Index: 2.4.x-xfs/fs/xattr.c
===================================================================
--- 2.4.x-xfs.orig/fs/xattr.c	2004-10-19 10:26:55.000000000 +1000
+++ 2.4.x-xfs/fs/xattr.c	2006-01-18 13:21:52.889829629 +1100
@@ -15,45 +15,112 @@
 #include <asm/uaccess.h>
 
 /*
- * Extended attribute memory allocation wrappers, originally
- * based on the Intermezzo PRESTO_ALLOC/PRESTO_FREE macros.
- * The vmalloc use here is very uncommon - extended attributes
- * are supposed to be small chunks of metadata, and it is quite
- * unusual to have very many extended attributes, so lists tend
- * to be quite short as well.  The 64K upper limit is derived
- * from the extended attribute size limit used by XFS.
- * Intentionally allow zero @size for value/list size requests.
+ * Check permissions for extended attribute access.  This is a bit complicated
+ * because different namespaces have very different rules.
  */
-static void *
-xattr_alloc(size_t size, size_t limit)
+static int
+xattr_permission(struct inode *inode, const char *name, int mask)
 {
-	void *ptr;
+	/*
+	 * We can never set or remove an extended attribute on a read-only
+	 * filesystem  or on an immutable / append-only inode.
+	 */
+	if (mask & MAY_WRITE) {
+		if (IS_RDONLY(inode))
+			return -EROFS;
+		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+			return -EPERM;
+	}
+
+	/*
+	 * No restriction for security.* and system.* from the VFS.  Decision
+	 * on these is left to the underlying filesystem / security module.
+	 */
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
+	    !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return 0;
+
+	/*
+	 * The trusted.* namespace can only accessed by a privilegued user.
+	 */
+	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
+		return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
+
+	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
+		if (!S_ISREG(inode->i_mode) &&
+		    (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
+			return -EPERM;
+	}
+
+	return permission(inode, mask);
+}
+
+int
+vfs_setxattr(struct dentry *dentry, char *name, void *value,
+		size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
 
-	if (size > limit)
-		return ERR_PTR(-E2BIG);
+	if (!inode->i_op->setxattr)
+		return -EOPNOTSUPP;
 
-	if (!size)	/* size request, no buffer is needed */
-		return NULL;
-	else if (size <= PAGE_SIZE)
-		ptr = kmalloc((unsigned long) size, GFP_KERNEL);
-	else
-		ptr = vmalloc((unsigned long) size);
-	if (!ptr)
-		return ERR_PTR(-ENOMEM);
-	return ptr;
-}
-
-static void
-xattr_free(void *ptr, size_t size)
-{
-	if (!size)	/* size request, no buffer was needed */
-		return;
-	else if (size <= PAGE_SIZE)
-		kfree(ptr);
-	else
-		vfree(ptr);
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	down(&inode->i_sem);
+	lock_kernel();
+	error = inode->i_op->setxattr(dentry, name, value, size, flags);
+	unlock_kernel();
+	up(&inode->i_sem);
+	return error;
 }
 
+ssize_t
+vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	if (!inode->i_op->getxattr)
+		return -EOPNOTSUPP;
+
+	error = xattr_permission(inode, name, MAY_READ);
+	if (error)
+		return error;
+
+	down(&inode->i_sem);
+	lock_kernel();
+	error = inode->i_op->getxattr(dentry, name, value, size);
+	unlock_kernel();
+	up(&inode->i_sem);
+	return error;
+}
+
+int
+vfs_removexattr(struct dentry *dentry, char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	if (!inode->i_op->removexattr)
+		return -EOPNOTSUPP;
+
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	down(&inode->i_sem);
+	lock_kernel();
+	error = inode->i_op->removexattr(dentry, name);
+	unlock_kernel();
+	up(&inode->i_sem);
+
+	return error;
+}
+
+
 /*
  * Extended attribute SET operations
  */
@@ -61,7 +128,7 @@
 setxattr(struct dentry *d, char *name, void *value, size_t size, int flags)
 {
 	int error;
-	void *kvalue;
+	void *kvalue = NULL;
 	char kname[XATTR_NAME_MAX + 1];
 
 	if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
@@ -73,25 +140,20 @@
 	if (error < 0)
 		return error;
 
-	kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
-	if (IS_ERR(kvalue))
-		return PTR_ERR(kvalue);
-
-	if (size > 0 && copy_from_user(kvalue, value, size)) {
-		xattr_free(kvalue, size);
-		return -EFAULT;
+	if (size) {
+		if (size > XATTR_SIZE_MAX)
+			return -E2BIG;
+		kvalue = kmalloc(size, GFP_KERNEL);
+		if (!kvalue)
+			return -ENOMEM;
+		if (copy_from_user(kvalue, value, size)) {
+			kfree(kvalue);
+			return -EFAULT;
+		}
 	}
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
-		down(&d->d_inode->i_sem);
-		lock_kernel();
-		error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
-		unlock_kernel();
-		up(&d->d_inode->i_sem);
-	}
-
-	xattr_free(kvalue, size);
+	error = vfs_setxattr(d, kname, kvalue, size, flags);
+	kfree(kvalue);
 	return error;
 }
 
@@ -144,7 +206,7 @@
 getxattr(struct dentry *d, char *name, void *value, size_t size)
 {
 	ssize_t error;
-	void *kvalue;
+	void *kvalue = NULL;
 	char kname[XATTR_NAME_MAX + 1];
 
 	error = strncpy_from_user(kname, name, sizeof(kname));
@@ -153,23 +215,25 @@
 	if (error < 0)
 		return error;
 
-	kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
-	if (IS_ERR(kvalue))
-		return PTR_ERR(kvalue);
-
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
-		down(&d->d_inode->i_sem);
-		lock_kernel();
-		error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
-		unlock_kernel();
-		up(&d->d_inode->i_sem);
+	if (size) {
+		if (size > XATTR_SIZE_MAX)
+			size = XATTR_SIZE_MAX;
+		kvalue = kmalloc(size, GFP_KERNEL);
+		if (!kvalue)
+			return -ENOMEM;
+		memset(kvalue, 0, size);
 	}
 
-	if (kvalue && error > 0)
-		if (copy_to_user(value, kvalue, error))
+	error = vfs_getxattr(d, kname, kvalue, size);
+	if (error > 0) {
+		if (size && copy_to_user(value, kvalue, error))
 			error = -EFAULT;
-	xattr_free(kvalue, size);
+	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
+		/* The file system tried to returned a value bigger
+		   than XATTR_SIZE_MAX bytes. Not possible. */
+		error = -E2BIG;
+	}
+	kfree(kvalue);
 	return error;
 }
 
@@ -222,25 +286,34 @@
 listxattr(struct dentry *d, char *list, size_t size)
 {
 	ssize_t error;
-	char *klist;
+	char *klist = NULL;
 
-	klist = (char *)xattr_alloc(size, XATTR_LIST_MAX);
-	if (IS_ERR(klist))
-		return PTR_ERR(klist);
+	if (size) {
+		if (size > XATTR_LIST_MAX)
+			size = XATTR_LIST_MAX;
+		klist = kmalloc(size, GFP_KERNEL);
+		if (!klist)
+			return -ENOMEM;
+	}
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
-		down(&d->d_inode->i_sem);
 		lock_kernel();
+		down(&d->d_inode->i_sem);
 		error = d->d_inode->i_op->listxattr(d, klist, size);
 		unlock_kernel();
 		up(&d->d_inode->i_sem);
 	}
-
-	if (klist && error > 0)
-		if (copy_to_user(list, klist, error))
+	if (error > 0) {
+		if (size && copy_to_user(list, klist, error))
 			error = -EFAULT;
-	xattr_free(klist, size);
+	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
+		/* The file system tried to returned a list bigger
+		   than XATTR_LIST_MAX bytes. Not possible. */
+		error = -E2BIG;
+	}
+
+	kfree(klist);
 	return error;
 }
 
@@ -301,15 +374,7 @@
 	if (error < 0)
 		return error;
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
-		down(&d->d_inode->i_sem);
-		lock_kernel();
-		error = d->d_inode->i_op->removexattr(d, kname);
-		unlock_kernel();
-		up(&d->d_inode->i_sem);
-	}
-	return error;
+	return vfs_removexattr(d, kname);
 }
 
 asmlinkage long
Index: 2.4.x-xfs/include/linux/xattr.h
===================================================================
--- 2.4.x-xfs.orig/include/linux/xattr.h	2004-10-19 10:28:04.000000000 +1000
+++ 2.4.x-xfs/include/linux/xattr.h	2006-01-18 13:21:41.819097121 +1100
@@ -11,5 +11,17 @@
 
 #define XATTR_CREATE	0x1	/* set the value, fail if attr already exists */
 #define XATTR_REPLACE	0x2	/* set the value, fail if attr does not exist */
+/* Namespaces */
+#define XATTR_SECURITY_PREFIX	"security."
+#define XATTR_SECURITY_PREFIX_LEN (sizeof (XATTR_SECURITY_PREFIX) - 1)
+
+#define XATTR_SYSTEM_PREFIX "system."
+#define XATTR_SYSTEM_PREFIX_LEN (sizeof (XATTR_SYSTEM_PREFIX) - 1)
+
+#define XATTR_TRUSTED_PREFIX "trusted."
+#define XATTR_TRUSTED_PREFIX_LEN (sizeof (XATTR_TRUSTED_PREFIX) - 1)
+
+#define XATTR_USER_PREFIX "user."
+#define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1)
 
 #endif	/* _LINUX_XATTR_H */