Nobody complained on the team-list, so commit it ...

This implements some kind of improved AFS support for Samba on Linux with
OpenAFS 1.2.10. ./configure --with-fake-kaserver assumes that you have
OpenAFS on your machine. To use this, you have to put the AFS server's KeyFile
into secrets.tdb with 'net afskey'. If this is done, on each tree connect
smbd creates a Kerberos V4 ticket suitable for use by the AFS client and
gives it to the kernel via the AFS syscall. This is meant to be very
light-weight, so I did not link in a whole lot of libraries to be more
platform-independent using the ka_SetToken function call.

Volker
(This used to be commit 5775690ee8e17d3e98355b5147e4aed47e8dc213)

1 files changed, 248 insertions, 0 deletions

diff --git a/source3/lib/afs.c b/source3/lib/afs.c
new file mode 100644
index 0000000000..b96703e986
--- /dev/null
+++ b/source3/lib/afs.c
@@ -0,0 +1,248 @@
+/* 
+ *  Unix SMB/CIFS implementation.
+ *  Generate AFS tickets
+ *  Copyright (C) Volker Lendecke 2003
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *  
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *  
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "includes.h"
+
+#ifdef WITH_FAKE_KASERVER
+
+#include <afs/stds.h>
+#include <afs/afs.h>
+#include <afs/auth.h>
+#include <afs/venus.h>
+#include <asm/unistd.h>
+#include <openssl/des.h>
+
+_syscall5(int, afs_syscall, int, subcall,
+	  char *, path,
+	  int, cmd,
+	  char *, cmarg,
+	  int, follow);
+
+char *afs_cell(void)
+{
+	static char *cell = NULL;
+
+	if (cell == NULL) {
+		cell = strdup(lp_realm());
+		strlower_m(cell);
+	}
+
+	return cell;
+}
+
+struct ClearToken {
+	uint32 AuthHandle;
+	char HandShakeKey[8];
+	uint32 ViceId;
+	uint32 BeginTimestamp;
+	uint32 EndTimestamp;
+};
+
+/*
+  Put an AFS token into the Kernel so that it can authenticate against
+  the AFS server. This assumes correct local uid settings.
+
+  This is currently highly Linux and OpenAFS-specific. The correct API
+  call for this would be ktc_SetToken. But to do that we would have to
+  import a REALLY big bunch of libraries which I would currently like
+  to avoid. 
+*/
+
+static BOOL afs_settoken(char *username, const struct ClearToken *ctok,
+			 char *v4tkt_data, int v4tkt_length)
+{
+	int ret;
+	struct {
+		char *in, *out;
+		uint16 in_size, out_size;
+	} iob;
+
+	char buf[1024];
+	char *p = buf;
+	int tmp;
+
+	memcpy(p, &v4tkt_length, sizeof(uint32));
+	p += sizeof(uint32);
+	memcpy(p, v4tkt_data, v4tkt_length);
+	p += v4tkt_length;
+
+	tmp = sizeof(struct ClearToken);
+	memcpy(p, &tmp, sizeof(uint32));
+	p += sizeof(uint32);
+	memcpy(p, ctok, tmp);
+	p += tmp;
+
+	tmp = 0;
+
+	memcpy(p, &tmp, sizeof(uint32));
+	p += sizeof(uint32);
+
+	tmp = strlen(afs_cell());
+	if (tmp >= MAXKTCREALMLEN) {
+		DEBUG(1, ("Realm too long\n"));
+		return False;
+	}
+
+	strncpy(p, afs_cell(), tmp);
+	p += tmp;
+	*p = 0;
+	p +=1;
+
+	iob.in = buf;
+	iob.in_size = PTR_DIFF(p,buf);
+	iob.out = buf;
+	iob.out_size = sizeof(buf);
+
+#if 0
+	file_save("/tmp/ioctlbuf", iob.in, iob.in_size);
+#endif
+
+	ret = afs_syscall(AFSCALL_PIOCTL, 0, VIOCSETTOK, (char *)&iob, 0);
+
+	DEBUG(10, ("afs VIOCSETTOK returned %d\n", ret));
+	return (ret == 0);
+}
+
+/*
+  This routine takes a radical approach completely defeating the
+  Kerberos idea of security and using AFS simply as an intelligent
+  file backend. Samba has persuaded itself somehow that the user is
+  actually correctly identified and then we create a ticket that the
+  AFS server hopefully accepts using its KeyFile that the admin has
+  kindly stored to our secrets.tdb.
+
+  Thanks to the book "Network Security -- PRIVATE Communication in a
+  PUBLIC World" by Charlie Kaufman, Radia Perlman and Mike Speciner
+  Kerberos 4 tickets are not really hard to construct.
+
+  For the comments "Alice" is the User to be auth'ed, and "Bob" is the
+  AFS server.  */
+
+BOOL afs_login(char *username)
+{
+	fstring ticket;
+	char *p = ticket;
+	uint32 len;
+	struct afs_key key;
+
+	struct ClearToken ct;
+
+	uint32 now;		/* I assume time() returns 32 bit */
+
+	des_key_schedule key_schedule;
+
+	DEBUG(10, ("Trying to log into AFS for user %s@%s\n",
+		   username, afs_cell()));
+
+	if (!secrets_init()) 
+		return False;
+
+	if (!secrets_fetch_afs_key(afs_cell(), &key)) {
+		DEBUG(5, ("Could not fetch AFS service key\n"));
+		return False;
+	}
+
+	ct.AuthHandle = key.kvno;
+
+	/* Build the ticket. This is going to be encrypted, so in our
+           way we fill in ct while we still have the unencrypted
+           form. */
+
+	p = ticket;
+
+	/* The byte-order */
+	*p = 1;
+	p += 1;
+
+	/* "Alice", the client username */
+	strncpy(p, username, sizeof(ticket)-PTR_DIFF(p,ticket)-1);
+	p += strlen(p)+1;
+	strncpy(p, "", sizeof(ticket)-PTR_DIFF(p,ticket)-1);
+	p += strlen(p)+1;
+	strncpy(p, afs_cell(), sizeof(ticket)-PTR_DIFF(p,ticket)-1);
+	p += strlen(p)+1;
+
+	ct.ViceId = getuid();
+	DEBUG(10, ("Creating Token for uid %d\n", ct.ViceId));
+
+	/* Alice's network layer address. At least Openafs-1.2.10
+           ignores this, so we fill in a dummy value here. */
+	SIVAL(p, 0, 0);
+	p += 4;
+
+	/* We need to create a session key */
+	generate_random_buffer(p, 8, False);
+
+	/* Our client code needs the the key in the clear, it does not
+           know the server-key ... */
+	memcpy(ct.HandShakeKey, p, 8);
+
+	p += 8;
+
+	/* Ticket lifetime. We fake everything here, so go as long as
+	   possible. This is in 5-minute intervals, so 255 is 21 hours
+	   and 15 minutes.*/
+	*p = 255;
+	p += 1;
+
+	/* Ticket creation time */
+	now = time(NULL);
+	SIVAL(p, 0, now);
+	ct.BeginTimestamp = now;
+
+	ct.EndTimestamp = now + (255*60*5);
+	if (((ct.EndTimestamp - ct.BeginTimestamp) & 1) == 1) {
+		ct.BeginTimestamp += 1; /* Lifetime must be even */
+	}
+	p += 4;
+
+	/* And here comes Bob's name and instance, in this case the
+           AFS server. */
+	strncpy(p, "afs", sizeof(ticket)-PTR_DIFF(p,ticket)-1);
+	p += strlen(p)+1;
+	strncpy(p, "", sizeof(ticket)-PTR_DIFF(p,ticket)-1);
+	p += strlen(p)+1;
+
+	/* And zero-pad to a multiple of 8 bytes */
+	len = PTR_DIFF(p, ticket);
+	if (len & 7) {
+		uint32 extra_space = 8-(len & 7);
+		memset(p, 0, extra_space);
+		p+=extra_space;
+	}
+	len = PTR_DIFF(p, ticket);
+
+	des_key_sched((const_des_cblock *)key.key, key_schedule);
+	des_pcbc_encrypt(ticket, ticket,
+			 len, key_schedule, (C_Block *)key.key, 1);
+
+	ZERO_STRUCT(key);
+
+	return afs_settoken(username, &ct, ticket, len);
+}
+
+#else
+
+BOOL afs_login(char *username)
+{
+	return True;
+}
+
+#endif /* WITH_FAKE_KASERVER */