From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 150C7C3A59F for ; Tue, 27 Aug 2019 01:45:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEB6E2080C for ; Tue, 27 Aug 2019 01:44:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728667AbfH0Bo7 (ORCPT ); Mon, 26 Aug 2019 21:44:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49280 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728335AbfH0Bo6 (ORCPT ); Mon, 26 Aug 2019 21:44:58 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CE27F30832E1; Tue, 27 Aug 2019 01:44:57 +0000 (UTC) Received: from x1.home (ovpn-116-99.phx2.redhat.com [10.3.116.99]) by smtp.corp.redhat.com (Postfix) with ESMTP id 19D2C1001281; Tue, 27 Aug 2019 01:44:57 +0000 (UTC) Date: Mon, 26 Aug 2019 19:44:56 -0600 From: Alex Williamson To: Parav Pandit Cc: jiri@mellanox.com, kwankhede@nvidia.com, cohuck@redhat.com, davem@davemloft.net, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 1/4] mdev: Introduce sha1 based mdev alias Message-ID: <20190826194456.6edef7d1@x1.home> In-Reply-To: <20190826204119.54386-2-parav@mellanox.com> References: <20190826204119.54386-1-parav@mellanox.com> <20190826204119.54386-2-parav@mellanox.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 27 Aug 2019 01:44:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 26 Aug 2019 15:41:16 -0500 Parav Pandit wrote: > Whenever a parent requests to generate mdev alias, generate a mdev > alias. > It is an optional attribute that parent can request to generate > for each of its child mdev. > mdev alias is generated using sha1 from the mdev name. > > Signed-off-by: Parav Pandit > --- > drivers/vfio/mdev/mdev_core.c | 98 +++++++++++++++++++++++++++++++- > drivers/vfio/mdev/mdev_private.h | 5 +- > drivers/vfio/mdev/mdev_sysfs.c | 13 +++-- > include/linux/mdev.h | 4 ++ > 4 files changed, 111 insertions(+), 9 deletions(-) > > diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c > index b558d4cfd082..e825ff38b037 100644 > --- a/drivers/vfio/mdev/mdev_core.c > +++ b/drivers/vfio/mdev/mdev_core.c > @@ -10,9 +10,11 @@ > #include > #include > #include > +#include > #include > #include > #include > +#include > > #include "mdev_private.h" > > @@ -27,6 +29,8 @@ static struct class_compat *mdev_bus_compat_class; > static LIST_HEAD(mdev_list); > static DEFINE_MUTEX(mdev_list_lock); > > +static struct crypto_shash *alias_hash; > + > struct device *mdev_parent_dev(struct mdev_device *mdev) > { > return mdev->parent->dev; > @@ -164,6 +168,18 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) > goto add_dev_err; > } > > + if (ops->get_alias_length) { > + unsigned int digest_size; > + unsigned int aligned_len; > + > + aligned_len = roundup(ops->get_alias_length(), 2); > + digest_size = crypto_shash_digestsize(alias_hash); > + if (aligned_len / 2 > digest_size) { > + ret = -EINVAL; > + goto add_dev_err; > + } > + } This looks like a sanity check, it could be done outside of the parent_list_lock, even before we get a parent device reference. I think we're using a callback for get_alias_length() rather than a fixed field to support the mtty module option added in patch 4, right? Its utility is rather limited with no args. I could imagine that if a parent wanted to generate an alias that could be incorporated into a string with the parent device name that it would be useful to call this with the parent device as an arg. I guess we can save that until a user comes along though. There doesn't seem to be anything serializing use of alias_hash. > + > parent = kzalloc(sizeof(*parent), GFP_KERNEL); > if (!parent) { > ret = -ENOMEM; > @@ -259,6 +275,7 @@ static void mdev_device_free(struct mdev_device *mdev) > mutex_unlock(&mdev_list_lock); > > dev_dbg(&mdev->dev, "MDEV: destroying\n"); > + kvfree(mdev->alias); > kfree(mdev); > } > > @@ -269,18 +286,86 @@ static void mdev_device_release(struct device *dev) > mdev_device_free(mdev); > } > > -int mdev_device_create(struct kobject *kobj, > - struct device *dev, const guid_t *uuid) > +static const char * > +generate_alias(const char *uuid, unsigned int max_alias_len) > +{ > + struct shash_desc *hash_desc; > + unsigned int digest_size; > + unsigned char *digest; > + unsigned int alias_len; > + char *alias; > + int ret = 0; > + > + /* Align to multiple of 2 as bin2hex will generate > + * even number of bytes. > + */ Comment style for non-networking code please. > + alias_len = roundup(max_alias_len, 2); > + alias = kvzalloc(alias_len + 1, GFP_KERNEL); The size we're generating here should be small enough to just use kzalloc(), probably below too. > + if (!alias) > + return NULL; > + > + /* Allocate and init descriptor */ > + hash_desc = kvzalloc(sizeof(*hash_desc) + > + crypto_shash_descsize(alias_hash), > + GFP_KERNEL); > + if (!hash_desc) > + goto desc_err; > + > + hash_desc->tfm = alias_hash; > + > + digest_size = crypto_shash_digestsize(alias_hash); > + > + digest = kvzalloc(digest_size, GFP_KERNEL); > + if (!digest) { > + ret = -ENOMEM; > + goto digest_err; > + } > + crypto_shash_init(hash_desc); > + crypto_shash_update(hash_desc, uuid, UUID_STRING_LEN); > + crypto_shash_final(hash_desc, digest); > + bin2hex(&alias[0], digest, &alias[0], ie. alias > + min_t(unsigned int, digest_size, alias_len / 2)); > + /* When alias length is odd, zero out and additional last byte > + * that bin2hex has copied. > + */ > + if (max_alias_len % 2) > + alias[max_alias_len] = 0; Doesn't this give us a null terminated string for odd numbers but not even numbers? Probably best to define that we always provide a null terminated string then we could do this unconditionally. > + > + kvfree(digest); > + kvfree(hash_desc); > + return alias; > + > +digest_err: > + kvfree(hash_desc); > +desc_err: > + kvfree(alias); > + return NULL; > +} > + > +int mdev_device_create(struct kobject *kobj, struct device *dev, > + const char *uuid_str, const guid_t *uuid) > { > int ret; > struct mdev_device *mdev, *tmp; > struct mdev_parent *parent; > struct mdev_type *type = to_mdev_type(kobj); > + unsigned int alias_len = 0; > + const char *alias = NULL; > > parent = mdev_get_parent(type->parent); > if (!parent) > return -EINVAL; > > + if (parent->ops->get_alias_length) > + alias_len = parent->ops->get_alias_length(); > + if (alias_len) { Why isn't this nested into the branch above? > + alias = generate_alias(uuid_str, alias_len); > + if (!alias) { > + ret = -ENOMEM; Could use an ERR_PTR and propagate an errno. > + goto alias_fail; > + } > + } > + > mutex_lock(&mdev_list_lock); > > /* Check for duplicate */ > @@ -300,6 +385,8 @@ int mdev_device_create(struct kobject *kobj, > } > > guid_copy(&mdev->uuid, uuid); > + mdev->alias = alias; > + alias = NULL; A comment justifying this null'ing might help prevent it getting culled as some point. It appears arbitrary at first look. Thanks, Alex > list_add(&mdev->next, &mdev_list); > mutex_unlock(&mdev_list_lock); > > @@ -346,6 +433,8 @@ int mdev_device_create(struct kobject *kobj, > up_read(&parent->unreg_sem); > put_device(&mdev->dev); > mdev_fail: > + kvfree(alias); > +alias_fail: > mdev_put_parent(parent); > return ret; > } > @@ -406,6 +495,10 @@ EXPORT_SYMBOL(mdev_get_iommu_device); > > static int __init mdev_init(void) > { > + alias_hash = crypto_alloc_shash("sha1", 0, 0); > + if (!alias_hash) > + return -ENOMEM; > + > return mdev_bus_register(); > } > > @@ -415,6 +508,7 @@ static void __exit mdev_exit(void) > class_compat_unregister(mdev_bus_compat_class); > > mdev_bus_unregister(); > + crypto_free_shash(alias_hash); > } > > module_init(mdev_init) > diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h > index 7d922950caaf..cf1c0d9842c6 100644 > --- a/drivers/vfio/mdev/mdev_private.h > +++ b/drivers/vfio/mdev/mdev_private.h > @@ -33,6 +33,7 @@ struct mdev_device { > struct kobject *type_kobj; > struct device *iommu_device; > bool active; > + const char *alias; > }; > > #define to_mdev_device(dev) container_of(dev, struct mdev_device, dev) > @@ -57,8 +58,8 @@ void parent_remove_sysfs_files(struct mdev_parent *parent); > int mdev_create_sysfs_files(struct device *dev, struct mdev_type *type); > void mdev_remove_sysfs_files(struct device *dev, struct mdev_type *type); > > -int mdev_device_create(struct kobject *kobj, > - struct device *dev, const guid_t *uuid); > +int mdev_device_create(struct kobject *kobj, struct device *dev, > + const char *uuid_str, const guid_t *uuid); > int mdev_device_remove(struct device *dev); > > #endif /* MDEV_PRIVATE_H */ > diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c > index 7570c7602ab4..43afe0e80b76 100644 > --- a/drivers/vfio/mdev/mdev_sysfs.c > +++ b/drivers/vfio/mdev/mdev_sysfs.c > @@ -63,15 +63,18 @@ static ssize_t create_store(struct kobject *kobj, struct device *dev, > return -ENOMEM; > > ret = guid_parse(str, &uuid); > - kfree(str); > if (ret) > - return ret; > + goto err; > > - ret = mdev_device_create(kobj, dev, &uuid); > + ret = mdev_device_create(kobj, dev, str, &uuid); > if (ret) > - return ret; > + goto err; > > - return count; > + ret = count; > + > +err: > + kfree(str); > + return ret; > } > > MDEV_TYPE_ATTR_WO(create); > diff --git a/include/linux/mdev.h b/include/linux/mdev.h > index 0ce30ca78db0..f036fe9854ee 100644 > --- a/include/linux/mdev.h > +++ b/include/linux/mdev.h > @@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev); > * @mmap: mmap callback > * @mdev: mediated device structure > * @vma: vma structure > + * @get_alias_length: Generate alias for the mdevs of this parent based on the > + * mdev device name when it returns non zero alias length. > + * It is optional. > * Parent device that support mediated device should be registered with mdev > * module with mdev_parent_ops structure. > **/ > @@ -92,6 +95,7 @@ struct mdev_parent_ops { > long (*ioctl)(struct mdev_device *mdev, unsigned int cmd, > unsigned long arg); > int (*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma); > + unsigned int (*get_alias_length)(void); > }; > > /* interface for exporting mdev supported type attributes */