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DNS: Make AFS go to the DNS for AFSDB records for unknown cells 

Add DNS query support for AFS so that it can get the IP addresses of Volume
Location servers from the DNS using an AFSDB record.

This requires userspace support.  /etc/request-key.conf must be configured to
invoke a helper for dns_resolver type keys with a subtype of "afsdb:" in the
description.

Signed-off-by: Wang Lei <wang840925@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Wang Lei 2010-08-04 15:16:38 +01:00 committed by Steve French
parent 1a4240f476
commit 07567a5509
2 changed files with 31 additions and 10 deletions
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1
fs/afs/Kconfig
View File

@ -2,6 +2,7 @@ config AFS_FS
tristate "Andrew File System support (AFS) (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL
select AF_RXRPC
select DNS_RESOLVER
help
If you say Y here, you will get an experimental Andrew File System
driver. It currently only supports unsecured read-only AFS access.

40
fs/afs/cell.c
View File

@ -13,6 +13,7 @@
#include <linux/slab.h>
#include <linux/key.h>
#include <linux/ctype.h>
#include <linux/dns_resolver.h>
#include <linux/sched.h>
#include <keys/rxrpc-type.h>
#include "internal.h"
@ -36,6 +37,8 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
struct key *key;
size_t namelen;
char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
char *dvllist = NULL, *_vllist = NULL;
char delimiter = ':';
int ret;
_enter("%s,%s", name, vllist);
@ -43,8 +46,10 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
namelen = strlen(name);
if (namelen > AFS_MAXCELLNAME)
if (namelen > AFS_MAXCELLNAME) {
_leave(" = -ENAMETOOLONG");
return ERR_PTR(-ENAMETOOLONG);
}
/* allocate and initialise a cell record */
cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
@ -64,15 +69,31 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
INIT_LIST_HEAD(&cell->vl_list);
spin_lock_init(&cell->vl_lock);
/* if the ip address is invalid, try dns query */
if (!vllist || strlen(vllist) < 7) {
ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
if (ret < 0) {
_leave(" = %d", ret);
return ERR_PTR(ret);
}
_vllist = dvllist;
/* change the delimiter for user-space reply */
delimiter = ',';
} else {
_vllist = vllist;
}
/* fill in the VL server list from the rest of the string */
do {
unsigned a, b, c, d;
next = strchr(vllist, ':');
next = strchr(_vllist, delimiter);
if (next)
*next++ = 0;
if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
if (sscanf(_vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
goto bad_address;
if (a > 255 || b > 255 || c > 255 || d > 255)
@ -81,7 +102,7 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
cell->vl_addrs[cell->vl_naddrs++].s_addr =
htonl((a << 24) | (b << 16) | (c << 8) | d);
} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (vllist = next));
} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (_vllist = next));
/* create a key to represent an anonymous user */
memcpy(keyname, "afs@", 4);
@ -110,6 +131,7 @@ bad_address:
ret = -EINVAL;
error:
key_put(cell->anonymous_key);
kfree(dvllist);
kfree(cell);
_leave(" = %d", ret);
return ERR_PTR(ret);
@ -201,14 +223,12 @@ int afs_cell_init(char *rootcell)
}
cp = strchr(rootcell, ':');
if (!cp) {
printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
_leave(" = -EINVAL");
return -EINVAL;
}
if (!cp)
_debug("kAFS: no VL server IP addresses specified");
else
*cp++ = 0;
/* allocate a cell record for the root cell */
*cp++ = 0;
new_root = afs_cell_create(rootcell, cp);
if (IS_ERR(new_root)) {
_leave(" = %ld", PTR_ERR(new_root));