sunrpc: make debugfs file creation failure non-fatal

commit f9c72d10d6fbf949558cd088389a42213ed7b12d upstream.

We currently have a problem that SELinux policy is being enforced when
creating debugfs files. If a debugfs file is created as a side effect of
doing some syscall, then that creation can fail if the SELinux policy
for that process prevents it.

This seems wrong. We don't do that for files under /proc, for instance,
so Bruce has proposed a patch to fix that.

While discussing that patch however, Greg K.H. stated:

    "No kernel code should care / fail if a debugfs function fails, so
     please fix up the sunrpc code first."

This patch converts all of the sunrpc debugfs setup code to be void
return functins, and the callers to not look for errors from those
functions.

This should allow rpc_clnt and rpc_xprt creation to work, even if the
kernel fails to create debugfs files for some reason.

Symptoms were failing krb5 mounts on systems using gss-proxy and
selinux.

Fixes: 388f0c776781 "sunrpc: add a debugfs rpc_xprt directory..."
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
index c57d8ea0716cddea1419a37481dbd7704b230d65..59a7889e15db51c3b24bc771dbe5d0b1c965212d 100644 (file)
--- a/include/linux/sunrpc/debug.h
+++ b/include/linux/sunrpc/debug.h
@@ -60,17 +60,17 @@ struct rpc_xprt;
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 void           rpc_register_sysctl(void);
 void           rpc_unregister_sysctl(void);
-int            sunrpc_debugfs_init(void);
+void           sunrpc_debugfs_init(void);
 void           sunrpc_debugfs_exit(void);
-int            rpc_clnt_debugfs_register(struct rpc_clnt *);
+void           rpc_clnt_debugfs_register(struct rpc_clnt *);
 void           rpc_clnt_debugfs_unregister(struct rpc_clnt *);
-int            rpc_xprt_debugfs_register(struct rpc_xprt *);
+void           rpc_xprt_debugfs_register(struct rpc_xprt *);
 void           rpc_xprt_debugfs_unregister(struct rpc_xprt *);
 #else
-static inline int
+static inline void
 sunrpc_debugfs_init(void)
 {
-       return 0;
+       return;
 }
 
 static inline void
@@ -79,10 +79,10 @@ sunrpc_debugfs_exit(void)
        return;
 }
 
-static inline int
+static inline void
 rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
 {
-       return 0;
+       return;
 }
 
 static inline void
@@ -91,10 +91,10 @@ rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
        return;
 }
 
-static inline int
+static inline void
 rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
 {
-       return 0;
+       return;
 }
 
 static inline void

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 3f5d4d48f0cbd28d407ce71f239bf2538c98bd0b..86e6cc5c09539631a649aa5f2f2f854ccaefc489 100644 (file)
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -303,9 +303,7 @@ static int rpc_client_register(struct rpc_clnt *clnt,
        struct super_block *pipefs_sb;
        int err;
 
-       err = rpc_clnt_debugfs_register(clnt);
-       if (err)
-               return err;
+       rpc_clnt_debugfs_register(clnt);
 
        pipefs_sb = rpc_get_sb_net(net);
        if (pipefs_sb) {

diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
index e811f390f9f67ceb2e897ee8da79189417eacc75..82962f7e6e888f619ad79754f038732d5d5b6333 100644 (file)
--- a/net/sunrpc/debugfs.c
+++ b/net/sunrpc/debugfs.c
@@ -129,48 +129,52 @@ static const struct file_operations tasks_fops = {
        .release        = tasks_release,
 };
 
-int
+void
 rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
 {
-       int len, err;
+       int len;
        char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
+       struct rpc_xprt *xprt;
 
        /* Already registered? */
-       if (clnt->cl_debugfs)
-               return 0;
+       if (clnt->cl_debugfs || !rpc_clnt_dir)
+               return;
 
        len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
        if (len >= sizeof(name))
-               return -EINVAL;
+               return;
 
        /* make the per-client dir */
        clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
        if (!clnt->cl_debugfs)
-               return -ENOMEM;
+               return;
 
        /* make tasks file */
-       err = -ENOMEM;
        if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs,
                                 clnt, &tasks_fops))
                goto out_err;
 
-       err = -EINVAL;
        rcu_read_lock();
+       xprt = rcu_dereference(clnt->cl_xprt);
+       /* no "debugfs" dentry? Don't bother with the symlink. */
+       if (!xprt->debugfs) {
+               rcu_read_unlock();
+               return;
+       }
        len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
-                       rcu_dereference(clnt->cl_xprt)->debugfs->d_name.name);
+                       xprt->debugfs->d_name.name);
        rcu_read_unlock();
+
        if (len >= sizeof(name))
                goto out_err;
 
-       err = -ENOMEM;
        if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name))
                goto out_err;
 
-       return 0;
+       return;
 out_err:
        debugfs_remove_recursive(clnt->cl_debugfs);
        clnt->cl_debugfs = NULL;
-       return err;
 }
 
 void
@@ -226,33 +230,33 @@ static const struct file_operations xprt_info_fops = {
        .release        = xprt_info_release,
 };
 
-int
+void
 rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
 {
        int len, id;
        static atomic_t cur_id;
        char            name[9]; /* 8 hex digits + NULL term */
 
+       if (!rpc_xprt_dir)
+               return;
+
        id = (unsigned int)atomic_inc_return(&cur_id);
 
        len = snprintf(name, sizeof(name), "%x", id);
        if (len >= sizeof(name))
-               return -EINVAL;
+               return;
 
        /* make the per-client dir */
        xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
        if (!xprt->debugfs)
-               return -ENOMEM;
+               return;
 
        /* make tasks file */
        if (!debugfs_create_file("info", S_IFREG | S_IRUSR, xprt->debugfs,
                                 xprt, &xprt_info_fops)) {
                debugfs_remove_recursive(xprt->debugfs);
                xprt->debugfs = NULL;
-               return -ENOMEM;
        }
-
-       return 0;
 }
 
 void
@@ -266,14 +270,17 @@ void __exit
 sunrpc_debugfs_exit(void)
 {
        debugfs_remove_recursive(topdir);
+       topdir = NULL;
+       rpc_clnt_dir = NULL;
+       rpc_xprt_dir = NULL;
 }
 
-int __init
+void __init
 sunrpc_debugfs_init(void)
 {
        topdir = debugfs_create_dir("sunrpc", NULL);
        if (!topdir)
-               goto out;
+               return;
 
        rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
        if (!rpc_clnt_dir)
@@ -283,10 +290,9 @@ sunrpc_debugfs_init(void)
        if (!rpc_xprt_dir)
                goto out_remove;
 
-       return 0;
+       return;
 out_remove:
        debugfs_remove_recursive(topdir);
        topdir = NULL;
-out:
-       return -ENOMEM;
+       rpc_clnt_dir = NULL;
 }

diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index e37fbed879568da535aa540656e7b7ace508e2cb..ee5d3d253102bf5d81a39f953248a6a6ca7a38d6 100644 (file)
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -98,10 +98,7 @@ init_sunrpc(void)
        if (err)
                goto out4;
 
-       err = sunrpc_debugfs_init();
-       if (err)
-               goto out5;
-
+       sunrpc_debugfs_init();
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
        rpc_register_sysctl();
 #endif
@@ -109,8 +106,6 @@ init_sunrpc(void)
        init_socket_xprt();     /* clnt sock transport */
        return 0;
 
-out5:
-       unregister_rpc_pipefs();
 out4:
        unregister_pernet_subsys(&sunrpc_net_ops);
 out3:

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index ebbefad21a370b7d4bb88b6c442d3fc04bfe1098..5dcf7eac30a6b3a83ae7c1b6a44d1c4c4f7f3bad 100644 (file)
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1303,7 +1303,6 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
  */
 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
 {
-       int err;
        struct rpc_xprt *xprt;
        struct xprt_class *t;
 
@@ -1344,11 +1343,7 @@ found:
                return ERR_PTR(-ENOMEM);
        }
 
-       err = rpc_xprt_debugfs_register(xprt);
-       if (err) {
-               xprt_destroy(xprt);
-               return ERR_PTR(err);
-       }
+       rpc_xprt_debugfs_register(xprt);
 
        dprintk("RPC:       created transport %p with %u slots\n", xprt,
                        xprt->max_reqs);