util/grub-editenv: Add probe call for external envblk

This patch adds the probe_fs_envblk() function to identify the root
filesystem and invoke fs_envblk_init() with the probed filesystem type
and device. This checks if the feature is available and initializes the
handle, fs_envblk, to access the external environment block. It avoids
configurations with diskfilter or cryptodisk where filesystem blocks may
be remapped or encrypted.

The probe is only invoked when grub-editenv is working on the default
environment file path. This restriction ensures that probing and
possible raw device access are not triggered for arbitrary user supplied
paths, but only for the standard grubenv file. In that case the code
checks if the filename equals DEFAULT_ENVBLK_PATH and then calls
probe_fs_envblk with fs_envblk_spec. The result is stored in the global
fs_envblk handle. At this stage the external environment block is only
detected and recorded, and the behavior of grub-editenv is unchanged.

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/util/grub-editenv.c b/util/grub-editenv.c
index f8fa294d8482ff378de0750310ad02e2912261e9..1b923bf97882f78a1efbb9d4fda7091c49f6accb 100644 (file)
--- a/util/grub-editenv.c
+++ b/util/grub-editenv.c
@@ -23,8 +23,11 @@
 #include <grub/util/misc.h>
 #include <grub/lib/envblk.h>
 #include <grub/i18n.h>
-#include <grub/emu/hostfile.h>
+#include <grub/emu/hostdisk.h>
 #include <grub/util/install.h>
+#include <grub/emu/getroot.h>
+#include <grub/fs.h>
+#include <grub/crypto.h>
 
 #include <stdio.h>
 #include <unistd.h>
@@ -158,7 +161,7 @@ static fs_envblk_spec_t fs_envblk_spec[] = {
 
 static fs_envblk_t fs_envblk = NULL;
 
-static void __attribute__ ((unused))
+static void
 fs_envblk_init (const char *fs_name, const char *dev)
 {
   fs_envblk_spec_t *p;
@@ -534,6 +537,111 @@ unset_variables (const char *name, int argc, char *argv[])
     }
 }
 
+static bool
+is_abstraction (grub_device_t dev)
+{
+  if (dev == NULL || dev->disk == NULL)
+    return false;
+
+  if (dev->disk->dev->id == GRUB_DISK_DEVICE_DISKFILTER_ID ||
+      dev->disk->dev->id == GRUB_DISK_DEVICE_CRYPTODISK_ID)
+    return true;
+
+  return false;
+}
+
+static void
+probe_fs_envblk (fs_envblk_spec_t *spec)
+{
+  char **grub_devices = NULL;
+  char **curdev, **curdrive;
+  size_t ndev = 0;
+  char **grub_drives = NULL;
+  grub_device_t grub_dev = NULL;
+  grub_fs_t grub_fs = NULL;
+  bool have_abstraction = false;
+
+  grub_util_biosdisk_init (DEFAULT_DEVICE_MAP);
+  grub_init_all ();
+  grub_gcry_init_all ();
+
+  grub_lvm_fini ();
+  grub_mdraid09_fini ();
+  grub_mdraid1x_fini ();
+  grub_diskfilter_fini ();
+  grub_diskfilter_init ();
+  grub_mdraid09_init ();
+  grub_mdraid1x_init ();
+  grub_lvm_init ();
+
+  grub_devices = grub_guess_root_devices (DEFAULT_DIRECTORY);
+
+  if (grub_devices == NULL || grub_devices[0] == NULL)
+    {
+      grub_util_warn (_("cannot find a device for %s (is /dev mounted?)"), DEFAULT_DIRECTORY);
+      goto cleanup;
+    }
+
+  for (curdev = grub_devices; *curdev != NULL; curdev++, ndev++)
+    grub_util_pull_device (*curdev);
+
+  grub_drives = xcalloc ((ndev + 1), sizeof (grub_drives[0]));
+
+  for (curdev = grub_devices, curdrive = grub_drives; *curdev != NULL; curdev++,
+       curdrive++)
+    {
+      *curdrive = grub_util_get_grub_dev (*curdev);
+      if (*curdrive == NULL)
+       {
+         grub_util_warn (_("cannot find a GRUB drive for %s.  Check your device.map"),
+                         *curdev);
+         goto cleanup;
+       }
+    }
+  *curdrive = NULL;
+
+  grub_dev = grub_device_open (grub_drives[0]);
+  if (grub_dev == NULL)
+    {
+      grub_util_warn (_("cannot open device %s: %s"), grub_drives[0], grub_errmsg);
+      grub_errno = GRUB_ERR_NONE;
+      goto cleanup;
+    }
+
+  grub_fs = grub_fs_probe (grub_dev);
+  if (grub_fs == NULL)
+    {
+      grub_util_warn (_("cannot probe fs for %s: %s"), grub_drives[0], grub_errmsg);
+      grub_errno = GRUB_ERR_NONE;
+      goto cleanup;
+    }
+
+  have_abstraction = is_abstraction (grub_dev);
+  for (curdrive = grub_drives + 1; *curdrive != NULL && have_abstraction == false; curdrive++)
+    {
+      grub_device_t dev = grub_device_open (*curdrive);
+
+      if (dev == NULL)
+       continue;
+      have_abstraction = is_abstraction (dev);
+      grub_device_close (dev);
+    }
+
+  if (have_abstraction == false)
+    fs_envblk_init (grub_fs->name, grub_devices[0]);
+
+ cleanup:
+  if (grub_devices != NULL)
+    for (curdev = grub_devices; *curdev != NULL; curdev++)
+      free (*curdev);
+  free (grub_devices);
+  free (grub_drives);
+  grub_device_close (grub_dev);
+  grub_gcry_fini_all ();
+  grub_fini_all ();
+  grub_util_biosdisk_fini ();
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -565,6 +673,9 @@ main (int argc, char *argv[])
       command  = argv[curindex++];
     }
 
+  if (strcmp (filename, DEFAULT_ENVBLK_PATH) == 0)
+    probe_fs_envblk (fs_envblk_spec);
+
   if (strcmp (command, "create") == 0)
     grub_util_create_envblk_file (filename);
   else if (strcmp (command, "list") == 0)