All of lore.kernel.org
 help / color / mirror / Atom feed
* [Xen-devel] [PATCH v2] xsm: hide detailed Xen version from unprivileged guests
@ 2020-01-10 10:37 Sergey Dyasli
  2020-01-10 11:02 ` Andrew Cooper
                   ` (2 more replies)
  0 siblings, 3 replies; 22+ messages in thread
From: Sergey Dyasli @ 2020-01-10 10:37 UTC (permalink / raw)
  To: xen-devel
  Cc: Sergey Dyasli, Stefano Stabellini, Julien Grall, Wei Liu,
	Konrad Rzeszutek Wilk, George Dunlap, Andrew Cooper, Ian Jackson,
	Jan Beulich, Daniel De Graaf

Hide the following information that can help identify the running Xen
binary version: XENVER_extraversion, XENVER_compile_info, XENVER_changeset.
Add explicit cases for XENVER_commandline and XENVER_build_id as well.

Introduce xsm_filter_denied() to hvmloader to remove "<denied>" string
from guest's DMI tables that otherwise would be shown in tools like
dmidecode.

Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
---
v1 --> v2:
- Added xsm_filter_denied() to hvmloader instead of modifying xen_deny()
- Made behaviour the same for both Release and Debug builds
- XENVER_capabilities is no longer hided

CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Julien Grall <julien@xen.org>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Wei Liu <wl@xen.org>
CC: Daniel De Graaf <dgdegra@tycho.nsa.gov>
---
 tools/firmware/hvmloader/hvmloader.c | 1 +
 tools/firmware/hvmloader/smbios.c    | 1 +
 tools/firmware/hvmloader/util.c      | 6 ++++++
 tools/firmware/hvmloader/util.h      | 2 ++
 xen/include/xsm/dummy.h              | 9 ++++++---
 5 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/firmware/hvmloader/hvmloader.c b/tools/firmware/hvmloader/hvmloader.c
index 598a226278..e760ed5fa6 100644
--- a/tools/firmware/hvmloader/hvmloader.c
+++ b/tools/firmware/hvmloader/hvmloader.c
@@ -147,6 +147,7 @@ static void init_hypercalls(void)
     /* Print version information. */
     cpuid(base + 1, &eax, &ebx, &ecx, &edx);
     hypercall_xen_version(XENVER_extraversion, extraversion);
+    xsm_filter_denied(extraversion, sizeof(extraversion));
     printf("Detected Xen v%u.%u%s\n", eax >> 16, eax & 0xffff, extraversion);
 }
 
diff --git a/tools/firmware/hvmloader/smbios.c b/tools/firmware/hvmloader/smbios.c
index 97a054e9e3..1ba352ed2c 100644
--- a/tools/firmware/hvmloader/smbios.c
+++ b/tools/firmware/hvmloader/smbios.c
@@ -275,6 +275,7 @@ hvm_write_smbios_tables(
     xen_minor_version = (uint16_t) xen_version;
 
     hypercall_xen_version(XENVER_extraversion, xen_extra_version);
+    xsm_filter_denied(xen_extra_version, sizeof(xen_extra_version));
 
     /* build up human-readable Xen version string */
     p = xen_version_str;
diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
index 0c3f2d24cd..09e355fa3d 100644
--- a/tools/firmware/hvmloader/util.c
+++ b/tools/firmware/hvmloader/util.c
@@ -995,6 +995,12 @@ void hvmloader_acpi_build_tables(struct acpi_config *config,
     hvm_param_set(HVM_PARAM_VM_GENERATION_ID_ADDR, config->vm_gid_addr);
 }
 
+void xsm_filter_denied(char *str, size_t len)
+{
+    if ( strcmp(str, "<denied>") == 0 )
+        memset(str, 0, len);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
index 7bca6418d2..f7d907ca00 100644
--- a/tools/firmware/hvmloader/util.h
+++ b/tools/firmware/hvmloader/util.h
@@ -286,6 +286,8 @@ struct acpi_config;
 void hvmloader_acpi_build_tables(struct acpi_config *config,
                                  unsigned int physical);
 
+void xsm_filter_denied(char *str, size_t len);
+
 #endif /* __HVMLOADER_UTIL_H__ */
 
 /*
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index b8e185e6fa..d15b078f10 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -750,14 +750,17 @@ static XSM_INLINE int xsm_xen_version (XSM_DEFAULT_ARG uint32_t op)
     case XENVER_get_features:
         /* These sub-ops ignore the permission checks and return data. */
         return 0;
-    case XENVER_extraversion:
-    case XENVER_compile_info:
     case XENVER_capabilities:
-    case XENVER_changeset:
     case XENVER_pagesize:
     case XENVER_guest_handle:
         /* These MUST always be accessible to any guest by default. */
         return xsm_default_action(XSM_HOOK, current->domain, NULL);
+
+    case XENVER_extraversion:
+    case XENVER_compile_info:
+    case XENVER_changeset:
+    case XENVER_commandline:
+    case XENVER_build_id:
     default:
         return xsm_default_action(XSM_PRIV, current->domain, NULL);
     }
-- 
2.17.1


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

^ permalink raw reply	[flat|nested] 22+ messages in thread

end of thread, other threads:[~2020-01-14 10:19 UTC | newest]

Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-10 10:37 [Xen-devel] [PATCH v2] xsm: hide detailed Xen version from unprivileged guests Sergey Dyasli
2020-01-10 11:02 ` Andrew Cooper
2020-01-10 15:28   ` George Dunlap
2020-01-10 15:56     ` Jan Beulich
2020-01-10 16:45       ` Jürgen Groß
2020-01-10 17:00         ` George Dunlap
2020-01-11  3:55     ` Doug Goldstein
2020-01-11  9:35       ` George Dunlap
2020-01-13 11:01   ` Sergey Dyasli
2020-01-10 11:09 ` Jan Beulich
2020-01-11  4:02 ` Doug Goldstein
2020-01-11  9:02   ` George Dunlap
2020-01-12 18:26     ` Doug Goldstein
2020-01-13 12:51       ` George Dunlap
2020-01-13 13:39         ` Julien Grall
2020-01-13 14:01           ` Andrew Cooper
2020-01-13 14:07             ` George Dunlap
2020-01-13 14:28               ` Julien Grall
2020-01-13 14:40         ` Andrew Cooper
2020-01-14 10:19           ` Sergey Dyasli
2020-01-13 14:52         ` Julien Grall
2020-01-13 14:01       ` Ian Jackson

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.