[Pkg-gnupg-commit] [gnupg2] 34/159: gpg: Improve the keyblock cache's transparency.

[Daniel Kahn Gillmor]

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dkg pushed a commit to branch master
in repository gnupg2.

commit 2e4e10c1dcd8dfeafec51f44ebf26acfeb770c41
Author: Neal H. Walfield <neal at g10code.com>
Date:   Tue Dec 15 12:21:30 2015 +0100

    gpg: Improve the keyblock cache's transparency.
    
    * kbx/keybox-search.c (keybox_offset): New function.
    * g10/keydb.c (struct keyblock_cache): Add fields resource and offset.
    (keyblock_cache_clear): Reset HD->KEYBLOCK_CACHE.RESOURCE and
    HD->KEYBLOCK_CACHE.OFFSET.
    (keydb_search): Don't use the cached result if it comes before the
    current file position.  When caching an entry, also record the
    position at which it was found.
    
    --
    Signed-off-by: Neal H. Walfield <neal at g10code.com>
    GnuPG-bug-id: 2187
---
 g10/keydb.c         | 19 ++++++++++++++++++-
 kbx/keybox-search.c |  8 ++++++++
 kbx/keybox.h        |  2 ++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/g10/keydb.c b/g10/keydb.c
index d7c35de..860187f 100644
--- a/g10/keydb.c
+++ b/g10/keydb.c
@@ -81,6 +81,9 @@ struct keyblock_cache {
   u32 *sigstatus;
   int pk_no;
   int uid_no;
+  /* Offset of the record in the keybox.  */
+  int resource;
+  off_t offset;
 };
 
 
@@ -245,6 +248,8 @@ keyblock_cache_clear (struct keydb_handle *hd)
   hd->keyblock_cache.sigstatus = NULL;
   iobuf_close (hd->keyblock_cache.iobuf);
   hd->keyblock_cache.iobuf = NULL;
+  hd->keyblock_cache.resource = -1;
+  hd->keyblock_cache.offset = -1;
 }
 
 
@@ -1701,7 +1706,13 @@ keydb_search (KEYDB_HANDLE hd, KEYDB_SEARCH_DESC *desc,
       && (desc[0].mode == KEYDB_SEARCH_MODE_FPR20
           || desc[0].mode == KEYDB_SEARCH_MODE_FPR)
       && hd->keyblock_cache.state  == KEYBLOCK_CACHE_FILLED
-      && !memcmp (hd->keyblock_cache.fpr, desc[0].u.fpr, 20))
+      && !memcmp (hd->keyblock_cache.fpr, desc[0].u.fpr, 20)
+      /* Make sure the current file position occurs before the cached
+         result to avoid an infinite loop.  */
+      && (hd->current < hd->keyblock_cache.resource
+          || (hd->current == hd->keyblock_cache.resource
+              && (keybox_offset (hd->active[hd->current].u.kb)
+                  <= hd->keyblock_cache.offset))))
     {
       /* (DESCINDEX is already set).  */
       if (DBG_CLOCK)
@@ -1772,6 +1783,12 @@ keydb_search (KEYDB_HANDLE hd, KEYDB_SEARCH_DESC *desc,
       && hd->active[hd->current].type == KEYDB_RESOURCE_TYPE_KEYBOX)
     {
       hd->keyblock_cache.state = KEYBLOCK_CACHE_PREPARED;
+      hd->keyblock_cache.resource = hd->current;
+      /* The current offset is at the start of the next record.  Since
+         a record is at least 1 byte, we just use offset - 1, which is
+         within the record.  */
+      hd->keyblock_cache.offset
+        = keybox_offset (hd->active[hd->current].u.kb) - 1;
       memcpy (hd->keyblock_cache.fpr, desc[0].u.fpr, 20);
     }
 
diff --git a/kbx/keybox-search.c b/kbx/keybox-search.c
index 78e0c23..df959b6 100644
--- a/kbx/keybox-search.c
+++ b/kbx/keybox-search.c
@@ -1188,3 +1188,11 @@ keybox_get_flags (KEYBOX_HANDLE hd, int what, int idx, unsigned int *value)
   ec = get_flag_from_image (buffer, length, what, value);
   return ec? gpg_error (ec):0;
 }
+
+off_t
+keybox_offset (KEYBOX_HANDLE hd)
+{
+  if (!hd->fp)
+    return 0;
+  return ftello (hd->fp);
+}
diff --git a/kbx/keybox.h b/kbx/keybox.h
index 8c31141..c91a282 100644
--- a/kbx/keybox.h
+++ b/kbx/keybox.h
@@ -77,6 +77,8 @@ int keybox_set_ephemeral (KEYBOX_HANDLE hd, int yes);
 
 int keybox_lock (KEYBOX_HANDLE hd, int yes);
 
+off_t keybox_offset (KEYBOX_HANDLE hd);
+
 /*-- keybox-file.c --*/
 /* Fixme: This function does not belong here: Provide a better
    interface to create a new keybox file.  */

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