Re: [libvirt] [PATCH] rpc: avoid ssh interpreting malicious hostname as arguments

Inspired by the recent GIT / Mercurial security flaws (http://blog.recurity-labs.com/2017-08-10/scm-vulns), consider someone/something manages to feed libvirt a bogus URI such as:

virsh -c qemu+ssh://-oProxyCommand=gnome-calculator/system In this case, the hosname "-oProxyCommand=gnome-calculator" will get interpreted as an argument to ssh, not a hostname. Fortunately, due to the set of args we have following the hostname, SSH will then interpret our bit of shell script that runs 'nc' on the remote host as a cipher name, which is clearly invalid. This makes ssh exit during argv parsing and so it never tries to run gnome-calculator. We are lucky this time, but lets be more paranoid, by using '--' to explicitly tell SSH when it has finished seeing command line options. This forces it to interpret "-oProxyCommand=gnome-calculator" as a hostname, and thus see a fail from hostname lookup. Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/rpc/virnetsocket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/rpc/virnetsocket.c b/src/rpc/virnetsocket.c index d228c8a8c..23089afef 100644 --- a/src/rpc/virnetsocket.c +++ b/src/rpc/virnetsocket.c @@ -868,7 +868,7 @@ int virNetSocketNewConnectSSH(const char *nodename, if (!netcat) netcat = "nc"; - virCommandAddArgList(cmd, nodename, "sh", "-c", NULL); + virCommandAddArgList(cmd, "--", nodename, "sh", "-c", NULL); virBufferEscapeShell(&buf, netcat); if (virBufferCheckError(&buf) < 0) {