On 18.12.2013 15:33, Reco wrote: > Hello, list. > > I was pointed here by maintainer of libvirt package in Debian, Guido > Günther. For the sake of completeness, the original bug report can be > viewed at this link: > > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732394 > > To sum up the bug report, current implementation of > virInitctlSetRunLevel function (src/util/virinitctl.c) lacks any sanity > checks before writing to container's /dev/initctl. In the absence of > such checks, libvirtd can be easily tricked to write runlevel check > request to an arbitrary main hosts' file (including > hosts' /run/initctl, as described in the bug report). All it takes is > one symlink in place of containers' /dev/initctl. > > I've checked current libvirtd's git, and it seems to me that the > problem is still here. > > Attached to this letter is a patch which tries to mitigate the issue by > checking whenever container's /dev/initctl is a pipe actually. > > Sincerely yours, Reco > > PS I'm not subscribed to this list, in case of further questions please > CC me. > > > > -- > libvir-list mailing list > libvir-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/libvir-list > [Pasting the patch here] > --- a/src/util/virinitctl.c 2013-12-18 11:13:10.078432196 +0400 > +++ b/src/util/virinitctl.c 2013-12-18 11:26:50.000000000 +0400 > @@ -24,7 +24,10 @@ > #include <config.h> > > #include <sys/param.h> > +#include <sys/types.h> > +#include <sys/stat.h> > #include <fcntl.h> > +#include <unistd.h> > > #include "internal.h" > #include "virinitctl.h" > @@ -122,6 +125,7 @@ > int fd = -1; > char *path = NULL; > int ret = -1; > + struct stat attrs; > > memset(&req, 0, sizeof(req)); > > @@ -139,7 +143,10 @@ > return -1; > } > > - if ((fd = open(path, O_WRONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY)) < 0) { > + if (lstat(path, &attrs) == -1) > + goto cleanup; While the part above looks okay, I think we should report error if the /dev/initctl is not a pipe. Moreover, with your approach, if it's really not a pipe, we don't call open() and proceed to safewrite(-1, ...) at line 153 which will report EBADF error. > + > + if ((attrs.st_mode & S_IFIFO) && (fd = open(path, O_WRONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY)) < 0) { > if (errno == ENOENT) { > ret = 0; > goto cleanup Missing ';' at EOL ^^^ - I guess you missed that during copy-paste. Looking forward to v2. BTW: consider using git when sending patches. I couldn't really apply this patch via 'git am'. http://libvirt.org/hacking.html#patches Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list