[Libguestfs] [PATCH common v2 2/3] options: Allow multiple --key parameters.

[Richard W.M. Jones]

This allows multiple --key parameters on the command line to match a
single device.  For example:

  tool --key /dev/sda1:key:trykey1 --key /dev/sda1:key:trykey2

would try "trykey1" and "trykey2" against /dev/sda1.
---
 options/decrypt.c | 41 ++++++++++++++++++++++++++++++++---------
 options/keys.c    | 45 +++++++++++++++++++++++++++++++++++----------
 options/options.h |  6 ++++--
 3 files changed, 71 insertions(+), 21 deletions(-)

diff --git a/options/decrypt.c b/options/decrypt.c
index 234163d..131e79c 100644
--- a/options/decrypt.c
+++ b/options/decrypt.c
@@ -26,6 +26,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <libintl.h>
+#include <error.h>
 
 #include "c-ctype.h"
 
@@ -74,21 +76,42 @@ inspect_do_decrypt (guestfs_h *g, struct key_store *ks)
   if (partitions == NULL)
     exit (EXIT_FAILURE);
 
-  int need_rescan = 0;
-  size_t i;
+  int need_rescan = 0, r;
+  size_t i, j;
+
   for (i = 0; partitions[i] != NULL; ++i) {
     CLEANUP_FREE char *type = guestfs_vfs_type (g, partitions[i]);
     if (type && STREQ (type, "crypto_LUKS")) {
       char mapname[32];
       make_mapname (partitions[i], mapname, sizeof mapname);
 
-      CLEANUP_FREE char *key = get_key (ks, partitions[i]);
-      /* XXX Should we call guestfs_luks_open_ro if readonly flag
-       * is set?  This might break 'mount_ro'.
-       */
-      if (guestfs_luks_open (g, partitions[i], key, mapname) == -1)
-        exit (EXIT_FAILURE);
-
+      CLEANUP_FREE_STRING_LIST char **keys = get_keys (ks, partitions[i]);
+
+      if (guestfs_int_count_strings (keys) == 0)
+        error (EXIT_FAILURE, 0,
+               _("no key was provided to open LUKS encrypted %s, "
+                 "try using --key on the command line"),
+               partitions[i]);
+
+      /* Try each key in turn. */
+      for (j = 0; keys[j] != NULL; ++j) {
+        /* XXX Should we call guestfs_luks_open_ro if readonly flag
+         * is set?  This might break 'mount_ro'.
+         */
+        guestfs_push_error_handler (g, NULL, NULL);
+        r = guestfs_luks_open (g, partitions[i], keys[j], mapname);
+        guestfs_pop_error_handler (g);
+        if (r == 0)
+          goto opened;
+      }
+      error (EXIT_FAILURE, 0,
+             _("could not find key to open LUKS encrypted %s.\n\n"
+               "Try using --key on the command line.\n\n"
+               "Original error: %s (%d)"),
+             partitions[i], guestfs_last_error (g),
+             guestfs_last_errno (g));
+
+    opened:
       need_rescan = 1;
     }
   }
diff --git a/options/keys.c b/options/keys.c
index 74b5497..782bdb6 100644
--- a/options/keys.c
+++ b/options/keys.c
@@ -121,15 +121,32 @@ read_first_line_from_file (const char *filename)
   return ret;
 }
 
-char *
-get_key (struct key_store *ks, const char *device)
+/* Return the key(s) matching this particular device from the
+ * keystore.  There may be multiple.  If none are read from the
+ * keystore, ask the user.
+ */
+char **
+get_keys (struct key_store *ks, const char *device)
 {
-  size_t i;
+  size_t i, j, len;
+  char **r;
+  char *s;
+
+  /* We know the returned list must have at least one element and not
+   * more than ks->nr_keys.
+   */
+  len = 1;
+  if (ks)
+    len = MIN (1, ks->nr_keys);
+  r = calloc (len+1, sizeof (char *));
+  if (r == NULL)
+    error (EXIT_FAILURE, errno, "calloc");
+
+  j = 0;
 
   if (ks) {
     for (i = 0; i < ks->nr_keys; ++i) {
       struct key_store_key *key = &ks->keys[i];
-      char *s;
 
       if (STRNEQ (key->device, device))
         continue;
@@ -139,17 +156,25 @@ get_key (struct key_store *ks, const char *device)
         s = strdup (key->string.s);
         if (!s)
           error (EXIT_FAILURE, errno, "strdup");
-        return s;
+        r[j++] = s;
+        break;
       case key_file:
-        return read_first_line_from_file (key->file.name);
+        s = read_first_line_from_file (key->file.name);
+        r[j++] = s;
+        break;
       }
-
-      /* Key not found in the key store, ask the user for it. */
-      break;
     }
   }
 
-  return read_key (device);
+  if (j == 0) {
+    /* Key not found in the key store, ask the user for it. */
+    s = read_key (device);
+    if (!s)
+      error (EXIT_FAILURE, 0, _("could not read key from user"));
+    r[0] = s;
+  }
+
+  return r;
 }
 
 struct key_store *
diff --git a/options/options.h b/options/options.h
index 6fadf1e..510e8a8 100644
--- a/options/options.h
+++ b/options/options.h
@@ -104,7 +104,9 @@ struct mp {
 
 /* A key in the key store. */
 struct key_store_key {
-  /* The device this key refers to. */
+  /* The device this key refers to.  There may be multiple matching
+   * devices in the list.
+   */
   char *device;
 
   enum {
@@ -146,7 +148,7 @@ extern void print_inspect_prompt (void);
 
 /* in key.c */
 extern char *read_key (const char *param);
-extern char *get_key (struct key_store *ks, const char *device);
+extern char **get_keys (struct key_store *ks, const char *device);
 extern struct key_store *key_store_add_from_selector (struct key_store *ks, const char *selector);
 extern struct key_store *key_store_import_key (struct key_store *ks, const struct key_store_key *key);
 extern void free_key_store (struct key_store *ks);
-- 
2.23.0