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[PATCH] sunrpc: cache_register can use wrong module reference

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When registering an RPC cache, cache_register() always sets the owner as the
sunrpc module.  However, there are RPC caches owned by other modules.  With
the incorrect owner setting, the real owning module can be removed potentially
with an open reference to the cache from userspace.

For example, if one were to stop the nfs server and unmount the nfsd
filesystem, the nfsd module could be removed eventhough rpc.idmapd had
references to the idtoname and nametoid caches (i.e.
/proc/net/rpc/nfs4.<cachename>/channel is still open).  This resulted in a
system panic on one of our machines when attempting to restart the nfs
services after reloading the nfsd module.

The following patch adds a 'struct module *owner' field in struct
cache_detail.  The owner is further assigned to the struct proc_dir_entry
in cache_register() so that the module cannot be unloaded while user-space
daemons have an open reference on the associated file under /proc.

Signed-off-by: Bruce Allan <bwa@us.ibm.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Bruce Allan
2005-09-06 15:17:08 -07:00
committed by Linus Torvalds
parent d013a068a5
commit f35279d3f7
8 changed files with 26 additions and 10 deletions
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3
fs/nfsd/export.c
View File

@@ -26,6 +26,7 @@
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/hash.h>
#include <linux/module.h>
#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>
@@ -221,6 +222,7 @@ static int expkey_show(struct seq_file *m,
}
struct cache_detail svc_expkey_cache = {
.owner = THIS_MODULE,
.hash_size = EXPKEY_HASHMAX,
.hash_table = expkey_table,
.name = "nfsd.fh",
@@ -456,6 +458,7 @@ static int svc_export_show(struct seq_file *m,
return 0;
}
struct cache_detail svc_export_cache = {
.owner = THIS_MODULE,
.hash_size = EXPORT_HASHMAX,
.hash_table = export_table,
.name = "nfsd.export",

8
fs/nfsd/nfs4idmap.c
View File

@@ -187,6 +187,7 @@ static int idtoname_parse(struct cache_detail *, char *, int);
static struct ent *idtoname_lookup(struct ent *, int);
static struct cache_detail idtoname_cache = {
.owner = THIS_MODULE,
.hash_size = ENT_HASHMAX,
.hash_table = idtoname_table,
.name = "nfs4.idtoname",
@@ -320,6 +321,7 @@ static struct ent *nametoid_lookup(struct ent *, int);
static int nametoid_parse(struct cache_detail *, char *, int);
static struct cache_detail nametoid_cache = {
.owner = THIS_MODULE,
.hash_size = ENT_HASHMAX,
.hash_table = nametoid_table,
.name = "nfs4.nametoid",
@@ -404,8 +406,10 @@ nfsd_idmap_init(void)
void
nfsd_idmap_shutdown(void)
{
cache_unregister(&idtoname_cache);
cache_unregister(&nametoid_cache);
if (cache_unregister(&idtoname_cache))
printk(KERN_ERR "nfsd: failed to unregister idtoname cache\n");
if (cache_unregister(&nametoid_cache))
printk(KERN_ERR "nfsd: failed to unregister nametoid cache\n");
}
/*