linux-kernel - Re: [PATCH] procfs task exe symlink

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: <8bd0f97a0802160412ve49103cya446b89d8560458b@mail.gmail.com>
Date:	Sat, 16 Feb 2008 07:12:01 -0500
From:	"Mike Frysinger" <vapier.adi@...il.com>
To:	"Matt Helsley" <matthltc@...ibm.com>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Oleg Nesterov" <oleg@...sign.ru>,
	"David Howells" <dhowells@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Christoph Hellwig" <chellwig@...ibm.com>,
	"Al Viro" <viro@...iv.linux.org.uk>,
	"Hugh Dickins" <hugh@...itas.com>, "Bryan Wu" <Bryan.Wu@...log.com>
Subject: Re: [PATCH] procfs task exe symlink

On Feb 6, 2008 8:44 PM, Matt Helsley <matthltc@...ibm.com> wrote:
> The kernel implements readlink of /proc/pid/exe by getting the file from the
> first executable VMA. Then the path to the file is reconstructed and reported as
> the result.
>
> Because of the VMA walk the code is slightly different on nommu systems. This
> patch avoids separate /proc/pid/exe code on nommu systems. Instead of walking
> the VMAs to find the first executable file-backed VMA we store a reference to
> the exec'd file in the mm_struct.
>
> That reference would prevent the filesystem holding the executable file from
> being unmounted even after unmapping the VMAs. So we track the number of
> VM_EXECUTABLE VMAs and drop the new reference when the last one is unmapped.
> This avoids pinning the mounted filesystem.
>
> Andrew, these are the updates I promised. Please consider this patch for
> inclusion in -mm.

mm/nommu.c wasnt compiled tested, it's trivially broken:

> --- linux-2.6.24.orig/mm/nommu.c
> +++ linux-2.6.24/mm/nommu.c
> @@ -960,12 +960,15 @@ unsigned long do_mmap_pgoff(struct file
>         if (!vma)
>                 goto error_getting_vma;
>
>         INIT_LIST_HEAD(&vma->anon_vma_node);
>         atomic_set(&vma->vm_usage, 1);
> -       if (file)
> +       if (file) {
>                 get_file(file);
> +               if (vm_flags & VM_EXECUTABLE)
> +                       added_exe_file_vma(mm);
> +       }
>         vma->vm_file    = file;
>         vma->vm_flags   = vm_flags;
>         vma->vm_start   = addr;
>         vma->vm_end     = addr + len;
>         vma->vm_pgoff   = pgoff;

this function has no variable named "mm"

mm/nommu.c: In function 'do_mmap_pgoff':
mm/nommu.c:968: error: 'mm' undeclared (first use in this function)
mm/nommu.c:968: error: (Each undeclared identifier is reported only once
mm/nommu.c:968: error: for each function it appears in.)
make[1]: *** [mm/nommu.o] Error 1
-mike
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/