lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths

The vfs_getxattr_alloc() function currently returns a ssize_t value
despite the fact that it only uses int values internally for return
values.  Fix this by converting vfs_getxattr_alloc() to return an
int type and adjust the callers as necessary.  As part of these
caller modifications, some of the callers are fixed to properly free
the xattr value buffer on both success and failure to ensure that
memory is not leaked in the failure case.

Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

6 files changed, 23 insertions, 17 deletions

diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 708de9656bbd..fa5ff13fa8c9 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -335,14 +335,15 @@ static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
 				(char **)&xattr_data, 0, GFP_NOFS);
 	if (rc <= 0) {
 		if (rc == -ENODATA)
-			return 0;
-		return rc;
+			rc = 0;
+		goto out;
 	}
 	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
 		rc = 1;
 	else
 		rc = 0;
 
+out:
 	kfree(xattr_data);
 	return rc;
 }
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 23d484e05e6f..bce72e80fd12 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -519,14 +519,17 @@ static int evm_xattr_change(struct user_namespace *mnt_userns,
 
 	rc = vfs_getxattr_alloc(&init_user_ns, dentry, xattr_name, &xattr_data,
 				0, GFP_NOFS);
-	if (rc < 0)
-		return 1;
+	if (rc < 0) {
+		rc = 1;
+		goto out;
+	}
 
 	if (rc == xattr_value_len)
 		rc = !!memcmp(xattr_value, xattr_data, rc);
 	else
 		rc = 1;
 
+out:
 	kfree(xattr_data);
 	return rc;
 }
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index be965a8715e4..03b440921e61 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -326,7 +326,7 @@ enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
 enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
 				 int xattr_len);
 int ima_read_xattr(struct dentry *dentry,
-		   struct evm_ima_xattr_data **xattr_value);
+		   struct evm_ima_xattr_data **xattr_value, int xattr_len);
 
 #else
 static inline int ima_check_blacklist(struct integrity_iint_cache *iint,
@@ -372,7 +372,8 @@ ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len)
 }
 
 static inline int ima_read_xattr(struct dentry *dentry,
-				 struct evm_ima_xattr_data **xattr_value)
+				 struct evm_ima_xattr_data **xattr_value,
+				 int xattr_len)
 {
 	return 0;
 }
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 3e0fbbd99534..88ffb15ca0e2 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -221,12 +221,12 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
 }
 
 int ima_read_xattr(struct dentry *dentry,
-		   struct evm_ima_xattr_data **xattr_value)
+		   struct evm_ima_xattr_data **xattr_value, int xattr_len)
 {
-	ssize_t ret;
+	int ret;
 
 	ret = vfs_getxattr_alloc(&init_user_ns, dentry, XATTR_NAME_IMA,
-				 (char **)xattr_value, 0, GFP_NOFS);
+				 (char **)xattr_value, xattr_len, GFP_NOFS);
 	if (ret == -EOPNOTSUPP)
 		ret = 0;
 	return ret;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 040b03ddc1c7..0226899947d6 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -293,7 +293,8 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	/* HASH sets the digital signature and update flags, nothing else */
 	if ((action & IMA_HASH) &&
 	    !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
-		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
+		xattr_len = ima_read_xattr(file_dentry(file),
+					   &xattr_value, xattr_len);
 		if ((xattr_value && xattr_len > 2) &&
 		    (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
 			set_bit(IMA_DIGSIG, &iint->atomic_flags);
@@ -316,7 +317,8 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	if ((action & IMA_APPRAISE_SUBMASK) ||
 	    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 		/* read 'security.ima' */
-		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
+		xattr_len = ima_read_xattr(file_dentry(file),
+					   &xattr_value, xattr_len);
 
 		/*
 		 * Read the appended modsig if allowed by the policy, and allow
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 7bf9b1507220..4564faae7d67 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -601,16 +601,15 @@ int ima_eventevmsig_init(struct ima_event_data *event_data,
 	rc = vfs_getxattr_alloc(&init_user_ns, file_dentry(event_data->file),
 				XATTR_NAME_EVM, (char **)&xattr_data, 0,
 				GFP_NOFS);
-	if (rc <= 0)
-		return 0;
-
-	if (xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG) {
-		kfree(xattr_data);
-		return 0;
+	if (rc <= 0 || xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG) {
+		rc = 0;
+		goto out;
 	}
 
 	rc = ima_write_template_field_data((char *)xattr_data, rc, DATA_FMT_HEX,
 					   field_data);
+
+out:
 	kfree(xattr_data);
 	return rc;
 }