kernel: Fix alignment problem for sendmsg ancillary message data.

Closes bug 2116; sending file descriptors is broken on amd64.

From: Darwin xnu-123.5, NetBSD socket.h 1.50

diff --git a/sys/sys/socket.h b/sys/sys/socket.h
index 593c423..0fa184e 100644 (file)
--- a/sys/sys/socket.h
+++ b/sys/sys/socket.h
@@ -407,17 +407,24 @@ struct cmsgcred {
        gid_t   cmcred_groups[CMGROUP_MAX];     /* groups */
 };
 
+/* Alignment requirement for CMSG struct manipulation */
+#define _CMSG_ALIGN(n)         (((n) + 3) & ~3)
+
+#ifdef _KERNEL
+#define CMSG_ALIGN(n)          _CMSG_ALIGN(n)
+#endif
+
 /* given pointer to struct cmsghdr, return pointer to data */
 #define        CMSG_DATA(cmsg)         ((unsigned char *)(cmsg) + \
-                                _ALIGN(sizeof(struct cmsghdr)))
+                                _CMSG_ALIGN(sizeof(struct cmsghdr)))
 
 /* given pointer to struct cmsghdr, return pointer to next cmsghdr */
 #define        CMSG_NXTHDR(mhdr, cmsg) \
-       (((caddr_t)(cmsg) + _ALIGN((cmsg)->cmsg_len) + \
-         _ALIGN(sizeof(struct cmsghdr)) > \
+       (((caddr_t)(cmsg) + _CMSG_ALIGN((cmsg)->cmsg_len) + \
+         _CMSG_ALIGN(sizeof(struct cmsghdr)) > \
            (caddr_t)(mhdr)->msg_control + (mhdr)->msg_controllen) ? \
            NULL : \
-           (struct cmsghdr *)((caddr_t)(cmsg) + _ALIGN((cmsg)->cmsg_len)))
+           (struct cmsghdr *)((caddr_t)(cmsg) + _CMSG_ALIGN((cmsg)->cmsg_len)))
 
 /*
  * RFC 2292 requires to check msg_controllen, in case that the kernel returns
@@ -430,12 +437,8 @@ struct cmsgcred {
 
 /* RFC 2292 additions */
        
-#define        CMSG_SPACE(l)           (_ALIGN(sizeof(struct cmsghdr)) + _ALIGN(l))
-#define        CMSG_LEN(l)             (_ALIGN(sizeof(struct cmsghdr)) + (l))
-
-#ifdef _KERNEL
-#define        CMSG_ALIGN(n)   _ALIGN(n)
-#endif
+#define        CMSG_SPACE(l)           (_CMSG_ALIGN(sizeof(struct cmsghdr)) + _CMSG_ALIGN(l))
+#define        CMSG_LEN(l)             (_CMSG_ALIGN(sizeof(struct cmsghdr)) + (l))
 
 /* "Socket"-level control message types: */
 #define        SCM_RIGHTS      0x01            /* access rights (array of int) */