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+++ This bug was initially created as a clone of Bug #1791679 +++
+++ This bug was initially created as a clone of Bug #1791677 +++
Description of problem:
Upstream libslirp has disabled emulation of the tcp programs like ftp/IRC etc. in user-mode SLiRP networking since v4.1.0.
-> https://gitlab.freedesktop.org/slirp/libslirp/commit/07c2a44b67e219ac14207f7a1b33704e1312cf91
emu: disable by default
tcp_emu() is known to have caused several CVEs, and not useful today in most cases.
https://nvd.nist.gov/vuln/detail/CVE-2019-6778https://nvd.nist.gov/vuln/detail/CVE-2019-9824
The feature can be still enabled by setting SlirpConfig.enable_emu to
true.
* Please include this patch in the qemu-kvm package versions of RHEL too.
* It'll probably be better to disable user-mode SLiRP networking itself in qemu-kvm.
ie. compile qemu-kvm package with '--disable-slirp' configure option.
--- Additional comment from RHEL Program Management on 2020-01-16 11:13:22 UTC ---
Since this bug report was entered in Red Hat Bugzilla, the release flag has been set to ? to ensure that it is properly evaluated for this release.
Hello Marc-Andre Lureau
I was using the reproduce steps from https://bugzilla.redhat.com/show_bug.cgi?id=1791677#c11, But I got the same output "1234 , 4321 " with the old-unfix-qemu qemu-kvm-0.12.1.2-2.506.el6_10.6. could you help check my steps.
Steps:
1. boot up guest with "/usr/libexec/qemu-kvm -enable-kvm -nographic -m 2048 -net user,hostfwd=tcp::2222-:22 -net nic,model=virtio /root/rhel610-64-virtio.qcow2"
2. nc -l 127.0.0.1 113 on host
3. run on guest
nc -C 10.0.2.2 113
1234 , 4321
Results:
With qemu-kvm-0.12.1.2-2.506.el6_10.6:
# nc -l 127.0.0.1 113
1234 , 4321
With qemu-kvm-0.12.1.2-2.506.el6_10.7:
# nc -l 127.0.0.1 113
1234 , 4321
Comment 6Marc-Andre Lureau
2020-03-30 10:54:47 UTC
(In reply to Quan Wenli from comment #5)
> 1. boot up guest with "/usr/libexec/qemu-kvm -enable-kvm -nographic -m 2048
> -net user,hostfwd=tcp::2222-:22 -net nic,model=virtio
> /root/rhel610-64-virtio.qcow2"
> 2. nc -l 127.0.0.1 113 on host
> 3. run on guest
> nc -C 10.0.2.2 113
> 1234 , 4321
>
> Results:
>
> With qemu-kvm-0.12.1.2-2.506.el6_10.6:
>
> # nc -l 127.0.0.1 113
> 1234 , 4321
>
> With qemu-kvm-0.12.1.2-2.506.el6_10.7:
> # nc -l 127.0.0.1 113
> 1234 , 4321
That looks correct: the input from the guest is unchanged.
(In reply to Marc-Andre Lureau from comment #6)
> (In reply to Quan Wenli from comment #5)
> > 1. boot up guest with "/usr/libexec/qemu-kvm -enable-kvm -nographic -m 2048
> > -net user,hostfwd=tcp::2222-:22 -net nic,model=virtio
> > /root/rhel610-64-virtio.qcow2"
> > 2. nc -l 127.0.0.1 113 on host
> > 3. run on guest
> > nc -C 10.0.2.2 113
> > 1234 , 4321
> >
> > Results:
> >
> > With qemu-kvm-0.12.1.2-2.506.el6_10.6:
> >
> > # nc -l 127.0.0.1 113
> > 1234 , 4321
> >
> > With qemu-kvm-0.12.1.2-2.506.el6_10.7:
> > # nc -l 127.0.0.1 113
> > 1234 , 4321
>
> That looks correct: the input from the guest is unchanged.
Yes, but according to https://bugzilla.redhat.com/show_bug.cgi?id=1791677#c11, before tcp_emu was disabled, we should get on host: "1234,4321" (without spaces) but we get still "1234 , 4321" with qemu-kvm-0.12.1.2-2.506.el6_10.6
Comment 8Marc-Andre Lureau
2020-03-31 13:26:15 UTC
(In reply to Quan Wenli from comment #7)
> (In reply to Marc-Andre Lureau from comment #6)
> > (In reply to Quan Wenli from comment #5)
> > > 1. boot up guest with "/usr/libexec/qemu-kvm -enable-kvm -nographic -m 2048
> > > -net user,hostfwd=tcp::2222-:22 -net nic,model=virtio
> > > /root/rhel610-64-virtio.qcow2"
> > > 2. nc -l 127.0.0.1 113 on host
> > > 3. run on guest
> > > nc -C 10.0.2.2 113
> > > 1234 , 4321
> > >
> > > Results:
> > >
> > > With qemu-kvm-0.12.1.2-2.506.el6_10.6:
> > >
> > > # nc -l 127.0.0.1 113
> > > 1234 , 4321
> > >
> > > With qemu-kvm-0.12.1.2-2.506.el6_10.7:
> > > # nc -l 127.0.0.1 113
> > > 1234 , 4321
> >
> > That looks correct: the input from the guest is unchanged.
>
> Yes, but according to
> https://bugzilla.redhat.com/show_bug.cgi?id=1791677#c11, before tcp_emu was
> disabled, we should get on host: "1234,4321" (without spaces) but we get
> still "1234 , 4321" with qemu-kvm-0.12.1.2-2.506.el6_10.6
with qemu-kvm-0.12.1.2-2.506.el6_10.6, it works for me.
Make sure you use "nc -C" on client side.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2020:1403