[PATCH] sunrpc: cache_register can use wrong module reference

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>

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 9a11aa39e2e4e887d549f9e0f942797bc902ada1..057aff745506da64d5ca6b61d00f0eb41c597029 100644 (file)
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -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",

diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c
index 5605a26efc57d9db3ca93471f437996dae91056e..13369650cdf9b8db38f2af1a456db8e7cff5a645 100644 (file)
--- a/fs/nfsd/nfs4idmap.c
+++ b/fs/nfsd/nfs4idmap.c
@@ -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");
 }
 
 /*

diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 6864063d1b9f0c6638a2c7fa94f525536179e522..c4e3ea7cf1545e5da79e504c8fabddbc1f4a8d87 100644 (file)
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -60,6 +60,7 @@ struct cache_head {
 #define        CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
 
 struct cache_detail {
+       struct module *         owner;
        int                     hash_size;
        struct cache_head **    hash_table;
        rwlock_t                hash_lock;

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 5c8fe3bfc49415195058c8b6c939767d619478bb..e3308195374e635b2ea617d64fc48684c24d1241 100644 (file)
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -250,6 +250,7 @@ out:
 }
 
 static struct cache_detail rsi_cache = {
+       .owner          = THIS_MODULE,
        .hash_size      = RSI_HASHMAX,
        .hash_table     = rsi_table,
        .name           = "auth.rpcsec.init",
@@ -436,6 +437,7 @@ out:
 }
 
 static struct cache_detail rsc_cache = {
+       .owner          = THIS_MODULE,
        .hash_size      = RSC_HASHMAX,
        .hash_table     = rsc_table,
        .name           = "auth.rpcsec.context",
@@ -1074,7 +1076,9 @@ gss_svc_init(void)
 void
 gss_svc_shutdown(void)
 {
-       cache_unregister(&rsc_cache);
-       cache_unregister(&rsi_cache);
+       if (cache_unregister(&rsc_cache))
+               printk(KERN_ERR "auth_rpcgss: failed to unregister rsc cache\n");
+       if (cache_unregister(&rsi_cache))
+               printk(KERN_ERR "auth_rpcgss: failed to unregister rsi cache\n");
        svc_auth_unregister(RPC_AUTH_GSS);
 }

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 900f5bc7e3366480426f0674ec4a2ca5c2113f7d..f509e99927675e173f251f44637f976489a0abf1 100644 (file)
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -177,7 +177,7 @@ void cache_register(struct cache_detail *cd)
        cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
        if (cd->proc_ent) {
                struct proc_dir_entry *p;
-               cd->proc_ent->owner = THIS_MODULE;
+               cd->proc_ent->owner = cd->owner;
                cd->channel_ent = cd->content_ent = NULL;
                
                p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
@@ -185,7 +185,7 @@ void cache_register(struct cache_detail *cd)
                cd->flush_ent =  p;
                if (p) {
                        p->proc_fops = &cache_flush_operations;
-                       p->owner = THIS_MODULE;
+                       p->owner = cd->owner;
                        p->data = cd;
                }
  
@@ -195,7 +195,7 @@ void cache_register(struct cache_detail *cd)
                        cd->channel_ent = p;
                        if (p) {
                                p->proc_fops = &cache_file_operations;
-                               p->owner = THIS_MODULE;
+                               p->owner = cd->owner;
                                p->data = cd;
                        }
                }
@@ -205,7 +205,7 @@ void cache_register(struct cache_detail *cd)
                        cd->content_ent = p;
                        if (p) {
                                p->proc_fops = &content_file_operations;
-                               p->owner = THIS_MODULE;
+                               p->owner = cd->owner;
                                p->data = cd;
                        }
                }

diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 62a0734952766b56ae48e1053dce92f91ecf278c..ed48ff022d3529055c4a508ca86db9379052107d 100644 (file)
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -176,8 +176,10 @@ cleanup_sunrpc(void)
 {
        unregister_rpc_pipefs();
        rpc_destroy_mempool();
-       cache_unregister(&auth_domain_cache);
-       cache_unregister(&ip_map_cache);
+       if (cache_unregister(&auth_domain_cache))
+               printk(KERN_ERR "sunrpc: failed to unregister auth_domain cache\n");
+       if (cache_unregister(&ip_map_cache))
+               printk(KERN_ERR "sunrpc: failed to unregister ip_map cache\n");
 #ifdef RPC_DEBUG
        rpc_unregister_sysctl();
 #endif

diff --git a/net/sunrpc/svcauth.c b/net/sunrpc/svcauth.c
index bde8147ef2db54dc35ad8dbf77dd43994aae84fa..dda4f0c63511ca74475e9d1259bc73c0db9c47ef 100644 (file)
--- a/net/sunrpc/svcauth.c
+++ b/net/sunrpc/svcauth.c
@@ -143,6 +143,7 @@ static void auth_domain_drop(struct cache_head *item, struct cache_detail *cd)
 
 
 struct cache_detail auth_domain_cache = {
+       .owner          = THIS_MODULE,
        .hash_size      = DN_HASHMAX,
        .hash_table     = auth_domain_table,
        .name           = "auth.domain",

diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index d6baf6fdf8a97d43f8569d9fef0bc762ebc616b9..cac2e774dd813669d810f464a2263f2c08354a6a 100644 (file)
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -242,6 +242,7 @@ static int ip_map_show(struct seq_file *m,
        
 
 struct cache_detail ip_map_cache = {
+       .owner          = THIS_MODULE,
        .hash_size      = IP_HASHMAX,
        .hash_table     = ip_table,
        .name           = "auth.unix.ip",