oss-sec mailing list archives
Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size
From: Roland McGrath <roland () redhat com>
Date: Tue, 14 Sep 2010 16:04:11 -0700 (PDT)
userland could never rely on the kernel's policy at all since get_arg_page could have failed for more reasons than overstepping the currently hardcoded ARG_MAX check in there.
I don't see how it could fail except for OOM cases where get_user_pages() failed rather than blocking. Is that what you mean?
so what AT_ARGMAX would buy us is to allow the kernel policy to change over time, but it's never been about guarantees, whether POSIX wants such a thing or not.
I understand the motivation for an explicit mechanism for the kernel to tell userland its limit. Since the kernel policy today depends on something that can change between execs, AT_ARGMAX is inadequate for that purpose for today's policy, let alone any future different policy.
The information that these give is about the conditions at startup. That's what they mean to userland, and userland only uses them to know the situation before it has made any calls. The definition of AT_EUID is "effective user ID at program startup", and that fact does not change.just for my own curiosity, where does this definition come from?
You mean documentation? I'm not really sure if there is any for that. But it's the inherent definition of auxv that all its information can only be about the conditions at program startup. Thanks, Roland
Current thread:
- [PATCH 0/3] execve argument-copying fixes, (continued)
- [PATCH 0/3] execve argument-copying fixes Roland McGrath (Sep 07)
- [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 07)
- Message not available
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size KOSAKI Motohiro (Sep 09)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 10)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size KOSAKI Motohiro (Sep 10)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 11)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 15)
- Message not available
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 10)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 11)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 14)
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size pageexec (Sep 14)
- Message not available
- Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath (Sep 10)
- [PATCH 2/3] execve: improve interactivity with large arguments Roland McGrath (Sep 07)
- [PATCH 3/3] execve: make responsive to SIGKILL with large arguments Roland McGrath (Sep 07)
- Re: [PATCH 0/3] execve argument-copying fixes KOSAKI Motohiro (Sep 07)
- [PATCH 0/2] execve memory exhaust of argument-copying fixes KOSAKI Motohiro (Sep 09)