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authorEric Biggers <ebiggers@google.com>2019-07-22 19:26:24 +0300
committerEric Biggers <ebiggers@google.com>2019-08-13 05:33:50 +0300
commitc93d8f88580921c84d2213161ef3c22560511b84 (patch)
treea113a5c4cbb04d656ebf22f10193745602d923c3 /fs/ext4/ioctl.c
parent432434c9f8e18cb4cf0fe05bc3eeceada0e10dc6 (diff)
downloadlinux-c93d8f88580921c84d2213161ef3c22560511b84.tar.xz
ext4: add basic fs-verity support
Add most of fs-verity support to ext4. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for the full documentation. This commit adds all of ext4 fs-verity support except for the actual data verification, including: - Adding a filesystem feature flag and an inode flag for fs-verity. - Implementing the fsverity_operations to support enabling verity on an inode and reading/writing the verity metadata. - Updating ->write_begin(), ->write_end(), and ->writepages() to support writing verity metadata pages. - Calling the fs-verity hooks for ->open(), ->setattr(), and ->ioctl(). ext4 stores the verity metadata (Merkle tree and fsverity_descriptor) past the end of the file, starting at the first 64K boundary beyond i_size. This approach works because (a) verity files are readonly, and (b) pages fully beyond i_size aren't visible to userspace but can be read/written internally by ext4 with only some relatively small changes to ext4. This approach avoids having to depend on the EA_INODE feature and on rearchitecturing ext4's xattr support to support paging multi-gigabyte xattrs into memory, and to support encrypting xattrs. Note that the verity metadata *must* be encrypted when the file is, since it contains hashes of the plaintext data. This patch incorporates work by Theodore Ts'o and Chandan Rajendra. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'fs/ext4/ioctl.c')
-rw-r--r--fs/ext4/ioctl.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 442f7ef873fc..ce811df71690 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1171,6 +1171,17 @@ out:
}
case EXT4_IOC_SHUTDOWN:
return ext4_shutdown(sb, arg);
+
+ case FS_IOC_ENABLE_VERITY:
+ if (!ext4_has_feature_verity(sb))
+ return -EOPNOTSUPP;
+ return fsverity_ioctl_enable(filp, (const void __user *)arg);
+
+ case FS_IOC_MEASURE_VERITY:
+ if (!ext4_has_feature_verity(sb))
+ return -EOPNOTSUPP;
+ return fsverity_ioctl_measure(filp, (void __user *)arg);
+
default:
return -ENOTTY;
}
@@ -1233,6 +1244,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case EXT4_IOC_GET_ENCRYPTION_POLICY:
case EXT4_IOC_SHUTDOWN:
case FS_IOC_GETFSMAP:
+ case FS_IOC_ENABLE_VERITY:
+ case FS_IOC_MEASURE_VERITY:
break;
default:
return -ENOIOCTLCMD;