maintainership question about nfs-utils/util/mount

maintainership question about nfs-utils/util/mount

[Chuck Lever]

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I'm looking at nfs-utils/utils/mount in order to patch in support for 
passing a string of mount options to the kernel instead of an 
nfs_mount_data.

In mount.c, main() invokes nfsmount() in nfsmount.c.  nfsmount() defines 
a structure on the stack called "data", then returns a pointer to "data" 
which is then passed to the kernel by main().

I think the only way this continues to work is that there are three 1024 
character buffers defined in nfsmount()'s stack frame before "data," 
which places "data" far enough up the stack that subsequent function 
calls in main() don't smash it.

Although this doesn't cause bad behavior today, it needs to be fixed to 
prevent future changes from breaking things badly.

Also found an interesting error message in here:

   permission died - no match for fstab

Should probably be "permission denied".  I'm not really sure what "no 
match for fstab" means, but looking at the context, this message appears 
if a non-root user tries to mount something that isn't already listed in 
/etc/fstab.

What's the current blessed procedure for sending patches and fixes for 
this particular code?  Mail to agud@redhat.com (last touch rule, and 
author of mount.c) is rejected.

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Re: maintainership question about nfs-utils/util/mount

[Jeff Layton]

On Fri, 06 Jul 2007 16:13:23 -0400
Chuck Lever <chuck.lever@oracle.com> wrote:

> I'm looking at nfs-utils/utils/mount in order to patch in support for 
> passing a string of mount options to the kernel instead of an 
> nfs_mount_data.
> 
> In mount.c, main() invokes nfsmount() in nfsmount.c.  nfsmount() defines 
> a structure on the stack called "data", then returns a pointer to "data" 
> which is then passed to the kernel by main().
> 
> I think the only way this continues to work is that there are three 1024 
> character buffers defined in nfsmount()'s stack frame before "data," 
> which places "data" far enough up the stack that subsequent function 
> calls in main() don't smash it.
> 
> Although this doesn't cause bad behavior today, it needs to be fixed to 
> prevent future changes from breaking things badly.
> 

In the git tree I'm looking at, "data" is declared static. Does that protect
it from getting smashed?

> Also found an interesting error message in here:
> 
>    permission died - no match for fstab
> 
> Should probably be "permission denied".  I'm not really sure what "no 
> match for fstab" means, but looking at the context, this message appears 
> if a non-root user tries to mount something that isn't already listed in 
> /etc/fstab.
> 
> What's the current blessed procedure for sending patches and fixes for 
> this particular code?  Mail to agud@redhat.com (last touch rule, and 
> author of mount.c) is rejected.
> 


-- 
Jeff Layton <jlayton@redhat.com>

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Re: maintainership question about nfs-utils/util/mount

[Chuck Lever]

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Jeff Layton wrote:
> On Fri, 06 Jul 2007 16:13:23 -0400
> Chuck Lever <chuck.lever@oracle.com> wrote:
> 
>> I'm looking at nfs-utils/utils/mount in order to patch in support for 
>> passing a string of mount options to the kernel instead of an 
>> nfs_mount_data.
>>
>> In mount.c, main() invokes nfsmount() in nfsmount.c.  nfsmount() defines 
>> a structure on the stack called "data", then returns a pointer to "data" 
>> which is then passed to the kernel by main().
>>
>> I think the only way this continues to work is that there are three 1024 
>> character buffers defined in nfsmount()'s stack frame before "data," 
>> which places "data" far enough up the stack that subsequent function 
>> calls in main() don't smash it.
>>
>> Although this doesn't cause bad behavior today, it needs to be fixed to 
>> prevent future changes from breaking things badly.
>>
> 
> In the git tree I'm looking at, "data" is declared static. Does that protect
> it from getting smashed?

Yes.  For some reason, I missed that entirely the first time I looked at 
it.  Notice that nfs4_mount_data is also declared static in nfs4mount.c.

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