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Date: Sat, 28 Nov 2015 23:55:23 +0100 From: Richard Weinberger <richard@....at> To: Mickaël Salaün <mic@...ikod.net>, linux-kernel@...r.kernel.org Cc: Jeff Dike <jdike@...toit.com>, Tristan Schmelcher <tschmelcher@...gle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, user-mode-linux-devel@...ts.sourceforge.net, user-mode-linux-user@...ts.sourceforge.net Subject: Re: [PATCH 1/2] um: Set secure access mode for temporary file Am 28.11.2015 um 23:52 schrieb Mickaël Salaün: > > On 28/11/2015 22:40, Richard Weinberger wrote: >> Am 28.11.2015 um 22:32 schrieb Mickaël Salaün: >>> Replace the default insecure mode 0777 with 0700 for temporary file. >>> >>> Prohibit other users to change the executable mapped code. >> >> Hmm, isn't the tmp file already unlinked at this stage? >> > > Yes, but if someone could open it before the unlink e.g. because of the umask (which does not seems to be the case thanks to mkstemp, but remains unspecified [1]), this user should then be able to have write access to the file descriptor/description. Yes, someone can open it before the unlink. But you change the file mode after that. How does it improve the situation? The attacker has already the file handle. Thanks, //richard -- 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/
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