linux/net/rxrpc/server_key.c
Xiaolong Huang ff8376ade4 rxrpc: fix some null-ptr-deref bugs in server_key.c
Some function calls are not implemented in rxrpc_no_security, there are
preparse_server_key, free_preparse_server_key and destroy_server_key.
When rxrpc security type is rxrpc_no_security, user can easily trigger a
null-ptr-deref bug via ioctl. So judgment should be added to prevent it

The crash log:
user@syzkaller:~$ ./rxrpc_preparse_s
[   37.956878][T15626] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   37.957645][T15626] #PF: supervisor instruction fetch in kernel mode
[   37.958229][T15626] #PF: error_code(0x0010) - not-present page
[   37.958762][T15626] PGD 4aadf067 P4D 4aadf067 PUD 4aade067 PMD 0
[   37.959321][T15626] Oops: 0010 [#1] PREEMPT SMP
[   37.959739][T15626] CPU: 0 PID: 15626 Comm: rxrpc_preparse_ Not tainted 5.17.0-01442-gb47d5a4f6b8d #43
[   37.960588][T15626] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[   37.961474][T15626] RIP: 0010:0x0
[   37.961787][T15626] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
[   37.962480][T15626] RSP: 0018:ffffc9000d9abdc0 EFLAGS: 00010286
[   37.963018][T15626] RAX: ffffffff84335200 RBX: ffff888012a1ce80 RCX: 0000000000000000
[   37.963727][T15626] RDX: 0000000000000000 RSI: ffffffff84a736dc RDI: ffffc9000d9abe48
[   37.964425][T15626] RBP: ffffc9000d9abe48 R08: 0000000000000000 R09: 0000000000000002
[   37.965118][T15626] R10: 000000000000000a R11: f000000000000000 R12: ffff888013145680
[   37.965836][T15626] R13: 0000000000000000 R14: ffffffffffffffec R15: ffff8880432aba80
[   37.966441][T15626] FS:  00007f2177907700(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000
[   37.966979][T15626] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   37.967384][T15626] CR2: ffffffffffffffd6 CR3: 000000004aaf1000 CR4: 00000000000006f0
[   37.967864][T15626] Call Trace:
[   37.968062][T15626]  <TASK>
[   37.968240][T15626]  rxrpc_preparse_s+0x59/0x90
[   37.968541][T15626]  key_create_or_update+0x174/0x510
[   37.968863][T15626]  __x64_sys_add_key+0x139/0x1d0
[   37.969165][T15626]  do_syscall_64+0x35/0xb0
[   37.969451][T15626]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   37.969824][T15626] RIP: 0033:0x43a1f9

Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com>
Tested-by: Xiaolong Huang <butterflyhuangxx@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: http://lists.infradead.org/pipermail/linux-afs/2022-March/005069.html
Fixes: 12da59fcab ("rxrpc: Hand server key parsing off to the security class")
Link: https://lore.kernel.org/r/164865013439.2941502.8966285221215590921.stgit@warthog.procyon.org.uk
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2022-03-31 15:21:31 +02:00

147 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* RxRPC key management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* RxRPC keys should have a description of describing their purpose:
* "afs@CAMBRIDGE.REDHAT.COM>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <crypto/skcipher.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/key-type.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <keys/rxrpc-type.h>
#include <keys/user-type.h>
#include "ar-internal.h"
static int rxrpc_vet_description_s(const char *);
static int rxrpc_preparse_s(struct key_preparsed_payload *);
static void rxrpc_free_preparse_s(struct key_preparsed_payload *);
static void rxrpc_destroy_s(struct key *);
static void rxrpc_describe_s(const struct key *, struct seq_file *);
/*
* rxrpc server keys take "<serviceId>:<securityIndex>[:<sec-specific>]" as the
* description and the key material as the payload.
*/
struct key_type key_type_rxrpc_s = {
.name = "rxrpc_s",
.flags = KEY_TYPE_NET_DOMAIN,
.vet_description = rxrpc_vet_description_s,
.preparse = rxrpc_preparse_s,
.free_preparse = rxrpc_free_preparse_s,
.instantiate = generic_key_instantiate,
.destroy = rxrpc_destroy_s,
.describe = rxrpc_describe_s,
};
/*
* Vet the description for an RxRPC server key.
*/
static int rxrpc_vet_description_s(const char *desc)
{
unsigned long service, sec_class;
char *p;
service = simple_strtoul(desc, &p, 10);
if (*p != ':' || service > 65535)
return -EINVAL;
sec_class = simple_strtoul(p + 1, &p, 10);
if ((*p && *p != ':') || sec_class < 1 || sec_class > 255)
return -EINVAL;
return 0;
}
/*
* Preparse a server secret key.
*/
static int rxrpc_preparse_s(struct key_preparsed_payload *prep)
{
const struct rxrpc_security *sec;
unsigned int service, sec_class;
int n;
_enter("%zu", prep->datalen);
if (!prep->orig_description)
return -EINVAL;
if (sscanf(prep->orig_description, "%u:%u%n", &service, &sec_class, &n) != 2)
return -EINVAL;
sec = rxrpc_security_lookup(sec_class);
if (!sec)
return -ENOPKG;
prep->payload.data[1] = (struct rxrpc_security *)sec;
if (!sec->preparse_server_key)
return -EINVAL;
return sec->preparse_server_key(prep);
}
static void rxrpc_free_preparse_s(struct key_preparsed_payload *prep)
{
const struct rxrpc_security *sec = prep->payload.data[1];
if (sec && sec->free_preparse_server_key)
sec->free_preparse_server_key(prep);
}
static void rxrpc_destroy_s(struct key *key)
{
const struct rxrpc_security *sec = key->payload.data[1];
if (sec && sec->destroy_server_key)
sec->destroy_server_key(key);
}
static void rxrpc_describe_s(const struct key *key, struct seq_file *m)
{
const struct rxrpc_security *sec = key->payload.data[1];
seq_puts(m, key->description);
if (sec && sec->describe_server_key)
sec->describe_server_key(key, m);
}
/*
* grab the security keyring for a server socket
*/
int rxrpc_server_keyring(struct rxrpc_sock *rx, sockptr_t optval, int optlen)
{
struct key *key;
char *description;
_enter("");
if (optlen <= 0 || optlen > PAGE_SIZE - 1)
return -EINVAL;
description = memdup_sockptr_nul(optval, optlen);
if (IS_ERR(description))
return PTR_ERR(description);
key = request_key(&key_type_keyring, description, NULL);
if (IS_ERR(key)) {
kfree(description);
_leave(" = %ld", PTR_ERR(key));
return PTR_ERR(key);
}
rx->securities = key;
kfree(description);
_leave(" = 0 [key %x]", key->serial);
return 0;
}