linux-kernel - Re: [PATCH] proc: Use seq_read

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Message-ID: <20210428130339.GA30329@lst.de>
Date:   Wed, 28 Apr 2021 15:03:39 +0200
From:   Christoph Hellwig <hch@....de>
To:     Arusekk <arek_koz@...pl>
Cc:     Christoph Hellwig <hch@....de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Alexey Dobriyan <adobriyan@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] proc: Use seq_read_iter where possible

On Wed, Apr 28, 2021 at 03:02:13PM +0200, Arusekk wrote:
> The instructions at the entry point of the executable being inspected.
> The flow of the tool:
> - parse ELF headers of the binary to be inspected,
> - locate its entry point position in the file,
> - write short code at the location (this short code has used sendfile so far),
> - execute the patched binary,
> - parse the output and extract information about the relevant mappings.
> This can be seen as equivalent to setting LD_TRACE_LOADED_OBJECTS,
> but also works for static binaries, and is a bit safer.
> 
> The problem was reported at:
> https://github.com/Gallopsled/pwntools/issues/1871

Oh, this patches just the userspace binarz, ok.

> > Linus did object to blindly switching over all instances.
> 
> I know, I read that, but I thought that pointing a real use case, combined 
> with the new interface being used all throughout the other code, might be 
> convincing.
> I would be happy with only changing the f_ops of /proc/.../maps, even if only 
> on MMU-enabled systems, but I thought that consistence would be better.
> This is my first time contributing to Linux, so I am very sorry for any wrong 
> assumptions, and glad to learn more.

Unless Linus changed his mind just patching the file you care about for
now seems like the best idea.