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authorLinus Torvalds <torvalds@linux-foundation.org>2022-05-24 23:50:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-05-24 23:50:39 +0300
commit0350785b0a092c99c5ddd2ace0260dbe7b3f919f (patch)
tree3b9189b609f05d097f3ea9cb42c1a523308d53cb /Documentation/filesystems
parent7cf6a8a17f5b134b7e783c2d45c53298faef82a7 (diff)
parent048ae41bb0806cde340f4e5d5030398037ab0be8 (diff)
downloadlinux-0350785b0a092c99c5ddd2ace0260dbe7b3f919f.tar.xz
Merge tag 'integrity-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
Pull IMA updates from Mimi Zohar: "New is IMA support for including fs-verity file digests and signatures in the IMA measurement list as well as verifying the fs-verity file digest based signatures, both based on policy. In addition, are two bug fixes: - avoid reading UEFI variables, which cause a page fault, on Apple Macs with T2 chips. - remove the original "ima" template Kconfig option to address a boot command line ordering issue. The rest is a mixture of code/documentation cleanup" * tag 'integrity-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: integrity: Fix sparse warnings in keyring_handler evm: Clean up some variables evm: Return INTEGRITY_PASS for enum integrity_status value '0' efi: Do not import certificates from UEFI Secure Boot for T2 Macs fsverity: update the documentation ima: support fs-verity file digest based version 3 signatures ima: permit fsverity's file digests in the IMA measurement list ima: define a new template field named 'd-ngv2' and templates fs-verity: define a function to return the integrity protected file digest ima: use IMA default hash algorithm for integrity violations ima: fix 'd-ng' comments and documentation ima: remove the IMA_TEMPLATE Kconfig option ima: remove redundant initialization of pointer 'file'.
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/fsverity.rst35
1 files changed, 23 insertions, 12 deletions
diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 8cc536d08f51..b7d42fd65e9d 100644
--- a/Documentation/filesystems/fsverity.rst
+++ b/Documentation/filesystems/fsverity.rst
@@ -70,12 +70,23 @@ must live on a read-write filesystem because they are independently
updated and potentially user-installed, so dm-verity cannot be used.
The base fs-verity feature is a hashing mechanism only; actually
-authenticating the files is up to userspace. However, to meet some
-users' needs, fs-verity optionally supports a simple signature
-verification mechanism where users can configure the kernel to require
-that all fs-verity files be signed by a key loaded into a keyring; see
-`Built-in signature verification`_. Support for fs-verity file hashes
-in IMA (Integrity Measurement Architecture) policies is also planned.
+authenticating the files may be done by:
+
+* Userspace-only
+
+* Builtin signature verification + userspace policy
+
+ fs-verity optionally supports a simple signature verification
+ mechanism where users can configure the kernel to require that
+ all fs-verity files be signed by a key loaded into a keyring;
+ see `Built-in signature verification`_.
+
+* Integrity Measurement Architecture (IMA)
+
+ IMA supports including fs-verity file digests and signatures in the
+ IMA measurement list and verifying fs-verity based file signatures
+ stored as security.ima xattrs, based on policy.
+
User API
========
@@ -653,12 +664,12 @@ weren't already directly answered in other parts of this document.
hashed and what to do with those hashes, such as log them,
authenticate them, or add them to a measurement list.
- IMA is planned to support the fs-verity hashing mechanism as an
- alternative to doing full file hashes, for people who want the
- performance and security benefits of the Merkle tree based hash.
- But it doesn't make sense to force all uses of fs-verity to be
- through IMA. As a standalone filesystem feature, fs-verity
- already meets many users' needs, and it's testable like other
+ IMA supports the fs-verity hashing mechanism as an alternative
+ to full file hashes, for those who want the performance and
+ security benefits of the Merkle tree based hash. However, it
+ doesn't make sense to force all uses of fs-verity to be through
+ IMA. fs-verity already meets many users' needs even as a
+ standalone filesystem feature, and it's testable like other
filesystem features e.g. with xfstests.
:Q: Isn't fs-verity useless because the attacker can just modify the