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authorFrancis Laniel <laniel_francis@privacyrequired.com>2020-11-15 18:08:05 +0100
committerJakub Kicinski <kuba@kernel.org>2020-11-16 08:08:54 -0800
commit9ca718743ad8402958637bfc196d7b62371a1b9f (patch)
tree89d5f226138c49fdd1bfd2116b28b2b469357280 /lib
parent8eeb99bc81bc1cb3d5e5323d9a82d8392e3a27b4 (diff)
Modify return value of nla_strlcpy to match that of strscpy.
nla_strlcpy now returns -E2BIG if src was truncated when written to dst. It also returns this error value if dstsize is 0 or higher than INT_MAX. For example, if src is "foo\0" and dst is 3 bytes long, the result will be: 1. "foG" after memcpy (G means garbage). 2. "fo\0" after memset. 3. -E2BIG is returned because src was not completely written into dst. The callers of nla_strlcpy were modified to take into account this modification. Signed-off-by: Francis Laniel <laniel_francis@privacyrequired.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/nlattr.c39
1 files changed, 25 insertions, 14 deletions
diff --git a/lib/nlattr.c b/lib/nlattr.c
index 07156e581997..447182543c03 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -710,33 +710,44 @@ EXPORT_SYMBOL(nla_find);
/**
* nla_strlcpy - Copy string attribute payload into a sized buffer
- * @dst: where to copy the string to
- * @nla: attribute to copy the string from
- * @dstsize: size of destination buffer
+ * @dst: Where to copy the string to.
+ * @nla: Attribute to copy the string from.
+ * @dstsize: Size of destination buffer.
*
* Copies at most dstsize - 1 bytes into the destination buffer.
- * The result is always a valid NUL-terminated string. Unlike
- * strlcpy the destination buffer is always padded out.
+ * Unlike strlcpy the destination buffer is always padded out.
*
- * Returns the length of the source buffer.
+ * Return:
+ * * srclen - Returns @nla length (not including the trailing %NUL).
+ * * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater
+ * than @dstsize.
*/
-size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
+ssize_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
{
size_t srclen = nla_len(nla);
char *src = nla_data(nla);
+ ssize_t ret;
+ size_t len;
+
+ if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))
+ return -E2BIG;
if (srclen > 0 && src[srclen - 1] == '\0')
srclen--;
- if (dstsize > 0) {
- size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
-
- memcpy(dst, src, len);
- /* Zero pad end of dst. */
- memset(dst + len, 0, dstsize - len);
+ if (srclen >= dstsize) {
+ len = dstsize - 1;
+ ret = -E2BIG;
+ } else {
+ len = srclen;
+ ret = len;
}
- return srclen;
+ memcpy(dst, src, len);
+ /* Zero pad end of dst. */
+ memset(dst + len, 0, dstsize - len);
+
+ return ret;
}
EXPORT_SYMBOL(nla_strlcpy);