ecryptfs: Replace memcpy + manual NUL termination with strscpy

Use strscpy() to copy the NUL-terminated '->token.password.signature'
and 'sig' to the destination buffers instead of using memcpy() followed
by manual NUL terminations.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Tyler Hicks <code@tyhicks.com>

Author: toblux

fs/ecryptfs/debug.c

@@ -7,6 +7,7 @@
  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  */
 
+#include <linux/string.h>
 #include "ecryptfs_kernel.h"
 
 /*
@@ -33,9 +34,7 @@ void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok)
 		    ECRYPTFS_PERSISTENT_PASSWORD) {
 			ecryptfs_printk(KERN_DEBUG, " * persistent\n");
 		}
-		memcpy(sig, auth_tok->token.password.signature,
-		       ECRYPTFS_SIG_SIZE_HEX);
-		sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
+		strscpy(sig, auth_tok->token.password.signature);
 		ecryptfs_printk(KERN_DEBUG, " * signature = [%s]\n", sig);
 	}
 	ecryptfs_printk(KERN_DEBUG, " * session_key.flags = [0x%x]\n",

fs/ecryptfs/keystore.c

@@ -2458,8 +2458,7 @@ int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
 	if (!new_key_sig)
 		return -ENOMEM;
 
-	memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
-	new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
+	strscpy(new_key_sig->keysig, sig);
 	/* Caller must hold keysig_list_mutex */
 	list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
 
@@ -2479,9 +2478,8 @@ ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 	if (!new_auth_tok)
 		return -ENOMEM;
 
-	memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
+	strscpy(new_auth_tok->sig, sig);
 	new_auth_tok->flags = global_auth_tok_flags;
-	new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 	list_add(&new_auth_tok->mount_crypt_stat_list,
 		 &mount_crypt_stat->global_auth_tok_list);