linux-kernel - [PATCH v2 0/3] evm: disable EVM on overlayfs

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Date: Tue, 19 Dec 2023 12:52:03 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: linux-unionfs@...r.kernel.org
Cc: Mimi Zohar <zohar@...ux.ibm.com>, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, Amir Goldstein <amir73il@...il.com>,
        Christian Brauner <brauner@...nel.org>,
        Seth Forshee <sforshee@...nel.org>,
        Roberto Sassu <roberto.sassu@...weicloud.com>
Subject: [PATCH v2 0/3] evm: disable EVM on overlayfs

EVM verifies the existing 'security.evm' value, before allowing it
to be updated.  The EVM HMAC and the original file signatures contain
filesystem specific metadata (e.g. i_ino, i_generation and s_uuid).

This poses a challenge when transitioning from the lower backing file
to the upper backing file.

Until a complete solution is developed, disable EVM on overlayfs.

Changelog v2:
Addressed Amir's comments:
- Simplified security_inode_copy_up_xattr() return.
- Identified filesystems that don't support EVM based on a new SB_I flag.

Mimi Zohar (3):
  evm: don't copy up 'security.evm' xattr
  evm: add support to disable EVM on unsupported filesystems
  overlay: disable EVM

 fs/overlayfs/super.c              |  1 +
 include/linux/evm.h               |  6 +++++
 include/linux/fs.h                |  1 +
 security/integrity/evm/evm_main.c | 42 ++++++++++++++++++++++++++++++-
 security/security.c               |  2 +-
 5 files changed, 50 insertions(+), 2 deletions(-)

-- 
2.39.3