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Message-ID: <fe377483-65e2-419a-8590-9d4b60a601bb@huawei.com>
Date: Fri, 27 Sep 2024 16:20:42 +0800
From: chenridong <chenridong@...wei.com>
To: Jarkko Sakkinen <jarkko@...nel.org>, Chen Ridong
<chenridong@...weicloud.com>, <dhowells@...hat.com>, <paul@...l-moore.com>,
<jmorris@...ei.org>, <serge@...lyn.com>
CC: <keyrings@...r.kernel.org>, <linux-security-module@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <James.Bottomley@...senPartnership.com>,
<roberto.sassu@...weicloud.com>
Subject: Re: [PATCH] security/keys: fix slab-out-of-bounds in
key_task_permission
On 2024/9/27 1:08, Jarkko Sakkinen wrote:
> On Thu Sep 26, 2024 at 2:20 PM EEST, chenridong wrote:
>>
>>
>> On 2024/9/26 17:54, Jarkko Sakkinen wrote:
>>> On Thu Sep 26, 2024 at 11:55 AM EEST, Jarkko Sakkinen wrote:
>>>> On Thu Sep 26, 2024 at 11:53 AM EEST, Jarkko Sakkinen wrote:
>>>>> On Thu Sep 26, 2024 at 6:48 AM EEST, Chen Ridong wrote:
>>>>>>
>>>>>> On 2024/9/19 4:57, Jarkko Sakkinen wrote:
>>>>>>> On Wed Sep 18, 2024 at 10:30 AM EEST, Chen Ridong wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2024/9/15 21:59, Jarkko Sakkinen wrote:
>>>>>>>>> On Sun Sep 15, 2024 at 3:55 AM EEST, Chen Ridong wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 2024/9/14 19:33, Jarkko Sakkinen wrote:
>>>>>>>>>>> On Fri Sep 13, 2024 at 10:09 AM EEST, Chen Ridong wrote:
>>>>>>>>>>>> We meet the same issue with the LINK, which reads memory out of bounds:
>>>>>>>>>>>
>>>>>>>>>>> Nit: don't use "we" anywhere".
>>>>>>>>>>>
>>>>>>>>>>> Tbh, I really don't understand the sentence above. I don't what
>>>>>>>>>>> "the same issue with the LINK" really is.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Hello, Jarkko.
>>>>>>>>>> I apologize for any confusion caused.
>>>>>>>>>>
>>>>>>>>>> I've encountered a bug reported by syzkaller. I also found the same bug
>>>>>>>>>> reported at this LINK:
>>>>>>>>>> https://syzkaller.appspot.com/bug?id=68a5e206c2a8e08d317eb83f05610c0484ad10b9.
>>>>>>>>>>
>>>>>>>>>>>> BUG: KASAN: slab-out-of-bounds in __kuid_val include/linux/uidgid.h:36
>>>>>>>>>>>> BUG: KASAN: slab-out-of-bounds in uid_eq include/linux/uidgid.h:63 [inline]
>>>>>>>>>>>> BUG: KASAN: slab-out-of-bounds in key_task_permission+0x394/0x410
>>>>>>>>>>>> security/keys/permission.c:54
>>>>>>>>>>>> Read of size 4 at addr ffff88813c3ab618 by task stress-ng/4362
>>>>>>>>>>>>
>>>>>>>>>>>> CPU: 2 PID: 4362 Comm: stress-ng Not tainted 5.10.0-14930-gafbffd6c3ede #15
>>>>>>>>>>>> Call Trace:
>>>>>>>>>>>> __dump_stack lib/dump_stack.c:82 [inline]
>>>>>>>>>>>> dump_stack+0x107/0x167 lib/dump_stack.c:123
>>>>>>>>>>>> print_address_description.constprop.0+0x19/0x170 mm/kasan/report.c:400
>>>>>>>>>>>> __kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560
>>>>>>>>>>>> kasan_report+0x3a/0x50 mm/kasan/report.c:585
>>>>>>>>>>>> __kuid_val include/linux/uidgid.h:36 [inline]
>>>>>>>>>>>> uid_eq include/linux/uidgid.h:63 [inline]
>>>>>>>>>>>> key_task_permission+0x394/0x410 security/keys/permission.c:54
>>>>>>>>>>>> search_nested_keyrings+0x90e/0xe90 security/keys/keyring.c:793
>>>>>>>>>>>> keyring_search_rcu+0x1b6/0x310 security/keys/keyring.c:922
>>>>>>>>>>>> search_cred_keyrings_rcu+0x111/0x2e0 security/keys/process_keys.c:459
>>>>>>>>>>>> search_process_keyrings_rcu+0x1d/0x310 security/keys/process_keys.c:544
>>>>>>>>>>>> lookup_user_key+0x782/0x12e0 security/keys/process_keys.c:762
>>>>>>>>>>>> keyctl_invalidate_key+0x20/0x190 security/keys/keyctl.c:434
>>>>>>>>>>>> __do_sys_keyctl security/keys/keyctl.c:1978 [inline]
>>>>>>>>>>>> __se_sys_keyctl+0x1de/0x5b0 security/keys/keyctl.c:1880
>>>>>>>>>>>> do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46
>>>>>>>>>>>> entry_SYSCALL_64_after_hwframe+0x67/0xd1
>>>>>>>>>>>>
>>>>>>>>>>>> However, we can't reproduce this issue.
>>>>>>>>>>>
>>>>>>>>>>> "The issue cannot be easily reproduced but by analyzing the code
>>>>>>>>>>> it can be broken into following steps:"
>>>>>>>>>>
>>>>>>>>>> Thank you for your correction.
>>>>>>>>>> Does this patch address the issue correctly? Is this patch acceptable?
>>>>>>>>>
>>>>>>>>> I only comment new patch versions so not giving any promises but I can
>>>>>>>>> say that it is I think definitely in the correct direction :-)
>>>>>>>>>
>>>>>>>>> BR, Jarkko
>>>>>>>>
>>>>>>>> Hello, Jarkko. I have reproduced this issue. It can be reproduced by
>>>>>>>> following these steps:
>>>>>>>>
>>>>>>>> 1. Add the helper patch.
>>>>>>>>
>>>>>>>> @@ -205,6 +205,9 @@ static void hash_key_type_and_desc(struct
>>>>>>>> keyring_index_key *index_key)
>>>>>>>> else if (index_key->type == &key_type_keyring && (hash &
>>>>>>>> fan_mask) != 0)
>>>>>>>> hash = (hash + (hash << level_shift)) & ~fan_mask;
>>>>>>>> index_key->hash = hash;
>>>>>>>> + if ((index_key->hash & 0xff) == 0xe6) {
>>>>>>>> + pr_err("hash_key_type_and_desc: type %s %s
>>>>>>>> 0x%x\n", index_key->type->name, index_key->description, index_key->hash);
>>>>>>>> + }
>>>>>>>> }
>>>>>>>>
>>>>>>>> 2. Pick up the inputs whose hash is xxe6 using the following cmd. If a
>>>>>>>> key's hash is xxe6, it will be printed.
>>>>>>>>
>>>>>>>> for ((i=0; i<=10000; i++)); do ./test_key user user$i "Some payload"; done
>>>>>>>>
>>>>>>>> You have complile test_key whith following code.
>>>>>>>>
>>>>>>>> #include <sys/types.h>
>>>>>>>> #include <keyutils.h>
>>>>>>>> #include <stdint.h>
>>>>>>>> #include <stdio.h>
>>>>>>>> #include <stdlib.h>
>>>>>>>> #include <string.h>
>>>>>>>>
>>>>>>>> int
>>>>>>>> main(int argc, char *argv[])
>>>>>>>> {
>>>>>>>> key_serial_t key;
>>>>>>>>
>>>>>>>> if (argc != 4) {
>>>>>>>> fprintf(stderr, "Usage: %s type description payload\n",
>>>>>>>> argv[0]);
>>>>>>>> exit(EXIT_FAILURE);
>>>>>>>> }
>>>>>>>>
>>>>>>>> key = add_key(argv[1], argv[2], argv[3], strlen(argv[3]),
>>>>>>>> KEY_SPEC_SESSION_KEYRING);
>>>>>>>> if (key == -1) {
>>>>>>>> perror("add_key");
>>>>>>>> exit(EXIT_FAILURE);
>>>>>>>> }
>>>>>>>>
>>>>>>>> printf("Key ID is %jx\n", (uintmax_t) key);
>>>>>>>>
>>>>>>>> exit(EXIT_SUCCESS);
>>>>>>>> }
>>>>>>>>
>>>>>>>>
>>>>>>>> 3. Have more than 32 inputs now. their hashes are xxe6.
>>>>>>>> eg.
>>>>>>>> hash_key_type_and_desc: type user user438 0xe3033fe6
>>>>>>>> hash_key_type_and_desc: type user user526 0xeb7eade6
>>>>>>>> ...
>>>>>>>> hash_key_type_and_desc: type user user9955 0x44bc99e6
>>>>>>>>
>>>>>>>> 4. Reboot and add the keys obtained from step 3.
>>>>>>>> When adding keys to the ROOT that their hashes are all xxe6, and up to
>>>>>>>> 16, the ROOT has keys with hashes that are not xxe6 (e.g., slot 0), so
>>>>>>>> the keys are dissimilar. The ROOT will then split NODE A without using a
>>>>>>>> shortcut. When NODE A is filled with keys that have hashes of xxe6, the
>>>>>>>> keys are similar. NODE A will split with a shortcut.
>>>>>>>>
>>>>>>>> As my analysis, if a slot of the root is a shortcut(slot 6), it may be
>>>>>>>> mistakenly be transferred to a key*, leading to an read out-of-bounds read.
>>>>>>>>
>>>>>>>> NODE A
>>>>>>>> +------>+---+
>>>>>>>> ROOT | | 0 | xxe6
>>>>>>>> +---+ | +---+
>>>>>>>> xxxx | 0 | shortcut : : xxe6
>>>>>>>> +---+ | +---+
>>>>>>>> xxe6 : : | | | xxe6
>>>>>>>> +---+ | +---+
>>>>>>>> | 6 |---+ : : xxe6
>>>>>>>> +---+ +---+
>>>>>>>> xxe6 : : | f | xxe6
>>>>>>>> +---+ +---+
>>>>>>>> xxe6 | f |
>>>>>>>> +---+
>>>>>>>>
>>>>>>>> 5. cat /proc/keys. and the issue is reproduced.
>>>>>>>
>>>>>>> Hi, I'll try to run through your procedure next week and give my comments.
>>>>>>> Thanks for doing this.
>>>>>>>
>>>>>>> BR, Jarkko
>>>>>>
>>>>>> Hi, Jarkko, have you run these procedure?
>>>>>> I have tested this patch with LTP and a pressure test(stress-ng --key),
>>>>>> and this patch have fixed this issue. Additionally, no new bugs have
>>>>>> been found so far.
>>>>>>
>>>>>> I am looking forward to your reply.
>>>>>>
>>>>>> Best regards,
>>>>>> Ridong
>>>>>
>>>>> Nope because we are apparently stuck with release critical bug:
>>>>>
>>>>> https://lore.kernel.org/linux-integrity/D4EPMF7G3E05.1VHS9CVG3DZDE@kernel.org/T/#t
>>>>>
>>>>> Might take several weeks before I look into this.
>>>>
>>>> I was expecting to send a PR early this week since the patch set
>>>> addresses the issue so thus wrong estimation.
>>>
>>> I asked David if he could look into this.
>>>
>>> BR, Jarkko
>>
>> Thank you very much.
>
> Further, I'm switching jobs. Tomorrow is my last day in the current
> job and next week starting a new job so given all these circumastances
> I rather look into this properly hopefully latest after my rc2 PR is
> out, rather than rushing.
>
> In a normal status quo situation this would not be such a huge issue.
>
> Similarly, for the performance bug I want to review James' comments
> etc with time and bake v6 that hopefully satisfies all the
> stateholders.
>
> So thank you for understanding, and I appreciate the work you've done
> on this. I.e. not ignoring this :-)
>
> BR, Jarkko
>
> BR, Jarkko
I am happy to fix this issue. I am also looking forward to your reply.
If this patch is acceptable, I will send a patch to update the commit
message you have mentioned.
Best regards,
Ridong
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