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[94.113.220.175]) by smtp.gmail.com with ESMTPSA id a206sm5605113wmf.15.2019.11.08.03.04.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Nov 2019 03:04:56 -0800 (PST) Date: Fri, 8 Nov 2019 12:04:56 +0100 From: Jiri Pirko To: Parav Pandit Cc: alex.williamson@redhat.com, davem@davemloft.net, kvm@vger.kernel.org, netdev@vger.kernel.org, saeedm@mellanox.com, kwankhede@nvidia.com, leon@kernel.org, cohuck@redhat.com, jiri@mellanox.com, linux-rdma@vger.kernel.org Subject: Re: [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias Message-ID: <20191108110456.GH6990@nanopsycho> References: <20191107160448.20962-1-parav@mellanox.com> <20191107160834.21087-1-parav@mellanox.com> <20191107160834.21087-7-parav@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191107160834.21087-7-parav@mellanox.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Thu, Nov 07, 2019 at 05:08:22PM CET, parav@mellanox.com wrote: >Some vendor drivers want an identifier for an mdev device that is >shorter than the UUID, due to length restrictions in the consumers of >that identifier. > >Add a callback that allows a vendor driver to request an alias of a >specified length to be generated for an mdev device. If generated, >that alias is checked for collisions. > >It is an optional attribute. >mdev alias is generated using sha1 from the mdev name. > >Reviewed-by: Saeed Mahameed >Signed-off-by: Parav Pandit >--- > drivers/vfio/mdev/mdev_core.c | 123 ++++++++++++++++++++++++++++++- > drivers/vfio/mdev/mdev_private.h | 5 +- > drivers/vfio/mdev/mdev_sysfs.c | 13 ++-- > include/linux/mdev.h | 4 + > 4 files changed, 135 insertions(+), 10 deletions(-) > >diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c >index b558d4cfd082..3bdff0469607 100644 >--- a/drivers/vfio/mdev/mdev_core.c >+++ b/drivers/vfio/mdev/mdev_core.c >@@ -10,9 +10,11 @@ [...] >-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; >+ >+ /* >+ * Align to multiple of 2 as bin2hex will generate >+ * even number of bytes. >+ */ >+ alias_len = roundup(max_alias_len, 2); This is odd, see below. >+ alias = kzalloc(alias_len + 1, GFP_KERNEL); >+ if (!alias) >+ return ERR_PTR(-ENOMEM); >+ >+ /* Allocate and init descriptor */ >+ hash_desc = kvzalloc(sizeof(*hash_desc) + >+ crypto_shash_descsize(alias_hash), >+ GFP_KERNEL); >+ if (!hash_desc) { >+ ret = -ENOMEM; >+ goto desc_err; >+ } >+ >+ hash_desc->tfm = alias_hash; >+ >+ digest_size = crypto_shash_digestsize(alias_hash); >+ >+ digest = kzalloc(digest_size, GFP_KERNEL); >+ if (!digest) { >+ ret = -ENOMEM; >+ goto digest_err; >+ } >+ ret = crypto_shash_init(hash_desc); >+ if (ret) >+ goto hash_err; >+ >+ ret = crypto_shash_update(hash_desc, uuid, UUID_STRING_LEN); >+ if (ret) >+ goto hash_err; >+ >+ ret = crypto_shash_final(hash_desc, digest); >+ if (ret) >+ goto hash_err; >+ >+ bin2hex(alias, digest, min_t(unsigned int, digest_size, alias_len / 2)); >+ /* >+ * When alias length is odd, zero out an additional last byte >+ * that bin2hex has copied. >+ */ >+ if (max_alias_len % 2) >+ alias[max_alias_len] = 0; >+ >+ kfree(digest); >+ kvfree(hash_desc); >+ return alias; >+ >+hash_err: >+ kfree(digest); >+digest_err: >+ kvfree(hash_desc); >+desc_err: >+ kfree(alias); >+ return ERR_PTR(ret); >+} >+ >+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); >+ const char *alias = NULL; > > parent = mdev_get_parent(type->parent); > if (!parent) > return -EINVAL; > >+ if (parent->ops->get_alias_length) { >+ unsigned int alias_len; >+ >+ alias_len = parent->ops->get_alias_length(); >+ if (alias_len) { I think this should be with WARN_ON. Driver should not never return such 0 and if it does, it's a bug. Also I think this check should be extended by checking value is multiple of 2. Then you can avoid the roundup() above. No need to allow even len. >+ alias = generate_alias(uuid_str, alias_len); >+ if (IS_ERR(alias)) { >+ ret = PTR_ERR(alias); >+ goto alias_fail; >+ } >+ } >+ } > mutex_lock(&mdev_list_lock); > > /* Check for duplicate */ [...] >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); Why to pass the same thing twice? Move the guid_parse() call to the beginning of mdev_device_create() function. > if (ret) >- return ret; >+ goto err; > >- return count; >+ ret = count; >+ >+err: >+ kfree(str); >+ return ret; > } > > MDEV_TYPE_ATTR_WO(create); [...]