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authorThiago Jung Bauermann <bauerman@linux.ibm.com>2019-07-04 15:57:34 -0300
committerMimi Zohar <zohar@linux.ibm.com>2019-08-05 18:39:56 -0400
commitc8424e776b093280d3fdd104d850706b3b229ac8 (patch)
tree3f14381fe576439fa1fa94736b67d1015c40752d /kernel/module_signature.c
parentb36f281f4a314de4be0a51d6511b794691f8a244 (diff)
downloadlinux-c8424e776b093280d3fdd104d850706b3b229ac8.tar.bz2
MODSIGN: Export module signature definitions
IMA will use the module_signature format for append signatures, so export the relevant definitions and factor out the code which verifies that the appended signature trailer is valid. Also, create a CONFIG_MODULE_SIG_FORMAT option so that IMA can select it and be able to use mod_check_sig() without having to depend on either CONFIG_MODULE_SIG or CONFIG_MODULES. s390 duplicated the definition of struct module_signature so now they can use the new <linux/module_signature.h> header instead. Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Acked-by: Jessica Yu <jeyu@kernel.org> Reviewed-by: Philipp Rudo <prudo@linux.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'kernel/module_signature.c')
-rw-r--r--kernel/module_signature.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/kernel/module_signature.c b/kernel/module_signature.c
new file mode 100644
index 000000000000..4224a1086b7d
--- /dev/null
+++ b/kernel/module_signature.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Module signature checker
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/errno.h>
+#include <linux/printk.h>
+#include <linux/module_signature.h>
+#include <asm/byteorder.h>
+
+/**
+ * mod_check_sig - check that the given signature is sane
+ *
+ * @ms: Signature to check.
+ * @file_len: Size of the file to which @ms is appended.
+ * @name: What is being checked. Used for error messages.
+ */
+int mod_check_sig(const struct module_signature *ms, size_t file_len,
+ const char *name)
+{
+ if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms))
+ return -EBADMSG;
+
+ if (ms->id_type != PKEY_ID_PKCS7) {
+ pr_err("%s: Module is not signed with expected PKCS#7 message\n",
+ 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",
+ name);
+ return -EBADMSG;
+ }
+
+ return 0;
+}