cifs: add replacement for cifs_strtoUCS_le called cifs_from_ucs2

Add a replacement function for cifs_strtoUCS_le. cifs_from_ucs2
takes args for the source and destination length so that we can ensure
that the function is confined within the intended buffers.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c
index 7d75272..8389f35 100644 (file)
--- a/fs/cifs/cifs_unicode.c
+++ b/fs/cifs/cifs_unicode.c
@@ -25,6 +25,130 @@
 #include "cifsglob.h"
 #include "cifs_debug.h"
 
+/*
+ * cifs_mapchar - convert a little-endian char to proper char in codepage
+ * @target - where converted character should be copied
+ * @src_char - 2 byte little-endian source character
+ * @cp - codepage to which character should be converted
+ * @mapchar - should character be mapped according to mapchars mount option?
+ *
+ * This function handles the conversion of a single character. It is the
+ * responsibility of the caller to ensure that the target buffer is large
+ * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
+ */
+static int
+cifs_mapchar(char *target, const __le16 src_char, const struct nls_table *cp,
+            bool mapchar)
+{
+       int len = 1;
+
+       if (!mapchar)
+               goto cp_convert;
+
+       /*
+        * BB: Cannot handle remapping UNI_SLASH until all the calls to
+        *     build_path_from_dentry are modified, as they use slash as
+        *     separator.
+        */
+       switch (le16_to_cpu(src_char)) {
+       case UNI_COLON:
+               *target = ':';
+               break;
+       case UNI_ASTERIK:
+               *target = '*';
+               break;
+       case UNI_QUESTION:
+               *target = '?';
+               break;
+       case UNI_PIPE:
+               *target = '|';
+               break;
+       case UNI_GRTRTHAN:
+               *target = '>';
+               break;
+       case UNI_LESSTHAN:
+               *target = '<';
+               break;
+       default:
+               goto cp_convert;
+       }
+
+out:
+       return len;
+
+cp_convert:
+       len = cp->uni2char(le16_to_cpu(src_char), target,
+                          NLS_MAX_CHARSET_SIZE);
+       if (len <= 0) {
+               *target = '?';
+               len = 1;
+       }
+       goto out;
+}
+
+/*
+ * cifs_from_ucs2 - convert utf16le string to local charset
+ * @to - destination buffer
+ * @from - source buffer
+ * @tolen - destination buffer size (in bytes)
+ * @fromlen - source buffer size (in bytes)
+ * @codepage - codepage to which characters should be converted
+ * @mapchar - should characters be remapped according to the mapchars option?
+ *
+ * Convert a little-endian ucs2le string (as sent by the server) to a string
+ * in the provided codepage. The tolen and fromlen parameters are to ensure
+ * that the code doesn't walk off of the end of the buffer (which is always
+ * a danger if the alignment of the source buffer is off). The destination
+ * string is always properly null terminated and fits in the destination
+ * buffer. Returns the length of the destination string in bytes (including
+ * null terminator).
+ *
+ * Note that some windows versions actually send multiword UTF-16 characters
+ * instead of straight UCS-2. The linux nls routines however aren't able to
+ * deal with those characters properly. In the event that we get some of
+ * those characters, they won't be translated properly.
+ */
+int
+cifs_from_ucs2(char *to, const __le16 *from, int tolen, int fromlen,
+                const struct nls_table *codepage, bool mapchar)
+{
+       int i, charlen, safelen;
+       int outlen = 0;
+       int nullsize = nls_nullsize(codepage);
+       int fromwords = fromlen / 2;
+       char tmp[NLS_MAX_CHARSET_SIZE];
+
+       /*
+        * because the chars can be of varying widths, we need to take care
+        * not to overflow the destination buffer when we get close to the
+        * end of it. Until we get to this offset, we don't need to check
+        * for overflow however.
+        */
+       safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);
+
+       for (i = 0; i < fromwords && from[i]; i++) {
+               /*
+                * check to see if converting this character might make the
+                * conversion bleed into the null terminator
+                */
+               if (outlen >= safelen) {
+                       charlen = cifs_mapchar(tmp, from[i], codepage, mapchar);
+                       if ((outlen + charlen) > (tolen - nullsize))
+                               break;
+               }
+
+               /* put converted char into 'to' buffer */
+               charlen = cifs_mapchar(&to[outlen], from[i], codepage, mapchar);
+               outlen += charlen;
+       }
+
+       /* properly null-terminate string */
+       for (i = 0; i < nullsize; i++)
+               to[outlen++] = 0;
+
+       return outlen;
+}
+
 /*
  * NAME:       cifs_strfromUCS()
  *

diff --git a/fs/cifs/cifs_unicode.h b/fs/cifs/cifs_unicode.h
index d6fe8ec..6aa6533 100644 (file)
--- a/fs/cifs/cifs_unicode.h
+++ b/fs/cifs/cifs_unicode.h
@@ -72,6 +72,8 @@ extern struct UniCaseRange UniLowerRange[];
 #endif                         /* UNIUPR_NOLOWER */
 
 #ifdef __KERNEL__
+int cifs_from_ucs2(char *to, const __le16 *from, int tolen, int fromlen,
+                  const struct nls_table *codepage, bool mapchar);
 int cifs_strfromUCS_le(char *, const __le16 *, int, const struct nls_table *);
 int cifs_strtoUCS(__le16 *, const char *, int, const struct nls_table *);
 #endif