| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CAGXu5jJOBqpGG_cdtDN0cTjEqWDHx-=u4sc=5mMD7_fxZnH7fQ@mail.gmail.com>
Date: Wed, 17 Oct 2018 21:44:32 -0700
From: Kees Cook <keescook@...omium.org>
To: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc: Joel Fernandes <joel@...lfernandes.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pstore: Refactor compression initialization
On Wed, Oct 17, 2018 at 9:42 PM, Sai Prakash Ranjan
<saiprakash.ranjan@...eaurora.org> wrote:
> On 10/18/2018 7:00 AM, Joel Fernandes wrote:
> On Wed, Oct 17, 2018 at 02:41:24PM -0700, Kees Cook wrote:
>>>
>>> With compression initialization now separated from pstore_register(),
>>> there is no longer a good reason to do compression method selection
>>> during fs init. Instead, merge everything together into the late init.
>>> Additionally cleans up the reporting to be more clear.
>>>
>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>> ---
>>> This patch goes on top of Joel's. I'll have both in linux-next shortly...
>>> ---
>>> fs/pstore/inode.c | 2 --
>>> fs/pstore/internal.h | 3 --
>>> fs/pstore/platform.c | 65 ++++++++++++++++++++++++++++----------------
>>> 3 files changed, 41 insertions(+), 29 deletions(-)
>>>
>>> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
>>> index 5fcb845b9fec..d814723fb27d 100644
>>> --- a/fs/pstore/inode.c
>>> +++ b/fs/pstore/inode.c
>>> @@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
>>> {
>>> int err;
>>> - pstore_choose_compression();
>>> -
>>> /* Create a convenient mount point for people to access pstore */
>>> err = sysfs_create_mount_point(fs_kobj, "pstore");
>>> if (err)
>>> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
>>> index fb767e28aeb2..c029314478fa 100644
>>> --- a/fs/pstore/internal.h
>>> +++ b/fs/pstore/internal.h
>>> @@ -37,7 +37,4 @@ extern bool pstore_is_mounted(void);
>>> extern void pstore_record_init(struct pstore_record *record,
>>> struct pstore_info *psi);
>>> -/* Called during module_init() */
>>> -extern void __init pstore_choose_compression(void);
>>> -
>>> #endif
>>> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
>>> index f09066db2d4d..e4737a5fa68c 100644
>>> --- a/fs/pstore/platform.c
>>> +++ b/fs/pstore/platform.c
>>> @@ -274,36 +274,56 @@ static int pstore_decompress(void *in, void *out,
>>> static void allocate_buf_for_compression(void)
>>> {
>>> + struct crypto_comp *ctx;
>>> + int size;
>>> + char *buf;
>>> +
>>> + /* Skip if not built-in or compression backend not selected yet.
>>> */
>>> if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
>>> return;
>>> + /* Skip if no pstore backend yet or compression init already
>>> done. */
>>> + if (!psinfo || tfm)
>>> + return;
>>> +
>>> if (!crypto_has_comp(zbackend->name, 0, 0)) {
>>> - pr_err("No %s compression\n", zbackend->name);
>>> + pr_err("Unknown compression: %s\n", zbackend->name);
>>> return;
>>> }
>>> - big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
>>> - if (big_oops_buf_sz <= 0)
>>> + size = zbackend->zbufsize(psinfo->bufsize);
>>> + if (size <= 0) {
>>> + pr_err("Invalid compression size for %s: %d\n",
>>> + zbackend->name, size);
>>> return;
>>> + }
>>> - big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
>>> - if (!big_oops_buf) {
>>> - pr_err("allocate compression buffer error!\n");
>>> + buf = kmalloc(size, GFP_KERNEL);
>>> + if (!buf) {
>>> + pr_err("Failed %d byte compression buffer allocation for:
>>> %s\n",
>>> + size, zbackend->name);
>>> return;
>>> }
>>> - tfm = crypto_alloc_comp(zbackend->name, 0, 0);
>>> - if (IS_ERR_OR_NULL(tfm)) {
>>> - kfree(big_oops_buf);
>>> - big_oops_buf = NULL;
>>> - pr_err("crypto_alloc_comp() failed!\n");
>>> + ctx = crypto_alloc_comp(zbackend->name, 0, 0);
>>> + if (IS_ERR_OR_NULL(ctx)) {
>>> + kfree(buf);
>>> + pr_err("crypto_alloc_comp('%s') failed: %ld\n",
>>> zbackend->name,
>>> + PTR_ERR(ctx));
>>> return;
>>> }
>>> +
>>> + /* A non-NULL big_oops_buf indicates compression is available. */
>>> + tfm = ctx;
>>> + big_oops_buf_sz = size;
>>> + big_oops_buf = buf;
>>> +
>>> + pr_info("Using compression: %s\n", zbackend->name);
>>> }
>>> static void free_buf_for_compression(void)
>>> {
>>> - if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
>>> + if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
>>> crypto_free_comp(tfm);
>>> kfree(big_oops_buf);
>>> big_oops_buf = NULL;
>>> @@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list
>>> *unused)
>>> jiffies + msecs_to_jiffies(pstore_update_ms));
>>> }
>>> -void __init pstore_choose_compression(void)
>>> +static int __init pstore_compression_late_init(void)
>>> {
>>> const struct pstore_zbackend *step;
>>> if (!compress)
>>> - return;
>>> + return 0;
>>> + /* Locate desired compression method. */
>>> for (step = zbackends; step->name; step++) {
>>> if (!strcmp(compress, step->name)) {
>>> zbackend = step;
>>> - pr_info("using %s compression\n",
>>> zbackend->name);
>>> - return;
>>> + break;
>>> }
>>> }
>>> -}
>>> -static int __init pstore_compression_late_init(void)
>>> -{
>>> /*
>>> - * Check if any pstore backends registered earlier but did not
>>> allocate
>>> - * for compression because crypto was not ready, if so then
>>> initialize
>>> - * compression.
>>> + * Check if any pstore backends registered earlier but did not
>>> + * initialize compression because crypto was not ready. If so,
>>> + * then initialize compression now.
>>> */
>>> - if (psinfo && !tfm)
>>> - allocate_buf_for_compression();
>>> + allocate_buf_for_compression();
>>
>>
>> We can also get rid of the 'zbackend' global variable since choosing the
>> compression backend and allocating the buffers are done at the same time?
>>
>> Otherwise looks good to me,
>>
>> Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
>>
>
> Tested this on top of Joel's patch, works fine on getting early crash pstore
> dmesg logs, thanks.
>
> Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Awesome! Thanks for testing it. :)
-Kees
--
Kees Cook
Pixel Security
Powered by blists - more mailing lists