From: Eric Biggers <ebiggers@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-kernel@vger.kernel.org,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Jaegeuk Kim <jaegeuk@kernel.org>,
Victor Hsieh <victorhsieh@google.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>
Subject: [PATCH v2 06/12] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl
Date: Thu, 1 Nov 2018 15:52:24 -0700 [thread overview]
Message-ID: <20181101225230.88058-7-ebiggers@kernel.org> (raw)
In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
Add a function for filesystems to call to implement the
FS_IOC_MEASURE_VERITY ioctl. This ioctl retrieves the file measurement
hash 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 logging or authentication of file hashes in userspace.
This ioctl is documented in Documentation/filesystem/fsverity.rst;
see there for more information.
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/verity/ioctl.c | 47 ++++++++++++++++++++++++++++++++++++++++
fs/verity/setup.c | 4 +++-
include/linux/fsverity.h | 6 +++++
3 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/fs/verity/ioctl.c b/fs/verity/ioctl.c
index c5f0022cb3bef..640aa78e1c00c 100644
--- a/fs/verity/ioctl.c
+++ b/fs/verity/ioctl.c
@@ -115,3 +115,50 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *arg)
return err;
}
EXPORT_SYMBOL_GPL(fsverity_ioctl_enable);
+
+/**
+ * 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 Documentation/filesystems/fsverity.rst, section
+ * 'FS_IOC_MEASURE_VERITY' for details.
+ *
+ * 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_fsverity_info(inode);
+ if (!vi)
+ return -ENODATA; /* not a verity file */
+ hash_alg = vi->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/fs/verity/setup.c b/fs/verity/setup.c
index 184bdc96abe51..e0b39c518b890 100644
--- a/fs/verity/setup.c
+++ b/fs/verity/setup.c
@@ -819,7 +819,9 @@ static int __init fsverity_module_init(void)
goto error;
err = -ENOMEM;
- fsverity_info_cachep = KMEM_CACHE(fsverity_info, SLAB_RECLAIM_ACCOUNT);
+ fsverity_info_cachep = KMEM_CACHE_USERCOPY(fsverity_info,
+ SLAB_RECLAIM_ACCOUNT,
+ measurement);
if (!fsverity_info_cachep)
goto error_free_workqueue;
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index 5de50b52ccc70..c30c4f6ed411c 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -23,6 +23,7 @@ struct fsverity_operations {
/* ioctl.c */
extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg);
+extern int fsverity_ioctl_measure(struct file *filp, void __user *arg);
/* setup.c */
extern int fsverity_file_open(struct inode *inode, struct file *filp);
@@ -51,6 +52,11 @@ static inline int fsverity_ioctl_enable(struct file *filp,
return -EOPNOTSUPP;
}
+static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg)
+{
+ return -EOPNOTSUPP;
+}
+
/* setup.c */
static inline int fsverity_file_open(struct inode *inode, struct file *filp)
--
2.19.1.568.g152ad8e336-goog
next prev parent reply other threads:[~2018-11-01 22:55 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 22:52 [PATCH v2 00/12] fs-verity: read-only file-based authenticity protection Eric Biggers
2018-11-01 22:52 ` [PATCH v2 01/12] fs-verity: add a documentation file Eric Biggers
2018-12-12 9:14 ` Christoph Hellwig
2018-12-12 20:26 ` Eric Biggers
2018-12-13 20:22 ` Christoph Hellwig
2018-12-14 4:48 ` Eric Biggers
2018-12-17 16:49 ` Christoph Hellwig
2018-12-17 18:32 ` Eric Biggers
2018-12-19 7:09 ` Christoph Hellwig
2018-12-17 20:00 ` Darrick J. Wong
2018-12-19 0:16 ` Theodore Y. Ts'o
2018-12-19 2:19 ` Dave Chinner
2018-12-19 19:30 ` Theodore Y. Ts'o
2018-12-19 21:35 ` Dave Chinner
2018-12-20 22:01 ` Theodore Y. Ts'o
2018-12-21 7:04 ` Christoph Hellwig
2018-12-21 10:06 ` Richard Weinberger
2018-12-21 15:47 ` Theodore Y. Ts'o
2018-12-21 15:53 ` Matthew Wilcox
2018-12-21 16:28 ` Theodore Y. Ts'o
2018-12-21 16:34 ` Matthew Wilcox
2018-12-21 19:13 ` Linus Torvalds
2018-12-22 4:17 ` Theodore Y. Ts'o
2018-12-22 22:47 ` Linus Torvalds
2018-12-23 4:34 ` Theodore Y. Ts'o
2018-12-23 4:10 ` Matthew Wilcox
2018-12-23 4:45 ` Theodore Y. Ts'o
2019-01-04 20:41 ` Daniel Colascione
2018-12-19 7:14 ` Christoph Hellwig
2018-12-19 7:11 ` Christoph Hellwig
[not found] ` <CAHk-=wiB8vGbje+NgNkMZupHsZ_cqg6YEBV+ZXSF4wnywFLRHQ@mail.gmail.com>
2018-12-19 7:19 ` Christoph Hellwig
2018-12-14 5:17 ` Theodore Y. Ts'o
2018-12-14 5:39 ` Eric Biggers
2018-12-17 16:52 ` Christoph Hellwig
2018-12-17 19:15 ` Eric Biggers
2018-12-21 16:11 ` Matthew Wilcox
2018-11-01 22:52 ` [PATCH v2 02/12] fs-verity: add setup code, UAPI, and Kconfig Eric Biggers
2018-11-01 22:52 ` [PATCH v2 03/12] fs-verity: add MAINTAINERS file entry Eric Biggers
2018-11-01 22:52 ` [PATCH v2 04/12] fs-verity: add data verification hooks for ->readpages() Eric Biggers
2018-11-01 22:52 ` [PATCH v2 05/12] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Eric Biggers
2018-11-01 22:52 ` Eric Biggers [this message]
2018-11-01 22:52 ` [PATCH v2 07/12] fs-verity: add SHA-512 support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 08/12] fs-verity: add CRC-32C support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 09/12] fs-verity: support builtin file signatures Eric Biggers
2018-11-01 22:52 ` [PATCH v2 10/12] ext4: add basic fs-verity support Eric Biggers
2018-11-02 9:43 ` Chandan Rajendra
2018-11-06 1:25 ` Eric Biggers
2018-11-06 6:52 ` Chandan Rajendra
2018-11-05 21:05 ` Andreas Dilger
2018-11-06 1:11 ` Eric Biggers
2018-11-01 22:52 ` [PATCH v2 11/12] ext4: add fs-verity read support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 12/12] f2fs: fs-verity support Eric Biggers
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