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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
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')
-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/module.c1
-rw-r--r--kernel/module_signature.c46
-rw-r--r--kernel/module_signing.c56
4 files changed, 56 insertions, 48 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index a8d923b5481b..179b44ab8b46 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -58,6 +58,7 @@ endif
obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_MODULE_SIG) += module_signing.o
+obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_CRASH_CORE) += crash_core.o
diff --git a/kernel/module.c b/kernel/module.c
index 5933395af9a0..5ac22efc3685 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -7,6 +7,7 @@
#include <linux/export.h>
#include <linux/extable.h>
#include <linux/moduleloader.h>
+#include <linux/module_signature.h>
#include <linux/trace_events.h>
#include <linux/init.h>
#include <linux/kallsyms.h>
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;
+}
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index b10fb1986ca9..9d9fc678c91d 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -7,37 +7,13 @@
#include <linux/kernel.h>
#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/module_signature.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.
*/
@@ -45,6 +21,7 @@ int mod_verify_sig(const void *mod, struct load_info *info)
{
struct module_signature ms;
size_t sig_len, modlen = info->len;
+ int ret;
pr_devel("==>%s(,%zu)\n", __func__, modlen);
@@ -52,32 +29,15 @@ int mod_verify_sig(const void *mod, struct load_info *info)
return -EBADMSG;
memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
- modlen -= sizeof(ms);
+
+ ret = mod_check_sig(&ms, modlen, info->name);
+ if (ret)
+ return ret;
sig_len = be32_to_cpu(ms.sig_len);
- if (sig_len >= modlen)
- return -EBADMSG;
- modlen -= sig_len;
+ modlen -= sig_len + sizeof(ms);
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,
VERIFY_USE_SECONDARY_KEYRING,
VERIFYING_MODULE_SIGNATURE,