linux-kernel - Re: [tpmdd-devel] [PATCH] TPM: Let the tpm char device be openable multiple times

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]

Date:	Tue, 3 Nov 2009 15:41:58 -0700
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Valdis.Kletnieks@...edu
Cc:	Hal Finney <hal.finney@...il.com>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	srajiv@...ux.vnet.ibm.com
Subject: Re: [tpmdd-devel] [PATCH] TPM: Let the tpm char device be openable
	multiple times

On Tue, Nov 03, 2009 at 01:14:28PM -0500, Valdis.Kletnieks@...edu wrote:
> On Tue, 03 Nov 2009 09:31:55 PST, Hal Finney said:
> > What if you don't want it accessible by user mode apps, you only want
> > your middleware (ie tcs daemon, tcsd) to open it? Will this still
> > allow that to be enforced, so nobody can interfere with tcsd's
> > exclusive access to the device?
> 
> Couldn't tcsd just open the device with O_EXCL? Or am I missing something
> subtle here?

O_EXCL isn't a locking flag...

       O_EXCL Ensure  that  this  call  creates  the file: if this flag is specified in conjunction with O_CREAT, and
              pathname already exists, then open() will fail.  The behavior of O_EXCL is undefined if O_CREAT is  not
              specified.

Jason
--
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/