From: "Kevin F. Quinn" <ml@kevquinn.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] bug report : kqemu and self-writing code
Date: Tue, 2 May 2006 08:55:04 +0200 [thread overview]
Message-ID: <20060502085504.66479ac3@c1358217.kevquinn.com> (raw)
In-Reply-To: <44567DD2.8040708@bellard.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 <fabrice@bellard.org> 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 <sys/mman.h>
> > #include <unistd.h>
> > #include <stdlib.h>
> > #include <stdio.h>
> >
> > 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
next prev parent reply other threads:[~2006-05-02 6:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-01 19:53 [Qemu-devel] bug report : kqemu and self-writing code Even Rouault
2006-05-01 21:29 ` Fabrice Bellard
2006-05-01 22:08 ` Even Rouault
2006-05-02 6:55 ` Kevin F. Quinn [this message]
2006-05-02 9:13 ` G Portokalidis
2006-05-02 21:04 ` Fabrice Bellard
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060502085504.66479ac3@c1358217.kevquinn.com \
--to=ml@kevquinn.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).