/* Module signature checker * * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/verification.h> #include <crypto/public_key.h> #include "module-internal.h" enum pkey_id_type { PKEY_ID_PGP, /* OpenPGP generated key ID */ PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ }; /* * Module signature information block. * * The constituents of the signature section are, in order: * * - Signer's name * - Key identifier * - Signature data * - Information block */ struct module_signature { u8 algo; /* Public-key crypto algorithm [0] */ u8 hash; /* Digest algorithm [0] */ u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ u8 signer_len; /* Length of signer's name [0] */ u8 key_id_len; /* Length of key identifier [0] */ u8 __pad[3]; __be32 sig_len; /* Length of signature data */ }; /* * Verify the signature on a module. */ int mod_verify_sig(const void *mod, struct load_info *info) { struct module_signature ms; size_t sig_len, modlen = info->len; pr_devel("==>%s(,%zu)\n", __func__, modlen); if (modlen <= sizeof(ms)) return -EBADMSG; memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); modlen -= sizeof(ms); sig_len = be32_to_cpu(ms.sig_len); if (sig_len >= modlen) return -EBADMSG; modlen -= sig_len; info->len = modlen; if (ms.id_type != PKEY_ID_PKCS7) { pr_err("%s: Module is not signed with expected PKCS#7 message\n", info->name); return -ENOPKG; } if (ms.algo != 0 || ms.hash != 0 || ms.signer_len != 0 || ms.key_id_len != 0 || ms.__pad[0] != 0 || ms.__pad[1] != 0 || ms.__pad[2] != 0) { pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", info->name); return -EBADMSG; } return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len, NULL, VERIFYING_MODULE_SIGNATURE, NULL, NULL); }