[RFC PATCH 5 7/7] KEYS: exec request key within service thread of key creator

[Ian Kent <raven@themaw.net>]

From: Ian Kent <ikent@redhat.com>

Containerized request key helper callbacks need the ability to execute
a binary in a container's context. To do that get a token to a service
thread created within the container environment for usermode helper calls.

Signed-off-by: Ian Kent <ikent@redhat.com>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Oleg Nesterov <onestero@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jeff Layton <jeff.layton@primarydata.com>
---
 include/linux/key.h         |    3 +++
 security/keys/gc.c          |    2 ++
 security/keys/key.c         |    5 +++++
 security/keys/request_key.c |   34 +++++++++++++++++++++++++++-------
 4 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index e1d4715..144727d 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -209,6 +209,9 @@ struct key {
 		} payload;
 		struct assoc_array keys;
 	};
+
+	/* Namespace token */
+	int umh_token;
 };
 
 extern struct key *key_alloc(struct key_type *type,
diff --git a/security/keys/gc.c b/security/keys/gc.c
index c795237..c689ffd 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -156,6 +156,8 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
 
 		kfree(key->description);
 
+		umh_wq_put_token(key->umh_token);
+
 #ifdef KEY_DEBUGGING
 		key->magic = KEY_DEBUG_MAGIC_X;
 #endif
diff --git a/security/keys/key.c b/security/keys/key.c
index aee2ec5..3ca0825 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -18,6 +18,8 @@
 #include <linux/workqueue.h>
 #include <linux/random.h>
 #include <linux/err.h>
+#include <net/net_namespace.h>
+#include <linux/nsproxy.h>
 #include "internal.h"
 
 struct kmem_cache *key_jar;
@@ -309,6 +311,9 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 	/* publish the key by giving it a serial number */
 	atomic_inc(&user->nkeys);
 	key_alloc_serial(key);
+	/* If running within a container use the container namespace */
+	if (current->nsproxy->net_ns != &init_net)
+		key->umh_token = umh_wq_get_token(0, "keys");
 
 error:
 	return key;
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index e865f9f..233e837 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -70,26 +70,40 @@ static void umh_keys_cleanup(struct subprocess_info *info)
 }
 
 /*
- * Call a usermode helper with a specific session keyring.
+ * Call a usermode helper with a specific session keyring and execute
+ * within a namespace.
  */
-static int call_usermodehelper_keys(char *path, char **argv, char **envp,
-					struct key *session_keyring, int wait)
+static int call_usermodehelper_keys_service(char *path,
+					    char **argv, char **envp,
+					    struct key *session_keyring,
+					    int token, unsigned int wait)
 {
 	struct subprocess_info *info;
 	unsigned int gfp_mask = (wait & UMH_NO_WAIT) ?
 					GFP_ATOMIC : GFP_KERNEL;
 
 	info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
-					  umh_keys_init, umh_keys_cleanup,
-					  session_keyring);
+					 umh_keys_init, umh_keys_cleanup,
+					 session_keyring);
 	if (!info)
 		return -ENOMEM;
+	info->wq_token = token;
 
 	key_get(session_keyring);
 	return call_usermodehelper_exec(info, wait);
 }
 
 /*
+ * Call a usermode helper with a specific session keyring.
+ */
+static int call_usermodehelper_keys(char *path, char **argv, char **envp,
+					struct key *session_keyring, int wait)
+{
+	return call_usermodehelper_keys_service(path, argv, envp,
+						session_keyring, 0, wait);
+}
+
+/*
  * Request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
  */
@@ -174,8 +188,14 @@ static int call_sbin_request_key(struct key_construction *cons,
 	argv[i] = NULL;
 
 	/* do it */
-	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
-				       UMH_WAIT_PROC);
+	/* If running within a container use the container namespace */
+	if (key->umh_token)
+		ret = call_usermodehelper_keys_service(argv[0], argv, envp,
+						       keyring, key->umh_token,
+						       UMH_WAIT_PROC);
+	else
+		ret = call_usermodehelper_keys(argv[0], argv, envp,
+					       keyring, UMH_WAIT_PROC);
 	kdebug("usermode -> 0x%x", ret);
 	if (ret >= 0) {
 		/* ret is the exit/wait code */