From: Stefan Berger <stefanb@linux.ibm.com>
To: linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-unionfs@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, paul@paul-moore.com,
jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com,
roberto.sassu@huawei.com, amir73il@gmail.com, miklos@szeredi.hu,
Stefan Berger <stefanb@linux.ibm.com>
Subject: [PATCH 5/5] evm: Enforce signatures on unsupported filesystem for EVM_INIT_X509
Date: Tue, 30 Jan 2024 16:46:20 -0500 [thread overview]
Message-ID: <20240130214620.3155380-6-stefanb@linux.ibm.com> (raw)
In-Reply-To: <20240130214620.3155380-1-stefanb@linux.ibm.com>
Unsupported filesystems currently do not enforce any signatures. Add
support for signature enforcement of the "original" and "portable &
immutable" signatures when EVM_INIT_X509 is enabled.
The "original" signature type contains filesystem specific metadata.
Thus it cannot be copied up and verified. However with EVM_INIT_X509
and EVM_ALLOW_METADATA_WRITES enabled, the "original" file signature
may be written.
When EVM_ALLOW_METADATA_WRITES is not set or once it is removed from
/sys/kernel/security/evm by setting EVM_INIT_HMAC for example, it is not
possible to write or remove xattrs on the overlay filesystem.
This change still prevents EVM from writing HMAC signatures on
unsupported filesystem when EVM_INIT_HMAC is enabled.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
security/integrity/evm/evm_main.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index e96d127b48a2..f49609dfcbc7 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -192,7 +192,11 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
return iint->evm_status;
- if (is_unsupported_fs(dentry))
+ /*
+ * On unsupported filesystems with EVM_INIT_X509 not enabled, skip
+ * signature verification.
+ */
+ if (!(evm_initialized & EVM_INIT_X509) && is_unsupported_fs(dentry))
return INTEGRITY_UNKNOWN;
/* if status is not PASS, try to check again - against -ENOMEM */
@@ -262,7 +266,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
evm_status = INTEGRITY_PASS_IMMUTABLE;
} else if (!IS_RDONLY(inode) &&
!(inode->i_sb->s_readonly_remount) &&
- !IS_IMMUTABLE(inode)) {
+ !IS_IMMUTABLE(inode) &&
+ !is_unsupported_fs(dentry)) {
evm_update_evmxattr(dentry, xattr_name,
xattr_value,
xattr_value_len);
@@ -422,9 +427,6 @@ enum integrity_status evm_verifyxattr(struct dentry *dentry,
if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
return INTEGRITY_UNKNOWN;
- if (is_unsupported_fs(dentry))
- return INTEGRITY_UNKNOWN;
-
if (!iint) {
iint = integrity_iint_find(d_backing_inode(dentry));
if (!iint)
--
2.43.0
next prev parent reply other threads:[~2024-01-30 21:46 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 21:46 [PATCH 0/5] evm: Support signatures on stacked filesystem Stefan Berger
2024-01-30 21:46 ` [PATCH 1/5] security: allow finer granularity in permitting copy-up of security xattrs Stefan Berger
2024-01-31 13:25 ` Amir Goldstein
2024-01-31 14:25 ` Christian Brauner
2024-01-31 14:56 ` Stefan Berger
2024-02-01 13:35 ` Christian Brauner
2024-02-01 14:18 ` Amir Goldstein
2024-02-02 11:58 ` Christian Brauner
2024-02-01 15:41 ` Stefan Berger
2024-01-31 16:47 ` kernel test robot
2024-01-31 19:06 ` kernel test robot
2024-01-30 21:46 ` [PATCH 2/5] evm: Implement per signature type decision in security_inode_copy_up_xattr Stefan Berger
2024-01-31 13:28 ` Amir Goldstein
2024-01-30 21:46 ` [PATCH 3/5] ima: Reset EVM status upon detecting changes to overlay backing file Stefan Berger
2024-01-31 13:56 ` Amir Goldstein
2024-01-31 14:46 ` Stefan Berger
2024-01-30 21:46 ` [PATCH 4/5] evm: Use the real inode's metadata to calculate metadata hash Stefan Berger
2024-01-31 2:10 ` Stefan Berger
2024-01-31 13:16 ` Amir Goldstein
2024-01-31 14:40 ` Stefan Berger
2024-01-31 15:54 ` Amir Goldstein
2024-01-31 17:23 ` Amir Goldstein
2024-01-31 17:46 ` Stefan Berger
2024-02-01 12:10 ` Amir Goldstein
2024-02-01 13:36 ` Stefan Berger
2024-02-01 14:11 ` Amir Goldstein
2024-02-01 20:35 ` Stefan Berger
2024-02-02 9:24 ` Amir Goldstein
2024-02-02 14:59 ` Stefan Berger
2024-02-02 15:51 ` Amir Goldstein
2024-02-02 16:06 ` Stefan Berger
2024-02-02 16:17 ` Amir Goldstein
2024-02-02 16:30 ` Stefan Berger
2024-01-31 17:25 ` Stefan Berger
2024-01-30 21:46 ` Stefan Berger [this message]
2024-01-31 14:06 ` [PATCH 5/5] evm: Enforce signatures on unsupported filesystem for EVM_INIT_X509 Amir Goldstein
2024-02-01 17:53 ` Mimi Zohar
2024-01-31 13:18 ` [PATCH 0/5] evm: Support signatures on stacked filesystem Amir Goldstein
2024-01-31 14:52 ` Stefan Berger
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