netdev - Re: [PATCH v4 5/20] lsm: Refactor return value of LSM hook inode_copy_up

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b371cb67-6fa4-499d-b572-496c6938d86d@huaweicloud.com>
Date: Sat, 20 Jul 2024 17:29:35 +0800
From: Xu Kuohai <xukuohai@...weicloud.com>
To: Paul Moore <paul@...l-moore.com>, bpf@...r.kernel.org,
 netdev@...r.kernel.org, linux-security-module@...r.kernel.org,
 linux-kselftest@...r.kernel.org, linux-integrity@...r.kernel.org,
 selinux@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>, Andrii Nakryiko <andrii@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
 Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
 Matt Bobrowski <mattbobrowski@...gle.com>,
 Brendan Jackman <jackmanb@...omium.org>, James Morris <jmorris@...ei.org>,
 "Serge E . Hallyn" <serge@...lyn.com>,
 Khadija Kamran <kamrankhadijadj@...il.com>,
 Casey Schaufler <casey@...aufler-ca.com>,
 Ondrej Mosnacek <omosnace@...hat.com>, Kees Cook <keescook@...omium.org>,
 John Johansen <john.johansen@...onical.com>,
 Lukas Bulwahn <lukas.bulwahn@...il.com>,
 Roberto Sassu <roberto.sassu@...wei.com>,
 Shung-Hsi Yu <shung-hsi.yu@...e.com>, Edward Cree <ecree.xilinx@...il.com>,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>,
 Trond Myklebust <trond.myklebust@...merspace.com>,
 Anna Schumaker <anna@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Stephen Smalley <stephen.smalley.work@...il.com>
Subject: Re: [PATCH v4 5/20] lsm: Refactor return value of LSM hook
 inode_copy_up_xattr

On 7/19/2024 10:08 AM, Paul Moore wrote:
> On Jul 11, 2024 Xu Kuohai <xukuohai@...weicloud.com> wrote:
>>
>> To be consistent with most LSM hooks, convert the return value of
>> hook inode_copy_up_xattr to 0 or a negative error code.
>>
>> Before:
>> - Hook inode_copy_up_xattr returns 0 when accepting xattr, 1 when
>>    discarding xattr, -EOPNOTSUPP if it does not know xattr, or any
>>    other negative error code otherwise.
>>
>> After:
>> - Hook inode_copy_up_xattr returns 0 when accepting xattr, *-ECANCELED*
>>    when discarding xattr, -EOPNOTSUPP if it does not know xattr, or
>>    any other negative error code otherwise.
>>
>> Signed-off-by: Xu Kuohai <xukuohai@...wei.com>
>> ---
>>   fs/overlayfs/copy_up.c            |  6 +++---
>>   security/integrity/evm/evm_main.c |  2 +-
>>   security/security.c               | 12 ++++++------
>>   security/selinux/hooks.c          |  4 ++--
>>   security/smack/smack_lsm.c        |  6 +++---
>>   5 files changed, 15 insertions(+), 15 deletions(-)
> 
> ...
> 
>> diff --git a/security/security.c b/security/security.c
>> index 26eea8f4cd74..12215ca286af 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2675,18 +2675,18 @@ EXPORT_SYMBOL(security_inode_copy_up);
>>    * lower layer to the union/overlay layer.   The caller is responsible for
>>    * reading and writing the xattrs, this hook is merely a filter.
>>    *
>> - * Return: Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP
>> - *         if the security module does not know about attribute, or a negative
>> - *         error code to abort the copy up.
>> + * Return: Returns 0 to accept the xattr, -ECANCELED to discard the xattr,
>> + *         -EOPNOTSUPP if the security module does not know about attribute,
>> + *         or a negative error code to abort the copy up.
>>    */
>>   int security_inode_copy_up_xattr(struct dentry *src, const char *name)
>>   {
>>   	int rc;
>>   
>>   	/*
>> -	 * The implementation can return 0 (accept the xattr), 1 (discard the
>> -	 * xattr), -EOPNOTSUPP if it does not know anything about the xattr or
>> -	 * any other error code in case of an error.
>> +	 * The implementation can return 0 (accept the xattr), -ECANCELED
>> +	 * (discard the xattr), -EOPNOTSUPP if it does not know anything
>> +	 *  about the xattr or any other error code in case of an error.
>>   	 */
> 
> Updating the comment here is good, but considering that we also discuss
> the return value in the function header comment, I think it might be
> better to just remove this comment entirely and leave the function header
> comment as the single source.  Duplicated comments/docs tend to fall out
> of sync and create confusion.
>

OK, will do

>>   	rc = call_int_hook(inode_copy_up_xattr, src, name);
>>   	if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr))
> 
> 
> --
> paul-moore.com
>