Module Name: src
Committed By: yamt
Date: Fri Jun 29 13:20:25 UTC 2012
Modified Files:
src/lib/librumphijack: hijack.c
Log Message:
implement descriptor passing.
To generate a diff of this commit:
cvs rdiff -u -r1.93 -r1.94 src/lib/librumphijack/hijack.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/librumphijack/hijack.c
diff -u src/lib/librumphijack/hijack.c:1.93 src/lib/librumphijack/hijack.c:1.94
--- src/lib/librumphijack/hijack.c:1.93 Mon Jun 25 22:32:47 2012
+++ src/lib/librumphijack/hijack.c Fri Jun 29 13:20:25 2012
@@ -1,4 +1,4 @@
-/* $NetBSD: hijack.c,v 1.93 2012/06/25 22:32:47 abs Exp $ */
+/* $NetBSD: hijack.c,v 1.94 2012/06/29 13:20:25 yamt Exp $ */
/*-
* Copyright (c) 2011 Antti Kantee. All Rights Reserved.
@@ -29,7 +29,7 @@
#undef _FORTIFY_SOURCE
#include <sys/cdefs.h>
-__RCSID("$NetBSD: hijack.c,v 1.93 2012/06/25 22:32:47 abs Exp $");
+__RCSID("$NetBSD: hijack.c,v 1.94 2012/06/29 13:20:25 yamt Exp $");
#include <sys/param.h>
#include <sys/types.h>
@@ -1335,6 +1335,122 @@ write(int fd, const void *buf, size_t bl
}
/*
+ * file descriptor passing
+ *
+ * we intercept sendmsg and recvmsg to convert file descriptors in
+ * control messages. an attempt to send a descriptor from a different kernel
+ * is rejected. (ENOTSUP)
+ */
+
+static int
+msg_convert(struct msghdr *msg, int (*func)(int))
+{
+ struct cmsghdr *cmsg;
+
+ for (cmsg = CMSG_FIRSTHDR(msg); cmsg != NULL;
+ cmsg = CMSG_NXTHDR(msg, cmsg)) {
+ if (cmsg->cmsg_level == SOL_SOCKET &&
+ cmsg->cmsg_type == SCM_RIGHTS) {
+ int *fdp = (void *)CMSG_DATA(cmsg);
+ const size_t size =
+ cmsg->cmsg_len - __CMSG_ALIGN(sizeof(*cmsg));
+ const int nfds = size / sizeof(int);
+ const int * const efdp = fdp + nfds;
+
+ while (fdp < efdp) {
+ const int newval = func(*fdp);
+
+ if (newval < 0) {
+ return ENOTSUP;
+ }
+ *fdp = newval;
+ fdp++;
+ }
+ }
+ }
+ return 0;
+}
+
+ssize_t
+recvmsg(int fd, struct msghdr *msg, int flags)
+{
+ ssize_t (*op_recvmsg)(int, struct msghdr *, int);
+ ssize_t ret;
+ const bool isrump = fd_isrump(fd);
+
+ if (isrump) {
+ fd = fd_host2rump(fd);
+ op_recvmsg = GETSYSCALL(rump, RECVMSG);
+ } else {
+ op_recvmsg = GETSYSCALL(host, RECVMSG);
+ }
+ ret = op_recvmsg(fd, msg, flags);
+ if (ret == -1) {
+ return ret;
+ }
+ /*
+ * convert descriptors in the message.
+ */
+ if (isrump) {
+ msg_convert(msg, fd_rump2host);
+ } else {
+ msg_convert(msg, fd_host2host);
+ }
+ return ret;
+}
+
+static int
+fd_check_rump(int fd)
+{
+
+ return fd_isrump(fd) ? 0 : -1;
+}
+
+static int
+fd_check_host(int fd)
+{
+
+ return !fd_isrump(fd) ? 0 : -1;
+}
+
+ssize_t
+sendmsg(int fd, const struct msghdr *msg, int flags)
+{
+ ssize_t (*op_sendmsg)(int, const struct msghdr *, int);
+ const bool isrump = fd_isrump(fd);
+ int error;
+
+ /*
+ * reject descriptors from a different kernel.
+ */
+ error = msg_convert(__UNCONST(msg),
+ isrump ? fd_check_rump: fd_check_host);
+ if (error != 0) {
+ errno = error;
+ return -1;
+ }
+ /*
+ * convert descriptors in the message to raw values.
+ */
+ if (isrump) {
+ fd = fd_host2rump(fd);
+ /*
+ * XXX we directly modify the given message assuming:
+ * - cmsg is writable (typically on caller's stack)
+ * - caller don't care cmsg's contents after calling sendmsg.
+ * (thus no need to restore values)
+ *
+ * it's safer to copy and modify instead.
+ */
+ msg_convert(__UNCONST(msg), fd_host2rump);
+ op_sendmsg = GETSYSCALL(rump, SENDMSG);
+ } else {
+ op_sendmsg = GETSYSCALL(host, SENDMSG);
+ }
+ return op_sendmsg(fd, msg, flags);
+}
+
+/*
* dup2 is special. we allow dup2 of a rump kernel fd to 0-2 since
* many programs do that. dup2 of a rump kernel fd to another value
* not >= fdoff is an error.
@@ -1949,16 +2065,6 @@ FDCALL(ssize_t, sendto, DUALCALL_SENDTO,
const struct sockaddr *, socklen_t), \
(fd, buf, len, flags, to, tolen))
-FDCALL(ssize_t, recvmsg, DUALCALL_RECVMSG, \
- (int fd, struct msghdr *msg, int flags), \
- (int, struct msghdr *, int), \
- (fd, msg, flags))
-
-FDCALL(ssize_t, sendmsg, DUALCALL_SENDMSG, \
- (int fd, const struct msghdr *msg, int flags), \
- (int, const struct msghdr *, int), \
- (fd, msg, flags))
-
FDCALL(int, getsockopt, DUALCALL_GETSOCKOPT, \
(int fd, int level, int optn, void *optval, socklen_t *optlen), \
(int, int, int, void *, socklen_t *), \
