On Friday 30 September 2011 06:02 pm, Jung-uk Kim wrote:
> [Removed freebsd-security@]
>
> On Friday 30 September 2011 04:00 am, FreeBSD Security Officer 
wrote:
> > Hi all,
> >
> > It appears that the security fix in SA-11:05.unix exposed a bug
> > in the linux emulation code: Linux has a different size of
> > sockaddr_un than FreeBSD, and the linux emulation code was
> > passing socket addresses through without doing any translation
> > first.
> >
> > This appears to break all X-using Linux code -- both applications
> > and plugins such as the widely-used flash plugin -- and probably
> > other Linux applications too.
> >
> > I am working on a fix for this and will send an updated advisory
> > out as soon as it's ready.
>
> For the impatient, I have written *unofficial* patch for this
> Linuxulator regression.
>
> Please note that I am posting this patch to this ML only because I
> wanted to point out Linuxulator is actually missing very important
> feature, i.e., anonymous Unix domain socket.

I have updated the patch.  It should be slightly more safer than the 
previous version.  This patch is also available from here:

http://people.freebsd.org/~jkim/linux_socket.diff

Please note this is an *unofficial* fix.

Jung-uk Kim
Index: sys/compat/linux/linux_socket.c
===================================================================
--- sys/compat/linux/linux_socket.c     (revision 225884)
+++ sys/compat/linux/linux_socket.c     (working copy)
@@ -96,14 +96,13 @@ static int
 do_sa_get(struct sockaddr **sap, const struct osockaddr *osa, int *osalen,
     struct malloc_type *mtype)
 {
-       int error=0, bdom;
        struct sockaddr *sa;
        struct osockaddr *kosa;
-       int alloclen;
 #ifdef INET6
+       struct sockaddr_in6 *sin6;
        int oldv6size;
-       struct sockaddr_in6 *sin6;
 #endif
+       int alloclen, bdom, error, hdrlen, pathlen;
 
        if (*osalen < 2 || *osalen > UCHAR_MAX || !osa)
                return (EINVAL);
@@ -133,6 +132,17 @@ do_sa_get(struct sockaddr **sap, const struct osoc
                goto out;
        }
 
+       if (bdom == AF_LOCAL) {
+               hdrlen = offsetof(struct sockaddr_un, sun_path);
+               if (alloclen > hdrlen) {
+                       pathlen = sizeof(struct sockaddr_un) - hdrlen;
+                       alloclen = strnlen(kosa->sa_data, pathlen);
+                       if (alloclen == pathlen)
+                               log(LOG_DEBUG, "long sockaddr_un truncated\n");
+                       alloclen += hdrlen;
+               }
+       }
+
 #ifdef INET6
        /*
         * Older Linux IPv6 code uses obsolete RFC2133 struct sockaddr_in6,
@@ -696,13 +706,26 @@ static int
 linux_bind(struct thread *td, struct linux_bind_args *args)
 {
        struct sockaddr *sa;
-       int error;
+       int error, pathlen;
 
        error = linux_getsockaddr(&sa, PTRIN(args->name),
            args->namelen);
        if (error)
                return (error);
 
+       /*
+        * XXX Anonymous Unix domain socket not supported.
+        */
+       if (sa->sa_family == AF_LOCAL) {
+               pathlen = sa->sa_len - offsetof(struct sockaddr_un, sun_path);
+               if (pathlen <= 0) {
+                       free(sa, M_SONAME);
+                       if (pathlen == 0)
+                               return (0);
+                       return (EINVAL);
+               }
+       }
+
        error = kern_bind(td, args->s, sa);
        free(sa, M_SONAME);
        if (error == EADDRNOTAVAIL && args->namelen != sizeof(struct 
sockaddr_in))
@@ -723,13 +746,26 @@ linux_connect(struct thread *td, struct linux_conn
        struct socket *so;
        struct sockaddr *sa;
        u_int fflag;
-       int error;
+       int error, pathlen;
 
        error = linux_getsockaddr(&sa, (struct osockaddr *)PTRIN(args->name),
            args->namelen);
        if (error)
                return (error);
 
+       /*
+        * XXX Anonymous Unix domain socket not supported.
+        */
+       if (sa->sa_family == AF_LOCAL) {
+               pathlen = sa->sa_len - offsetof(struct sockaddr_un, sun_path);
+               if (pathlen <= 0) {
+                       free(sa, M_SONAME);
+                       if (pathlen == 0)
+                               return (ENOENT);
+                       return (EINVAL);
+               }
+       }
+
        error = kern_connect(td, args->s, sa);
        free(sa, M_SONAME);
        if (error != EISCONN)
Index: sys/conf/files
===================================================================
--- sys/conf/files      (revision 225884)
+++ sys/conf/files      (working copy)
@@ -2548,6 +2548,7 @@ libkern/strlcpy.c         standard
 libkern/strlen.c               standard
 libkern/strncmp.c              standard
 libkern/strncpy.c              standard
+libkern/strnlen.c              standard
 libkern/strsep.c               standard
 libkern/strspn.c               standard
 libkern/strstr.c               standard
Index: sys/libkern/strnlen.c
===================================================================
--- sys/libkern/strnlen.c       (revision 225884)
+++ sys/libkern/strnlen.c       (working copy)
@@ -0,0 +1,42 @@
+/*-
+ * Copyright (c) 2009 David Schultz <[email protected]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/libkern.h>
+
+size_t
+strnlen(const char *s, size_t maxlen)
+{
+       size_t len;
+
+       for (len = 0; len < maxlen; len++, s++) {
+               if (!*s)
+                       break;
+       }
+       return (len);
+}
Index: sys/sys/libkern.h
===================================================================
--- sys/sys/libkern.h   (revision 225884)
+++ sys/sys/libkern.h   (working copy)
@@ -116,6 +116,7 @@ size_t       strlen(const char *);
 int     strncasecmp(const char *, const char *, size_t);
 int     strncmp(const char *, const char *, size_t);
 char   *strncpy(char * __restrict, const char * __restrict, size_t);
+size_t  strnlen(const char *, size_t);
 char   *strsep(char **, const char *delim);
 size_t  strspn(const char *, const char *);
 char   *strstr(const char *, const char *);
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