From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Eric Biggers Subject: [PATCH v3 10/15] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Date: Thu, 23 May 2019 09:18:06 -0700 Message-Id: <20190523161811.6259-11-ebiggers@kernel.org> In-Reply-To: <20190523161811.6259-1-ebiggers@kernel.org> References: <20190523161811.6259-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-integrity-owner@vger.kernel.org To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-api@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh List-ID: From: Eric Biggers Add a function for filesystems to call to implement the FS_IOC_MEASURE_VERITY ioctl. This ioctl retrieves the file measurement that fs-verity calculated for the given file and is enforcing for reads; i.e., reads that don't match this hash will fail. This ioctl can be used for authentication or logging of file measurements in userspace. See the "FS_IOC_MEASURE_VERITY" section of Documentation/filesystems/fsverity.rst for the documentation. Signed-off-by: Eric Biggers --- fs/verity/Makefile | 1 + fs/verity/measure.c | 57 ++++++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 11 ++++++++ 3 files changed, 69 insertions(+) create mode 100644 fs/verity/measure.c diff --git a/fs/verity/Makefile b/fs/verity/Makefile index 04b37475fd280..6f7675ae0a311 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -3,5 +3,6 @@ obj-$(CONFIG_FS_VERITY) += enable.o \ hash_algs.o \ init.o \ + measure.o \ open.o \ verify.o diff --git a/fs/verity/measure.c b/fs/verity/measure.c new file mode 100644 index 0000000000000..f29557c0ee3da --- /dev/null +++ b/fs/verity/measure.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/measure.c: ioctl to get a verity file's measurement + * + * Copyright 2019 Google LLC + */ + +#include "fsverity_private.h" + +#include + +/** + * fsverity_ioctl_measure() - get a verity file's measurement + * + * Retrieve the file measurement that the kernel is enforcing for reads from a + * verity file. See the "FS_IOC_MEASURE_VERITY" section of + * Documentation/filesystems/fsverity.rst for the documentation. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) +{ + const struct inode *inode = file_inode(filp); + struct fsverity_digest __user *uarg = _uarg; + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + struct fsverity_digest arg; + + vi = get_verity_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + hash_alg = vi->tree_params.hash_alg; + + /* + * The user specifies the digest_size their buffer has space for; we can + * return the digest if it fits in the available space. We write back + * the actual size, which may be shorter than the user-specified size. + */ + + if (get_user(arg.digest_size, &uarg->digest_size)) + return -EFAULT; + if (arg.digest_size < hash_alg->digest_size) + return -EOVERFLOW; + + memset(&arg, 0, sizeof(arg)); + arg.digest_algorithm = hash_alg - fsverity_hash_algs; + arg.digest_size = hash_alg->digest_size; + + if (copy_to_user(uarg, &arg, sizeof(arg))) + return -EFAULT; + + if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 9a84fe4bcfc88..df0b620c6897f 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -110,6 +110,10 @@ struct fsverity_operations { extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg); +/* measure.c */ + +extern int fsverity_ioctl_measure(struct file *filp, void __user *arg); + /* open.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); @@ -132,6 +136,13 @@ static inline int fsverity_ioctl_enable(struct file *filp, return -EOPNOTSUPP; } +/* measure.c */ + +static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) +{ + return -EOPNOTSUPP; +} + /* open.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp) -- 2.21.0 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [PATCH v3 10/15] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Date: Thu, 23 May 2019 09:18:06 -0700 Message-ID: <20190523161811.6259-11-ebiggers@kernel.org> References: <20190523161811.6259-1-ebiggers@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190523161811.6259-1-ebiggers@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-fscrypt@vger.kernel.org Cc: "Theodore Y . Ts'o" , linux-api@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-integrity@vger.kernel.org, linux-ext4@vger.kernel.org, Victor Hsieh List-Id: linux-api@vger.kernel.org From: Eric Biggers Add a function for filesystems to call to implement the FS_IOC_MEASURE_VERITY ioctl. This ioctl retrieves the file measurement that fs-verity calculated for the given file and is enforcing for reads; i.e., reads that don't match this hash will fail. This ioctl can be used for authentication or logging of file measurements in userspace. See the "FS_IOC_MEASURE_VERITY" section of Documentation/filesystems/fsverity.rst for the documentation. Signed-off-by: Eric Biggers --- fs/verity/Makefile | 1 + fs/verity/measure.c | 57 ++++++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 11 ++++++++ 3 files changed, 69 insertions(+) create mode 100644 fs/verity/measure.c diff --git a/fs/verity/Makefile b/fs/verity/Makefile index 04b37475fd280..6f7675ae0a311 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -3,5 +3,6 @@ obj-$(CONFIG_FS_VERITY) += enable.o \ hash_algs.o \ init.o \ + measure.o \ open.o \ verify.o diff --git a/fs/verity/measure.c b/fs/verity/measure.c new file mode 100644 index 0000000000000..f29557c0ee3da --- /dev/null +++ b/fs/verity/measure.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/measure.c: ioctl to get a verity file's measurement + * + * Copyright 2019 Google LLC + */ + +#include "fsverity_private.h" + +#include + +/** + * fsverity_ioctl_measure() - get a verity file's measurement + * + * Retrieve the file measurement that the kernel is enforcing for reads from a + * verity file. See the "FS_IOC_MEASURE_VERITY" section of + * Documentation/filesystems/fsverity.rst for the documentation. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) +{ + const struct inode *inode = file_inode(filp); + struct fsverity_digest __user *uarg = _uarg; + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + struct fsverity_digest arg; + + vi = get_verity_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + hash_alg = vi->tree_params.hash_alg; + + /* + * The user specifies the digest_size their buffer has space for; we can + * return the digest if it fits in the available space. We write back + * the actual size, which may be shorter than the user-specified size. + */ + + if (get_user(arg.digest_size, &uarg->digest_size)) + return -EFAULT; + if (arg.digest_size < hash_alg->digest_size) + return -EOVERFLOW; + + memset(&arg, 0, sizeof(arg)); + arg.digest_algorithm = hash_alg - fsverity_hash_algs; + arg.digest_size = hash_alg->digest_size; + + if (copy_to_user(uarg, &arg, sizeof(arg))) + return -EFAULT; + + if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 9a84fe4bcfc88..df0b620c6897f 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -110,6 +110,10 @@ struct fsverity_operations { extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg); +/* measure.c */ + +extern int fsverity_ioctl_measure(struct file *filp, void __user *arg); + /* open.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); @@ -132,6 +136,13 @@ static inline int fsverity_ioctl_enable(struct file *filp, return -EOPNOTSUPP; } +/* measure.c */ + +static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) +{ + return -EOPNOTSUPP; +} + /* open.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp) -- 2.21.0