An ULP is supposed to be able to replace a GSS rpc_auth object with
another GSS rpc_auth object using rpcauth_create(). However,
rpcauth_create() in 3.5 reliably fails with -EEXIST in this case.
This is because when gss_create() attempts to create the upcall pipes,
sometimes they are already there. For example if a pipe FS mount
event occurs, or a previous GSS flavor was in use for this rpc_clnt.
The ->pipes_destroy method works only on whatever rpc_auth is
associated with the rpc_clnt when it is destroyed. But there is no
guarantee that this is the same rpc_auth that was created when
the rpc_clnt was created. Thus cached pipe data must be reference
counted and destroyed when no more gss_auth's are using it. And,
->pipes_destroy must ensure that both the dentries and the pipe
data are gone so the pipe data does not leak.
The dentries appear to be created and deleted independently of the
rpc_pipe data. We must allow this to continue in order that mounting
and unmounting the pipe FS can work. However, pipe dentries must
remain in place during gss_free(), since they could be shared.
In the meantime, we need to provide a way for gss_create() to find
an existing pipe of a particular name so it may be shared.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
---
include/linux/sunrpc/clnt.h | 1
net/sunrpc/auth_gss/auth_gss.c | 141 ++++++++++++++++++++++++++++++++++------
net/sunrpc/clnt.c | 1
3 files changed, 123 insertions(+), 20 deletions(-)
diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 523547e..31857e0 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -62,6 +62,7 @@ struct rpc_clnt {
struct rpc_timeout cl_timeout_default;
const struct rpc_program *cl_program;
char *cl_principal; /* target to authenticate to */
+ struct list_head cl_pipes; /* clnt's upcall pipes */
};
/*
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 2264776..8ff5103 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -84,6 +84,14 @@ struct gss_auth {
struct rpc_pipe *pipe[2];
};
+struct gss_cached_pipe {
+ struct list_head gp_list;
+ unsigned int gp_ref;
+ char *gp_name;
+ struct rpc_pipe *gp_pipe;
+};
+DEFINE_MUTEX(gss_pipe_mutex);
+
/* pipe_version >= 0 if and only if someone has a pipe open. */
static int pipe_version = -1;
static atomic_t pipe_users = ATOMIC_INIT(0);
@@ -765,6 +773,20 @@ static void gss_pipe_dentry_destroy(struct rpc_pipe *pipe)
}
}
+static void gss_pipe_dentry_destroy_net(struct rpc_clnt *clnt,
+ struct rpc_pipe *pipe)
+{
+ struct net *net = rpc_net_ns(clnt);
+ struct super_block *sb;
+
+ sb = rpc_get_sb_net(net);
+ if (sb) {
+ if (clnt->cl_dentry)
+ gss_pipe_dentry_destroy(pipe);
+ rpc_put_sb_net(net);
+ }
+}
+
/*
* Release existing pipe dentries, but leave the rpc_pipe data
* ready to receive fresh dentries if subsequently needed.
@@ -827,20 +849,6 @@ out_err:
return err;
}
-static void gss_pipes_dentries_destroy_net(struct rpc_clnt *clnt,
- struct rpc_auth *auth)
-{
- struct net *net = rpc_net_ns(clnt);
- struct super_block *sb;
-
- sb = rpc_get_sb_net(net);
- if (sb) {
- if (clnt->cl_dentry)
- gss_pipes_dentries_destroy(auth);
- rpc_put_sb_net(net);
- }
-}
-
static int gss_pipes_dentries_create_net(struct rpc_clnt *clnt,
struct rpc_auth *auth)
{
@@ -857,16 +865,111 @@ static int gss_pipes_dentries_create_net(struct rpc_clnt *clnt,
return err;
}
+static struct gss_cached_pipe *gss_alloc_cached_pipe(char *name)
+{
+ struct gss_cached_pipe *cp;
+
+ cp = kmalloc(sizeof(*cp), GFP_KERNEL);
+ if (cp == NULL)
+ return NULL;
+
+ cp->gp_name = kstrdup(name, GFP_KERNEL);
+ if (cp->gp_name == NULL) {
+ kfree(cp);
+ return NULL;
+ }
+
+ INIT_LIST_HEAD(&cp->gp_list);
+ cp->gp_ref = 1;
+ return cp;
+}
+
+static void gss_free_cached_pipe(struct gss_cached_pipe *cp)
+{
+ kfree(cp->gp_name);
+ kfree(cp);
+}
+
+/*
+ * Returns a fresh or cached pipe data object. A cached pipe
+ * data object may already have a dentry attached to it. If an
+ * object cannot be found or created, an ERR_PTR is returned.
+ */
static struct rpc_pipe *gss_mkpipe_data(struct rpc_clnt *clnt,
const struct rpc_pipe_ops *ops,
char *name)
{
- return rpc_mkpipe_data(ops, RPC_PIPE_WAIT_FOR_OPEN);
+ struct gss_cached_pipe *cp;
+ struct rpc_pipe *pipe;
+
+ mutex_lock(&gss_pipe_mutex);
+
+ list_for_each_entry(cp, &clnt->cl_pipes, gp_list) {
+ if (strcmp(cp->gp_name, name) == 0) {
+ dprintk("RPC: %s found '%s' for clnt %p: %p\n",
+ __func__, name, clnt, cp->gp_pipe);
+ cp->gp_ref++;
+ pipe = cp->gp_pipe;
+ goto out;
+ }
+ }
+
+ pipe = ERR_PTR(-ENOMEM);
+ cp = gss_alloc_cached_pipe(name);
+ if (cp == NULL)
+ goto out;
+
+ pipe = rpc_mkpipe_data(ops, RPC_PIPE_WAIT_FOR_OPEN);
+ if (IS_ERR(pipe)) {
+ gss_free_cached_pipe(cp);
+ goto out;
+ }
+
+ dprintk("RPC: %s created '%s' for clnt %p: %p\n",
+ __func__, name, clnt, pipe);
+ cp->gp_pipe = pipe;
+ list_add(&cp->gp_list, &clnt->cl_pipes);
+
+out:
+ mutex_unlock(&gss_pipe_mutex);
+ return pipe;
}
+/*
+ * Decrements a cached pipes reference count, and releases it if
+ * the count goes to zero. Associated dentry is freed if present.
+ */
static void gss_destroy_pipe_data(struct rpc_clnt *clnt, struct rpc_pipe *pipe)
{
- rpc_destroy_pipe_data(pipe);
+ struct gss_cached_pipe *cp;
+
+ mutex_lock(&gss_pipe_mutex);
+
+ list_for_each_entry(cp, &clnt->cl_pipes, gp_list) {
+ if (cp->gp_pipe == pipe)
+ goto found;
+ }
+
+ dprintk("RPC: %s missing cache for pipe %p for clnt %p\n",
+ __func__, pipe, clnt);
+ WARN_ON(true);
+
+ mutex_unlock(&gss_pipe_mutex);
+ return;
+
+found:
+ if (--cp->gp_ref == 0) {
+ dprintk("RPC: %s destroying '%s' (%p) for clnt %p\n",
+ __func__, cp->gp_name, pipe, clnt);
+ gss_pipe_dentry_destroy_net(clnt, pipe);
+ rpc_destroy_pipe_data(pipe);
+ list_del(&cp->gp_list);
+ gss_free_cached_pipe(cp);
+ } else
+ dprintk("RPC: %s leaving '%s' (%p) for clnt %p\n",
+ __func__, cp->gp_name, pipe, clnt);
+
+ mutex_unlock(&gss_pipe_mutex);
}
/*
@@ -925,13 +1028,12 @@ gss_create(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
err = gss_pipes_dentries_create_net(clnt, auth);
if (err)
goto err_destroy_pipe_0;
+
err = rpcauth_init_credcache(auth);
if (err)
- goto err_unlink_pipes;
+ goto err_destroy_pipe_0;
return auth;
-err_unlink_pipes:
- gss_pipes_dentries_destroy_net(clnt, auth);
err_destroy_pipe_0:
gss_destroy_pipe_data(clnt, gss_auth->pipe[0]);
err_destroy_pipe_1:
@@ -948,7 +1050,6 @@ out_dec:
static void
gss_free(struct gss_auth *gss_auth)
{
- gss_pipes_dentries_destroy_net(gss_auth->client, &gss_auth->rpc_auth);
gss_destroy_pipe_data(gss_auth->client, gss_auth->pipe[0]);
gss_destroy_pipe_data(gss_auth->client, gss_auth->pipe[1]);
gss_mech_put(gss_auth->mech);
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f56f045..7bf6ed1 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -349,6 +349,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
if (!clnt->cl_principal)
goto out_no_principal;
}
+ INIT_LIST_HEAD(&clnt->cl_pipes);
atomic_set(&clnt->cl_count, 1);
--
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