From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-integrity@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Victor Hsieh <victorhsieh@google.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@lst.de>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH v7 11/17] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl
Date: Mon, 22 Jul 2019 09:50:55 -0700 [thread overview]
Message-ID: <20190722165101.12840-12-ebiggers@kernel.org> (raw)
In-Reply-To: <20190722165101.12840-1-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
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.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
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..05049b68c7455
--- /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 <linux/uaccess.h>
+
+/**
+ * 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 = fsverity_get_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 d1a5dbf450c46..3b6b8ccebe7d2 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -118,6 +118,10 @@ static inline struct fsverity_info *fsverity_get_info(const struct inode *inode)
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);
@@ -145,6 +149,13 @@ 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)
--
2.22.0
next prev parent reply other threads:[~2019-07-22 16:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 16:50 [PATCH v7 00/17] fs-verity: read-only file-based authenticity protection Eric Biggers
2019-07-22 16:50 ` [PATCH v7 01/17] fs-verity: add a documentation file Eric Biggers
2019-07-22 16:50 ` [PATCH v7 02/17] fs-verity: add MAINTAINERS file entry Eric Biggers
2019-07-22 16:50 ` [PATCH v7 03/17] fs-verity: add UAPI header Eric Biggers
2019-07-22 16:50 ` [PATCH v7 04/17] fs: uapi: define verity bit for FS_IOC_GETFLAGS Eric Biggers
2019-07-22 16:50 ` [PATCH v7 05/17] fs-verity: add Kconfig and the helper functions for hashing Eric Biggers
2019-07-22 16:50 ` [PATCH v7 06/17] fs-verity: add inode and superblock fields Eric Biggers
2019-07-22 16:50 ` [PATCH v7 07/17] fs-verity: add the hook for file ->open() Eric Biggers
2019-07-22 16:50 ` [PATCH v7 08/17] fs-verity: add the hook for file ->setattr() Eric Biggers
2019-07-22 16:50 ` [PATCH v7 09/17] fs-verity: add data verification hooks for ->readpages() Eric Biggers
2019-07-22 16:50 ` [PATCH v7 10/17] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Eric Biggers
2019-07-27 20:39 ` Theodore Y. Ts'o
2019-07-22 16:50 ` Eric Biggers [this message]
2019-07-22 16:50 ` [PATCH v7 12/17] fs-verity: add SHA-512 support Eric Biggers
2019-07-22 16:50 ` [PATCH v7 13/17] fs-verity: support builtin file signatures Eric Biggers
2019-07-22 16:50 ` [PATCH v7 14/17] ext4: add basic fs-verity support Eric Biggers
2019-07-22 16:50 ` [PATCH v7 15/17] ext4: add fs-verity read support Eric Biggers
2019-07-22 16:51 ` [PATCH v7 16/17] ext4: update on-disk format documentation for fs-verity Eric Biggers
2019-07-22 16:51 ` [PATCH v7 17/17] f2fs: add fs-verity support Eric Biggers
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