[libvirt] [PATCH v2 3/3] Honor blacklist for modprobe command

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1045124

When loading modules, libvirt does not honor the modprobe blacklist.
By adding a "-b" to the modprobe command libvirt will fail to load a
module if it's on the blacklist

Check if the failure to load a driver was due to it being on the blacklist
using the output of a "modprobe -c" searching for "blacklist <driver_Name>"
where driver_Name is possibly a modified string of the input driver changing
all '-' into '_' since that's what modprobe does.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/util/virpci.c | 49 ++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/util/virpci.c b/src/util/virpci.c
index e2d222e..5d4168a 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -42,6 +42,7 @@
 #include "vircommand.h"
 #include "virerror.h"
 #include "virfile.h"
+#include "virkmod.h"
 #include "virstring.h"
 #include "virutil.h"
 
@@ -979,6 +980,9 @@ virPCIProbeStubDriver(const char *driver)
 {
     char *drvpath = NULL;
     bool probed = false;
+    size_t i;
+    char *drvblklst = NULL;
+    char *outbuf = NULL;
 
 recheck:
     if (virPCIDriverDir(&drvpath, driver) == 0 && virFileExists(drvpath)) {
@@ -990,18 +994,44 @@ recheck:
     VIR_FREE(drvpath);
 
     if (!probed) {
-        const char *const probecmd[] = { MODPROBE, driver, NULL };
+        char *errbuf = NULL;
         probed = true;
-        if (virRun(probecmd, NULL) < 0) {
-            char ebuf[1024];
-            VIR_WARN("failed to load driver %s: %s", driver,
-                     virStrerror(errno, ebuf, sizeof(ebuf)));
-            return -1;
+        if ((errbuf = virModprobeUseBlacklist(driver))) {
+            VIR_WARN("failed to load driver %s: %s", driver, errbuf);
+            VIR_FREE(errbuf);
+            goto cleanup;
         }
 
         goto recheck;
     }
 
+    /* All error path code - purpose is to determine whether the failure
+     * occurs because device is on blacklist in order to add an error
+     * message to help detect why load failed
+     */
+    if (virAsprintfQuiet(&drvblklst, "blacklist %s", driver) < 0)
+        goto cleanup;
+
+    /* modprobe will convert all '-' into '_', so we need to as well */
+    for (i = 0; i < drvblklst[i]; i++)
+        if (drvblklst[i] == '-')
+            drvblklst[i] = '_';
+
+    outbuf = virModprobeConfig();
+    if (!outbuf)
+        goto cleanup;
+
+    /* Find driver on blacklist? */
+    if (strstr(outbuf, drvblklst)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Failed to load PCI stub module %s: "
+                         "administratively prohibited"),
+                       driver);
+    }
+
+cleanup:
+    VIR_FREE(drvblklst);
+    VIR_FREE(outbuf);
     return -1;
 }
 
@@ -1313,9 +1343,10 @@ virPCIDeviceDetach(virPCIDevicePtr dev,
                    virPCIDeviceList *inactiveDevs)
 {
     if (virPCIProbeStubDriver(dev->stubDriver) < 0) {
-        virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("Failed to load PCI stub module %s"),
-                       dev->stubDriver);
+        if (virGetLastError() == NULL)
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Failed to load PCI stub module %s"),
+                           dev->stubDriver);
         return -1;
     }
 
-- 
1.8.4.2