[PATCH 3.13 035/187] sunrpc: create a new dummy pipe for gssd to hold open

Kamal Mostafa
2014-09-15T22:21:16Z

From: Jeff Layton <jlayton@redhat.com>

commit 4b9a445e3eeb8bd9278b1ae51c1b3a651e370cd6 upstream.

rpc.gssd will naturally hold open any pipe named */clnt*/gssd that shows
up under rpc_pipefs. That behavior gives us a reliable mechanism to tell
whether it's actually running or not.

Create a new toplevel "gssd" directory in rpc_pipefs when it's mounted.
Under that directory create another directory called "clntXX", and then
within that a pipe called "gssd".

We'll never send an upcall along that pipe, and any downcall written to
it will just return -EINVAL.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ kamal: 3.13-stable prereq for 6aa23d76 "nfs: check if gssd is running
before attempting to use krb5i auth in SETCLIENTID call" ]
Cc: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
include/linux/sunrpc/rpc_pipe_fs.h | 3 +-
net/sunrpc/netns.h | 1 +
net/sunrpc/rpc_pipe.c | 93 ++++++++++++++++++++++++++++++++++++--
net/sunrpc/sunrpc_syms.c | 8 +++-
4 files changed, 100 insertions(+), 5 deletions(-)

diff --git a/include/linux/sunrpc/rpc_pipe_fs.h b/include/linux/sunrpc/rpc_pipe_fs.h
index a353e03..85f1342 100644
--- a/include/linux/sunrpc/rpc_pipe_fs.h
+++ b/include/linux/sunrpc/rpc_pipe_fs.h
@@ -84,7 +84,8 @@ enum {

extern struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
const unsigned char *dir_name);
-extern void rpc_pipefs_init_net(struct net *net);
+extern int rpc_pipefs_init_net(struct net *net);
+extern void rpc_pipefs_exit_net(struct net *net);
extern struct super_block *rpc_get_sb_net(const struct net *net);
extern void rpc_put_sb_net(const struct net *net);

diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index 3a260e4..c804ed4 100644
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -14,6 +14,7 @@ struct sunrpc_net {
struct cache_detail *rsi_cache;

struct super_block *pipefs_sb;
+ struct rpc_pipe *gssd_dummy;
struct mutex pipefs_sb_lock;

struct list_head all_clients;
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index bf04b30..c23458b 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -38,7 +38,7 @@
#define NET_NAME(net) ((net == &init_net) ? " (init_net)" : "")

static struct file_system_type rpc_pipe_fs_type;
-
+static const struct rpc_pipe_ops gssd_dummy_pipe_ops;

static struct kmem_cache *rpc_inode_cachep __read_mostly;

@@ -1159,6 +1159,7 @@ enum {
RPCAUTH_nfsd4_cb,
RPCAUTH_cache,
RPCAUTH_nfsd,
+ RPCAUTH_gssd,
RPCAUTH_RootEOF
};

@@ -1195,6 +1196,10 @@ static const struct rpc_filelist files[] = {
.name = "nfsd",
.mode = S_IFDIR | S_IRUGO | S_IXUGO,
},
+ [RPCAUTH_gssd] = {
+ .name = "gssd",
+ .mode = S_IFDIR | S_IRUGO | S_IXUGO,
+ },
};

/*
@@ -1208,13 +1213,25 @@ struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
}
EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);

-void rpc_pipefs_init_net(struct net *net)
+int rpc_pipefs_init_net(struct net *net)
{
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

+ sn->gssd_dummy = rpc_mkpipe_data(&gssd_dummy_pipe_ops, 0);
+ if (IS_ERR(sn->gssd_dummy))
+ return PTR_ERR(sn->gssd_dummy);
+
mutex_init(&sn->pipefs_sb_lock);
sn->gssd_running = 1;
sn->pipe_version = -1;
+ return 0;
+}
+
+void rpc_pipefs_exit_net(struct net *net)
+{
+ struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+ rpc_destroy_pipe_data(sn->gssd_dummy);
}

/*
@@ -1244,11 +1261,73 @@ void rpc_put_sb_net(const struct net *net)
}
EXPORT_SYMBOL_GPL(rpc_put_sb_net);

+static const struct rpc_filelist gssd_dummy_clnt_dir[] = {
+ [0] = {
+ .name = "clntXX",
+ .mode = S_IFDIR | S_IRUGO | S_IXUGO,
+ },
+};
+
+static ssize_t
+dummy_downcall(struct file *filp, const char __user *src, size_t len)
+{
+ return -EINVAL;
+}
+
+static const struct rpc_pipe_ops gssd_dummy_pipe_ops = {
+ .upcall = rpc_pipe_generic_upcall,
+ .downcall = dummy_downcall,
+};
+
+/**
+ * rpc_gssd_dummy_populate - create a dummy gssd pipe
+ * @root: root of the rpc_pipefs filesystem
+ * @pipe_data: pipe data created when netns is initialized
+ *
+ * Create a dummy set of directories and a pipe that gssd can hold open to
+ * indicate that it is up and running.
+ */
+static struct dentry *
+rpc_gssd_dummy_populate(struct dentry *root, struct rpc_pipe *pipe_data)
+{
+ int ret = 0;
+ struct dentry *gssd_dentry;
+ struct dentry *clnt_dentry = NULL;
+ struct dentry *pipe_dentry = NULL;
+ struct qstr q = QSTR_INIT(files[RPCAUTH_gssd].name,
+ strlen(files[RPCAUTH_gssd].name));
+
+ /* We should never get this far if "gssd" doesn't exist */
+ gssd_dentry = d_hash_and_lookup(root, &q);
+ if (!gssd_dentry)
+ return ERR_PTR(-ENOENT);
+
+ ret = rpc_populate(gssd_dentry, gssd_dummy_clnt_dir, 0, 1, NULL);
+ if (ret) {
+ pipe_dentry = ERR_PTR(ret);
+ goto out;
+ }
+
+ q.name = gssd_dummy_clnt_dir[0].name;
+ q.len = strlen(gssd_dummy_clnt_dir[0].name);
+ clnt_dentry = d_hash_and_lookup(gssd_dentry, &q);
+ if (!clnt_dentry) {
+ pipe_dentry = ERR_PTR(-ENOENT);
+ goto out;
+ }
+
+ pipe_dentry = rpc_mkpipe_dentry(clnt_dentry, "gssd", NULL, pipe_data);
+out:
+ dput(clnt_dentry);
+ dput(gssd_dentry);
+ return pipe_dentry;
+}
+
static int
rpc_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
- struct dentry *root;
+ struct dentry *root, *gssd_dentry;
struct net *net = data;
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
int err;
@@ -1266,6 +1345,13 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
return -ENOMEM;
if (rpc_populate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF, NULL))
return -ENOMEM;
+
+ gssd_dentry = rpc_gssd_dummy_populate(root, sn->gssd_dummy);
+ if (IS_ERR(gssd_dentry)) {
+ __rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);
+ return PTR_ERR(gssd_dentry);
+ }
+
dprintk("RPC: sending pipefs MOUNT notification for net %p%s\n",
net, NET_NAME(net));
mutex_lock(&sn->pipefs_sb_lock);
@@ -1280,6 +1366,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
return 0;

err_depopulate:
+ dput(gssd_dentry);
blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
RPC_PIPEFS_UMOUNT,
sb);
diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 3d6498a..cd30120 100644
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -44,12 +44,17 @@ static __net_init int sunrpc_init_net(struct net *net)
if (err)
goto err_unixgid;

- rpc_pipefs_init_net(net);
+ err = rpc_pipefs_init_net(net);
+ if (err)
+ goto err_pipefs;
+
INIT_LIST_HEAD(&sn->all_clients);
spin_lock_init(&sn->rpc_client_lock);
spin_lock_init(&sn->rpcb_clnt_lock);
return 0;

+err_pipefs:
+ unix_gid_cache_destroy(net);
err_unixgid:
ip_map_cache_destroy(net);
err_ipmap:
@@ -60,6 +65,7 @@ err_proc:

static __net_exit void sunrpc_exit_net(struct net *net)
{
+ rpc_pipefs_exit_net(net);
unix_gid_cache_destroy(net);
ip_map_cache_destroy(net);
rpc_proc_exit(net);
--
1.9.1