linux-kernel - Re: [PATCH] debugfs show actual source in /proc/mounts

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] [day] [month] [year] [list]

Message-ID: <alpine.WNT.2.20.2408302142040.2560@CLUIJ>
Date: Fri, 30 Aug 2024 21:51:00 -0600 (Mountain Daylight Time)
From: Marc Aurèle La France <tsi@...oix.net>
To: Eric Sandeen <sandeen@...hat.com>
cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        David Howells <dhowells@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] debugfs show actual source in /proc/mounts

On Fri, 2024-Aug-30, Eric Sandeen wrote:
> On 8/29/24 10:44 PM, Marc Aurèle La France wrote:
>> After commit 0c07c273a5fe ("debugfs: continue to ignore unknown mount
>> options"), debugfs displays "none" in /proc/mounts instead of the actual
>> source.  Fix this by recognising its "source" mount option.

>> Signed-off-by: Marc Aurèle La France <tsi@...oix.net>
>> Fixes: 0c07c273a5fe ("debugfs: continue to ignore unknown mount options")
>> Cc: stable@...r.kernel.org # 6.10.x: 9f111059e725: fs_parse: add uid & gid option option parsing helpers
>> Cc: stable@...r.kernel.org # 6.10.x: 49abee5991e1: debugfs: Convert to new uid/gid option parsing helpers

>> diff -NRapruz -X /etc/diff.excludes linux-6.11.0-rc2/fs/debugfs/inode.c devel-6.11.0-rc2/fs/debugfs/inode.c
>> --- linux-6.11.0-rc5/fs/debugfs/inode.c
>> +++ devel-6.11.0-rc5/fs/debugfs/inode.c
>> @@ -89,12 +89,14 @@ enum {
>>  	Opt_uid,
>>  	Opt_gid,
>>  	Opt_mode,
>> +	Opt_source,
>>  };
>>
>>  static const struct fs_parameter_spec debugfs_param_specs[] = {
>>  	fsparam_gid	("gid",		Opt_gid),
>>  	fsparam_u32oct	("mode",	Opt_mode),
>>  	fsparam_uid	("uid",		Opt_uid),
>> +	fsparam_string	("source",	Opt_source),
>>  	{}
>>  };
>>
>> @@ -126,6 +128,12 @@ static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
>>  	case Opt_mode:
>>  		opts->mode = result.uint_32 & S_IALLUGO;
>>  		break;

> Sorry for missing your earlier question, I was thinking that perhaps a
> comment along the lines of this would be helpful:

> 	/*
> 	 * Because debugfs accepts all mount options and indicates
> 	 * success even for unknown options, we must process "source"
> 	 * ourselves here; the vfs won't do it for us.
> 	 */

I disagree.  It is the new mount API that treats the source as a mount
"option", so to speak, despite what `man mount` says.  Therefore the
consequences of that change should be documented in the API, not here nor
in any other fs.  Besides, there's already too much echo in the comments
around this code.

>> +	case Opt_source:
>> +		if (fc->source)
>> +			return invalfc(fc, "Multiple sources specified");
>> +		fc->source = param->string;
>> +		param->string = NULL;
>> +		break;

> but I suppose it's not a big deal unless others think it is.

> Reviewed-by: Eric Sandeen <sandeen@...hat.com>

Thanks.

Marc.