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e65ce2a50c
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>
109 lines
2.8 KiB
C
109 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "reiserfs.h"
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/xattr.h>
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#include <linux/slab.h>
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#include "xattr.h"
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#include <linux/security.h>
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#include <linux/uaccess.h>
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static int
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security_get(const struct xattr_handler *handler, struct dentry *unused,
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struct inode *inode, const char *name, void *buffer, size_t size)
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{
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if (IS_PRIVATE(inode))
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return -EPERM;
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return reiserfs_xattr_get(inode, xattr_full_name(handler, name),
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buffer, size);
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}
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static int
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security_set(const struct xattr_handler *handler,
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struct user_namespace *mnt_userns, struct dentry *unused,
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struct inode *inode, const char *name, const void *buffer,
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size_t size, int flags)
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{
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if (IS_PRIVATE(inode))
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return -EPERM;
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return reiserfs_xattr_set(inode,
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xattr_full_name(handler, name),
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buffer, size, flags);
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}
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static bool security_list(struct dentry *dentry)
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{
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return !IS_PRIVATE(d_inode(dentry));
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}
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/* Initializes the security context for a new inode and returns the number
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* of blocks needed for the transaction. If successful, reiserfs_security
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* must be released using reiserfs_security_free when the caller is done. */
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int reiserfs_security_init(struct inode *dir, struct inode *inode,
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const struct qstr *qstr,
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struct reiserfs_security_handle *sec)
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{
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int blocks = 0;
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int error;
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sec->name = NULL;
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/* Don't add selinux attributes on xattrs - they'll never get used */
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if (IS_PRIVATE(dir))
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return 0;
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error = security_old_inode_init_security(inode, dir, qstr, &sec->name,
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&sec->value, &sec->length);
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if (error) {
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if (error == -EOPNOTSUPP)
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error = 0;
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sec->name = NULL;
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sec->value = NULL;
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sec->length = 0;
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return error;
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}
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if (sec->length && reiserfs_xattrs_initialized(inode->i_sb)) {
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blocks = reiserfs_xattr_jcreate_nblocks(inode) +
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reiserfs_xattr_nblocks(inode, sec->length);
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/* We don't want to count the directories twice if we have
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* a default ACL. */
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REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
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}
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return blocks;
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}
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int reiserfs_security_write(struct reiserfs_transaction_handle *th,
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struct inode *inode,
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struct reiserfs_security_handle *sec)
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{
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int error;
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if (strlen(sec->name) < sizeof(XATTR_SECURITY_PREFIX))
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return -EINVAL;
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error = reiserfs_xattr_set_handle(th, inode, sec->name, sec->value,
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sec->length, XATTR_CREATE);
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if (error == -ENODATA || error == -EOPNOTSUPP)
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error = 0;
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return error;
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}
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void reiserfs_security_free(struct reiserfs_security_handle *sec)
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{
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kfree(sec->name);
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kfree(sec->value);
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sec->name = NULL;
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sec->value = NULL;
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}
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const struct xattr_handler reiserfs_xattr_security_handler = {
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.prefix = XATTR_SECURITY_PREFIX,
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.get = security_get,
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.set = security_set,
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.list = security_list,
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};
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