1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Module signature checker 4 * 5 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. 6 * Written by David Howells (dhowells@redhat.com) 7 */ 8 9 #include <linux/errno.h> 10 #include <linux/printk.h> 11 #include <linux/module_signature.h> 12 #include <asm/byteorder.h> 13 14 /** 15 * mod_check_sig - check that the given signature is sane 16 * 17 * @ms: Signature to check. 18 * @file_len: Size of the file to which @ms is appended. 19 * @name: What is being checked. Used for error messages. 20 */ 21 int mod_check_sig(const struct module_signature *ms, size_t file_len, 22 const char *name) 23 { 24 if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms)) 25 return -EBADMSG; 26 27 if (ms->id_type != PKEY_ID_PKCS7) { 28 pr_err("%s: not signed with expected PKCS#7 message\n", 29 name); 30 return -ENOPKG; 31 } 32 33 if (ms->algo != 0 || 34 ms->hash != 0 || 35 ms->signer_len != 0 || 36 ms->key_id_len != 0 || 37 ms->__pad[0] != 0 || 38 ms->__pad[1] != 0 || 39 ms->__pad[2] != 0) { 40 pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", 41 name); 42 return -EBADMSG; 43 } 44 45 return 0; 46 } 47