[RFC PATCH v4 09/12] nfs - cache_lib use namespace if not executing in init namespace

[Ian Kent]

From: Ian Kent <ik...@redhat.com>

If pipefs is registered within a namespace other than the root init
namespace subsequent pipefs requests should be run within the init
namespace of registration.

Signed-off-by: Ian Kent <ik...@redhat.com>
Cc: Benjamin Coddington <bcodd...@redhat.com>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: J. Bruce Fields <bfie...@fieldses.org>
Cc: David Howells <dhowe...@redhat.com>
Cc: Trond Myklebust <trond.mykleb...@primarydata.com>
Cc: Oleg Nesterov <onest...@redhat.com>
Cc: Eric W. Biederman <ebied...@xmission.com>
Cc: Jeff Layton <jeff.lay...@primarydata.com>
---
 fs/nfs/cache_lib.c           |    7 ++++++-
 include/linux/sunrpc/cache.h |    2 ++
 net/sunrpc/cache.c           |    5 +++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/cache_lib.c b/fs/nfs/cache_lib.c
index 5f7b053..4f381ad 100644
--- a/fs/nfs/cache_lib.c
+++ b/fs/nfs/cache_lib.c
@@ -48,7 +48,12 @@ int nfs_cache_upcall(struct cache_detail *cd, char 
*entry_name)
 
        if (nfs_cache_getent_prog[0] == '\0')
                goto out;
-       ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+       if (cd->u.pipefs.umh_token) {
+               long token = cd->u.pipefs.umh_token;
+               ret = call_usermodehelper_ns(argv[0], argv, envp,
+                                            UMH_WAIT_EXEC, token);
+       } else
+               ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
        /*
         * Disable the upcall mechanism if we're getting an ENOENT or
         * EACCES error. The admin can re-enable it on the fly by using
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 437ddb6..f6c1eb2 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -68,6 +68,8 @@ struct cache_detail_procfs {
 
 struct cache_detail_pipefs {
        struct dentry *dir;
+       /* Namespace token */
+       long umh_token;
 };
 
 struct cache_detail {
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 5199bb1..a635efb 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1811,6 +1811,9 @@ int sunrpc_cache_register_pipefs(struct dentry *parent,
        if (IS_ERR(dir))
                return PTR_ERR(dir);
        cd->u.pipefs.dir = dir;
+       if (cd->net != &init_net)
+               cd->u.pipefs.umh_token =
+                        umh_ns_get_token(cd->u.pipefs.umh_token);
        return 0;
 }
 EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
@@ -1819,6 +1822,8 @@ void sunrpc_cache_unregister_pipefs(struct cache_detail 
*cd)
 {
        rpc_remove_cache_dir(cd->u.pipefs.dir);
        cd->u.pipefs.dir = NULL;
+       umh_ns_put_token(cd->u.pipefs.umh_token);
+       cd->u.pipefs.umh_token = 0;
 }
 EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
 

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