linux/security/keys/compat.c
David Howells f36f8c75ae KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches
Add support for per-user_namespace registers of persistent per-UID kerberos
caches held within the kernel.

This allows the kerberos cache to be retained beyond the life of all a user's
processes so that the user's cron jobs can work.

The kerberos cache is envisioned as a keyring/key tree looking something like:

	struct user_namespace
	  \___ .krb_cache keyring		- The register
		\___ _krb.0 keyring		- Root's Kerberos cache
		\___ _krb.5000 keyring		- User 5000's Kerberos cache
		\___ _krb.5001 keyring		- User 5001's Kerberos cache
			\___ tkt785 big_key	- A ccache blob
			\___ tkt12345 big_key	- Another ccache blob

Or possibly:

	struct user_namespace
	  \___ .krb_cache keyring		- The register
		\___ _krb.0 keyring		- Root's Kerberos cache
		\___ _krb.5000 keyring		- User 5000's Kerberos cache
		\___ _krb.5001 keyring		- User 5001's Kerberos cache
			\___ tkt785 keyring	- A ccache
				\___ krbtgt/REDHAT.COM@REDHAT.COM big_key
				\___ http/REDHAT.COM@REDHAT.COM user
				\___ afs/REDHAT.COM@REDHAT.COM user
				\___ nfs/REDHAT.COM@REDHAT.COM user
				\___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key
				\___ http/KERNEL.ORG@KERNEL.ORG big_key

What goes into a particular Kerberos cache is entirely up to userspace.  Kernel
support is limited to giving you the Kerberos cache keyring that you want.

The user asks for their Kerberos cache by:

	krb_cache = keyctl_get_krbcache(uid, dest_keyring);

The uid is -1 or the user's own UID for the user's own cache or the uid of some
other user's cache (requires CAP_SETUID).  This permits rpc.gssd or whatever to
mess with the cache.

The cache returned is a keyring named "_krb.<uid>" that the possessor can read,
search, clear, invalidate, unlink from and add links to.  Active LSMs get a
chance to rule on whether the caller is permitted to make a link.

Each uid's cache keyring is created when it first accessed and is given a
timeout that is extended each time this function is called so that the keyring
goes away after a while.  The timeout is configurable by sysctl but defaults to
three days.

Each user_namespace struct gets a lazily-created keyring that serves as the
register.  The cache keyrings are added to it.  This means that standard key
search and garbage collection facilities are available.

The user_namespace struct's register goes away when it does and anything left
in it is then automatically gc'd.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
2013-09-24 10:35:19 +01:00

148 lines
3.8 KiB
C

/* 32-bit compatibility syscall for 64-bit systems
*
* Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/syscalls.h>
#include <linux/keyctl.h>
#include <linux/compat.h>
#include <linux/slab.h>
#include "internal.h"
/*
* Instantiate a key with the specified compatibility multipart payload and
* link the key into the destination keyring if one is given.
*
* The caller must have the appropriate instantiation permit set for this to
* work (see keyctl_assume_authority). No other permissions are required.
*
* If successful, 0 will be returned.
*/
static long compat_keyctl_instantiate_key_iov(
key_serial_t id,
const struct compat_iovec __user *_payload_iov,
unsigned ioc,
key_serial_t ringid)
{
struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
long ret;
if (!_payload_iov || !ioc)
goto no_payload;
ret = compat_rw_copy_check_uvector(WRITE, _payload_iov, ioc,
ARRAY_SIZE(iovstack),
iovstack, &iov);
if (ret < 0)
goto err;
if (ret == 0)
goto no_payload_free;
ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
err:
if (iov != iovstack)
kfree(iov);
return ret;
no_payload_free:
if (iov != iovstack)
kfree(iov);
no_payload:
return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
}
/*
* The key control system call, 32-bit compatibility version for 64-bit archs
*
* This should only be called if the 64-bit arch uses weird pointers in 32-bit
* mode or doesn't guarantee that the top 32-bits of the argument registers on
* taking a 32-bit syscall are zero. If you can, you should call sys_keyctl()
* directly.
*/
asmlinkage long compat_sys_keyctl(u32 option,
u32 arg2, u32 arg3, u32 arg4, u32 arg5)
{
switch (option) {
case KEYCTL_GET_KEYRING_ID:
return keyctl_get_keyring_ID(arg2, arg3);
case KEYCTL_JOIN_SESSION_KEYRING:
return keyctl_join_session_keyring(compat_ptr(arg2));
case KEYCTL_UPDATE:
return keyctl_update_key(arg2, compat_ptr(arg3), arg4);
case KEYCTL_REVOKE:
return keyctl_revoke_key(arg2);
case KEYCTL_DESCRIBE:
return keyctl_describe_key(arg2, compat_ptr(arg3), arg4);
case KEYCTL_CLEAR:
return keyctl_keyring_clear(arg2);
case KEYCTL_LINK:
return keyctl_keyring_link(arg2, arg3);
case KEYCTL_UNLINK:
return keyctl_keyring_unlink(arg2, arg3);
case KEYCTL_SEARCH:
return keyctl_keyring_search(arg2, compat_ptr(arg3),
compat_ptr(arg4), arg5);
case KEYCTL_READ:
return keyctl_read_key(arg2, compat_ptr(arg3), arg4);
case KEYCTL_CHOWN:
return keyctl_chown_key(arg2, arg3, arg4);
case KEYCTL_SETPERM:
return keyctl_setperm_key(arg2, arg3);
case KEYCTL_INSTANTIATE:
return keyctl_instantiate_key(arg2, compat_ptr(arg3), arg4,
arg5);
case KEYCTL_NEGATE:
return keyctl_negate_key(arg2, arg3, arg4);
case KEYCTL_SET_REQKEY_KEYRING:
return keyctl_set_reqkey_keyring(arg2);
case KEYCTL_SET_TIMEOUT:
return keyctl_set_timeout(arg2, arg3);
case KEYCTL_ASSUME_AUTHORITY:
return keyctl_assume_authority(arg2);
case KEYCTL_GET_SECURITY:
return keyctl_get_security(arg2, compat_ptr(arg3), arg4);
case KEYCTL_SESSION_TO_PARENT:
return keyctl_session_to_parent();
case KEYCTL_REJECT:
return keyctl_reject_key(arg2, arg3, arg4, arg5);
case KEYCTL_INSTANTIATE_IOV:
return compat_keyctl_instantiate_key_iov(
arg2, compat_ptr(arg3), arg4, arg5);
case KEYCTL_INVALIDATE:
return keyctl_invalidate_key(arg2);
case KEYCTL_GET_PERSISTENT:
return keyctl_get_persistent(arg2, arg3);
default:
return -EOPNOTSUPP;
}
}