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![Herbert Xu](/assets/img/avatar_default.png)
On Thu, Jun 20, 2013 at 10:00:21AM +0200, Daniel Borkmann wrote:
> After having fixed a NULL pointer dereference in SCTP 1abd165e
("net:
> sctp: fix NULL pointer dereference in socket destruction"), I ran into
> the following NULL pointer dereference in the crypto subsystem with
> the same reproducer, easily hit each time:
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffff81070321>] __wake_up_common+0x31/0x90
> PGD 0
> Oops: 0000 [#1] SMP
> Modules linked in: padlock_sha(F-) sha256_generic(F) sctp(F) libcrc32c(F) [..]
> CPU: 6 PID: 3326 Comm: cryptomgr_probe Tainted: GF 3.10.0-rc5+ #1
> Hardware name: Dell Inc. PowerEdge T410/0H19HD, BIOS 1.6.3 02/01/2011
> task: ffff88007b6cf4e0 ti: ffff88007b7cc000 task.ti: ffff88007b7cc000
> RIP: 0010:[<ffffffff81070321>] [<ffffffff81070321>] __wake_up_common+0x31/0x90
> RSP: 0018:ffff88007b7cde08 EFLAGS: 00010082
> RAX: ffffffffffffffe8 RBX: ffff88003756c130 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffff88003756c130
> RBP: ffff88007b7cde48 R08: 0000000000000000 R09: ffff88012b173200
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000282
> R13: ffff88003756c138 R14: 0000000000000000 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff88012fc60000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000000 CR3: 0000000001a0b000 CR4: 00000000000007e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Stack:
> ffff88007b7cde28 0000000300000000 ffff88007b7cde28 ffff88003756c130
> 0000000000000282 ffff88003756c128 ffffffff81227670 0000000000000000
> ffff88007b7cde78 ffffffff810722b7 ffff88007cdcf000 ffffffff81a90540
> Call Trace:
> [<ffffffff81227670>] ? crypto_alloc_pcomp+0x20/0x20
> [<ffffffff810722b7>] complete_all+0x47/0x60
> [<ffffffff81227708>] cryptomgr_probe+0x98/0xc0
> [<ffffffff81227670>] ? crypto_alloc_pcomp+0x20/0x20
> [<ffffffff8106760e>] kthread+0xce/0xe0
> [<ffffffff81067540>] ? kthread_freezable_should_stop+0x70/0x70
> [<ffffffff815450dc>] ret_from_fork+0x7c/0xb0
> [<ffffffff81067540>] ? kthread_freezable_should_stop+0x70/0x70
> Code: 41 56 41 55 41 54 53 48 83 ec 18 66 66 66 66 90 89 75 cc 89 55 c8
> 4c 8d 6f 08 48 8b 57 08 41 89 cf 4d 89 c6 48 8d 42 e
> RIP [<ffffffff81070321>] __wake_up_common+0x31/0x90
> RSP <ffff88007b7cde08>
> CR2: 0000000000000000
> ---[ end trace b495b19270a4d37e ]---
>
> My assumption is that the following is happening: the minimal SCTP
> tool runs under ``echo 1 > /proc/sys/net/sctp/auth_enable'', hence
> it's making use of crypto_alloc_hash() via sctp_auth_init_hmacs().
> It forks itself, heavily allocates, binds, listens and waits in
> accept on sctp sockets, and then randomly kills some of them (no
> need for an actual client in this case to hit this). Then, again,
> allocating, binding, etc, and then killing child processes.
>
> The problem that might be happening here is that cryptomgr requests
> the module to probe/load through cryptomgr_schedule_probe(), but
> before the thread handler cryptomgr_probe() returns, we return from
> the wait_for_completion_interruptible() function and probably already
> have cleared up larval, thus we run into a NULL pointer dereference
> when in cryptomgr_probe() complete_all() is being called.
>
> If we wait with wait_for_completion() instead, this panic will not
> occur anymore. This is valid, because in case a signal is pending,
> cryptomgr_probe() returns from probing anyway with properly calling
> complete_all().
The use of wait_for_completion_interruptible is intentional so that
we don't lock up the thread if a bug causes us to never wake up.
This bug is caused by the helper thread using the larval without
holding a reference count on it. If the helper thread completes
after the original thread requesting for help has gone away and
destroyed the larval, then we get the crash above.
So the fix is to hold a reference count on the larval.
Cc: <stable@vger.kernel.org> # 3.6+
Reported-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
600 lines
13 KiB
C
600 lines
13 KiB
C
/*
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* Scatterlist Cryptographic API.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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* Copyright (c) 2002 David S. Miller (davem@redhat.com)
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* Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
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* and Nettle, by Niels Möller.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/kmod.h>
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#include <linux/module.h>
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#include <linux/param.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include "internal.h"
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LIST_HEAD(crypto_alg_list);
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EXPORT_SYMBOL_GPL(crypto_alg_list);
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DECLARE_RWSEM(crypto_alg_sem);
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EXPORT_SYMBOL_GPL(crypto_alg_sem);
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BLOCKING_NOTIFIER_HEAD(crypto_chain);
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EXPORT_SYMBOL_GPL(crypto_chain);
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struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
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{
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return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
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}
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EXPORT_SYMBOL_GPL(crypto_mod_get);
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void crypto_mod_put(struct crypto_alg *alg)
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{
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struct module *module = alg->cra_module;
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crypto_alg_put(alg);
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module_put(module);
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}
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EXPORT_SYMBOL_GPL(crypto_mod_put);
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static inline int crypto_is_test_larval(struct crypto_larval *larval)
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{
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return larval->alg.cra_driver_name[0];
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}
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static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
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u32 mask)
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{
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struct crypto_alg *q, *alg = NULL;
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int best = -2;
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list_for_each_entry(q, &crypto_alg_list, cra_list) {
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int exact, fuzzy;
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if (crypto_is_moribund(q))
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continue;
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if ((q->cra_flags ^ type) & mask)
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continue;
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if (crypto_is_larval(q) &&
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!crypto_is_test_larval((struct crypto_larval *)q) &&
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((struct crypto_larval *)q)->mask != mask)
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continue;
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exact = !strcmp(q->cra_driver_name, name);
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fuzzy = !strcmp(q->cra_name, name);
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if (!exact && !(fuzzy && q->cra_priority > best))
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continue;
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if (unlikely(!crypto_mod_get(q)))
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continue;
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best = q->cra_priority;
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if (alg)
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crypto_mod_put(alg);
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alg = q;
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if (exact)
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break;
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}
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return alg;
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}
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static void crypto_larval_destroy(struct crypto_alg *alg)
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{
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struct crypto_larval *larval = (void *)alg;
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BUG_ON(!crypto_is_larval(alg));
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if (larval->adult)
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crypto_mod_put(larval->adult);
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kfree(larval);
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}
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struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
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{
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struct crypto_larval *larval;
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larval = kzalloc(sizeof(*larval), GFP_KERNEL);
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if (!larval)
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return ERR_PTR(-ENOMEM);
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larval->mask = mask;
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larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
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larval->alg.cra_priority = -1;
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larval->alg.cra_destroy = crypto_larval_destroy;
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strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
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init_completion(&larval->completion);
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return larval;
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}
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EXPORT_SYMBOL_GPL(crypto_larval_alloc);
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static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
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u32 mask)
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{
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struct crypto_alg *alg;
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struct crypto_larval *larval;
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larval = crypto_larval_alloc(name, type, mask);
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if (IS_ERR(larval))
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return ERR_CAST(larval);
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atomic_set(&larval->alg.cra_refcnt, 2);
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down_write(&crypto_alg_sem);
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alg = __crypto_alg_lookup(name, type, mask);
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if (!alg) {
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alg = &larval->alg;
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list_add(&alg->cra_list, &crypto_alg_list);
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}
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up_write(&crypto_alg_sem);
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if (alg != &larval->alg)
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kfree(larval);
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return alg;
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}
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void crypto_larval_kill(struct crypto_alg *alg)
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{
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struct crypto_larval *larval = (void *)alg;
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down_write(&crypto_alg_sem);
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list_del(&alg->cra_list);
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up_write(&crypto_alg_sem);
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complete_all(&larval->completion);
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crypto_alg_put(alg);
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}
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EXPORT_SYMBOL_GPL(crypto_larval_kill);
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static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
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{
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struct crypto_larval *larval = (void *)alg;
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long timeout;
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timeout = wait_for_completion_interruptible_timeout(
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&larval->completion, 60 * HZ);
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alg = larval->adult;
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if (timeout < 0)
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alg = ERR_PTR(-EINTR);
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else if (!timeout)
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alg = ERR_PTR(-ETIMEDOUT);
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else if (!alg)
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alg = ERR_PTR(-ENOENT);
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else if (crypto_is_test_larval(larval) &&
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!(alg->cra_flags & CRYPTO_ALG_TESTED))
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alg = ERR_PTR(-EAGAIN);
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else if (!crypto_mod_get(alg))
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alg = ERR_PTR(-EAGAIN);
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crypto_mod_put(&larval->alg);
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return alg;
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}
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struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
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{
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struct crypto_alg *alg;
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down_read(&crypto_alg_sem);
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alg = __crypto_alg_lookup(name, type, mask);
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up_read(&crypto_alg_sem);
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return alg;
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}
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EXPORT_SYMBOL_GPL(crypto_alg_lookup);
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struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
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{
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struct crypto_alg *alg;
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if (!name)
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return ERR_PTR(-ENOENT);
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mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
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type &= mask;
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alg = crypto_alg_lookup(name, type, mask);
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if (!alg) {
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request_module("%s", name);
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if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
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CRYPTO_ALG_NEED_FALLBACK))
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request_module("%s-all", name);
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alg = crypto_alg_lookup(name, type, mask);
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}
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if (alg)
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return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
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return crypto_larval_add(name, type, mask);
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}
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EXPORT_SYMBOL_GPL(crypto_larval_lookup);
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int crypto_probing_notify(unsigned long val, void *v)
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{
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int ok;
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ok = blocking_notifier_call_chain(&crypto_chain, val, v);
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if (ok == NOTIFY_DONE) {
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request_module("cryptomgr");
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ok = blocking_notifier_call_chain(&crypto_chain, val, v);
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}
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return ok;
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}
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EXPORT_SYMBOL_GPL(crypto_probing_notify);
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struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
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{
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struct crypto_alg *alg;
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struct crypto_alg *larval;
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int ok;
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if (!((type | mask) & CRYPTO_ALG_TESTED)) {
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type |= CRYPTO_ALG_TESTED;
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mask |= CRYPTO_ALG_TESTED;
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}
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larval = crypto_larval_lookup(name, type, mask);
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if (IS_ERR(larval) || !crypto_is_larval(larval))
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return larval;
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ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
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if (ok == NOTIFY_STOP)
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alg = crypto_larval_wait(larval);
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else {
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crypto_mod_put(larval);
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alg = ERR_PTR(-ENOENT);
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}
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crypto_larval_kill(larval);
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return alg;
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}
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EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
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static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
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{
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const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
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if (type_obj)
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return type_obj->init(tfm, type, mask);
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switch (crypto_tfm_alg_type(tfm)) {
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case CRYPTO_ALG_TYPE_CIPHER:
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return crypto_init_cipher_ops(tfm);
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case CRYPTO_ALG_TYPE_COMPRESS:
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return crypto_init_compress_ops(tfm);
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default:
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break;
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}
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BUG();
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return -EINVAL;
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}
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static void crypto_exit_ops(struct crypto_tfm *tfm)
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{
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const struct crypto_type *type = tfm->__crt_alg->cra_type;
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if (type) {
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if (tfm->exit)
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tfm->exit(tfm);
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return;
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}
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switch (crypto_tfm_alg_type(tfm)) {
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case CRYPTO_ALG_TYPE_CIPHER:
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crypto_exit_cipher_ops(tfm);
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break;
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case CRYPTO_ALG_TYPE_COMPRESS:
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crypto_exit_compress_ops(tfm);
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break;
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default:
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BUG();
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}
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}
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static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
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{
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const struct crypto_type *type_obj = alg->cra_type;
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unsigned int len;
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len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
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if (type_obj)
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return len + type_obj->ctxsize(alg, type, mask);
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switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
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default:
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BUG();
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case CRYPTO_ALG_TYPE_CIPHER:
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len += crypto_cipher_ctxsize(alg);
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break;
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case CRYPTO_ALG_TYPE_COMPRESS:
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len += crypto_compress_ctxsize(alg);
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break;
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}
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return len;
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}
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void crypto_shoot_alg(struct crypto_alg *alg)
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{
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down_write(&crypto_alg_sem);
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alg->cra_flags |= CRYPTO_ALG_DYING;
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up_write(&crypto_alg_sem);
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}
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EXPORT_SYMBOL_GPL(crypto_shoot_alg);
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struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
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u32 mask)
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{
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struct crypto_tfm *tfm = NULL;
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unsigned int tfm_size;
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int err = -ENOMEM;
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tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
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tfm = kzalloc(tfm_size, GFP_KERNEL);
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if (tfm == NULL)
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goto out_err;
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tfm->__crt_alg = alg;
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err = crypto_init_ops(tfm, type, mask);
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if (err)
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goto out_free_tfm;
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if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
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goto cra_init_failed;
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goto out;
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cra_init_failed:
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crypto_exit_ops(tfm);
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out_free_tfm:
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if (err == -EAGAIN)
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crypto_shoot_alg(alg);
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kfree(tfm);
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out_err:
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tfm = ERR_PTR(err);
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out:
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return tfm;
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}
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EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
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/*
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* crypto_alloc_base - Locate algorithm and allocate transform
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* @alg_name: Name of algorithm
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* @type: Type of algorithm
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* @mask: Mask for type comparison
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*
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* This function should not be used by new algorithm types.
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* Plesae use crypto_alloc_tfm instead.
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*
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* crypto_alloc_base() will first attempt to locate an already loaded
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* algorithm. If that fails and the kernel supports dynamically loadable
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* modules, it will then attempt to load a module of the same name or
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* alias. If that fails it will send a query to any loaded crypto manager
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* to construct an algorithm on the fly. A refcount is grabbed on the
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* algorithm which is then associated with the new transform.
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*
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* The returned transform is of a non-determinate type. Most people
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* should use one of the more specific allocation functions such as
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* crypto_alloc_blkcipher.
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*
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* In case of error the return value is an error pointer.
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*/
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struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
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{
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struct crypto_tfm *tfm;
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int err;
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for (;;) {
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struct crypto_alg *alg;
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alg = crypto_alg_mod_lookup(alg_name, type, mask);
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if (IS_ERR(alg)) {
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err = PTR_ERR(alg);
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goto err;
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}
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tfm = __crypto_alloc_tfm(alg, type, mask);
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if (!IS_ERR(tfm))
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return tfm;
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crypto_mod_put(alg);
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err = PTR_ERR(tfm);
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err:
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if (err != -EAGAIN)
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break;
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if (signal_pending(current)) {
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err = -EINTR;
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break;
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}
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}
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL_GPL(crypto_alloc_base);
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void *crypto_create_tfm(struct crypto_alg *alg,
|
|
const struct crypto_type *frontend)
|
|
{
|
|
char *mem;
|
|
struct crypto_tfm *tfm = NULL;
|
|
unsigned int tfmsize;
|
|
unsigned int total;
|
|
int err = -ENOMEM;
|
|
|
|
tfmsize = frontend->tfmsize;
|
|
total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
|
|
|
|
mem = kzalloc(total, GFP_KERNEL);
|
|
if (mem == NULL)
|
|
goto out_err;
|
|
|
|
tfm = (struct crypto_tfm *)(mem + tfmsize);
|
|
tfm->__crt_alg = alg;
|
|
|
|
err = frontend->init_tfm(tfm);
|
|
if (err)
|
|
goto out_free_tfm;
|
|
|
|
if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
|
|
goto cra_init_failed;
|
|
|
|
goto out;
|
|
|
|
cra_init_failed:
|
|
crypto_exit_ops(tfm);
|
|
out_free_tfm:
|
|
if (err == -EAGAIN)
|
|
crypto_shoot_alg(alg);
|
|
kfree(mem);
|
|
out_err:
|
|
mem = ERR_PTR(err);
|
|
out:
|
|
return mem;
|
|
}
|
|
EXPORT_SYMBOL_GPL(crypto_create_tfm);
|
|
|
|
struct crypto_alg *crypto_find_alg(const char *alg_name,
|
|
const struct crypto_type *frontend,
|
|
u32 type, u32 mask)
|
|
{
|
|
struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
|
|
crypto_alg_mod_lookup;
|
|
|
|
if (frontend) {
|
|
type &= frontend->maskclear;
|
|
mask &= frontend->maskclear;
|
|
type |= frontend->type;
|
|
mask |= frontend->maskset;
|
|
|
|
if (frontend->lookup)
|
|
lookup = frontend->lookup;
|
|
}
|
|
|
|
return lookup(alg_name, type, mask);
|
|
}
|
|
EXPORT_SYMBOL_GPL(crypto_find_alg);
|
|
|
|
/*
|
|
* crypto_alloc_tfm - Locate algorithm and allocate transform
|
|
* @alg_name: Name of algorithm
|
|
* @frontend: Frontend algorithm type
|
|
* @type: Type of algorithm
|
|
* @mask: Mask for type comparison
|
|
*
|
|
* crypto_alloc_tfm() will first attempt to locate an already loaded
|
|
* algorithm. If that fails and the kernel supports dynamically loadable
|
|
* modules, it will then attempt to load a module of the same name or
|
|
* alias. If that fails it will send a query to any loaded crypto manager
|
|
* to construct an algorithm on the fly. A refcount is grabbed on the
|
|
* algorithm which is then associated with the new transform.
|
|
*
|
|
* The returned transform is of a non-determinate type. Most people
|
|
* should use one of the more specific allocation functions such as
|
|
* crypto_alloc_blkcipher.
|
|
*
|
|
* In case of error the return value is an error pointer.
|
|
*/
|
|
void *crypto_alloc_tfm(const char *alg_name,
|
|
const struct crypto_type *frontend, u32 type, u32 mask)
|
|
{
|
|
void *tfm;
|
|
int err;
|
|
|
|
for (;;) {
|
|
struct crypto_alg *alg;
|
|
|
|
alg = crypto_find_alg(alg_name, frontend, type, mask);
|
|
if (IS_ERR(alg)) {
|
|
err = PTR_ERR(alg);
|
|
goto err;
|
|
}
|
|
|
|
tfm = crypto_create_tfm(alg, frontend);
|
|
if (!IS_ERR(tfm))
|
|
return tfm;
|
|
|
|
crypto_mod_put(alg);
|
|
err = PTR_ERR(tfm);
|
|
|
|
err:
|
|
if (err != -EAGAIN)
|
|
break;
|
|
if (signal_pending(current)) {
|
|
err = -EINTR;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return ERR_PTR(err);
|
|
}
|
|
EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
|
|
|
|
/*
|
|
* crypto_destroy_tfm - Free crypto transform
|
|
* @mem: Start of tfm slab
|
|
* @tfm: Transform to free
|
|
*
|
|
* This function frees up the transform and any associated resources,
|
|
* then drops the refcount on the associated algorithm.
|
|
*/
|
|
void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
|
|
{
|
|
struct crypto_alg *alg;
|
|
|
|
if (unlikely(!mem))
|
|
return;
|
|
|
|
alg = tfm->__crt_alg;
|
|
|
|
if (!tfm->exit && alg->cra_exit)
|
|
alg->cra_exit(tfm);
|
|
crypto_exit_ops(tfm);
|
|
crypto_mod_put(alg);
|
|
kzfree(mem);
|
|
}
|
|
EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
|
|
|
|
int crypto_has_alg(const char *name, u32 type, u32 mask)
|
|
{
|
|
int ret = 0;
|
|
struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
|
|
|
|
if (!IS_ERR(alg)) {
|
|
crypto_mod_put(alg);
|
|
ret = 1;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(crypto_has_alg);
|
|
|
|
MODULE_DESCRIPTION("Cryptographic core API");
|
|
MODULE_LICENSE("GPL");
|