common: Use new function to print status strings.

* common/asshelp2.c (vprint_assuan_status_strings): New.
(print_assuan_status_strings): New.
* agent/command.c (agent_write_status): Replace by call to new
function.
* dirmngr/server.c (dirmngr_status): Ditto.
* g13/server.c (g13_status): Ditto.
* g13/sh-cmd.c (g13_status): Ditto.
* sm/server.c (gpgsm_status2): Ditto.
* scd/command.c (send_status_info): Bump up N.
--

This fixes a potential overflow if LFs are passed to the status
string functions.  This is actually not the case and would be wrong
because neither the truncating in libassuan or our escaping is not the
Right Thing.  In any case the functions need to be more robust and
comply to the promised interface.  Thus the code has been factored out
to a helper function and N has been bumped up correctly and checked in
all cases.

For some uses this changes the behaviour in the error case (i.e. CR or
LF passed): It will now always be C-escaped and not passed to
libassuan which would truncate the line at the first LF.

Reported-by: private_pers

8 files changed, 90 insertions, 116 deletions

diff --git a/agent/command.c b/agent/command.c
index 0916f886a..3a547ffaa 100644
--- a/agent/command.c
+++ b/agent/command.c
@@ -293,50 +293,19 @@ parse_keygrip (assuan_context_t ctx, const char *string, unsigned char *buf)
 
 
 /* Write an Assuan status line.  KEYWORD is the first item on the
-   status line.  The following arguments are all separated by a space
-   in the output.  The last argument must be a NULL.  Linefeeds and
-   carriage returns characters (which are not allowed in an Assuan
-   status line) are silently quoted in C-style.  */
+ * status line.  The following arguments are all separated by a space
+ * in the output.  The last argument must be a NULL.  Linefeeds and
+ * carriage returns characters (which are not allowed in an Assuan
+ * status line) are silently quoted in C-style.  */
 gpg_error_t
 agent_write_status (ctrl_t ctrl, const char *keyword, ...)
 {
-  gpg_error_t err = 0;
+  gpg_error_t err;
   va_list arg_ptr;
-  const char *text;
   assuan_context_t ctx = ctrl->server_local->assuan_ctx;
-  char buf[950], *p;
-  size_t n;
 
   va_start (arg_ptr, keyword);
-
-  p = buf;
-  n = 0;
-  while ( (text = va_arg (arg_ptr, const char *)) )
-    {
-      if (n)
-        {
-          *p++ = ' ';
-          n++;
-        }
-      for ( ; *text && n < DIM (buf)-3; n++, text++)
-        {
-          if (*text == '\n')
-            {
-              *p++ = '\\';
-              *p++ = 'n';
-            }
-          else if (*text == '\r')
-            {
-              *p++ = '\\';
-              *p++ = 'r';
-            }
-          else
-            *p++ = *text;
-        }
-    }
-  *p = 0;
-  err = assuan_write_status (ctx, keyword, buf);
-
+  err = vprint_assuan_status_strings (ctx, keyword, arg_ptr);
   va_end (arg_ptr);
   return err;
 }
diff --git a/common/asshelp.h b/common/asshelp.h
index f169d8774..bf1bd1705 100644
--- a/common/asshelp.h
+++ b/common/asshelp.h
@@ -93,5 +93,12 @@ gpg_error_t vprint_assuan_status (assuan_context_t ctx,
                                   const char *format,
                                   va_list arg_ptr) GPGRT_ATTR_PRINTF(3,0);
 
+gpg_error_t vprint_assuan_status_strings (assuan_context_t ctx,
+                                          const char *keyword,
+                                          va_list arg_ptr);
+gpg_error_t print_assuan_status_strings (assuan_context_t ctx,
+                                         const char *keyword,
+                                         ...) GPGRT_ATTR_SENTINEL(1);
+
 
 #endif /*GNUPG_COMMON_ASSHELP_H*/
diff --git a/common/asshelp2.c b/common/asshelp2.c
index f85c1e67e..0a7c4549d 100644
--- a/common/asshelp2.c
+++ b/common/asshelp2.c
@@ -71,3 +71,66 @@ print_assuan_status (assuan_context_t ctx,
   va_end (arg_ptr);
   return err;
 }
+
+
+/* Helper function to print a list of strings as an assuan status
+ * line.  KEYWORD is the first item on the status line.  ARG_PTR is a
+ * list of strings which are all separated by a space in the output.
+ * The last argument must be a NULL.  Linefeeds and carriage returns
+ * characters (which are not allowed in an Assuan status line) are
+ * silently quoted in C-style.  */
+gpg_error_t
+vprint_assuan_status_strings (assuan_context_t ctx,
+                              const char *keyword, va_list arg_ptr)
+{
+  gpg_error_t err = 0;
+  const char *text;
+  char buf[950], *p;
+  size_t n;
+
+  p = buf;
+  n = 0;
+  while ((text = va_arg (arg_ptr, const char *)) && n < DIM (buf)-3 )
+    {
+      if (n)
+        {
+          *p++ = ' ';
+          n++;
+        }
+      for ( ; *text && n < DIM (buf)-3; n++, text++)
+        {
+          if (*text == '\n')
+            {
+              *p++ = '\\';
+              *p++ = 'n';
+              n++;
+            }
+          else if (*text == '\r')
+            {
+              *p++ = '\\';
+              *p++ = 'r';
+              n++;
+            }
+          else
+            *p++ = *text;
+        }
+    }
+  *p = 0;
+  err = assuan_write_status (ctx, keyword, buf);
+
+  return err;
+}
+
+
+/* See vprint_assuan_status_strings.  */
+gpg_error_t
+print_assuan_status_strings (assuan_context_t ctx, const char *keyword, ...)
+{
+  va_list arg_ptr;
+  gpg_error_t err;
+
+  va_start (arg_ptr, keyword);
+  err = vprint_assuan_status_strings (ctx, keyword, arg_ptr);
+  va_end (arg_ptr);
+  return err;
+}
diff --git a/dirmngr/server.c b/dirmngr/server.c
index ab2ca852f..60d980211 100644
--- a/dirmngr/server.c
+++ b/dirmngr/server.c
@@ -2834,30 +2834,13 @@ dirmngr_status (ctrl_t ctrl, const char *keyword, ...)
 {
   gpg_error_t err = 0;
   va_list arg_ptr;
-  const char *text;
   assuan_context_t ctx;
 
   va_start (arg_ptr, keyword);
 
   if (ctrl->server_local && (ctx = ctrl->server_local->assuan_ctx))
     {
-      char buf[950], *p;
-      size_t n;
-
-      p = buf;
-      n = 0;
-      while ( (text = va_arg (arg_ptr, const char *)) )
-        {
-          if (n)
-            {
-              *p++ = ' ';
-              n++;
-            }
-          for ( ; *text && n < DIM (buf)-2; n++)
-            *p++ = *text++;
-        }
-      *p = 0;
-      err = assuan_write_status (ctx, keyword, buf);
+      err = vprint_assuan_status_strings (ctx, keyword, arg_ptr);
     }
 
   va_end (arg_ptr);
diff --git a/g13/server.c b/g13/server.c
index bbe42d4f6..defde6c02 100644
--- a/g13/server.c
+++ b/g13/server.c
@@ -34,6 +34,7 @@
 #include "mount.h"
 #include "suspend.h"
 #include "../common/server-help.h"
+#include "../common/asshelp.h"
 #include "../common/call-gpg.h"
 
 
@@ -737,24 +738,8 @@ g13_status (ctrl_t ctrl, int no, ...)
     }
   else
     {
-      assuan_context_t ctx = ctrl->server_local->assuan_ctx;
-      char buf[950], *p;
-      size_t n;
-
-      p = buf;
-      n = 0;
-      while ( (text = va_arg (arg_ptr, const char *)) )
-        {
-          if (n)
-            {
-              *p++ = ' ';
-              n++;
-            }
-          for ( ; *text && n < DIM (buf)-2; n++)
-            *p++ = *text++;
-        }
-      *p = 0;
-      err = assuan_write_status (ctx, get_status_string (no), buf);
+      err = vprint_assuan_status_strings (ctrl->server_local->assuan_ctx,
+                                          get_status_string (no), arg_ptr);
     }
 
   va_end (arg_ptr);
diff --git a/g13/sh-cmd.c b/g13/sh-cmd.c
index b57369d9c..791e3b7f4 100644
--- a/g13/sh-cmd.c
+++ b/g13/sh-cmd.c
@@ -28,6 +28,7 @@
 #include "g13-syshelp.h"
 #include <assuan.h>
 #include "../common/i18n.h"
+#include "../common/asshelp.h"
 #include "keyblob.h"
 
 
@@ -904,34 +905,13 @@ sh_encrypt_keyblob (ctrl_t ctrl, const void *keyblob, size_t keybloblen,
 gpg_error_t
 g13_status (ctrl_t ctrl, int no, ...)
 {
-  gpg_error_t err = 0;
+  gpg_error_t err;
   va_list arg_ptr;
-  const char *text;
 
   va_start (arg_ptr, no);
 
-  if (1)
-    {
-      assuan_context_t ctx = ctrl->server_local->assuan_ctx;
-      char buf[950], *p;
-      size_t n;
-
-      p = buf;
-      n = 0;
-      while ( (text = va_arg (arg_ptr, const char *)) )
-        {
-          if (n)
-            {
-              *p++ = ' ';
-              n++;
-            }
-          for ( ; *text && n < DIM (buf)-2; n++)
-            *p++ = *text++;
-        }
-      *p = 0;
-      err = assuan_write_status (ctx, get_status_string (no), buf);
-    }
-
+  err = vprint_assuan_status_strings (ctrl->server_local->assuan_ctx,
+                                      get_status_string (no), arg_ptr);
   va_end (arg_ptr);
   return err;
 }
diff --git a/scd/command.c b/scd/command.c
index 6bcbce4fc..701151894 100644
--- a/scd/command.c
+++ b/scd/command.c
@@ -1848,7 +1848,8 @@ send_status_info (ctrl_t ctrl, const char *keyword, ...)
 
   p = buf;
   n = 0;
-  while ( (value = va_arg (arg_ptr, const unsigned char *)) )
+  while ( (value = va_arg (arg_ptr, const unsigned char *))
+           && n < DIM (buf)-2 )
     {
       valuelen = va_arg (arg_ptr, size_t);
       if (!valuelen)
@@ -1865,6 +1866,7 @@ send_status_info (ctrl_t ctrl, const char *keyword, ...)
             {
               sprintf (p, "%%%02X", *value);
               p += 3;
+              n += 2;
             }
           else if (*value == ' ')
             *p++ = '+';
diff --git a/sm/server.c b/sm/server.c
index 568e51b17..721f3faf0 100644
--- a/sm/server.c
+++ b/sm/server.c
@@ -31,6 +31,7 @@
 #include <assuan.h>
 #include "../common/sysutils.h"
 #include "../common/server-help.h"
+#include "../common/asshelp.h"
 
 #define set_error(e,t) assuan_set_error (ctx, gpg_error (e), (t))
 
@@ -1426,24 +1427,8 @@ gpgsm_status2 (ctrl_t ctrl, int no, ...)
     }
   else
     {
-      assuan_context_t ctx = ctrl->server_local->assuan_ctx;
-      char buf[950], *p;
-      size_t n;
-
-      p = buf;
-      n = 0;
-      while ( (text = va_arg (arg_ptr, const char *)) )
-        {
-          if (n)
-            {
-              *p++ = ' ';
-              n++;
-            }
-          for ( ; *text && n < DIM (buf)-2; n++)
-            *p++ = *text++;
-        }
-      *p = 0;
-      err = assuan_write_status (ctx, get_status_string (no), buf);
+      err = vprint_assuan_status_strings (ctrl->server_local->assuan_ctx,
+                                          get_status_string (no), arg_ptr);
     }
 
   va_end (arg_ptr);