[PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
subprocess_info->cred in advance. Now that we have info->init() we can
change this code to set tgcred->session_keyring in context of execing
kernel thread.

Note: since currently call_usermodehelper_keys() is never called with
UMH_NO_WAIT, umh_keys_cleanup() is not really needed, we could just move
key_get() from call_usermodehelper_keys() to umh_keys_init().

Compile tested.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

 include/linux/kmod.h        |   17 -----------------
 kernel/kmod.c               |   18 ------------------
 security/keys/request_key.c |   37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 35 deletions(-)

--- mm/include/linux/kmod.h~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-25 18:56:41.000000000 +0100
@@ -71,8 +71,6 @@ struct subprocess_info *call_usermodehel
 						  char **envp, gfp_t gfp_mask);
 
 /* Set various pieces of state into the subprocess_info structure */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring);
 void call_usermodehelper_setfns(struct subprocess_info *info,
 		    int (*init)(struct subprocess_info *info),
 		    void (*cleanup)(struct subprocess_info *info),
@@ -108,21 +106,6 @@ call_usermodehelper(char *path, char **a
 				       wait, NULL, NULL, NULL);
 }
 
-static inline int
-call_usermodehelper_keys(char *path, char **argv, char **envp,
-			 struct key *session_keyring, enum umh_wait wait)
-{
-	struct subprocess_info *info;
-	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
-	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
-	if (info == NULL)
-		return -ENOMEM;
-
-	call_usermodehelper_setkeys(info, session_keyring);
-	return call_usermodehelper_exec(info, wait);
-}
-
 extern void usermodehelper_init(void);
 
 extern int usermodehelper_disable(void);
--- mm/kernel/kmod.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-25 18:56:41.000000000 +0100
@@ -386,24 +386,6 @@ struct subprocess_info *call_usermodehel
 EXPORT_SYMBOL(call_usermodehelper_setup);
 
 /**
- * call_usermodehelper_setkeys - set the session keys for usermode helper
- * @info: a subprocess_info returned by call_usermodehelper_setup
- * @session_keyring: the session keyring for the process
- */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = info->cred->tgcred;
-	key_put(tgcred->session_keyring);
-	tgcred->session_keyring = key_get(session_keyring);
-#else
-	BUG();
-#endif
-}
-EXPORT_SYMBOL(call_usermodehelper_setkeys);
-
-/**
  * call_usermodehelper_setfns - set a cleanup/init function
  * @info: a subprocess_info returned by call_usermodehelper_setup
  * @cleanup: a cleanup function
--- mm/security/keys/request_key.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/security/keys/request_key.c	2010-02-25 19:01:26.000000000 +0100
@@ -58,6 +58,43 @@ void complete_request_key(struct key_con
 }
 EXPORT_SYMBOL(complete_request_key);
 
+static int umh_keys_init(struct subprocess_info *info)
+{
+	struct thread_group_cred *tgcred = current_cred()->tgcred;
+	struct key *session_keyring = info->data;
+	/*
+	 * This is called in context of freshly forked kthread before
+	 * kernel_execve(), we can just change our ->session_keyring.
+	 */
+	WARN_ON(tgcred->session_keyring);
+	tgcred->session_keyring = session_keyring;
+
+	info->data = NULL;		/* for umh_keys_cleanup() */
+	return 0;
+}
+
+static void umh_keys_cleanup(struct subprocess_info *info)
+{
+	struct key *session_keyring = info->data;
+	key_put(session_keyring);	/* NULL if successs */
+}
+
+static inline int
+call_usermodehelper_keys(char *path, char **argv, char **envp,
+			 struct key *session_keyring, enum umh_wait wait)
+{
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+	struct subprocess_info *info =
+		call_usermodehelper_setup(path, argv, envp, gfp_mask);
+
+	if (!info)
+		return -ENOMEM;
+
+	call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
+					key_get(session_keyring));
+	return call_usermodehelper_exec(info, wait);
+}
+
 /*
  * request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"

Re: [PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[David Howells]

Oleg Nesterov <oleg@redhat.com> wrote:

> +	/*
> +	 * This is called in context of freshly forked kthread before
> +	 * kernel_execve(), we can just change our ->session_keyring.
> +	 */

Ummmm....  What gives you that idea?

You may be sharing init_cred...

You need to create, modify and commit a new set of creds.

David

Re: [PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

On 02/26, David Howells wrote:
>
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > +	/*
> > +	 * This is called in context of freshly forked kthread before
> > +	 * kernel_execve(), we can just change our ->session_keyring.
> > +	 */
>
> Ummmm....  What gives you that idea?
>
> You may be sharing init_cred...

How? Without CLONE_THREAD copy_creds() always creates the new
struct cred for the child?

Oleg.

Re: [PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[David Howells]

Oleg Nesterov <oleg@redhat.com> wrote:

> How? Without CLONE_THREAD copy_creds() always creates the new
> struct cred for the child?

Okay, that's a good point.

In which case, you should be calling install_session_keyring_to_cred(), just
so that the credentials installation is always done by the same piece of code.

David

Re: [PATCH -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

On 02/26, David Howells wrote:
>
> In which case, you should be calling install_session_keyring_to_cred(), just
> so that the credentials installation is always done by the same piece of code.

OK, will redo and resend tomorrow, thanks.

Oleg.

[PATCH v2 -mm 0/2] umh && creds: kill sub_info->cred

[Oleg Nesterov]

Changes:

	1/2: do not change ->session_keyring by hand, use
	     install_session_keyring_to_cred() helper as David suggested.

	2/2: unchanged


Andrew, this is on top of

	kmod-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch

plus trivial

	"[PATCH -mm] kmod-replace-call_usermodehelper_pipe-with-use-of-umh-init-function- and-resolve-limit.cleanup"
	http://marc.info/?l=linux-kernel&m=126711062108298

cleanup.

Oleg.

[PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
subprocess_info->cred in advance. Now that we have info->init() we can
change this code to set tgcred->session_keyring in context of execing
kernel thread.

Note: since currently call_usermodehelper_keys() is never called with
UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
are not really needed, we could rely on install_session_keyring_to_cred()
which does key_get() on success.

Compile tested.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

 include/linux/kmod.h         |   17 -----------------
 kernel/kmod.c                |   18 ------------------
 security/keys/internal.h     |    1 +
 security/keys/process_keys.c |    3 +--
 security/keys/request_key.c  |   33 +++++++++++++++++++++++++++++++++
 5 files changed, 35 insertions(+), 37 deletions(-)

--- mm/include/linux/kmod.h~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-26 20:18:48.000000000 +0100
@@ -71,8 +71,6 @@ struct subprocess_info *call_usermodehel
 						  char **envp, gfp_t gfp_mask);
 
 /* Set various pieces of state into the subprocess_info structure */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring);
 void call_usermodehelper_setfns(struct subprocess_info *info,
 		    int (*init)(struct subprocess_info *info),
 		    void (*cleanup)(struct subprocess_info *info),
@@ -108,21 +106,6 @@ call_usermodehelper(char *path, char **a
 				       wait, NULL, NULL, NULL);
 }
 
-static inline int
-call_usermodehelper_keys(char *path, char **argv, char **envp,
-			 struct key *session_keyring, enum umh_wait wait)
-{
-	struct subprocess_info *info;
-	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
-	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
-	if (info == NULL)
-		return -ENOMEM;
-
-	call_usermodehelper_setkeys(info, session_keyring);
-	return call_usermodehelper_exec(info, wait);
-}
-
 extern void usermodehelper_init(void);
 
 extern int usermodehelper_disable(void);
--- mm/kernel/kmod.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-26 20:18:48.000000000 +0100
@@ -386,24 +386,6 @@ struct subprocess_info *call_usermodehel
 EXPORT_SYMBOL(call_usermodehelper_setup);
 
 /**
- * call_usermodehelper_setkeys - set the session keys for usermode helper
- * @info: a subprocess_info returned by call_usermodehelper_setup
- * @session_keyring: the session keyring for the process
- */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = info->cred->tgcred;
-	key_put(tgcred->session_keyring);
-	tgcred->session_keyring = key_get(session_keyring);
-#else
-	BUG();
-#endif
-}
-EXPORT_SYMBOL(call_usermodehelper_setkeys);
-
-/**
  * call_usermodehelper_setfns - set a cleanup/init function
  * @info: a subprocess_info returned by call_usermodehelper_setup
  * @cleanup: a cleanup function
--- mm/security/keys/internal.h~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/internal.h	2010-02-26 20:30:52.000000000 +0100
@@ -115,6 +115,7 @@ extern struct key *find_keyring_by_name(
 extern int install_user_keyrings(void);
 extern int install_thread_keyring_to_cred(struct cred *);
 extern int install_process_keyring_to_cred(struct cred *);
+extern int install_session_keyring_to_cred(struct cred *, struct key *);
 
 extern struct key *request_key_and_link(struct key_type *type,
 					const char *description,
--- mm/security/keys/process_keys.c~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/process_keys.c	2010-02-26 20:22:14.000000000 +0100
@@ -217,8 +217,7 @@ static int install_process_keyring(void)
 /*
  * install a session keyring directly to a credentials struct
  */
-static int install_session_keyring_to_cred(struct cred *cred,
-					   struct key *keyring)
+int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 {
 	unsigned long flags;
 	struct key *old;
--- mm/security/keys/request_key.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/security/keys/request_key.c	2010-02-26 20:42:56.000000000 +0100
@@ -58,6 +58,39 @@ void complete_request_key(struct key_con
 }
 EXPORT_SYMBOL(complete_request_key);
 
+static int umh_keys_init(struct subprocess_info *info)
+{
+	struct cred *cred = (struct cred*)current_cred();
+	struct key *keyring = info->data;
+	/*
+	 * This is called in context of freshly forked kthread before
+	 * kernel_execve(), we can just change our ->session_keyring.
+	 */
+	return install_session_keyring_to_cred(cred, keyring);
+}
+
+static void umh_keys_cleanup(struct subprocess_info *info)
+{
+	struct key *keyring = info->data;
+	key_put(keyring);
+}
+
+static inline int
+call_usermodehelper_keys(char *path, char **argv, char **envp,
+			 struct key *session_keyring, enum umh_wait wait)
+{
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+	struct subprocess_info *info =
+		call_usermodehelper_setup(path, argv, envp, gfp_mask);
+
+	if (!info)
+		return -ENOMEM;
+
+	call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
+					key_get(session_keyring));
+	return call_usermodehelper_exec(info, wait);
+}
+
 /*
  * request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"

Re: [PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Neil Horman]

On Fri, Feb 26, 2010 at 09:03:57PM +0100, Oleg Nesterov wrote:
> call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
> subprocess_info->cred in advance. Now that we have info->init() we can
> change this code to set tgcred->session_keyring in context of execing
> kernel thread.
> 
> Note: since currently call_usermodehelper_keys() is never called with
> UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
> are not really needed, we could rely on install_session_keyring_to_cred()
> which does key_get() on success.
> 
> Compile tested.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>

Re: [PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[David Howells]

Oleg Nesterov <oleg@redhat.com> wrote:

> +static inline int
> +call_usermodehelper_keys(char *path, char **argv, char **envp,
> +			 struct key *session_keyring, enum umh_wait wait)

You should get rid of the inline there.  I think it's okay otherwise.

David

Re: [PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

On 02/26, David Howells wrote:
>
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > +static inline int
> > +call_usermodehelper_keys(char *path, char **argv, char **envp,
> > +			 struct key *session_keyring, enum umh_wait wait)
>
> You should get rid of the inline there.  I think it's okay otherwise.

OK, please find v3 below.

(Neil, I retained your ack, hopefully you won't object...)

------------------------------------------------------------------------------
[PATCH v3 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
subprocess_info->cred in advance. Now that we have info->init() we can
change this code to set tgcred->session_keyring in context of execing
kernel thread.

Note: since currently call_usermodehelper_keys() is never called with
UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
are not really needed, we could rely on install_session_keyring_to_cred()
which does key_get() on success.

Compile tested.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
---

 include/linux/kmod.h         |   17 -----------------
 kernel/kmod.c                |   18 ------------------
 security/keys/internal.h     |    1 +
 security/keys/process_keys.c |    3 +--
 security/keys/request_key.c  |   32 ++++++++++++++++++++++++++++++++
 5 files changed, 34 insertions(+), 37 deletions(-)

--- mm/include/linux/kmod.h~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-26 21:45:28.000000000 +0100
@@ -71,8 +71,6 @@ struct subprocess_info *call_usermodehel
 						  char **envp, gfp_t gfp_mask);
 
 /* Set various pieces of state into the subprocess_info structure */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring);
 void call_usermodehelper_setfns(struct subprocess_info *info,
 		    int (*init)(struct subprocess_info *info),
 		    void (*cleanup)(struct subprocess_info *info),
@@ -108,21 +106,6 @@ call_usermodehelper(char *path, char **a
 				       wait, NULL, NULL, NULL);
 }
 
-static inline int
-call_usermodehelper_keys(char *path, char **argv, char **envp,
-			 struct key *session_keyring, enum umh_wait wait)
-{
-	struct subprocess_info *info;
-	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
-	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
-	if (info == NULL)
-		return -ENOMEM;
-
-	call_usermodehelper_setkeys(info, session_keyring);
-	return call_usermodehelper_exec(info, wait);
-}
-
 extern void usermodehelper_init(void);
 
 extern int usermodehelper_disable(void);
--- mm/kernel/kmod.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-26 21:45:28.000000000 +0100
@@ -386,24 +386,6 @@ struct subprocess_info *call_usermodehel
 EXPORT_SYMBOL(call_usermodehelper_setup);
 
 /**
- * call_usermodehelper_setkeys - set the session keys for usermode helper
- * @info: a subprocess_info returned by call_usermodehelper_setup
- * @session_keyring: the session keyring for the process
- */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = info->cred->tgcred;
-	key_put(tgcred->session_keyring);
-	tgcred->session_keyring = key_get(session_keyring);
-#else
-	BUG();
-#endif
-}
-EXPORT_SYMBOL(call_usermodehelper_setkeys);
-
-/**
  * call_usermodehelper_setfns - set a cleanup/init function
  * @info: a subprocess_info returned by call_usermodehelper_setup
  * @cleanup: a cleanup function
--- mm/security/keys/internal.h~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/internal.h	2010-02-26 20:30:52.000000000 +0100
@@ -115,6 +115,7 @@ extern struct key *find_keyring_by_name(
 extern int install_user_keyrings(void);
 extern int install_thread_keyring_to_cred(struct cred *);
 extern int install_process_keyring_to_cred(struct cred *);
+extern int install_session_keyring_to_cred(struct cred *, struct key *);
 
 extern struct key *request_key_and_link(struct key_type *type,
 					const char *description,
--- mm/security/keys/process_keys.c~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/process_keys.c	2010-02-26 20:22:14.000000000 +0100
@@ -217,8 +217,7 @@ static int install_process_keyring(void)
 /*
  * install a session keyring directly to a credentials struct
  */
-static int install_session_keyring_to_cred(struct cred *cred,
-					   struct key *keyring)
+int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 {
 	unsigned long flags;
 	struct key *old;
--- mm/security/keys/request_key.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/security/keys/request_key.c	2010-02-26 21:46:23.000000000 +0100
@@ -58,6 +58,38 @@ void complete_request_key(struct key_con
 }
 EXPORT_SYMBOL(complete_request_key);
 
+static int umh_keys_init(struct subprocess_info *info)
+{
+	struct cred *cred = (struct cred*)current_cred();
+	struct key *keyring = info->data;
+	/*
+	 * This is called in context of freshly forked kthread before
+	 * kernel_execve(), we can just change our ->session_keyring.
+	 */
+	return install_session_keyring_to_cred(cred, keyring);
+}
+
+static void umh_keys_cleanup(struct subprocess_info *info)
+{
+	struct key *keyring = info->data;
+	key_put(keyring);
+}
+
+static int call_usermodehelper_keys(char *path, char **argv, char **envp,
+			 struct key *session_keyring, enum umh_wait wait)
+{
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+	struct subprocess_info *info =
+		call_usermodehelper_setup(path, argv, envp, gfp_mask);
+
+	if (!info)
+		return -ENOMEM;
+
+	call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
+					key_get(session_keyring));
+	return call_usermodehelper_exec(info, wait);
+}
+
 /*
  * request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"

Re: [PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[David Howells]

I'm not going to be able to test it before I get back from skiing in a week's
time, but it looks ackable otherwise.

It can be tested by doing something like this:

	[root@andromeda ~]# keyctl request2 user debug:a b @s
	102880396
	[root@andromeda ~]# keyctl show
	Session Keyring
	       -3 --alswrv      0     0  keyring: _ses
	404996112 --alswrv      0    -1   \_ keyring: _uid.0
	102880396 --alswrv      0     0   \_ user: debug:a
	[root@andromeda ~]# keyctl print 102880396
	Debug b

On a system with the keyutils package installed.

David

Re: [PATCH v2 -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

On 02/26, David Howells wrote:
>
> I'm not going to be able to test it before I get back from skiing in a week's
> time, but it looks ackable otherwise.
>
> It can be tested by doing something like this:
>
> 	[root@andromeda ~]# keyctl request2 user debug:a b @s
> 	102880396
> 	[root@andromeda ~]# keyctl show
> 	Session Keyring
> 	       -3 --alswrv      0     0  keyring: _ses
> 	404996112 --alswrv      0    -1   \_ keyring: _uid.0
> 	102880396 --alswrv      0     0   \_ user: debug:a
> 	[root@andromeda ~]# keyctl print 102880396
> 	Debug b
>
> On a system with the keyutils package installed.

Thanks David.

Finally I reserved the machine for the testing,

	[root@hp-dl360-01 ~]# keyctl request2 user debug:a b @s
	623133085
	[root@hp-dl360-01 ~]# keyctl show
	Session Keyring
	       -3 --alswrv      0     0  keyring: _ses
	845914766 --alswrv      0    -1   \_ keyring: _uid.0
	623133085 --alswrv      0     0   \_ user: debug:a
	[root@hp-dl360-01 ~]# keyctl print 623133085
	Debug b

Hopefully this all is right.

Oleg.

[PATCH,RESEND -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Oleg Nesterov]

(on top of kmod-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch)

call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
subprocess_info->cred in advance. Now that we have info->init() we can
change this code to set tgcred->session_keyring in context of execing
kernel thread.

Note: since currently call_usermodehelper_keys() is never called with
UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
are not really needed, we could rely on install_session_keyring_to_cred()
which does key_get() on success.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
---

 include/linux/kmod.h         |   17 -----------------
 kernel/kmod.c                |   18 ------------------
 security/keys/internal.h     |    1 +
 security/keys/process_keys.c |    3 +--
 security/keys/request_key.c  |   32 ++++++++++++++++++++++++++++++++
 5 files changed, 34 insertions(+), 37 deletions(-)

--- mm/include/linux/kmod.h~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-26 21:45:28.000000000 +0100
@@ -71,8 +71,6 @@ struct subprocess_info *call_usermodehel
 						  char **envp, gfp_t gfp_mask);
 
 /* Set various pieces of state into the subprocess_info structure */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring);
 void call_usermodehelper_setfns(struct subprocess_info *info,
 		    int (*init)(struct subprocess_info *info),
 		    void (*cleanup)(struct subprocess_info *info),
@@ -108,21 +106,6 @@ call_usermodehelper(char *path, char **a
 				       wait, NULL, NULL, NULL);
 }
 
-static inline int
-call_usermodehelper_keys(char *path, char **argv, char **envp,
-			 struct key *session_keyring, enum umh_wait wait)
-{
-	struct subprocess_info *info;
-	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
-	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
-	if (info == NULL)
-		return -ENOMEM;
-
-	call_usermodehelper_setkeys(info, session_keyring);
-	return call_usermodehelper_exec(info, wait);
-}
-
 extern void usermodehelper_init(void);
 
 extern int usermodehelper_disable(void);
--- mm/kernel/kmod.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-26 21:45:28.000000000 +0100
@@ -386,24 +386,6 @@ struct subprocess_info *call_usermodehel
 EXPORT_SYMBOL(call_usermodehelper_setup);
 
 /**
- * call_usermodehelper_setkeys - set the session keys for usermode helper
- * @info: a subprocess_info returned by call_usermodehelper_setup
- * @session_keyring: the session keyring for the process
- */
-void call_usermodehelper_setkeys(struct subprocess_info *info,
-				 struct key *session_keyring)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = info->cred->tgcred;
-	key_put(tgcred->session_keyring);
-	tgcred->session_keyring = key_get(session_keyring);
-#else
-	BUG();
-#endif
-}
-EXPORT_SYMBOL(call_usermodehelper_setkeys);
-
-/**
  * call_usermodehelper_setfns - set a cleanup/init function
  * @info: a subprocess_info returned by call_usermodehelper_setup
  * @cleanup: a cleanup function
--- mm/security/keys/internal.h~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/internal.h	2010-02-26 20:30:52.000000000 +0100
@@ -115,6 +115,7 @@ extern struct key *find_keyring_by_name(
 extern int install_user_keyrings(void);
 extern int install_thread_keyring_to_cred(struct cred *);
 extern int install_process_keyring_to_cred(struct cred *);
+extern int install_session_keyring_to_cred(struct cred *, struct key *);
 
 extern struct key *request_key_and_link(struct key_type *type,
 					const char *description,
--- mm/security/keys/process_keys.c~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
+++ mm/security/keys/process_keys.c	2010-02-26 20:22:14.000000000 +0100
@@ -217,8 +217,7 @@ static int install_process_keyring(void)
 /*
  * install a session keyring directly to a credentials struct
  */
-static int install_session_keyring_to_cred(struct cred *cred,
-					   struct key *keyring)
+int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 {
 	unsigned long flags;
 	struct key *old;
--- mm/security/keys/request_key.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
+++ mm/security/keys/request_key.c	2010-02-26 21:46:23.000000000 +0100
@@ -58,6 +58,38 @@ void complete_request_key(struct key_con
 }
 EXPORT_SYMBOL(complete_request_key);
 
+static int umh_keys_init(struct subprocess_info *info)
+{
+	struct cred *cred = (struct cred*)current_cred();
+	struct key *keyring = info->data;
+	/*
+	 * This is called in context of freshly forked kthread before
+	 * kernel_execve(), we can just change our ->session_keyring.
+	 */
+	return install_session_keyring_to_cred(cred, keyring);
+}
+
+static void umh_keys_cleanup(struct subprocess_info *info)
+{
+	struct key *keyring = info->data;
+	key_put(keyring);
+}
+
+static int call_usermodehelper_keys(char *path, char **argv, char **envp,
+			 struct key *session_keyring, enum umh_wait wait)
+{
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+	struct subprocess_info *info =
+		call_usermodehelper_setup(path, argv, envp, gfp_mask);
+
+	if (!info)
+		return -ENOMEM;
+
+	call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
+					key_get(session_keyring));
+	return call_usermodehelper_exec(info, wait);
+}
+
 /*
  * request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"

Re: [PATCH,RESEND -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[David Howells]

Oleg Nesterov <oleg@redhat.com> wrote:

> (on top of kmod-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch)
> 
> call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
> subprocess_info->cred in advance. Now that we have info->init() we can
> change this code to set tgcred->session_keyring in context of execing
> kernel thread.
> 
> Note: since currently call_usermodehelper_keys() is never called with
> UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
> are not really needed, we could rely on install_session_keyring_to_cred()
> which does key_get() on success.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: Neil Horman <nhorman@tuxdriver.com>

Acked-by: David Howells <dhowells@redhat.com>

Re: [PATCH,RESEND -mm 1/2] umh && creds: convert call_usermodehelper_keys() to use subprocess_info->init()

[Neil Horman]

On Sat, Mar 06, 2010 at 12:09:57AM +0100, Oleg Nesterov wrote:
> (on top of kmod-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch)
> 
> call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
> subprocess_info->cred in advance. Now that we have info->init() we can
> change this code to set tgcred->session_keyring in context of execing
> kernel thread.
> 
> Note: since currently call_usermodehelper_keys() is never called with
> UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
> are not really needed, we could rely on install_session_keyring_to_cred()
> which does key_get() on success.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: Neil Horman <nhorman@tuxdriver.com>
> ---
> 
Acked-by: Neil Horman <nhorman@tuxdriver.com>

>  include/linux/kmod.h         |   17 -----------------
>  kernel/kmod.c                |   18 ------------------
>  security/keys/internal.h     |    1 +
>  security/keys/process_keys.c |    3 +--
>  security/keys/request_key.c  |   32 ++++++++++++++++++++++++++++++++
>  5 files changed, 34 insertions(+), 37 deletions(-)
> 
> --- mm/include/linux/kmod.h~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
> +++ mm/include/linux/kmod.h	2010-02-26 21:45:28.000000000 +0100
> @@ -71,8 +71,6 @@ struct subprocess_info *call_usermodehel
>  						  char **envp, gfp_t gfp_mask);
>  
>  /* Set various pieces of state into the subprocess_info structure */
> -void call_usermodehelper_setkeys(struct subprocess_info *info,
> -				 struct key *session_keyring);
>  void call_usermodehelper_setfns(struct subprocess_info *info,
>  		    int (*init)(struct subprocess_info *info),
>  		    void (*cleanup)(struct subprocess_info *info),
> @@ -108,21 +106,6 @@ call_usermodehelper(char *path, char **a
>  				       wait, NULL, NULL, NULL);
>  }
>  
> -static inline int
> -call_usermodehelper_keys(char *path, char **argv, char **envp,
> -			 struct key *session_keyring, enum umh_wait wait)
> -{
> -	struct subprocess_info *info;
> -	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
> -
> -	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
> -	if (info == NULL)
> -		return -ENOMEM;
> -
> -	call_usermodehelper_setkeys(info, session_keyring);
> -	return call_usermodehelper_exec(info, wait);
> -}
> -
>  extern void usermodehelper_init(void);
>  
>  extern int usermodehelper_disable(void);
> --- mm/kernel/kmod.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
> +++ mm/kernel/kmod.c	2010-02-26 21:45:28.000000000 +0100
> @@ -386,24 +386,6 @@ struct subprocess_info *call_usermodehel
>  EXPORT_SYMBOL(call_usermodehelper_setup);
>  
>  /**
> - * call_usermodehelper_setkeys - set the session keys for usermode helper
> - * @info: a subprocess_info returned by call_usermodehelper_setup
> - * @session_keyring: the session keyring for the process
> - */
> -void call_usermodehelper_setkeys(struct subprocess_info *info,
> -				 struct key *session_keyring)
> -{
> -#ifdef CONFIG_KEYS
> -	struct thread_group_cred *tgcred = info->cred->tgcred;
> -	key_put(tgcred->session_keyring);
> -	tgcred->session_keyring = key_get(session_keyring);
> -#else
> -	BUG();
> -#endif
> -}
> -EXPORT_SYMBOL(call_usermodehelper_setkeys);
> -
> -/**
>   * call_usermodehelper_setfns - set a cleanup/init function
>   * @info: a subprocess_info returned by call_usermodehelper_setup
>   * @cleanup: a cleanup function
> --- mm/security/keys/internal.h~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
> +++ mm/security/keys/internal.h	2010-02-26 20:30:52.000000000 +0100
> @@ -115,6 +115,7 @@ extern struct key *find_keyring_by_name(
>  extern int install_user_keyrings(void);
>  extern int install_thread_keyring_to_cred(struct cred *);
>  extern int install_process_keyring_to_cred(struct cred *);
> +extern int install_session_keyring_to_cred(struct cred *, struct key *);
>  
>  extern struct key *request_key_and_link(struct key_type *type,
>  					const char *description,
> --- mm/security/keys/process_keys.c~1_CONVERT_KEYS	2010-02-25 15:22:14.000000000 +0100
> +++ mm/security/keys/process_keys.c	2010-02-26 20:22:14.000000000 +0100
> @@ -217,8 +217,7 @@ static int install_process_keyring(void)
>  /*
>   * install a session keyring directly to a credentials struct
>   */
> -static int install_session_keyring_to_cred(struct cred *cred,
> -					   struct key *keyring)
> +int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
>  {
>  	unsigned long flags;
>  	struct key *old;
> --- mm/security/keys/request_key.c~1_CONVERT_KEYS	2010-02-25 17:37:41.000000000 +0100
> +++ mm/security/keys/request_key.c	2010-02-26 21:46:23.000000000 +0100
> @@ -58,6 +58,38 @@ void complete_request_key(struct key_con
>  }
>  EXPORT_SYMBOL(complete_request_key);
>  
> +static int umh_keys_init(struct subprocess_info *info)
> +{
> +	struct cred *cred = (struct cred*)current_cred();
> +	struct key *keyring = info->data;
> +	/*
> +	 * This is called in context of freshly forked kthread before
> +	 * kernel_execve(), we can just change our ->session_keyring.
> +	 */
> +	return install_session_keyring_to_cred(cred, keyring);
> +}
> +
> +static void umh_keys_cleanup(struct subprocess_info *info)
> +{
> +	struct key *keyring = info->data;
> +	key_put(keyring);
> +}
> +
> +static int call_usermodehelper_keys(char *path, char **argv, char **envp,
> +			 struct key *session_keyring, enum umh_wait wait)
> +{
> +	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
> +	struct subprocess_info *info =
> +		call_usermodehelper_setup(path, argv, envp, gfp_mask);
> +
> +	if (!info)
> +		return -ENOMEM;
> +
> +	call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
> +					key_get(session_keyring));
> +	return call_usermodehelper_exec(info, wait);
> +}
> +
>  /*
>   * request userspace finish the construction of a key
>   * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
> 
> 

[PATCH,RESEND -mm 2/2] umh && creds: kill subprocess_info->cred logic

[Oleg Nesterov]

Now that nobody ever changes subprocess_info->cred we can kill this
member and related code. ____call_usermodehelper() always runs in the
context of freshly forked kernel thread, it has the proper ->cred
copied from its parent kthread, keventd.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
---

 include/linux/cred.h |    1 
 include/linux/kmod.h |    1 
 kernel/cred.c        |   54 ---------------------------------------------------
 kernel/kmod.c        |   19 -----------------
 4 files changed, 75 deletions(-)

--- mm/include/linux/cred.h~2_KILL_INFO_CRED	2010-02-26 21:45:28.000000000 +0100
+++ mm/include/linux/cred.h	2010-02-26 22:07:38.000000000 +0100
@@ -156,7 +156,6 @@ extern int copy_creds(struct task_struct
 extern struct cred *cred_alloc_blank(void);
 extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
-extern struct cred *prepare_usermodehelper_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
 extern const struct cred *override_creds(const struct cred *);
--- mm/include/linux/kmod.h~2_KILL_INFO_CRED	2010-02-26 21:45:28.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-26 22:07:38.000000000 +0100
@@ -55,7 +55,6 @@ enum umh_wait {
 struct subprocess_info {
 	struct work_struct work;
 	struct completion *complete;
-	struct cred *cred;
 	char *path;
 	char **argv;
 	char **envp;
--- mm/kernel/cred.c~2_KILL_INFO_CRED	2010-02-26 21:45:28.000000000 +0100
+++ mm/kernel/cred.c	2010-02-26 22:07:38.000000000 +0100
@@ -347,60 +347,6 @@ struct cred *prepare_exec_creds(void)
 }
 
 /*
- * prepare new credentials for the usermode helper dispatcher
- */
-struct cred *prepare_usermodehelper_creds(void)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = NULL;
-#endif
-	struct cred *new;
-
-#ifdef CONFIG_KEYS
-	tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
-	if (!tgcred)
-		return NULL;
-#endif
-
-	new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
-	if (!new)
-		return NULL;
-
-	kdebug("prepare_usermodehelper_creds() alloc %p", new);
-
-	memcpy(new, &init_cred, sizeof(struct cred));
-
-	atomic_set(&new->usage, 1);
-	set_cred_subscribers(new, 0);
-	get_group_info(new->group_info);
-	get_uid(new->user);
-
-#ifdef CONFIG_KEYS
-	new->thread_keyring = NULL;
-	new->request_key_auth = NULL;
-	new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
-
-	atomic_set(&tgcred->usage, 1);
-	spin_lock_init(&tgcred->lock);
-	new->tgcred = tgcred;
-#endif
-
-#ifdef CONFIG_SECURITY
-	new->security = NULL;
-#endif
-	if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
-		goto error;
-	validate_creds(new);
-
-	BUG_ON(atomic_read(&new->usage) != 1);
-	return new;
-
-error:
-	put_cred(new);
-	return NULL;
-}
-
-/*
  * Copy credentials for the new process created by fork()
  *
  * We share if we can, but under some circumstances we have to generate a new
--- mm/kernel/kmod.c~2_KILL_INFO_CRED	2010-02-26 21:45:28.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-26 22:07:38.000000000 +0100
@@ -153,8 +153,6 @@ static int ____call_usermodehelper(void 
 	struct subprocess_info *sub_info = data;
 	int retval;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
 	/* Unblock all signals */
 	spin_lock_irq(&current->sighand->siglock);
 	flush_signal_handlers(current, 1);
@@ -162,10 +160,6 @@ static int ____call_usermodehelper(void 
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 
-	/* Install the credentials */
-	commit_creds(sub_info->cred);
-	sub_info->cred = NULL;
-
 	/* We can run anywhere, unlike our parent keventd(). */
 	set_cpus_allowed_ptr(current, cpu_all_mask);
 
@@ -193,8 +187,6 @@ void call_usermodehelper_freeinfo(struct
 {
 	if (info->cleanup)
 		(*info->cleanup)(info);
-	if (info->cred)
-		put_cred(info->cred);
 	kfree(info);
 }
 EXPORT_SYMBOL(call_usermodehelper_freeinfo);
@@ -250,8 +242,6 @@ static void __call_usermodehelper(struct
 	pid_t pid;
 	enum umh_wait wait = sub_info->wait;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
 	/* CLONE_VFORK: wait until the usermode helper has execve'd
 	 * successfully We need the data structures to stay around
 	 * until that is done.  */
@@ -374,12 +364,6 @@ struct subprocess_info *call_usermodehel
 	sub_info->path = path;
 	sub_info->argv = argv;
 	sub_info->envp = envp;
-	sub_info->cred = prepare_usermodehelper_creds();
-	if (!sub_info->cred) {
-		kfree(sub_info);
-		return NULL;
-	}
-
   out:
 	return sub_info;
 }
@@ -430,9 +414,6 @@ int call_usermodehelper_exec(struct subp
 	DECLARE_COMPLETION_ONSTACK(done);
 	int retval = 0;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-	validate_creds(sub_info->cred);
-
 	helper_lock();
 	if (sub_info->path[0] == '\0')
 		goto out;

Re: [PATCH,RESEND -mm 2/2] umh && creds: kill subprocess_info->cred logic

[David Howells]

Oleg Nesterov <oleg@redhat.com> wrote:

> Now that nobody ever changes subprocess_info->cred we can kill this
> member and related code. ____call_usermodehelper() always runs in the
> context of freshly forked kernel thread, it has the proper ->cred
> copied from its parent kthread, keventd.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: Neil Horman <nhorman@tuxdriver.com>

Acked-by: David Howells <dhowells@redhat.com>

Re: [PATCH,RESEND -mm 2/2] umh && creds: kill subprocess_info->cred logic

[Neil Horman]

On Sat, Mar 06, 2010 at 12:10:54AM +0100, Oleg Nesterov wrote:
> Now that nobody ever changes subprocess_info->cred we can kill this
> member and related code. ____call_usermodehelper() always runs in the
> context of freshly forked kernel thread, it has the proper ->cred
> copied from its parent kthread, keventd.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: Neil Horman <nhorman@tuxdriver.com>
> ---
> 

Acked-by: Neil Horman <nhorman@tuxdriver.com>

> 

[PATCH v2 -mm 2/2] umh && creds: kill subprocess_info->cred logic

[Oleg Nesterov]

Now that nobody ever changes subprocess_info->cred we can kill this
member and related code. ____call_usermodehelper() always runs in the
context of freshly forked kernel thread, it has the proper ->cred
copied from its parent kthread, keventd.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

 include/linux/cred.h |    1 
 include/linux/kmod.h |    1 
 kernel/cred.c        |   54 ---------------------------------------------------
 kernel/kmod.c        |   19 -----------------
 4 files changed, 75 deletions(-)

--- mm/include/linux/cred.h~2_KILL_INFO_CRED	2010-02-26 20:18:48.000000000 +0100
+++ mm/include/linux/cred.h	2010-02-26 20:53:04.000000000 +0100
@@ -156,7 +156,6 @@ extern int copy_creds(struct task_struct
 extern struct cred *cred_alloc_blank(void);
 extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
-extern struct cred *prepare_usermodehelper_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
 extern const struct cred *override_creds(const struct cred *);
--- mm/include/linux/kmod.h~2_KILL_INFO_CRED	2010-02-26 20:18:48.000000000 +0100
+++ mm/include/linux/kmod.h	2010-02-26 20:53:04.000000000 +0100
@@ -55,7 +55,6 @@ enum umh_wait {
 struct subprocess_info {
 	struct work_struct work;
 	struct completion *complete;
-	struct cred *cred;
 	char *path;
 	char **argv;
 	char **envp;
--- mm/kernel/cred.c~2_KILL_INFO_CRED	2010-02-26 20:18:48.000000000 +0100
+++ mm/kernel/cred.c	2010-02-26 20:53:04.000000000 +0100
@@ -347,60 +347,6 @@ struct cred *prepare_exec_creds(void)
 }
 
 /*
- * prepare new credentials for the usermode helper dispatcher
- */
-struct cred *prepare_usermodehelper_creds(void)
-{
-#ifdef CONFIG_KEYS
-	struct thread_group_cred *tgcred = NULL;
-#endif
-	struct cred *new;
-
-#ifdef CONFIG_KEYS
-	tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
-	if (!tgcred)
-		return NULL;
-#endif
-
-	new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
-	if (!new)
-		return NULL;
-
-	kdebug("prepare_usermodehelper_creds() alloc %p", new);
-
-	memcpy(new, &init_cred, sizeof(struct cred));
-
-	atomic_set(&new->usage, 1);
-	set_cred_subscribers(new, 0);
-	get_group_info(new->group_info);
-	get_uid(new->user);
-
-#ifdef CONFIG_KEYS
-	new->thread_keyring = NULL;
-	new->request_key_auth = NULL;
-	new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
-
-	atomic_set(&tgcred->usage, 1);
-	spin_lock_init(&tgcred->lock);
-	new->tgcred = tgcred;
-#endif
-
-#ifdef CONFIG_SECURITY
-	new->security = NULL;
-#endif
-	if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
-		goto error;
-	validate_creds(new);
-
-	BUG_ON(atomic_read(&new->usage) != 1);
-	return new;
-
-error:
-	put_cred(new);
-	return NULL;
-}
-
-/*
  * Copy credentials for the new process created by fork()
  *
  * We share if we can, but under some circumstances we have to generate a new
--- mm/kernel/kmod.c~2_KILL_INFO_CRED	2010-02-26 20:18:48.000000000 +0100
+++ mm/kernel/kmod.c	2010-02-26 20:53:04.000000000 +0100
@@ -153,8 +153,6 @@ static int ____call_usermodehelper(void 
 	struct subprocess_info *sub_info = data;
 	int retval;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
 	/* Unblock all signals */
 	spin_lock_irq(&current->sighand->siglock);
 	flush_signal_handlers(current, 1);
@@ -162,10 +160,6 @@ static int ____call_usermodehelper(void 
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 
-	/* Install the credentials */
-	commit_creds(sub_info->cred);
-	sub_info->cred = NULL;
-
 	/* We can run anywhere, unlike our parent keventd(). */
 	set_cpus_allowed_ptr(current, cpu_all_mask);
 
@@ -193,8 +187,6 @@ void call_usermodehelper_freeinfo(struct
 {
 	if (info->cleanup)
 		(*info->cleanup)(info);
-	if (info->cred)
-		put_cred(info->cred);
 	kfree(info);
 }
 EXPORT_SYMBOL(call_usermodehelper_freeinfo);
@@ -250,8 +242,6 @@ static void __call_usermodehelper(struct
 	pid_t pid;
 	enum umh_wait wait = sub_info->wait;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
 	/* CLONE_VFORK: wait until the usermode helper has execve'd
 	 * successfully We need the data structures to stay around
 	 * until that is done.  */
@@ -374,12 +364,6 @@ struct subprocess_info *call_usermodehel
 	sub_info->path = path;
 	sub_info->argv = argv;
 	sub_info->envp = envp;
-	sub_info->cred = prepare_usermodehelper_creds();
-	if (!sub_info->cred) {
-		kfree(sub_info);
-		return NULL;
-	}
-
   out:
 	return sub_info;
 }
@@ -430,9 +414,6 @@ int call_usermodehelper_exec(struct subp
 	DECLARE_COMPLETION_ONSTACK(done);
 	int retval = 0;
 
-	BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-	validate_creds(sub_info->cred);
-
 	helper_lock();
 	if (sub_info->path[0] == '\0')
 		goto out;

Re: [PATCH v2 -mm 2/2] umh && creds: kill subprocess_info->cred logic

[Neil Horman]

On Fri, Feb 26, 2010 at 09:04:35PM +0100, Oleg Nesterov wrote:
> Now that nobody ever changes subprocess_info->cred we can kill this
> member and related code. ____call_usermodehelper() always runs in the
> context of freshly forked kernel thread, it has the proper ->cred
> copied from its parent kthread, keventd.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>