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138060ba92
The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. Since some filesystem rely on the dentry being available to them when setting posix acls (e.g., 9p and cifs) they cannot rely on set acl inode operation. But since ->set_acl() is required in order to use the generic posix acl xattr handlers filesystems that do not implement this inode operation cannot use the handler and need to implement their own dedicated posix acl handlers. Update the ->set_acl() inode method to take a dentry argument. This allows all filesystems to rely on ->set_acl(). As far as I can tell all codepaths can be switched to rely on the dentry instead of just the inode. Note that the original motivation for passing the dentry separate from the inode instead of just the dentry in the xattr handlers was because of security modules that call security_d_instantiate(). This hook is called during d_instantiate_new(), d_add(), __d_instantiate_anon(), and d_splice_alias() to initialize the inode's security context and possibly to set security.* xattrs. Since this only affects security.* xattrs this is completely irrelevant for posix acls. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
159 lines
4 KiB
C
159 lines
4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* (C) 2001 Clemson University and The University of Chicago
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*
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* See COPYING in top-level directory.
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*/
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#include "protocol.h"
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#include "orangefs-kernel.h"
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#include "orangefs-bufmap.h"
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#include <linux/posix_acl_xattr.h>
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struct posix_acl *orangefs_get_acl(struct inode *inode, int type, bool rcu)
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{
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struct posix_acl *acl;
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int ret;
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char *key = NULL, *value = NULL;
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if (rcu)
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return ERR_PTR(-ECHILD);
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switch (type) {
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case ACL_TYPE_ACCESS:
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key = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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key = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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gossip_err("orangefs_get_acl: bogus value of type %d\n", type);
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return ERR_PTR(-EINVAL);
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}
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/*
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* Rather than incurring a network call just to determine the exact
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* length of the attribute, I just allocate a max length to save on
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* the network call. Conceivably, we could pass NULL to
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* orangefs_inode_getxattr() to probe the length of the value, but
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* I don't do that for now.
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*/
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value = kmalloc(ORANGEFS_MAX_XATTR_VALUELEN, GFP_KERNEL);
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if (!value)
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return ERR_PTR(-ENOMEM);
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gossip_debug(GOSSIP_ACL_DEBUG,
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"inode %pU, key %s, type %d\n",
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get_khandle_from_ino(inode),
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key,
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type);
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ret = orangefs_inode_getxattr(inode, key, value,
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ORANGEFS_MAX_XATTR_VALUELEN);
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/* if the key exists, convert it to an in-memory rep */
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if (ret > 0) {
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acl = posix_acl_from_xattr(&init_user_ns, value, ret);
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} else if (ret == -ENODATA || ret == -ENOSYS) {
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acl = NULL;
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} else {
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gossip_err("inode %pU retrieving acl's failed with error %d\n",
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get_khandle_from_ino(inode),
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ret);
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acl = ERR_PTR(ret);
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}
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/* kfree(NULL) is safe, so don't worry if value ever got used */
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kfree(value);
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return acl;
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}
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int __orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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{
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int error = 0;
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void *value = NULL;
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size_t size = 0;
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const char *name = 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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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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gossip_err("%s: invalid type %d!\n", __func__, type);
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return -EINVAL;
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}
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gossip_debug(GOSSIP_ACL_DEBUG,
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"%s: inode %pU, key %s type %d\n",
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__func__, get_khandle_from_ino(inode),
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name,
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type);
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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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error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
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if (error < 0)
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goto out;
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}
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gossip_debug(GOSSIP_ACL_DEBUG,
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"%s: name %s, value %p, size %zd, acl %p\n",
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__func__, name, value, size, acl);
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/*
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* Go ahead and set the extended attribute now. NOTE: Suppose acl
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* was NULL, then value will be NULL and size will be 0 and that
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* will xlate to a removexattr. However, we don't want removexattr
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* complain if attributes does not exist.
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*/
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error = orangefs_inode_setxattr(inode, name, value, size, 0);
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out:
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kfree(value);
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if (!error)
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set_cached_acl(inode, type, acl);
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return error;
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}
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int orangefs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
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struct posix_acl *acl, int type)
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{
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int error;
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struct iattr iattr;
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int rc;
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struct inode *inode = d_inode(dentry);
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memset(&iattr, 0, sizeof iattr);
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if (type == ACL_TYPE_ACCESS && acl) {
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/*
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* posix_acl_update_mode checks to see if the permissions
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* described by the ACL can be encoded into the
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* object's mode. If so, it sets "acl" to NULL
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* and "mode" to the new desired value. It is up to
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* us to propagate the new mode back to the server...
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*/
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error = posix_acl_update_mode(&init_user_ns, inode,
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&iattr.ia_mode, &acl);
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if (error) {
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gossip_err("%s: posix_acl_update_mode err: %d\n",
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__func__,
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error);
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return error;
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}
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if (inode->i_mode != iattr.ia_mode)
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iattr.ia_valid = ATTR_MODE;
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}
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rc = __orangefs_set_acl(inode, acl, type);
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if (!rc && (iattr.ia_valid == ATTR_MODE))
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rc = __orangefs_setattr_mode(dentry, &iattr);
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return rc;
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}
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