds, 1991, 1992
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*/
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/posix_acl_xattr.h>
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#include "jfs_incore.h"
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#include "jfs_txnmgr.h"
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#include "jfs_xattr.h"
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#include "jfs_acl.h"
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struct posix_acl *jfs_get_acl(struct inode *inode, int type)
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{
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struct posix_acl *acl;
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char *ea_name;
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int size;
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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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ea_name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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ea_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 = __jfs_getxattr(inode, ea_name, NULL, 0);
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if (size > 0) {
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value = kmalloc(size, GFP_KERNEL);
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if (!value)
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return ERR_PTR(-ENOMEM);
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size = __jfs_getxattr(inode, ea_name, value, size);
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}
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if (size < 0) {
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if (size == -ENODATA)
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acl = NULL;
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else
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acl = ERR_PTR(size);
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} else {
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acl = posix_acl_from_xattr(&init_user_ns, value, size);
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}
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kfree(value);
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return acl;
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}
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static int __jfs_set_acl(tid_t tid, struct inode *inode, int type,
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struct posix_acl *acl)
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{
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char *ea_name;
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int rc;
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int size = 0;
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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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ea_name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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ea_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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size = posix_acl_xattr_size(acl->a_count);
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value = kmalloc(size, GFP_KERNEL);
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if (!value)
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return -ENOMEM;
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rc = posix_acl_to_xattr(&init_user_ns, acl, value, size);
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if (rc < 0)
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goto out;
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}
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rc = __jfs_setxattr(tid, inode, ea_name, value, size, 0);
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out:
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kfree(value);
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if (!rc)
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set_cached_acl(inode, type, acl);
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return rc;
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}
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int jfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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{
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int rc;
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tid_t tid;
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int update_mode = 0;
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umode_t mode = inode->i_mode;
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tid = txBegin(inode->i_sb, 0);
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mutex_lock(&JFS_IP(inode)->commit_mutex);
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if (type == ACL_TYPE_ACCESS && acl) {
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rc = posix_acl_update_mode(&init_user_ns, inode, &mode, &acl);
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if (rc)
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goto end_tx;
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if (mode != inode->i_mode)
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update_mode = 1;
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}
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rc = __jfs_set_acl(tid, inode, type, acl);
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if (!rc) {
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if (update_mode) {
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inode->i_mode = mode;
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inode->i_ctime = current_time(inode);
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mark_inode_dirty(inode);
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}
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rc = txCommit(tid, 1, &inode, 0);
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}
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end_tx:
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txEnd(tid);
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mutex_unlock(&JFS_IP(inode)->commit_mutex);
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return rc;
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}
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int jfs_init_acl(tid_t tid, 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 rc = 0;
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rc = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
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if (rc)
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return rc;
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if (default_acl) {
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rc = __jfs_set_acl(tid, inode, ACL_TYPE_DEFAULT, default_acl);
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posix_acl_release(default_acl);
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} else {
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inode->i_default_acl = NULL;
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}
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if (acl) {
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if (!rc)
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rc = __jfs_set_acl(tid, inode, ACL_TYPE_ACCESS, acl);
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posix_acl_release(acl);
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} else {
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inode->i_acl = NULL;
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}
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JFS_IP(inode)->mode2 = (JFS_IP(inode)->mode2 & 0xffff0000) |
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inode->i_mode;
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return rc;
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}
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