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Re: 2.6.14-mm1



On Mon, 2005-11-07 at 12:19 +0000, David Woodhouse wrote:
> On Mon, 2005-11-07 at 13:00 +0100, Jiri Slaby wrote:
> > There should be something like if (len == -EOPNOTSUPP) goto ret, where ret
> > should be right before return NULL. 
> 
> Yeah, that would seem to make sense.
> 
> > Or am I missing something? David, it's from your tree, do you have any
> > comments, ideas?
> 
> At the moment I'm mostly just collecting patches in a repository for
> those working in earnest on LSPP -- particularly when it comes to
> selinux, I'm mostly clueless. Deferring to Dustin, whose code this is.

Ok, I've gotten to the bottom of this "audit on, selinux off" problem
and tested the fix.  Attached is a patch against David's current git
tree.

The changes integrate:
- Jiri's suggested handling of EOPNOTSUPP.  Avoids audit_panic() calls
in EOPNOTSUPP situations
- David's suggested correction of a couple of warnings (using the const
char* suffix assignment at the top of audit_inode_context())
- And the real reason why this kernel wouldn't boot when SELinux was
off...  There was a missing dummy() function that should be stubbed in
and return NULL when SELinux is off.

Thanks for your help reporting this, Jiri.  Our linux-audit mailing list
really should have shaken out this bug earlier.

:-Dustin


diff --git a/include/linux/security.h b/include/linux/security.h
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1121,7 +1121,7 @@ struct security_operations {
 	int (*inode_getxattr) (struct dentry *dentry, char *name);
 	int (*inode_listxattr) (struct dentry *dentry);
 	int (*inode_removexattr) (struct dentry *dentry, char *name);
-	char *(*inode_xattr_getsuffix) (void);
+	const char *(*inode_xattr_getsuffix) (void);
   	int (*inode_getsecurity)(struct inode *inode, const char *name, void *buffer, size_t size, int err);
   	int (*inode_setsecurity)(struct inode *inode, const char *name, const void *value, size_t size, int flags);
   	int (*inode_listsecurity)(struct inode *inode, char *buffer, size_t buffer_size);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1301,13 +1301,16 @@ void audit_putname(const char *name)
 void audit_inode_context(int idx, const struct inode *inode)
 {
 	struct audit_context *context = current->audit_context;
+	const char *suffix = security_inode_xattr_getsuffix();
 	char *ctx = NULL;
 	int len = 0;
 
-	if (!security_inode_xattr_getsuffix())
-		return;
+	if (!suffix)
+		goto ret;
 
-	len = security_inode_getsecurity(inode, (char *)security_inode_xattr_getsuffix(), NULL, 0, 0);
+	len = security_inode_getsecurity(inode, suffix, NULL, 0, 0);
+	if (len == -EOPNOTSUPP)
+		goto ret;
 	if (len < 0) 
 		goto error_path;
 
@@ -1315,17 +1318,18 @@ void audit_inode_context(int idx, const 
 	if (!ctx) 
 		goto error_path;
 
-	len = security_inode_getsecurity(inode, (char *)security_inode_xattr_getsuffix(), ctx, len, 0);
+	len = security_inode_getsecurity(inode, suffix, ctx, len, 0);
 	if (len < 0)
 		goto error_path;
 
 	context->names[idx].ctx = ctx;
-	return;
+	goto ret;
 
 error_path:
 	if (ctx)
 		kfree(ctx);
 	audit_panic("error in audit_inode_context");
+ret:
 	return;
 }
 
@@ -1555,6 +1559,8 @@ char *audit_ipc_context(struct kern_ipc_
 		return NULL;
 
 	len = security_ipc_getsecurity(ipcp, NULL, 0);
+	if (len == -EOPNOTSUPP)
+		goto ret;
 	if (len < 0)
 		goto error_path;
 
@@ -1571,6 +1577,7 @@ char *audit_ipc_context(struct kern_ipc_
 error_path:
 	kfree(ctx);
 	audit_panic("error in audit_ipc_context");
+ret:
 	return NULL;
 }
 
diff --git a/security/dummy.c b/security/dummy.c
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -392,6 +392,11 @@ static int dummy_inode_listsecurity(stru
 	return 0;
 }
 
+static const char *dummy_inode_xattr_getsuffix(void)
+{
+	return NULL;
+}
+
 static int dummy_file_permission (struct file *file, int mask)
 {
 	return 0;
@@ -895,6 +900,7 @@ void security_fixup_ops (struct security
 	set_to_dummy_if_null(ops, inode_getxattr);
 	set_to_dummy_if_null(ops, inode_listxattr);
 	set_to_dummy_if_null(ops, inode_removexattr);
+	set_to_dummy_if_null(ops, inode_xattr_getsuffix);
 	set_to_dummy_if_null(ops, inode_getsecurity);
 	set_to_dummy_if_null(ops, inode_setsecurity);
 	set_to_dummy_if_null(ops, inode_listsecurity);

-- 
Dustin Kirkland <dustin kirkland us ibm com>

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