Implement getpeereid(3), a front-end to the LOCAL_PEERCRED

socket option for the Unix domain.  It's weaker than the
socket option (this only returns the uid and gid, while the
socket opt. can return the entire group list), and is
implemented mostly for compatibility with OpenBSD.

3 files changed, 191 insertions, 2 deletions

diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index 4d2806b..24cd03d 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -13,7 +13,7 @@ SRCS+=  __xuname.c _pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
 	getcap.c getcwd.c getdomainname.c getgrent.c getgrouplist.c \
 	gethostname.c getloadavg.c getlogin.c getmntinfo.c getnetgrent.c \
 	getobjformat.c getosreldate.c getpagesize.c \
-	getpass.c getprogname.c getpwent.c getttyent.c \
+	getpass.c getpeereid.c getprogname.c getpwent.c getttyent.c \
 	getusershell.c getvfsbyname.c getvfsent.c glob.c \
 	initgroups.c isatty.c jrand48.c lcong48.c \
 	lockf.c lrand48.c mrand48.c msgctl.c \
@@ -46,7 +46,7 @@ MAN+=	alarm.3 arc4random.3 clock.3 \
 	getdiskbyname.3 getdomainname.3 getfsent.3 \
 	getgrent.3 getgrouplist.3 gethostname.3 getloadavg.3 \
 	getmntinfo.3 getnetgrent.3 getobjformat.3 \
-	getpagesize.3 getpass.3 getprogname.3 getpwent.3 \
+	getpagesize.3 getpass.3 getpeereid.3 getprogname.3 getpwent.3 \
 	getttyent.3 getusershell.3 getvfsbyname.3 getvfsent.3 \
 	glob.3 initgroups.3 isinf.3 \
 	ldexp.3 lockf.3 modf.3 msgctl.3 msgget.3 msgrcv.3 msgsnd.3 \
diff --git a/lib/libc/gen/getpeereid.3 b/lib/libc/gen/getpeereid.3
new file mode 100644
index 0000000..f59a96e
--- /dev/null
+++ b/lib/libc/gen/getpeereid.3
@@ -0,0 +1,136 @@
+.\"
+.\" Copyright (c) 2001 Dima Dorfman.
+.\" 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd July 15, 2001
+.Dt GETPEEREID 3
+.Os
+.Sh NAME
+.Nm getpeereid
+.Nd get the effective credentials of a UNIX-domain peer
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <unistd.h>
+.Ft int
+.Fn getpeereid "int s" "uid_t *euid" "gid_t *egid"
+.Sh DESCRIPTION
+The
+.Fn getpeereid
+routine returns the effective user and group IDs of the
+peer connected to a UNIX-domain socket.
+The argument
+.Fa s
+must be a UNIX-domain socket
+.Pq Xr unix 4
+of type
+.Dv SOCK_STREAM
+on which either
+.Xr connect 2
+or
+.Xr listen 2
+have been called.
+The effective used ID is placed in
+.Fa euid ,
+and the effective group ID in
+.Fa egid .
+.Pp
+The credentials returned to the
+.Xr listen 2
+caller are those of its peer at the time it called
+.Xr connect 2 ;
+the credentials returned to the
+.Xr connect 2
+caller are those of its peer at the time it called
+.Xr listen 2 .
+This mechanism is reliable; there is no way for either side to influence
+the credentials returned to its peer except by calling the appropriate
+system call (i.e., either
+.Xr connect 2
+or
+.Xr listen 2 )
+under different effective credentials.
+.Pp
+One common use of this routine is for a UNIX-domain server
+to verify the credentials of its client.
+Likewise, the client can verify the credentials of the server.
+.Sh IMPLEMENTATION NOTES
+On
+.Fx ,
+.Fn getpeereid
+is implemented in terms of the
+.Dv LOCAL_PEERCRED
+.Xr unix 4
+socket option.
+.Sh RETURN VALUES
+If the call succeeds, a value of 0 is returned and
+.Fa euid
+and
+.Fa egid
+contain the effective user and group IDs of the peer on
+.Fa s ,
+respectively.
+If the call fails, a value of \-1 is returned and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+The call succeeds unless:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The argument
+.Fa s
+is not a valid descriptor.
+.It Bq Er ENOTSOCK
+The argument
+.Fa s
+is a file, not a socket.
+.It Bq Er ENOTCONN
+The argument
+.Fa s
+does not refer to a socket on which
+.Xr connect 2
+or
+.Xr listen 2
+have been called.
+.It Bq Er EINVAL
+The argument
+.Fa s
+does not refer to a socket of type
+.Dv SOCK_STREAM .
+.El
+.Sh SEE ALSO
+.Xr connect 2 ,
+.Xr getpeername 2 ,
+.Xr getsockname 2 ,
+.Xr getsockopt 2 ,
+.Xr listen 2 ,
+.Xr unix 4
+.Sh HISTORY
+The
+.Fn getpeereid
+routine appeared in
+.Fx 5.0 .
diff --git a/lib/libc/gen/getpeereid.c b/lib/libc/gen/getpeereid.c
new file mode 100644
index 0000000..bd070db
--- /dev/null
+++ b/lib/libc/gen/getpeereid.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2001 Dima Dorfman.
+ * 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.
+ */
+
+#if defined(LIBC_RCS) && !defined(lint)
+static const char rcsid[] =
+  "$FreeBSD$";
+#endif /* LIBC_RCS and not lint */
+
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/ucred.h>
+#include <sys/un.h>
+
+#include <unistd.h>
+
+int
+getpeereid(int s, uid_t *euid, gid_t *egid)
+{
+	struct xucred xuc;
+	socklen_t xuclen;
+	int error;
+
+	xuclen = sizeof(xuc);
+	error = getsockopt(s, LOCAL_PEERCRED, 1, &xuc, &xuclen);
+	if (error != 0)
+		return (error);
+	*euid = xuc.cr_uid;
+	*egid = xuc.cr_gid;
+	return (0);
+}