mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-23 14:13:49 +07:00
2e12256b9a
Replace the uid/gid/perm permissions checking on a key with an ACL to allow the SETATTR and SEARCH permissions to be split. This will also allow a greater range of subjects to represented. ============ WHY DO THIS? ============ The problem is that SETATTR and SEARCH cover a slew of actions, not all of which should be grouped together. For SETATTR, this includes actions that are about controlling access to a key: (1) Changing a key's ownership. (2) Changing a key's security information. (3) Setting a keyring's restriction. And actions that are about managing a key's lifetime: (4) Setting an expiry time. (5) Revoking a key. and (proposed) managing a key as part of a cache: (6) Invalidating a key. Managing a key's lifetime doesn't really have anything to do with controlling access to that key. Expiry time is awkward since it's more about the lifetime of the content and so, in some ways goes better with WRITE permission. It can, however, be set unconditionally by a process with an appropriate authorisation token for instantiating a key, and can also be set by the key type driver when a key is instantiated, so lumping it with the access-controlling actions is probably okay. As for SEARCH permission, that currently covers: (1) Finding keys in a keyring tree during a search. (2) Permitting keyrings to be joined. (3) Invalidation. But these don't really belong together either, since these actions really need to be controlled separately. Finally, there are number of special cases to do with granting the administrator special rights to invalidate or clear keys that I would like to handle with the ACL rather than key flags and special checks. =============== WHAT IS CHANGED =============== The SETATTR permission is split to create two new permissions: (1) SET_SECURITY - which allows the key's owner, group and ACL to be changed and a restriction to be placed on a keyring. (2) REVOKE - which allows a key to be revoked. The SEARCH permission is split to create: (1) SEARCH - which allows a keyring to be search and a key to be found. (2) JOIN - which allows a keyring to be joined as a session keyring. (3) INVAL - which allows a key to be invalidated. The WRITE permission is also split to create: (1) WRITE - which allows a key's content to be altered and links to be added, removed and replaced in a keyring. (2) CLEAR - which allows a keyring to be cleared completely. This is split out to make it possible to give just this to an administrator. (3) REVOKE - see above. Keys acquire ACLs which consist of a series of ACEs, and all that apply are unioned together. An ACE specifies a subject, such as: (*) Possessor - permitted to anyone who 'possesses' a key (*) Owner - permitted to the key owner (*) Group - permitted to the key group (*) Everyone - permitted to everyone Note that 'Other' has been replaced with 'Everyone' on the assumption that you wouldn't grant a permit to 'Other' that you wouldn't also grant to everyone else. Further subjects may be made available by later patches. The ACE also specifies a permissions mask. The set of permissions is now: VIEW Can view the key metadata READ Can read the key content WRITE Can update/modify the key content SEARCH Can find the key by searching/requesting LINK Can make a link to the key SET_SECURITY Can change owner, ACL, expiry INVAL Can invalidate REVOKE Can revoke JOIN Can join this keyring CLEAR Can clear this keyring The KEYCTL_SETPERM function is then deprecated. The KEYCTL_SET_TIMEOUT function then is permitted if SET_SECURITY is set, or if the caller has a valid instantiation auth token. The KEYCTL_INVALIDATE function then requires INVAL. The KEYCTL_REVOKE function then requires REVOKE. The KEYCTL_JOIN_SESSION_KEYRING function then requires JOIN to join an existing keyring. The JOIN permission is enabled by default for session keyrings and manually created keyrings only. ====================== BACKWARD COMPATIBILITY ====================== To maintain backward compatibility, KEYCTL_SETPERM will translate the permissions mask it is given into a new ACL for a key - unless KEYCTL_SET_ACL has been called on that key, in which case an error will be returned. It will convert possessor, owner, group and other permissions into separate ACEs, if each portion of the mask is non-zero. SETATTR permission turns on all of INVAL, REVOKE and SET_SECURITY. WRITE permission turns on WRITE, REVOKE and, if a keyring, CLEAR. JOIN is turned on if a keyring is being altered. The KEYCTL_DESCRIBE function translates the ACL back into a permissions mask to return depending on possessor, owner, group and everyone ACEs. It will make the following mappings: (1) INVAL, JOIN -> SEARCH (2) SET_SECURITY -> SETATTR (3) REVOKE -> WRITE if SETATTR isn't already set (4) CLEAR -> WRITE Note that the value subsequently returned by KEYCTL_DESCRIBE may not match the value set with KEYCTL_SETATTR. ======= TESTING ======= This passes the keyutils testsuite for all but a couple of tests: (1) tests/keyctl/dh_compute/badargs: The first wrong-key-type test now returns EOPNOTSUPP rather than ENOKEY as READ permission isn't removed if the type doesn't have ->read(). You still can't actually read the key. (2) tests/keyctl/permitting/valid: The view-other-permissions test doesn't work as Other has been replaced with Everyone in the ACL. Signed-off-by: David Howells <dhowells@redhat.com>
182 lines
5.0 KiB
C
182 lines
5.0 KiB
C
/* Upcall routine, designed to work as a key type and working through
|
|
* /sbin/request-key to contact userspace when handling DNS queries.
|
|
*
|
|
* See Documentation/networking/dns_resolver.txt
|
|
*
|
|
* Copyright (c) 2007 Igor Mammedov
|
|
* Author(s): Igor Mammedov (niallain@gmail.com)
|
|
* Steve French (sfrench@us.ibm.com)
|
|
* Wang Lei (wang840925@gmail.com)
|
|
* David Howells (dhowells@redhat.com)
|
|
*
|
|
* The upcall wrapper used to make an arbitrary DNS query.
|
|
*
|
|
* This function requires the appropriate userspace tool dns.upcall to be
|
|
* installed and something like the following lines should be added to the
|
|
* /etc/request-key.conf file:
|
|
*
|
|
* create dns_resolver * * /sbin/dns.upcall %k
|
|
*
|
|
* For example to use this module to query AFSDB RR:
|
|
*
|
|
* create dns_resolver afsdb:* * /sbin/dns.afsdb %k
|
|
*
|
|
* This library is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU Lesser General Public License as published
|
|
* by the Free Software Foundation; either version 2.1 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This library is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
|
|
* the GNU Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public License
|
|
* along with this library; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/cred.h>
|
|
#include <linux/dns_resolver.h>
|
|
#include <linux/err.h>
|
|
#include <net/net_namespace.h>
|
|
|
|
#include <keys/dns_resolver-type.h>
|
|
#include <keys/user-type.h>
|
|
|
|
#include "internal.h"
|
|
|
|
static struct key_acl dns_key_acl = {
|
|
.usage = REFCOUNT_INIT(1),
|
|
.nr_ace = 2,
|
|
.possessor_viewable = true,
|
|
.aces = {
|
|
KEY_POSSESSOR_ACE(KEY_ACE_VIEW | KEY_ACE_SEARCH | KEY_ACE_READ),
|
|
KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_INVAL),
|
|
}
|
|
};
|
|
|
|
/**
|
|
* dns_query - Query the DNS
|
|
* @net: The network namespace to operate in.
|
|
* @type: Query type (or NULL for straight host->IP lookup)
|
|
* @name: Name to look up
|
|
* @namelen: Length of name
|
|
* @options: Request options (or NULL if no options)
|
|
* @_result: Where to place the returned data (or NULL)
|
|
* @_expiry: Where to store the result expiry time (or NULL)
|
|
* @invalidate: Always invalidate the key after use
|
|
*
|
|
* The data will be returned in the pointer at *result, if provided, and the
|
|
* caller is responsible for freeing it.
|
|
*
|
|
* The description should be of the form "[<query_type>:]<domain_name>", and
|
|
* the options need to be appropriate for the query type requested. If no
|
|
* query_type is given, then the query is a straight hostname to IP address
|
|
* lookup.
|
|
*
|
|
* The DNS resolution lookup is performed by upcalling to userspace by way of
|
|
* requesting a key of type dns_resolver.
|
|
*
|
|
* Returns the size of the result on success, -ve error code otherwise.
|
|
*/
|
|
int dns_query(struct net *net,
|
|
const char *type, const char *name, size_t namelen,
|
|
const char *options, char **_result, time64_t *_expiry,
|
|
bool invalidate)
|
|
{
|
|
struct key *rkey;
|
|
struct user_key_payload *upayload;
|
|
const struct cred *saved_cred;
|
|
size_t typelen, desclen;
|
|
char *desc, *cp;
|
|
int ret, len;
|
|
|
|
kenter("%s,%*.*s,%zu,%s",
|
|
type, (int)namelen, (int)namelen, name, namelen, options);
|
|
|
|
if (!name || namelen == 0)
|
|
return -EINVAL;
|
|
|
|
/* construct the query key description as "[<type>:]<name>" */
|
|
typelen = 0;
|
|
desclen = 0;
|
|
if (type) {
|
|
typelen = strlen(type);
|
|
if (typelen < 1)
|
|
return -EINVAL;
|
|
desclen += typelen + 1;
|
|
}
|
|
|
|
if (namelen < 3 || namelen > 255)
|
|
return -EINVAL;
|
|
desclen += namelen + 1;
|
|
|
|
desc = kmalloc(desclen, GFP_KERNEL);
|
|
if (!desc)
|
|
return -ENOMEM;
|
|
|
|
cp = desc;
|
|
if (type) {
|
|
memcpy(cp, type, typelen);
|
|
cp += typelen;
|
|
*cp++ = ':';
|
|
}
|
|
memcpy(cp, name, namelen);
|
|
cp += namelen;
|
|
*cp = '\0';
|
|
|
|
if (!options)
|
|
options = "";
|
|
kdebug("call request_key(,%s,%s)", desc, options);
|
|
|
|
/* make the upcall, using special credentials to prevent the use of
|
|
* add_key() to preinstall malicious redirections
|
|
*/
|
|
saved_cred = override_creds(dns_resolver_cache);
|
|
rkey = request_key_net(&key_type_dns_resolver, desc, net, options,
|
|
&dns_key_acl);
|
|
revert_creds(saved_cred);
|
|
kfree(desc);
|
|
if (IS_ERR(rkey)) {
|
|
ret = PTR_ERR(rkey);
|
|
goto out;
|
|
}
|
|
|
|
down_read(&rkey->sem);
|
|
set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags);
|
|
ret = key_validate(rkey);
|
|
if (ret < 0)
|
|
goto put;
|
|
|
|
/* If the DNS server gave an error, return that to the caller */
|
|
ret = PTR_ERR(rkey->payload.data[dns_key_error]);
|
|
if (ret)
|
|
goto put;
|
|
|
|
upayload = user_key_payload_locked(rkey);
|
|
len = upayload->datalen;
|
|
|
|
if (_result) {
|
|
ret = -ENOMEM;
|
|
*_result = kmemdup_nul(upayload->data, len, GFP_KERNEL);
|
|
if (!*_result)
|
|
goto put;
|
|
}
|
|
|
|
if (_expiry)
|
|
*_expiry = rkey->expiry;
|
|
|
|
ret = len;
|
|
put:
|
|
up_read(&rkey->sem);
|
|
if (invalidate)
|
|
key_invalidate(rkey);
|
|
key_put(rkey);
|
|
out:
|
|
kleave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(dns_query);
|