IRIX 6.5 patch for Compression with UsePrivilegeSeparation

[David Kaelbling]

Simon Cooper already mailed in a patch to get the effects of MAP_ANON on
IRIX systems, but it was against openssh/3.3p1.  I've reapplied his
patach to openssh/3.4p1 and include it as an attachment.

Here's his explanation:

> I noticed that the recent release requires the existence of MAP_ANON to get
> an anonymous memory region.  In Irix the equivalent functionality can be
> obtained by mapping the file /dev/zero.  This feature is rather obliquely
> documented in the "zero(7)"  man page...
> 
>      Mapping a zero special file creates a zero-initialized unnamed memory
>      object of a length equal to the length of the mapping and rounded up to
>      the nearest page size as returned by getpagesize(2).  Multiple processes
>      can share such a zero special file object provided a common ancestor
>      mapped the object MAP_SHARED.
> 
> I will be fixing our "mmap" documentation to include this useful bit of
> information.
> 
> So,
> 
>   address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_ANON|MAP_SHARED,-1,0);
> 
> becomes,
> 
>   fd_zero = open ("/dev/zero", O_RDRW); /* Check missing */
>   address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_SHARED, fd_zero, 0);
>   close (fd_zero)
> 
> With this in mind the following diffs will permit openssh-3.3p1 with
> compression and UsePrivilegeSeparation to work on all Irix 6.5 sub versions
> and likely anything since Irix 5.3 (ie 10 years ago!).

	David

-- 
David KAELBLING <drk at sgi.com>	    Silicon Graphics Computer Systems
1 Cabot Rd, suite 250; Hudson, MA 01749	    781.839.2157, fax ...2357
-------------- next part --------------
--- ./config.h.in	Wed Jun 26 10:08:19 2002
+++ ../openssh-3.4p1/./config.h.in	Wed Jun 26 17:46:01 2002
@@ -358,6 +358,9 @@
 /* Define if you have the `mmap' function that supports MAP_ANON|SHARED */
 #undef HAVE_MMAP_ANON_SHARED
 
+/* Define if mmap of /dev/zero gives an anonymous memory region. */
+#undef HAVE_MMAP_DEV_ZERO
+
 /* Define if sendmsg()/recvmsg() has problems passing file descriptors */
 #undef BROKEN_FD_PASSING
 
--- ./servconf.c	Mon Jun 24 23:22:04 2002
+++ ../openssh-3.4p1/./servconf.c	Wed Jun 26 17:54:55 2002
@@ -257,7 +257,7 @@
 	if (use_privsep == -1)
 		use_privsep = 1;
 
-#if !defined(HAVE_MMAP_ANON_SHARED)
+#if !defined(HAVE_MMAP_ANON_SHARED) && !defined(HAVE_MMAP_DEV_ZERO)
 	if (use_privsep && options->compression == 1) {
 		error("This platform does not support both privilege "
 		    "separation and compression");
--- ./configure.ac	Tue Jun 25 18:35:16 2002
+++ ../openssh-3.4p1/./configure.ac	Wed Jun 26 18:18:32 2002
@@ -154,6 +154,7 @@
 	AC_CHECK_FUNC(jlimit_startjob, [AC_DEFINE(WITH_IRIX_JOBS)])
 	AC_DEFINE(BROKEN_INET_NTOA)
 	AC_DEFINE(WITH_ABBREV_NO_TTY)
+	AC_DEFINE(HAVE_MMAP_DEV_ZERO)
 	;;
 *-*-linux*)
 	no_dev_ptmx=1
--- ./monitor_mm.c	Tue Jun 25 20:29:03 2002
+++ ../openssh-3.4p1/./monitor_mm.c	Wed Jun 26 17:54:29 2002
@@ -71,6 +71,9 @@
 {
 	void *address;
 	struct mm_master *mm;
+#if defined(HAVE_MMAP_DEV_ZERO)
+	int   fd_zero;
+#endif
 
 	if (mmalloc == NULL)
 		mm = xmalloc(sizeof(struct mm_master));
@@ -84,7 +87,16 @@
 	 */
 	mm->mmalloc = mmalloc;
 
-#ifdef HAVE_MMAP_ANON_SHARED
+#if defined(HAVE_MMAP_DEV_ZERO)
+	fd_zero = open ("/dev/zero", O_RDWR);
+	if (!fd_zero)
+		fatal("open(/dev/zero): %s", strerror(errno));
+	address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_SHARED,
+	    fd_zero, 0);
+ 	if (address == MAP_FAILED)
+ 		fatal("mmap(%lu): %s", (u_long)size, strerror(errno));
+	close (fd_zero);
+#elif defined(HAVE_MMAP_ANON_SHARED)
 	address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_ANON|MAP_SHARED,
 	    -1, 0);
 	if (address == MAP_FAILED)
@@ -130,7 +142,7 @@
 	mm_freelist(mm->mmalloc, &mm->rb_free);
 	mm_freelist(mm->mmalloc, &mm->rb_allocated);
 
-#ifdef HAVE_MMAP_ANON_SHARED
+#if defined(HAVE_MMAP_ANON_SHARED) || defined(HAVE_MMAP_DEV_ZERO)
 	if (munmap(mm->address, mm->size) == -1)
 		fatal("munmap(%p, %lu): %s", mm->address, (u_long)mm->size,
 		    strerror(errno));
--- ./configure	Wed Jun 26 10:08:18 2002
+++ ../openssh-3.4p1/./configure	Wed Jun 26 18:19:05 2002
@@ -3898,6 +3898,10 @@
 #define WITH_ABBREV_NO_TTY 1
 _ACEOF
 
+	cat >>confdefs.h <<\_ACEOF
+#define HAVE_MMAP_DEV_ZERO 1
+_ACEOF
+
 	;;
 *-*-linux*)
 	no_dev_ptmx=1