Put the msg/cmsg checks in CHECK_MSG() and CHECK_CMSG() macros. Add support

for Linux 2.0 kernels by checking if LINUX20 is defined.

--HG--
branch : HEAD

diff --git a/src/lib/fdpass.c b/src/lib/fdpass.c
index 40cd403ee3c92248277a24a5bccf2fa297c1bbc5..0f749144e1f3d4f6d8a1ab730cc884399e83c8a3 100644 (file)
--- a/src/lib/fdpass.c
+++ b/src/lib/fdpass.c
@@ -78,6 +78,22 @@ ssize_t fd_send(int handle, int send_fd, const void *data, size_t size)
        return sendmsg(handle, &msg, 0);
 }
 
+#ifdef __osf__
+#  define CHECK_MSG(msg) TRUE /* Tru64 */
+#else
+#  define CHECK_MSG(msg) (msg).msg_controllen >= CMSG_SPACE(sizeof(int))
+#endif
+
+#ifdef LINUX20
+/* Linux 2.0.x doesn't set any cmsg fields. Note that this might make some
+   attacks possible so don't do it unless you really have to. */
+#  define CHECK_CMSG(cmsg) ((cmsg) != NULL)
+#else
+#  define CHECK_CMSG(cmsg) \
+       ((cmsg) != NULL && (cmsg)->cmsg_len >= CMSG_LEN(sizeof(int)) && \
+        (cmsg)->cmsg_level == SOL_SOCKET && (cmsg)->cmsg_type == SCM_RIGHTS)
+#endif
+
 ssize_t fd_read(int handle, void *data, size_t size, int *fd)
 {
        struct msghdr msg;
@@ -109,17 +125,10 @@ ssize_t fd_read(int handle, void *data, size_t size, int *fd)
        /* at least one byte transferred - we should have the fd now.
           do extra checks to make sure it really is an fd that is being
           transferred to avoid potential DoS conditions. some systems don't
-          set all these values correctly however:
-
-          Linux 2.0.x - cmsg_len, cmsg_level, cmsg_type are not set
-          Tru64 - msg_controllen isn't set */
+          set all these values correctly however so CHECK_MSG() and
+          CHECK_CMSG() are somewhat system dependent */
        cmsg = CMSG_FIRSTHDR(&msg);
-       if (
-#ifndef __osf__ /* Tru64 */
-           msg.msg_controllen < CMSG_SPACE(sizeof(int)) ||
-#endif
-           cmsg == NULL || cmsg->cmsg_len < CMSG_LEN(sizeof(int)) ||
-           cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
+       if (!CHECK_MSG(msg) || !CHECK_CMSG(cmsg))
                *fd = -1;
        else
                *fd = *((int *) CMSG_DATA(cmsg));