@@ -293,7 +293,10 @@ static void nfs4_shutdown_client(struct nfs_client *clp)
rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
kfree(clp->cl_serverowner);
kfree(clp->cl_serverscope);
- kfree(clp->cl_implid);
+#ifdef CONFIG_NFS_V4_1
+ if (clp->cl_implid)
+ kfree_rcu(clp->cl_implid, __rcu_head);
+#endif
kfree(clp->cl_owner_id);
}
@@ -8884,7 +8884,8 @@ static void nfs4_exchange_id_release(void *data)
(struct nfs41_exchange_id_data *)data;
nfs_put_client(cdata->args.client);
- kfree(cdata->res.impl_id);
+ if (cdata->res.impl_id)
+ kfree_rcu(cdata->res.impl_id, __rcu_head);
kfree(cdata->res.server_scope);
kfree(cdata->res.server_owner);
kfree(cdata);
@@ -9046,7 +9047,7 @@ static int _nfs4_proc_exchange_id(struct nfs_client *clp, const struct cred *cre
swap(clp->cl_serverowner, resp->server_owner);
swap(clp->cl_serverscope, resp->server_scope);
- swap(clp->cl_implid, resp->impl_id);
+ resp->impl_id = rcu_replace_pointer(clp->cl_implid, resp->impl_id, 1);
/* Save the EXCHANGE_ID verifier session trunk tests */
memcpy(clp->cl_confirm.data, argp->verifier.data,
@@ -615,13 +615,19 @@ static void show_pnfs(struct seq_file *m, struct nfs_server *server)
static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
{
- if (nfss->nfs_client && nfss->nfs_client->cl_implid) {
- struct nfs41_impl_id *impl_id = nfss->nfs_client->cl_implid;
+ struct nfs_client *clp = nfss->nfs_client;
+ struct nfs41_impl_id *impl_id;
+
+ if (!clp)
+ return;
+ rcu_read_lock();
+ impl_id = rcu_dereference(clp->cl_implid);
+ if (impl_id)
seq_printf(m, "\n\timpl_id:\tname='%s',domain='%s',"
"date='%llu,%u'",
impl_id->name, impl_id->domain,
impl_id->date.seconds, impl_id->date.nseconds);
- }
+ rcu_read_unlock();
}
#else
#if IS_ENABLED(CONFIG_NFS_V4)
@@ -104,7 +104,7 @@ struct nfs_client {
bool cl_preserve_clid;
struct nfs41_server_owner *cl_serverowner;
struct nfs41_server_scope *cl_serverscope;
- struct nfs41_impl_id *cl_implid;
+ struct nfs41_impl_id __rcu *cl_implid;
/* nfs 4.1+ state protection modes: */
unsigned long cl_sp4_flags;
#define NFS_SP4_MACH_CRED_MINIMAL 1 /* Minimal sp4_mach_cred - state ops
@@ -1374,6 +1374,7 @@ struct nfs41_impl_id {
char domain[NFS4_OPAQUE_LIMIT + 1];
char name[NFS4_OPAQUE_LIMIT + 1];
struct nfstime4 date;
+ struct rcu_head __rcu_head;
};
#define MAX_BIND_CONN_TO_SESSION_RETRIES 3
@@ -1397,7 +1398,7 @@ struct nfs41_exchange_id_res {
u32 flags;
struct nfs41_server_owner *server_owner;
struct nfs41_server_scope *server_scope;
- struct nfs41_impl_id *impl_id;
+ struct nfs41_impl_id __rcu *impl_id;
struct nfs41_state_protection state_protect;
};
When performing exchange id call, a new nfs41_impl_id will be allocated to store some information from server. The pointers to the old and new nfs41_impl_ids are swapped, and the old one will be freed. However, UAF may be triggered as follows: After T2 has got a pointer to the nfs41_impl_id, the nfs41_impl_id is freed by T1 before it is used. T1 T2 nfs4_proc_exchange_id _nfs4_proc_exchange_id nfs4_run_exchange_id kzalloc // alloc nfs41_impl_id-B rpc_run_task nfs_show_stats show_implementation_id impl_id = nfss->nfs_client->cl_implid // get alloc nfs41_impl_id-A swap(clp->cl_implid, resp->impl_id) rpc_put_task ... nfs4_exchange_id_release kfree // free nfs41_impl_id-A impl_id->name // UAF Fix this issue by using rcu to protect the nfs41_impl_id. Fixes: 7d2ed9ac22bc ("NFSv4: parse and display server implementation ids") Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- v1->v2: Free nfs41_impl_id by call_rcu in nfs4_shutdown_client to resolve warning. v2->v3: Free nfs41_impl_id by kfree_rcu and check CONFIG_NFS_V4_1 before freeing nfs41_impl_id in nfs4_shutdown_client. fs/nfs/nfs4client.c | 5 ++++- fs/nfs/nfs4proc.c | 5 +++-- fs/nfs/super.c | 12 +++++++++--- include/linux/nfs_fs_sb.h | 2 +- include/linux/nfs_xdr.h | 3 ++- 5 files changed, 19 insertions(+), 8 deletions(-)