| Message ID | 20171013110450.19176-2-ross.lagerwall@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Ross Lagerwall writes ("[PATCH v2 2/2] xentoolcore_restrict_all: Implement for libxenevtchn"):
> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
...
> int osdep_evtchn_open(xenevtchn_handle *xce);
> diff --git a/tools/libs/toolcore/include/xentoolcore.h b/tools/libs/toolcore/include/xentoolcore.h
> index be6c570..ef9c670 100644
> --- a/tools/libs/toolcore/include/xentoolcore.h
> +++ b/tools/libs/toolcore/include/xentoolcore.h
> @@ -31,11 +31,6 @@
> * Arranges that Xen library handles (fds etc.) which are currently held
> * by Xen libraries, can no longer be used other than to affect domid.
> *
> - * Does not prevent effects that amount only to
> - * - denial of service, possibly host-wide, by resource exhaustion etc.
> - * - leak of not-very-interesting metainformation about other domains
> - * eg, specifically, event channel signals relating to other domains
Are we sure that all possible resource exhaustion attacks are now
excluded ?
Ian.
On 10/16/2017 11:55 AM, Ian Jackson wrote: > Ross Lagerwall writes ("[PATCH v2 2/2] xentoolcore_restrict_all: Implement for libxenevtchn"): >> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> > ... >> int osdep_evtchn_open(xenevtchn_handle *xce); >> diff --git a/tools/libs/toolcore/include/xentoolcore.h b/tools/libs/toolcore/include/xentoolcore.h >> index be6c570..ef9c670 100644 >> --- a/tools/libs/toolcore/include/xentoolcore.h >> +++ b/tools/libs/toolcore/include/xentoolcore.h >> @@ -31,11 +31,6 @@ >> * Arranges that Xen library handles (fds etc.) which are currently held >> * by Xen libraries, can no longer be used other than to affect domid. >> * >> - * Does not prevent effects that amount only to >> - * - denial of service, possibly host-wide, by resource exhaustion etc. >> - * - leak of not-very-interesting metainformation about other domains >> - * eg, specifically, event channel signals relating to other domains > > Are we sure that all possible resource exhaustion attacks are now > excluded ? > No, I'm not sure. I'll keep the first point for now.
diff --git a/tools/Rules.mk b/tools/Rules.mk index be92f0a..61515d3 100644 --- a/tools/Rules.mk +++ b/tools/Rules.mk @@ -109,7 +109,7 @@ LDLIBS_libxentoolcore = $(SHDEPS_libxentoolcore) $(XEN_LIBXENTOOLCORE)/libxentoo SHLIB_libxentoolcore = $(SHDEPS_libxentoolcore) -Wl,-rpath-link=$(XEN_LIBXENTOOLCORE) CFLAGS_libxenevtchn = -I$(XEN_LIBXENEVTCHN)/include $(CFLAGS_xeninclude) -SHDEPS_libxenevtchn = +SHDEPS_libxenevtchn = $(SHLIB_libxentoolcore) LDLIBS_libxenevtchn = $(SHDEPS_libxenevtchn) $(XEN_LIBXENEVTCHN)/libxenevtchn$(libextension) SHLIB_libxenevtchn = $(SHDEPS_libxenevtchn) -Wl,-rpath-link=$(XEN_LIBXENEVTCHN) diff --git a/tools/libs/evtchn/Makefile b/tools/libs/evtchn/Makefile index bc98aed..9952b30 100644 --- a/tools/libs/evtchn/Makefile +++ b/tools/libs/evtchn/Makefile @@ -7,7 +7,7 @@ SHLIB_LDFLAGS += -Wl,--version-script=libxenevtchn.map CFLAGS += -Werror -Wmissing-prototypes CFLAGS += -I./include $(CFLAGS_xeninclude) -CFLAGS += $(CFLAGS_libxentoollog) +CFLAGS += $(CFLAGS_libxentoollog) $(CFLAGS_libxentoolcore) SRCS-y += core.c SRCS-$(CONFIG_Linux) += linux.c @@ -61,7 +61,7 @@ libxenevtchn.so.$(MAJOR): libxenevtchn.so.$(MAJOR).$(MINOR) $(SYMLINK_SHLIB) $< $@ libxenevtchn.so.$(MAJOR).$(MINOR): $(PIC_OBJS) libxenevtchn.map - $(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenevtchn.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $(PIC_OBJS) $(LDLIBS_libxentoollog) $(APPEND_LDFLAGS) + $(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenevtchn.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $(PIC_OBJS) $(LDLIBS_libxentoollog) $(LDLIBS_libxentoolcore) $(APPEND_LDFLAGS) .PHONY: install install: build diff --git a/tools/libs/evtchn/core.c b/tools/libs/evtchn/core.c index 41621ff..14b7549 100644 --- a/tools/libs/evtchn/core.c +++ b/tools/libs/evtchn/core.c @@ -18,6 +18,16 @@ #include "private.h" +static int all_restrict_cb(Xentoolcore__Active_Handle *ah, domid_t domid) { + xenevtchn_handle *xce = CONTAINER_OF(ah, *xce, tc_ah); + + if (xce->fd < 0) + /* just in case */ + return 0; + + return xenevtchn_restrict(xce, domid); +} + xenevtchn_handle *xenevtchn_open(xentoollog_logger *logger, unsigned open_flags) { xenevtchn_handle *xce = malloc(sizeof(*xce)); @@ -29,6 +39,9 @@ xenevtchn_handle *xenevtchn_open(xentoollog_logger *logger, unsigned open_flags) xce->logger = logger; xce->logger_tofree = NULL; + xce->tc_ah.restrict_callback = all_restrict_cb; + xentoolcore__register_active_handle(&xce->tc_ah); + if (!xce->logger) { xce->logger = xce->logger_tofree = (xentoollog_logger*) diff --git a/tools/libs/evtchn/private.h b/tools/libs/evtchn/private.h index 3d34862..31e595b 100644 --- a/tools/libs/evtchn/private.h +++ b/tools/libs/evtchn/private.h @@ -4,11 +4,14 @@ #include <xentoollog.h> #include <xenevtchn.h> +#include <xentoolcore_internal.h> + #include <xen/xen.h> struct xenevtchn_handle { xentoollog_logger *logger, *logger_tofree; int fd; + Xentoolcore__Active_Handle tc_ah; }; int osdep_evtchn_open(xenevtchn_handle *xce); diff --git a/tools/libs/toolcore/include/xentoolcore.h b/tools/libs/toolcore/include/xentoolcore.h index be6c570..ef9c670 100644 --- a/tools/libs/toolcore/include/xentoolcore.h +++ b/tools/libs/toolcore/include/xentoolcore.h @@ -31,11 +31,6 @@ * Arranges that Xen library handles (fds etc.) which are currently held * by Xen libraries, can no longer be used other than to affect domid. * - * Does not prevent effects that amount only to - * - denial of service, possibly host-wide, by resource exhaustion etc. - * - leak of not-very-interesting metainformation about other domains - * eg, specifically, event channel signals relating to other domains - * * If this cannot be achieved, returns -1 and sets errno. * If called again with the same domid, it may succeed, or it may * fail (even though such a call is potentially meaningful).
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> --- tools/Rules.mk | 2 +- tools/libs/evtchn/Makefile | 4 ++-- tools/libs/evtchn/core.c | 13 +++++++++++++ tools/libs/evtchn/private.h | 3 +++ tools/libs/toolcore/include/xentoolcore.h | 5 ----- 5 files changed, 19 insertions(+), 8 deletions(-)