[PATCH] Keys: Export user-defined keyring operations

[PATCH] Keys: Export user-defined keyring operations

[David Howells]

The attached patch exports user-defined key operations so that those who wish
to define their own key type based on the user-defined key operations may do
so (as has been requested).

The header file created has been placed into include/keys/user-type.h, thus
creating a directory where other key types may also be placed. Any objections
to doing this?

Signed-Off-By: David Howells <dhowells@redhat.com>
---
warthog>diffstat -p1 keys-userexp-2614rc3.diff
 include/keys/user-type.h     |   47 +++++++++++++++++++++++++++++++++++++++++
 security/keys/user_defined.c |   49 +++++++++++++++++++++----------------------
 2 files changed, 71 insertions(+), 25 deletions(-)

diff -uNrp linux-2.6.14-rc3/include/keys/user-type.h linux-2.6.14-rc3-keys/include/keys/user-type.h
--- linux-2.6.14-rc3/include/keys/user-type.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.14-rc3-keys/include/keys/user-type.h	2005-10-05 11:44:54.000000000 +0100
@@ -0,0 +1,47 @@
+/* user-type.h: User-defined key type
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _KEYS_USER_TYPE_H
+#define _KEYS_USER_TYPE_H
+
+#include <linux/key.h>
+#include <linux/rcupdate.h>
+
+/*****************************************************************************/
+/*
+ * the payload for a key of type "user"
+ * - once filled in and attached to a key:
+ *   - the payload struct is invariant may not be changed, only replaced
+ *   - the payload must be read with RCU procedures or with the key semaphore
+ *     held
+ *   - the payload may only be replaced with the key semaphore write-locked
+ * - the key's data length is the size of the actual data, not including the
+ *   payload wrapper
+ */
+struct user_key_payload {
+	struct rcu_head	rcu;		/* RCU destructor */
+	unsigned short	datalen;	/* length of this data */
+	char		data[0];	/* actual data */
+};
+
+extern struct key_type key_type_user;
+
+extern int user_instantiate(struct key *key, const void *data, size_t datalen);
+extern int user_duplicate(struct key *key, const struct key *source);
+extern int user_update(struct key *key, const void *data, size_t datalen);
+extern int user_match(const struct key *key, const void *criterion);
+extern void user_destroy(struct key *key);
+extern void user_describe(const struct key *user, struct seq_file *m);
+extern long user_read(const struct key *key,
+		      char __user *buffer, size_t buflen);
+
+
+#endif /* _KEYS_USER_TYPE_H */
diff -uNrp linux-2.6.14-rc3/security/keys/user_defined.c linux-2.6.14-rc3-keys/security/keys/user_defined.c
--- linux-2.6.14-rc3/security/keys/user_defined.c	2005-08-30 13:56:44.000000000 +0100
+++ linux-2.6.14-rc3-keys/security/keys/user_defined.c	2005-10-05 11:37:04.000000000 +0100
@@ -15,18 +15,10 @@
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <linux/err.h>
+#include <keys/user-type.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
-static int user_instantiate(struct key *key, const void *data, size_t datalen);
-static int user_duplicate(struct key *key, const struct key *source);
-static int user_update(struct key *key, const void *data, size_t datalen);
-static int user_match(const struct key *key, const void *criterion);
-static void user_destroy(struct key *key);
-static void user_describe(const struct key *user, struct seq_file *m);
-static long user_read(const struct key *key,
-		      char __user *buffer, size_t buflen);
-
 /*
  * user defined keys take an arbitrary string as the description and an
  * arbitrary blob of data as the payload
@@ -42,19 +34,13 @@ struct key_type key_type_user = {
 	.read		= user_read,
 };
 
-struct user_key_payload {
-	struct rcu_head	rcu;		/* RCU destructor */
-	unsigned short	datalen;	/* length of this data */
-	char		data[0];	/* actual data */
-};
-
 EXPORT_SYMBOL_GPL(key_type_user);
 
 /*****************************************************************************/
 /*
  * instantiate a user defined key
  */
-static int user_instantiate(struct key *key, const void *data, size_t datalen)
+int user_instantiate(struct key *key, const void *data, size_t datalen)
 {
 	struct user_key_payload *upayload;
 	int ret;
@@ -78,18 +64,20 @@ static int user_instantiate(struct key *
 	rcu_assign_pointer(key->payload.data, upayload);
 	ret = 0;
 
- error:
+error:
 	return ret;
 
 } /* end user_instantiate() */
 
+EXPORT_SYMBOL(user_instantiate);
+
 /*****************************************************************************/
 /*
  * duplicate a user defined key
  * - both keys' semaphores are locked against further modification
  * - the new key cannot yet be accessed
  */
-static int user_duplicate(struct key *key, const struct key *source)
+int user_duplicate(struct key *key, const struct key *source)
 {
 	struct user_key_payload *upayload, *spayload;
 	int ret;
@@ -112,6 +100,8 @@ static int user_duplicate(struct key *ke
 
 } /* end user_duplicate() */
 
+EXPORT_SYMBOL(user_duplicate);
+
 /*****************************************************************************/
 /*
  * dispose of the old data from an updated user defined key
@@ -131,7 +121,7 @@ static void user_update_rcu_disposal(str
  * update a user defined key
  * - the key's semaphore is write-locked
  */
-static int user_update(struct key *key, const void *data, size_t datalen)
+int user_update(struct key *key, const void *data, size_t datalen)
 {
 	struct user_key_payload *upayload, *zap;
 	int ret;
@@ -163,26 +153,30 @@ static int user_update(struct key *key, 
 
 	call_rcu(&zap->rcu, user_update_rcu_disposal);
 
- error:
+error:
 	return ret;
 
 } /* end user_update() */
 
+EXPORT_SYMBOL(user_update);
+
 /*****************************************************************************/
 /*
  * match users on their name
  */
-static int user_match(const struct key *key, const void *description)
+int user_match(const struct key *key, const void *description)
 {
 	return strcmp(key->description, description) == 0;
 
 } /* end user_match() */
 
+EXPORT_SYMBOL(user_match);
+
 /*****************************************************************************/
 /*
  * dispose of the data dangling from the corpse of a user
  */
-static void user_destroy(struct key *key)
+void user_destroy(struct key *key)
 {
 	struct user_key_payload *upayload = key->payload.data;
 
@@ -190,11 +184,13 @@ static void user_destroy(struct key *key
 
 } /* end user_destroy() */
 
+EXPORT_SYMBOL(user_destroy);
+
 /*****************************************************************************/
 /*
  * describe the user key
  */
-static void user_describe(const struct key *key, struct seq_file *m)
+void user_describe(const struct key *key, struct seq_file *m)
 {
 	seq_puts(m, key->description);
 
@@ -202,13 +198,14 @@ static void user_describe(const struct k
 
 } /* end user_describe() */
 
+EXPORT_SYMBOL(user_describe);
+
 /*****************************************************************************/
 /*
  * read the key data
  * - the key's semaphore is read-locked
  */
-static long user_read(const struct key *key,
-		      char __user *buffer, size_t buflen)
+long user_read(const struct key *key, char __user *buffer, size_t buflen)
 {
 	struct user_key_payload *upayload;
 	long ret;
@@ -228,3 +225,5 @@ static long user_read(const struct key *
 	return ret;
 
 } /* end user_read() */
+
+EXPORT_SYMBOL(user_read);

Re: [PATCH] Keys: Export user-defined keyring operations

[Arjan van de Ven]

On Wed, 2005-10-05 at 11:58 +0100, David Howells wrote:
> The attached patch exports user-defined key operations so that those who wish
> to define their own key type based on the user-defined key operations may do
> so (as has been requested).
> 
> The header file created has been placed into include/keys/user-type.h, thus
> creating a directory where other key types may also be placed. Any objections
> to doing this?

since this is new unique-to-linux functionality, could you please
consider making the exports _GPL please?

Re: [PATCH] Keys: Export user-defined keyring operations

[David Howells]

Arjan van de Ven <arjan@infradead.org> wrote:

> since this is new unique-to-linux functionality, could you please
> consider making the exports _GPL please?

I have.

David

Re: [PATCH] Keys: Export user-defined keyring operations

[Arjan van de Ven]

On Wed, 2005-10-05 at 12:40 +0100, David Howells wrote:
> Arjan van de Ven <arjan@infradead.org> wrote:
> 
> > since this is new unique-to-linux functionality, could you please
> > consider making the exports _GPL please?
> 
> I have.

the patch doesn't show it though ;)

are there any users of this? Is this accidentally for an external
non-GPL module??? If so sounds like a bad idea.

Re: [PATCH] Keys: Export user-defined keyring operations

[David Howells]

Arjan van de Ven <arjan@infradead.org> wrote:

> > > since this is new unique-to-linux functionality, could you please
> > > consider making the exports _GPL please?
> > 
> > I have.
> 
> the patch doesn't show it though ;)

I have considered it.

> are there any users of this?

Potentially - I've been asked for it.

> Is this accidentally for an external non-GPL module???

No.

David

Re: [PATCH] Keys: Export user-defined keyring operations

[Arjan van de Ven]

On Wed, 2005-10-05 at 13:06 +0100, David Howells wrote:
> Arjan van de Ven <arjan@infradead.org> wrote:
> 
> > > > since this is new unique-to-linux functionality, could you please
> > > > consider making the exports _GPL please?
> > > 
> > > I have.
> > 
> > the patch doesn't show it though ;)
> 
> I have considered it.
> 
> > are there any users of this?
> 
> Potentially - I've been asked for it.

below is the patch with _GPL exports instead, and as agreed with you
with your sign-off as well


From: David Howells <dhowells@redhat.com>

The attached patch exports user-defined key operations so that those who wish
to define their own key type based on the user-defined key operations may do
so (as has been requested).

The header file created has been placed into include/keys/user-type.h, thus
creating a directory where other key types may also be placed. Any objections
to doing this?

Modified to make the exports _GPL

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Arjan van de Ven <arjan@infradead.org>
---
warthog>diffstat -p1 keys-userexp-2614rc3.diff
 include/keys/user-type.h     |   47 +++++++++++++++++++++++++++++++++++++++++
 security/keys/user_defined.c |   49 +++++++++++++++++++++----------------------
 2 files changed, 71 insertions(+), 25 deletions(-)

diff -uNrp linux-2.6.14-rc3/include/keys/user-type.h linux-2.6.14-rc3-keys/include/keys/user-type.h
--- linux-2.6.14-rc3/include/keys/user-type.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.14-rc3-keys/include/keys/user-type.h	2005-10-05 11:44:54.000000000 +0100
@@ -0,0 +1,47 @@
+/* user-type.h: User-defined key type
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _KEYS_USER_TYPE_H
+#define _KEYS_USER_TYPE_H
+
+#include <linux/key.h>
+#include <linux/rcupdate.h>
+
+/*****************************************************************************/
+/*
+ * the payload for a key of type "user"
+ * - once filled in and attached to a key:
+ *   - the payload struct is invariant may not be changed, only replaced
+ *   - the payload must be read with RCU procedures or with the key semaphore
+ *     held
+ *   - the payload may only be replaced with the key semaphore write-locked
+ * - the key's data length is the size of the actual data, not including the
+ *   payload wrapper
+ */
+struct user_key_payload {
+	struct rcu_head	rcu;		/* RCU destructor */
+	unsigned short	datalen;	/* length of this data */
+	char		data[0];	/* actual data */
+};
+
+extern struct key_type key_type_user;
+
+extern int user_instantiate(struct key *key, const void *data, size_t datalen);
+extern int user_duplicate(struct key *key, const struct key *source);
+extern int user_update(struct key *key, const void *data, size_t datalen);
+extern int user_match(const struct key *key, const void *criterion);
+extern void user_destroy(struct key *key);
+extern void user_describe(const struct key *user, struct seq_file *m);
+extern long user_read(const struct key *key,
+		      char __user *buffer, size_t buflen);
+
+
+#endif /* _KEYS_USER_TYPE_H */
diff -uNrp linux-2.6.14-rc3/security/keys/user_defined.c linux-2.6.14-rc3-keys/security/keys/user_defined.c
--- linux-2.6.14-rc3/security/keys/user_defined.c	2005-08-30 13:56:44.000000000 +0100
+++ linux-2.6.14-rc3-keys/security/keys/user_defined.c	2005-10-05 11:37:04.000000000 +0100
@@ -15,18 +15,10 @@
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <linux/err.h>
+#include <keys/user-type.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
-static int user_instantiate(struct key *key, const void *data, size_t datalen);
-static int user_duplicate(struct key *key, const struct key *source);
-static int user_update(struct key *key, const void *data, size_t datalen);
-static int user_match(const struct key *key, const void *criterion);
-static void user_destroy(struct key *key);
-static void user_describe(const struct key *user, struct seq_file *m);
-static long user_read(const struct key *key,
-		      char __user *buffer, size_t buflen);
-
 /*
  * user defined keys take an arbitrary string as the description and an
  * arbitrary blob of data as the payload
@@ -42,19 +34,13 @@ struct key_type key_type_user = {
 	.read		= user_read,
 };
 
-struct user_key_payload {
-	struct rcu_head	rcu;		/* RCU destructor */
-	unsigned short	datalen;	/* length of this data */
-	char		data[0];	/* actual data */
-};
-
 EXPORT_SYMBOL_GPL(key_type_user);
 
 /*****************************************************************************/
 /*
  * instantiate a user defined key
  */
-static int user_instantiate(struct key *key, const void *data, size_t datalen)
+int user_instantiate(struct key *key, const void *data, size_t datalen)
 {
 	struct user_key_payload *upayload;
 	int ret;
@@ -78,18 +64,20 @@ static int user_instantiate(struct key *
 	rcu_assign_pointer(key->payload.data, upayload);
 	ret = 0;
 
- error:
+error:
 	return ret;
 
 } /* end user_instantiate() */
 
+EXPORT_SYMBOL_GPL(user_instantiate);
+
 /*****************************************************************************/
 /*
  * duplicate a user defined key
  * - both keys' semaphores are locked against further modification
  * - the new key cannot yet be accessed
  */
-static int user_duplicate(struct key *key, const struct key *source)
+int user_duplicate(struct key *key, const struct key *source)
 {
 	struct user_key_payload *upayload, *spayload;
 	int ret;
@@ -112,6 +100,8 @@ static int user_duplicate(struct key *ke
 
 } /* end user_duplicate() */
 
+EXPORT_SYMBOL_GPL(user_duplicate);
+
 /*****************************************************************************/
 /*
  * dispose of the old data from an updated user defined key
@@ -131,7 +121,7 @@ static void user_update_rcu_disposal(str
  * update a user defined key
  * - the key's semaphore is write-locked
  */
-static int user_update(struct key *key, const void *data, size_t datalen)
+int user_update(struct key *key, const void *data, size_t datalen)
 {
 	struct user_key_payload *upayload, *zap;
 	int ret;
@@ -163,26 +153,30 @@ static int user_update(struct key *key, 
 
 	call_rcu(&zap->rcu, user_update_rcu_disposal);
 
- error:
+error:
 	return ret;
 
 } /* end user_update() */
 
+EXPORT_SYMBOL_GPL(user_update);
+
 /*****************************************************************************/
 /*
  * match users on their name
  */
-static int user_match(const struct key *key, const void *description)
+int user_match(const struct key *key, const void *description)
 {
 	return strcmp(key->description, description) == 0;
 
 } /* end user_match() */
 
+EXPORT_SYMBOL_GPL(user_match);
+
 /*****************************************************************************/
 /*
  * dispose of the data dangling from the corpse of a user
  */
-static void user_destroy(struct key *key)
+void user_destroy(struct key *key)
 {
 	struct user_key_payload *upayload = key->payload.data;
 
@@ -190,11 +184,13 @@ static void user_destroy(struct key *key
 
 } /* end user_destroy() */
 
+EXPORT_SYMBOL_GPL(user_destroy);
+
 /*****************************************************************************/
 /*
  * describe the user key
  */
-static void user_describe(const struct key *key, struct seq_file *m)
+void user_describe(const struct key *key, struct seq_file *m)
 {
 	seq_puts(m, key->description);
 
@@ -202,13 +198,14 @@ static void user_describe(const struct k
 
 } /* end user_describe() */
 
+EXPORT_SYMBOL_GPL(user_describe);
+
 /*****************************************************************************/
 /*
  * read the key data
  * - the key's semaphore is read-locked
  */
-static long user_read(const struct key *key,
-		      char __user *buffer, size_t buflen)
+long user_read(const struct key *key, char __user *buffer, size_t buflen)
 {
 	struct user_key_payload *upayload;
 	long ret;
@@ -228,3 +225,5 @@ static long user_read(const struct key *
 	return ret;
 
 } /* end user_read() */
+
+EXPORT_SYMBOL_GPL(user_read);
-

Re: [PATCH] Keys: Export user-defined keyring operations

[David Woodhouse]

On Wed, 2005-10-05 at 13:02 +0200, Arjan van de Ven wrote:
> since this is new unique-to-linux functionality, could you please
> consider making the exports _GPL please?

What's the point? There can be no difference between the meaning of
EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() anyway.

§6 of the GPL says "You may not impose any further restrictions on the
recipients' exercise of the rights granted herein."

If there was really a meaningful difference between EXPORT_SYMBOL_GPL()
and EXPORT_SYMBOL(), then the GPL _itself_ would forbid the use of
EXPORT_SYMBOL_GPL() within the kernel, because that would impose
additional restrictions.

We should abolish the meaningless distinction between the two, because
it only encourages people to believe that EXPORT_SYMBOL() can be used
for non-GPL code. Either use EXPORT_SYMBOL() for everything, or switch
to EXPORT_SYMBOL_GPL() for everything. It doesn't really matter.

-- 
dwmw2

Re: [PATCH] Keys: Export user-defined keyring operations

[Linus Torvalds]

On Wed, 5 Oct 2005, David Woodhouse wrote:
> 
> What's the point? There can be no difference between the meaning of
> EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() anyway.

I've talked to a lawyer or two, and (a) there's an absolutely _huge_ 
difference and (b) they liked it.

The fact is, the law isn't a blind and mindless computer that takes what 
you say literally. Intent matters a LOT. And using the xxx_GPL() version 
to show that it's an internal interface is very meaningful indeed.

One of the lawyers said that it was a much better approach than trying to 
make the license explain all the details - codifying the intention in the 
code itself is not only more flexible, but a lot less likely to be 
misunderstood.

I think both them said that anybody who were to change a xyz_GPL to the 
non-GPL one in order to use it with a non-GPL module would almost 
immediately fall under the "willful infringement" thing, and that it would 
make it MUCH easier to get triple damages and/or injunctions, since they 
clearly knew about it.

I suspect programmers make horrible lawyers. They nitpick on details that 
sane humans don't. I think programmers often end up forgetting about the 
fact that human interactions don't work that way. Common sense makes a lot 
of difference, and DWIM is not just possible, but it's the only thing that 
matters.

		Linus