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Message-ID: <20150205023423.8382.69433.stgit@pluto.fritz.box>
Date: Thu, 05 Feb 2015 10:34:24 +0800
From: Ian Kent <ikent@...hat.com>
To: Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: David Howells <dhowells@...hat.com>,
Oleg Nesterov <onestero@...hat.com>,
Trond Myklebust <trond.myklebust@...marydata.com>,
"J. Bruce Fields" <bfields@...ldses.org>,
Benjamin Coddington <bcodding@...hat.com>,
Al Viro <viro@...IV.linux.org.uk>,
Jeff Layton <jeff.layton@...marydata.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [RFC PATCH 5/8] KEYS: exec request-key within the requesting task's
init namespace
Containerized request key helper callbacks need the ability to execute
a binary in a container's context. To do this calling an in kernel
equivalent of setns(2) should be sufficient since the user mode helper
execution kernel thread ultimately calls do_execve().
Signed-off-by: Ian Kent <ikent@...hat.com>
Cc: Benjamin Coddington <bcodding@...hat.com>
Cc: Al Viro <viro@...IV.linux.org.uk>
Cc: J. Bruce Fields <bfields@...ldses.org>
Cc: David Howells <dhowells@...hat.com>
Cc: Trond Myklebust <trond.myklebust@...marydata.com>
Cc: Oleg Nesterov <onestero@...hat.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Jeff Layton <jeff.layton@...marydata.com>
---
security/keys/request_key.c | 60 +++++++++++++++++++++++++++++++++++++------
1 file changed, 52 insertions(+), 8 deletions(-)
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 9e79bbf..59282aa 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -17,6 +17,9 @@
#include <linux/err.h>
#include <linux/keyctl.h>
#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/nsproxy.h>
+#include <net/net_namespace.h>
#include "internal.h"
#define key_negative_timeout 60 /* default timeout on a negative key's existence */
@@ -46,6 +49,11 @@ void complete_request_key(struct key_construction *cons, int error)
}
EXPORT_SYMBOL(complete_request_key);
+struct request_key_info {
+ struct key *keyring;
+ struct task_struct *tsk;
+};
+
/*
* Initialise a usermode helper that is going to have a specific session
* keyring.
@@ -55,9 +63,18 @@ EXPORT_SYMBOL(complete_request_key);
*/
static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
{
- struct key *keyring = info->data;
+ struct request_key_info *rki = info->data;
+ struct task_struct *tsk = rki->tsk;
+
+ if (tsk) {
+ int err;
+
+ err = umh_enter_ns(tsk, cred);
+ if (err)
+ return err;
+ }
- return install_session_keyring_to_cred(cred, keyring);
+ return install_session_keyring_to_cred(cred, rki->keyring);
}
/*
@@ -65,8 +82,11 @@ static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
*/
static void umh_keys_cleanup(struct subprocess_info *info)
{
- struct key *keyring = info->data;
- key_put(keyring);
+ struct request_key_info *rki = info->data;
+ if (rki->tsk)
+ put_task_struct(rki->tsk);
+ key_put(rki->keyring);
+ kfree(rki);
}
/*
@@ -76,12 +96,32 @@ static int call_usermodehelper_keys(char *path, char **argv, char **envp,
struct key *session_keyring, int flags)
{
struct subprocess_info *info;
+ struct request_key_info *rki;
+ unsigned int use_ns = flags & UMH_USE_NS;
+ struct task_struct *tsk = NULL;
+
+ rki = kmalloc(sizeof(*rki), GFP_KERNEL);
+ if (!rki)
+ return -ENOMEM;
+
+ if (use_ns) {
+ tsk = umh_get_init_pid();
+ if (IS_ERR(tsk))
+ return PTR_ERR(tsk);
+ }
+
+ rki->keyring = session_keyring;
+ rki->tsk = tsk;
info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
umh_keys_init, umh_keys_cleanup,
- session_keyring);
- if (!info)
+ rki);
+ if (!info) {
+ if (tsk)
+ put_task_struct(rki->tsk);
+ kfree(rki);
return -ENOMEM;
+ }
key_get(session_keyring);
return call_usermodehelper_exec(info, flags);
@@ -102,10 +142,15 @@ static int call_sbin_request_key(struct key_construction *cons,
char *argv[9], *envp[3], uid_str[12], gid_str[12];
char key_str[12], keyring_str[3][12];
char desc[20];
+ int flags = UMH_WAIT_PROC;
int ret, i;
kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
+ /* If running within a container use the container namespace */
+ if (current->nsproxy->net_ns != &init_net)
+ flags |= UMH_USE_NS;
+
ret = install_user_keyrings();
if (ret < 0)
goto error_alloc;
@@ -172,8 +217,7 @@ 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);
+ ret = call_usermodehelper_keys(argv[0], argv, envp, keyring, flags);
kdebug("usermode -> 0x%x", ret);
if (ret >= 0) {
/* ret is the exit/wait code */
--
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