From: Bruce Allan 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./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 Cc: Trond Myklebust Cc: Neil Brown Signed-off-by: Andrew Morton --- fs/nfsd/export.c | 3 +++ fs/nfsd/nfs4idmap.c | 8 ++++++-- include/linux/sunrpc/cache.h | 1 + net/sunrpc/auth_gss/svcauth_gss.c | 8 ++++++-- net/sunrpc/cache.c | 8 ++++---- net/sunrpc/sunrpc_syms.c | 6 ++++-- net/sunrpc/svcauth.c | 1 + net/sunrpc/svcauth_unix.c | 1 + 8 files changed, 26 insertions(+), 10 deletions(-) diff -puN fs/nfsd/export.c~sunrpc-cache_register-can-use-wrong-module-reference fs/nfsd/export.c --- devel/fs/nfsd/export.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/fs/nfsd/export.c 2005-08-05 00:19:35.000000000 -0700 @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -221,6 +222,7 @@ static int expkey_show(struct seq_file * } 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_fi return 0; } struct cache_detail svc_export_cache = { + .owner = THIS_MODULE, .hash_size = EXPORT_HASHMAX, .hash_table = export_table, .name = "nfsd.export", diff -puN fs/nfsd/nfs4idmap.c~sunrpc-cache_register-can-use-wrong-module-reference fs/nfsd/nfs4idmap.c --- devel/fs/nfsd/nfs4idmap.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/fs/nfsd/nfs4idmap.c 2005-08-05 00:19:35.000000000 -0700 @@ -187,6 +187,7 @@ static int idtoname_parse(struct 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(struc 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 -puN include/linux/sunrpc/cache.h~sunrpc-cache_register-can-use-wrong-module-reference include/linux/sunrpc/cache.h --- devel/include/linux/sunrpc/cache.h~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/include/linux/sunrpc/cache.h 2005-08-05 00:19:35.000000000 -0700 @@ -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 -puN net/sunrpc/auth_gss/svcauth_gss.c~sunrpc-cache_register-can-use-wrong-module-reference net/sunrpc/auth_gss/svcauth_gss.c --- devel/net/sunrpc/auth_gss/svcauth_gss.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/net/sunrpc/auth_gss/svcauth_gss.c 2005-08-05 00:19:35.000000000 -0700 @@ -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 -puN net/sunrpc/cache.c~sunrpc-cache_register-can-use-wrong-module-reference net/sunrpc/cache.c --- devel/net/sunrpc/cache.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/net/sunrpc/cache.c 2005-08-05 00:19:35.000000000 -0700 @@ -177,7 +177,7 @@ void cache_register(struct cache_detail 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->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->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->content_ent = p; if (p) { p->proc_fops = &content_file_operations; - p->owner = THIS_MODULE; + p->owner = cd->owner; p->data = cd; } } diff -puN net/sunrpc/sunrpc_syms.c~sunrpc-cache_register-can-use-wrong-module-reference net/sunrpc/sunrpc_syms.c --- devel/net/sunrpc/sunrpc_syms.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/net/sunrpc/sunrpc_syms.c 2005-08-05 00:19:35.000000000 -0700 @@ -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 -puN net/sunrpc/svcauth.c~sunrpc-cache_register-can-use-wrong-module-reference net/sunrpc/svcauth.c --- devel/net/sunrpc/svcauth.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/net/sunrpc/svcauth.c 2005-08-05 00:19:35.000000000 -0700 @@ -143,6 +143,7 @@ static void auth_domain_drop(struct cach struct cache_detail auth_domain_cache = { + .owner = THIS_MODULE, .hash_size = DN_HASHMAX, .hash_table = auth_domain_table, .name = "auth.domain", diff -puN net/sunrpc/svcauth_unix.c~sunrpc-cache_register-can-use-wrong-module-reference net/sunrpc/svcauth_unix.c --- devel/net/sunrpc/svcauth_unix.c~sunrpc-cache_register-can-use-wrong-module-reference 2005-08-05 00:19:35.000000000 -0700 +++ devel-akpm/net/sunrpc/svcauth_unix.c 2005-08-05 00:19:35.000000000 -0700 @@ -242,6 +242,7 @@ static int ip_map_show(struct seq_file * struct cache_detail ip_map_cache = { + .owner = THIS_MODULE, .hash_size = IP_HASHMAX, .hash_table = ip_table, .name = "auth.unix.ip", _