linux-kernel - [PATCH v8 08/14] ima: Introduce is

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Message-Id: <20181116200712.14154-9-bauerman@linux.ibm.com>
Date:   Fri, 16 Nov 2018 18:07:06 -0200
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        David Howells <dhowells@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Jessica Yu <jeyu@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Jonathan Corbet <corbet@....net>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Subject: [PATCH v8 08/14] ima: Introduce is_signed()

With the introduction of another IMA signature type (modsig), some places
will need to check for both of them. It is cleaner to do that if there's a
helper function to tell whether an xattr_value represents an IMA
signature.

Suggested-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
---
 security/integrity/ima/ima.h              | 5 +++++
 security/integrity/ima/ima_appraise.c     | 7 +++----
 security/integrity/ima/ima_template_lib.c | 2 +-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index cc12f3449a72..e4f72b30cb28 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -154,6 +154,11 @@ unsigned long ima_get_binary_runtime_size(void);
 int ima_init_template(void);
 void ima_init_template_list(void);
 
+static inline bool is_signed(const struct evm_ima_xattr_data *xattr_value)
+{
+	return xattr_value && xattr_value->type == EVM_IMA_XATTR_DIGSIG;
+}
+
 /*
  * used to protect h_table and sha_table
  */
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 8bcef90939f8..c6459408e6b2 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -325,15 +325,14 @@ int ima_appraise_measurement(enum ima_hooks func,
 	} else if (status != INTEGRITY_PASS) {
 		/* Fix mode, but don't replace file signatures. */
 		if ((ima_appraise & IMA_APPRAISE_FIX) &&
-		    (!xattr_value ||
-		     xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
+		    !is_signed(xattr_value)) {
 			if (!ima_fix_xattr(dentry, iint))
 				status = INTEGRITY_PASS;
 		}
 
 		/* Permit new files with file signatures, but without data. */
 		if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE &&
-		    xattr_value && xattr_value->type == EVM_IMA_XATTR_DIGSIG) {
+		    is_signed(xattr_value)) {
 			status = INTEGRITY_PASS;
 		}
 
@@ -448,7 +447,7 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 		if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
 			return -EINVAL;
 		ima_reset_appraise_flags(d_backing_inode(dentry),
-			xvalue->type == EVM_IMA_XATTR_DIGSIG);
+					 is_signed(xvalue));
 		result = 0;
 	}
 	return result;
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 43752002c222..300912914b17 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -382,7 +382,7 @@ int ima_eventsig_init(struct ima_event_data *event_data,
 {
 	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
 
-	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
+	if (!is_signed(xattr_value))
 		return 0;
 
 	return ima_write_template_field_data(xattr_value, event_data->xattr_len,