From: Roberto Sassu <roberto.sassu@huawei.com>
To: <zohar@linux.ibm.com>, <jmorris@namei.org>, <paul@paul-moore.com>,
<casey@schaufler-ca.com>
Cc: <linux-integrity@vger.kernel.org>,
<linux-security-module@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <selinux@vger.kernel.org>,
<reiserfs-devel@vger.kernel.org>,
Roberto Sassu <roberto.sassu@huawei.com>
Subject: [PATCH v2 6/6] evm: Support multiple LSMs providing an xattr
Date: Wed, 21 Apr 2021 18:19:25 +0200 [thread overview]
Message-ID: <20210421161925.968825-7-roberto.sassu@huawei.com> (raw)
In-Reply-To: <20210421161925.968825-1-roberto.sassu@huawei.com>
Currently, evm_inode_init_security() processes a single LSM xattr from
the array passed by security_inode_init_security(), and calculates the
HMAC on it and other inode metadata.
Given that initxattrs(), called by security_inode_init_security(), expects
that this array is terminated when the xattr name is set to NULL, this
patch reuses the same assumption for evm_inode_init_security() to scan all
xattrs and to calculate the HMAC on all of them.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/evm/evm.h | 2 ++
security/integrity/evm/evm_crypto.c | 9 ++++++++-
security/integrity/evm/evm_main.c | 15 +++++++++++----
3 files changed, 21 insertions(+), 5 deletions(-)
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index ae590f71ce7d..24eac42b9f32 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -49,6 +49,8 @@ struct evm_digest {
char digest[IMA_MAX_DIGEST_SIZE];
} __packed;
+int evm_protected_xattr(const char *req_xattr_name);
+
int evm_init_key(void);
int __init evm_init_crypto(void);
int evm_update_evmxattr(struct dentry *dentry,
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index b66264b53d5d..35c5eec0517d 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -358,6 +358,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
char *hmac_val)
{
struct shash_desc *desc;
+ const struct xattr *xattr;
desc = init_desc(EVM_XATTR_HMAC, evm_hash_algo);
if (IS_ERR(desc)) {
@@ -365,7 +366,13 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
return PTR_ERR(desc);
}
- crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
+ for (xattr = lsm_xattr; xattr->name != NULL; xattr++) {
+ if (!evm_protected_xattr(xattr->name))
+ continue;
+
+ crypto_shash_update(desc, xattr->value, xattr->value_len);
+ }
+
hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
kfree(desc);
return 0;
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 336a421e2e5a..c43e75cd37f3 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -261,7 +261,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
return evm_status;
}
-static int evm_protected_xattr(const char *req_xattr_name)
+int evm_protected_xattr(const char *req_xattr_name)
{
int namelen;
int found = 0;
@@ -712,14 +712,21 @@ int evm_inode_init_security(struct inode *inode, struct inode *dir,
struct xattr *xattrs, void *fs_data)
{
struct evm_xattr *xattr_data;
+ struct xattr *xattr;
struct xattr *evm_xattr = lsm_find_xattr_slot(xattrs);
- int rc;
+ int rc, evm_protected_xattrs = 0;
if (!xattrs || !xattrs->name)
return 0;
- if (!(evm_initialized & EVM_INIT_HMAC) ||
- !evm_protected_xattr(xattrs->name))
+ if (!(evm_initialized & EVM_INIT_HMAC))
+ return -EOPNOTSUPP;
+
+ for (xattr = xattrs; xattr->name != NULL; xattr++)
+ if (evm_protected_xattr(xattr->name))
+ evm_protected_xattrs++;
+
+ if (!evm_protected_xattrs)
return -EOPNOTSUPP;
xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
--
2.25.1
prev parent reply other threads:[~2021-04-21 16:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 16:19 [PATCH v2 0/6] evm: Prepare for moving to the LSM infrastructure Roberto Sassu
2021-04-21 16:19 ` [PATCH v2 1/6] xattr: Complete constify ->name member of "struct xattr" Roberto Sassu
2021-04-21 16:19 ` [PATCH v2 2/6] reiserfs: Add missing calls to reiserfs_security_free() Roberto Sassu
2021-04-21 16:19 ` [PATCH v2 3/6] security: Pass xattrs allocated by LSMs to the inode_init_security hook Roberto Sassu
2021-04-21 22:43 ` Casey Schaufler
2021-04-22 13:46 ` Roberto Sassu
2021-04-22 15:46 ` Casey Schaufler
2021-04-22 16:12 ` Roberto Sassu
2021-04-22 21:39 ` Casey Schaufler
2021-04-21 16:19 ` [PATCH v2 4/6] security: Support multiple LSMs implementing " Roberto Sassu
2021-04-21 23:09 ` Casey Schaufler
2021-04-21 16:19 ` [PATCH v2 5/6] evm: Align evm_inode_init_security() definition with LSM infrastructure Roberto Sassu
2021-04-21 16:19 ` Roberto Sassu [this message]
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