From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Faojg-00037C-DB for qemu-devel@nongnu.org; Tue, 02 May 2006 02:51:52 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Faojf-00036z-Mv for qemu-devel@nongnu.org; Tue, 02 May 2006 02:51:52 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Faojf-00036w-HM for qemu-devel@nongnu.org; Tue, 02 May 2006 02:51:51 -0400 Received: from [213.205.33.42] (helo=mail-relay-2.tiscali.it) by monty-python.gnu.org with esmtp (Exim 4.52) id 1Faojl-0003vS-9J for qemu-devel@nongnu.org; Tue, 02 May 2006 02:51:57 -0400 Received: from c1358217.kevquinn.com (84.222.86.168) by mail-relay-2.tiscali.it (7.3.104) id 443AD4620024A8D1 for qemu-devel@nongnu.org; Tue, 2 May 2006 08:51:49 +0200 Date: Tue, 2 May 2006 08:55:04 +0200 From: "Kevin F. Quinn" Subject: Re: [Qemu-devel] bug report : kqemu and self-writing code Message-ID: <20060502085504.66479ac3@c1358217.kevquinn.com> In-Reply-To: <44567DD2.8040708@bellard.org> References: <200605012153.51699.even.rouault@mines-paris.org> <44567DD2.8040708@bellard.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Looks like SELinux to me. Even - you should raise it with whoever writes your policy. On Mon, 01 May 2006 23:29:54 +0200 Fabrice Bellard wrote: > Are you sure that the bug is really in kqemu ? It is possible that > your guest kernel implements a security system which prevents self > modifying code using segment limits which QEMU does not check (but > kqemu checks them !). > > Regards, > > Fabrice. > > Even Rouault wrote: > > Guest OS : Linux 2.6.15-1.2054_FC5 i686 (Fedora Core 5 i386) > > Host OS: Linux 2.6.12-10-amd64-k8 #1 x86_64 (Ubuntu 5.10 amd64) > > QEMU Version : today CVS compiled with kqemu support > > KQEMU : 1.3.0pre6 > > Binary used : qemu-system-x86-64 (so kqemu user-mode is used) > > > > I'm running the simple C code attached. With kqemu user-mode, this > > fails (sigsegv) with the following warning in dmesg : > > > > audit(1146505373.813:12): avc: denied { execheap } for pid=1860 > > comm="selfmodifying scontext=user_u:system_r:unconfined_t:s0 > > tcontext=user_u:system_r:unconfined_t:s0 tclass=process > > Erreur de segmentation > > > > Without kqemu enabled, it runs fine. > > > > > > > > ------------------------------------------------------------------------ > > > > #define _XOPEN_SOURCE 600 > > #include > > #include > > #include > > #include > > > > int main(int argc, char** argv) > > { > > int pagesize = getpagesize(); > > unsigned char* addr = NULL; > > posix_memalign((void**)&addr, pagesize, pagesize); > > mprotect(addr, pagesize, PROT_WRITE | PROT_READ | PROT_EXEC); > > addr[0] = 0x8b; addr[1] = 0x44; addr[2] = 0x24; addr[3] = > > 0x04; /* mov 0x4(%esp),%eax */ addr[4] = 0x83; addr[5] = 0xc0; > > addr[6] = 0x01; /* add $0x1,%eax */ addr[7] = 0xc3; /* ret */ > > > > printf("10+1=%d\n", ((int (*)(int))addr)(10)); > > free(addr); > > return 0; > > } > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Qemu-devel mailing list > > Qemu-devel@nongnu.org > > http://lists.nongnu.org/mailman/listinfo/qemu-devel > > > > _______________________________________________ > Qemu-devel mailing list > Qemu-devel@nongnu.org > http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Kevin F. Quinn