Date: Fri, 7 Sep 2012 15:40:42 -0400 From: John Baldwin <jhb@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-current@freebsd.org, Svatopluk Kraus <onwahe@gmail.com> Subject: Re: [patch] mmap() MAP_TEXT implementation (to use for shared libraries) Message-ID: <201209071540.43013.jhb@freebsd.org> In-Reply-To: <20120907184120.GD33100@deviant.kiev.zoral.com.ua> References: <CAFHCsPX6HrCXHA%2BS31Dz9QP8eiwbo21Vzju4K4paohciu2vPTw@mail.gmail.com> <201209071405.28831.jhb@freebsd.org> <20120907184120.GD33100@deviant.kiev.zoral.com.ua>
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On Friday, September 07, 2012 2:41:20 pm Konstantin Belousov wrote: > > I think these would be rare? There's no good reason for anything to write to > > a shared library that I can think of. install(1) does an atomic rename to swap > > in the new libraries already. > > After a second thought, I do not like your proposal as well. +x is set for > shebang scripts, and allowing PROT_EXEC to set VV_TEXT for them means > that such scripts are subject for write denial. Yeah, that's fair. Also, I hunted around to find the description of MAP_TEXT in Solaris 11. It seems from reading that that MAP_TEXT on Solaris isn't used to prevent writes ala VV_TEXT. Instead, it is used as a hint that is apparently used to use superpages for text. -- John Baldwin
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