KEYS: Generalise system_verify_data() to provide access to internal content

Generalise system_verify_data() to provide access to internal content
through a callback.  This allows all the PKCS#7 stuff to be hidden inside
this function and removed from the PE file parser and the PKCS#7 test key.

If external content is not required, NULL should be passed as data to the
function.  If the callback is not required, that can be set to NULL.

The function is now called verify_pkcs7_signature() to contrast with
verify_pefile_signature() and the definitions of both have been moved into
linux/verification.h along with the key_being_used_for enum.

Signed-off-by: David Howells <dhowells@redhat.com>

15 files changed, 155 insertions, 173 deletions

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 2af478e3fd4e..f2356bda2b05 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -19,8 +19,7 @@
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/efi.h>
-#include <linux/verify_pefile.h>
-#include <keys/system_keyring.h>
+#include <linux/verification.h>
 
 #include <asm/bootparam.h>
 #include <asm/setup.h>
@@ -529,18 +528,9 @@ static int bzImage64_cleanup(void *loader_data)
 #ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
 static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
 {
-        bool trusted;
-        int ret;
-
-        ret = verify_pefile_signature(kernel, kernel_len,
-                                      system_trusted_keyring,
-                                      VERIFYING_KEXEC_PE_SIGNATURE,
-                                      &trusted);
-        if (ret < 0)
-                return ret;
-        if (!trusted)
-                return -EKEYREJECTED;
-        return 0;
+        return verify_pefile_signature(kernel, kernel_len,
+                                       NULL,
+                                       VERIFYING_KEXEC_PE_SIGNATURE);
 }
 #endif
 
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index f4180326c2e1..a83bffedc0aa 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -108,16 +108,25 @@ late_initcall(load_system_certificate_list);
 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
 
 /**
- * Verify a PKCS#7-based signature on system data.
- * @data: The data to be verified.
+ * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
+ * @data: The data to be verified (NULL if expecting internal data).
  * @len: Size of @data.
  * @raw_pkcs7: The PKCS#7 message that is the signature.
  * @pkcs7_len: The size of @raw_pkcs7.
+ * @trusted_keys: Trusted keys to use (NULL for system_trusted_keyring).
  * @usage: The use to which the key is being put.
+ * @view_content: Callback to gain access to content.
+ * @ctx: Context for callback.
  */
-int system_verify_data(const void *data, unsigned long len,
-                       const void *raw_pkcs7, size_t pkcs7_len,
-                       enum key_being_used_for usage)
+int verify_pkcs7_signature(const void *data, size_t len,
+                           const void *raw_pkcs7, size_t pkcs7_len,
+                           struct key *trusted_keys,
+                           int untrusted_error,
+                           enum key_being_used_for usage,
+                           int (*view_content)(void *ctx,
+                                               const void *data, size_t len,
+                                               size_t asn1hdrlen),
+                           void *ctx)
 {
         struct pkcs7_message *pkcs7;
         bool trusted;
@@ -128,7 +137,7 @@ int system_verify_data(const void *data, unsigned long len,
                 return PTR_ERR(pkcs7);
 
         /* The data should be detached - so we need to supply it. */
-        if (pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
+        if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
                 pr_err("PKCS#7 signature with non-detached data\n");
                 ret = -EBADMSG;
                 goto error;
@@ -138,13 +147,29 @@ int system_verify_data(const void *data, unsigned long len,
         if (ret < 0)
                 goto error;
 
-        ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
+        if (!trusted_keys)
+                trusted_keys = system_trusted_keyring;
+        ret = pkcs7_validate_trust(pkcs7, trusted_keys, &trusted);
         if (ret < 0)
                 goto error;
 
-        if (!trusted) {
+        if (!trusted && untrusted_error) {
                 pr_err("PKCS#7 signature not signed with a trusted key\n");
-                ret = -ENOKEY;
+                ret = untrusted_error;
+                goto error;
+        }
+
+        if (view_content) {
+                size_t asn1hdrlen;
+
+                ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
+                if (ret < 0) {
+                        if (ret == -ENODATA)
+                                pr_devel("PKCS#7 message does not contain data\n");
+                        goto error;
+                }
+
+                ret = view_content(ctx, data, len, asn1hdrlen);
         }
 
 error:
@@ -152,6 +177,6 @@ error:
         pr_devel("<==%s() = %d\n", __func__, ret);
         return ret;
 }
-EXPORT_SYMBOL_GPL(system_verify_data);
+EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
 
 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 91a7e047a765..f7d2ef9789d8 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -40,8 +40,7 @@ config PKCS7_MESSAGE_PARSER
 
 config PKCS7_TEST_KEY
         tristate "PKCS#7 testing key type"
-        depends on PKCS7_MESSAGE_PARSER
-        select SYSTEM_TRUSTED_KEYRING
+        depends on SYSTEM_DATA_VERIFICATION
         help
           This option provides a type of key that can be loaded up from a
           PKCS#7 message - provided the message is signed by a trusted key.  If
@@ -54,6 +53,7 @@ config PKCS7_TEST_KEY
 config SIGNED_PE_FILE_VERIFICATION
         bool "Support for PE file signature verification"
         depends on PKCS7_MESSAGE_PARSER=y
+        depends on SYSTEM_DATA_VERIFICATION
         select ASN1
         select OID_REGISTRY
         help
diff --git a/crypto/asymmetric_keys/mscode_parser.c b/crypto/asymmetric_keys/mscode_parser.c
index 3242cbfaeaa2..6a76d5c70ef6 100644
--- a/crypto/asymmetric_keys/mscode_parser.c
+++ b/crypto/asymmetric_keys/mscode_parser.c
@@ -21,19 +21,13 @@
 /*
  * Parse a Microsoft Individual Code Signing blob
  */
-int mscode_parse(struct pefile_context *ctx)
+int mscode_parse(void *_ctx, const void *content_data, size_t data_len,
+                 size_t asn1hdrlen)
 {
-        const void *content_data;
-        size_t data_len;
-        int ret;
-
-        ret = pkcs7_get_content_data(ctx->pkcs7, &content_data, &data_len, 1);
-
-        if (ret) {
-                pr_debug("PKCS#7 message does not contain data\n");
-                return ret;
-        }
+        struct pefile_context *ctx = _ctx;
 
+        content_data -= asn1hdrlen;
+        data_len += asn1hdrlen;
         pr_devel("Data: %zu [%*ph]\n", data_len, (unsigned)(data_len),
                  content_data);
 
@@ -129,7 +123,6 @@ int mscode_note_digest(void *context, size_t hdrlen,
 {
         struct pefile_context *ctx = context;
 
-        ctx->digest = value;
-        ctx->digest_len = vlen;
-        return 0;
+        ctx->digest = kmemdup(value, vlen, GFP_KERNEL);
+        return ctx->digest ? 0 : -ENOMEM;
 }
diff --git a/crypto/asymmetric_keys/pkcs7_key_type.c b/crypto/asymmetric_keys/pkcs7_key_type.c
index e2d0edbbc71a..ab9bf5363ecd 100644
--- a/crypto/asymmetric_keys/pkcs7_key_type.c
+++ b/crypto/asymmetric_keys/pkcs7_key_type.c
@@ -13,12 +13,9 @@
 #include <linux/key.h>
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/verification.h>
 #include <linux/key-type.h>
-#include <keys/asymmetric-type.h>
-#include <crypto/pkcs7.h>
 #include <keys/user-type.h>
-#include <keys/system_keyring.h>
-#include "pkcs7_parser.h"
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("PKCS#7 testing key type");
@@ -29,60 +26,47 @@ MODULE_PARM_DESC(pkcs7_usage,
                  "Usage to specify when verifying the PKCS#7 message");
 
 /*
- * Preparse a PKCS#7 wrapped and validated data blob.
+ * Retrieve the PKCS#7 message content.
  */
-static int pkcs7_preparse(struct key_preparsed_payload *prep)
+static int pkcs7_view_content(void *ctx, const void *data, size_t len,
+                              size_t asn1hdrlen)
 {
-        enum key_being_used_for usage = pkcs7_usage;
-        struct pkcs7_message *pkcs7;
-        const void *data, *saved_prep_data;
-        size_t datalen, saved_prep_datalen;
-        bool trusted;
+        struct key_preparsed_payload *prep = ctx;
+        const void *saved_prep_data;
+        size_t saved_prep_datalen;
         int ret;
 
-        kenter("");
-
-        if (usage >= NR__KEY_BEING_USED_FOR) {
-                pr_err("Invalid usage type %d\n", usage);
-                return -EINVAL;
-        }
-
         saved_prep_data = prep->data;
         saved_prep_datalen = prep->datalen;
-        pkcs7 = pkcs7_parse_message(saved_prep_data, saved_prep_datalen);
-        if (IS_ERR(pkcs7)) {
-                ret = PTR_ERR(pkcs7);
-                goto error;
-        }
-
-        ret = pkcs7_verify(pkcs7, usage);
-        if (ret < 0)
-                goto error_free;
-
-        ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
-        if (ret < 0)
-                goto error_free;
-        if (!trusted)
-                pr_warn("PKCS#7 message doesn't chain back to a trusted key\n");
-
-        ret = pkcs7_get_content_data(pkcs7, &data, &datalen, false);
-        if (ret < 0)
-                goto error_free;
-
         prep->data = data;
-        prep->datalen = datalen;
+        prep->datalen = len;
+
         ret = user_preparse(prep);
+
         prep->data = saved_prep_data;
         prep->datalen = saved_prep_datalen;
-
-error_free:
-        pkcs7_free_message(pkcs7);
-error:
-        kleave(" = %d", ret);
         return ret;
 }
 
 /*
+ * Preparse a PKCS#7 wrapped and validated data blob.
+ */
+static int pkcs7_preparse(struct key_preparsed_payload *prep)
+{
+        enum key_being_used_for usage = pkcs7_usage;
+
+        if (usage >= NR__KEY_BEING_USED_FOR) {
+                pr_err("Invalid usage type %d\n", usage);
+                return -EINVAL;
+        }
+
+        return verify_pkcs7_signature(NULL, 0,
+                                      prep->data, prep->datalen,
+                                      NULL, -ENOKEY, usage,
+                                      pkcs7_view_content, prep);
+}
+
+/*
  * user defined keys take an arbitrary string as the description and an
  * arbitrary blob of data as the payload
  */
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 835701613125..af4cd8649117 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -168,24 +168,25 @@ EXPORT_SYMBOL_GPL(pkcs7_parse_message);
  * @pkcs7: The preparsed PKCS#7 message to access
  * @_data: Place to return a pointer to the data
  * @_data_len: Place to return the data length
- * @want_wrapper: True if the ASN.1 object header should be included in the data
+ * @_headerlen: Size of ASN.1 header not included in _data
  *
- * Get access to the data content of the PKCS#7 message, including, optionally,
- * the header of the ASN.1 object that contains it.  Returns -ENODATA if the
- * data object was missing from the message.
+ * Get access to the data content of the PKCS#7 message.  The size of the
+ * header of the ASN.1 object that contains it is also provided and can be used
+ * to adjust *_data and *_data_len to get the entire object.
+ *
+ * Returns -ENODATA if the data object was missing from the message.
  */
 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
                            const void **_data, size_t *_data_len,
-                           bool want_wrapper)
+                           size_t *_headerlen)
 {
-        size_t wrapper;
-
         if (!pkcs7->data)
                 return -ENODATA;
 
-        wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
-        *_data = pkcs7->data - wrapper;
-        *_data_len = pkcs7->data_len + wrapper;
+        *_data = pkcs7->data;
+        *_data_len = pkcs7->data_len;
+        if (_headerlen)
+                *_headerlen = pkcs7->data_hdrlen;
         return 0;
 }
 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 7e8c2338ae25..265351075b0e 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -16,7 +16,7 @@
 #include <linux/err.h>
 #include <linux/pe.h>
 #include <linux/asn1.h>
-#include <crypto/pkcs7.h>
+#include <linux/verification.h>
 #include <crypto/hash.h>
 #include "verify_pefile.h"
 
@@ -392,9 +392,8 @@ error_no_desc:
  * verify_pefile_signature - Verify the signature on a PE binary image
  * @pebuf: Buffer containing the PE binary image
  * @pelen: Length of the binary image
- * @trust_keyring: Signing certificates to use as starting points
+ * @trust_keys: Signing certificate(s) to use as starting points
  * @usage: The use to which the key is being put.
- * @_trusted: Set to true if trustworth, false otherwise
  *
  * Validate that the certificate chain inside the PKCS#7 message inside the PE
  * binary image intersects keys we already know and trust.
@@ -418,14 +417,10 @@ error_no_desc:
  * May also return -ENOMEM.
  */
 int verify_pefile_signature(const void *pebuf, unsigned pelen,
-                            struct key *trusted_keyring,
-                            enum key_being_used_for usage,
-                            bool *_trusted)
+                            struct key *trusted_keys,
+                            enum key_being_used_for usage)
 {
-        struct pkcs7_message *pkcs7;
         struct pefile_context ctx;
-        const void *data;
-        size_t datalen;
         int ret;
 
         kenter("");
@@ -439,19 +434,10 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
         if (ret < 0)
                 return ret;
 
-        pkcs7 = pkcs7_parse_message(pebuf + ctx.sig_offset, ctx.sig_len);
-        if (IS_ERR(pkcs7))
-                return PTR_ERR(pkcs7);
-        ctx.pkcs7 = pkcs7;
-
-        ret = pkcs7_get_content_data(ctx.pkcs7, &data, &datalen, false);
-        if (ret < 0 || datalen == 0) {
-                pr_devel("PKCS#7 message does not contain data\n");
-                ret = -EBADMSG;
-                goto error;
-        }
-
-        ret = mscode_parse(&ctx);
+        ret = verify_pkcs7_signature(NULL, 0,
+                                     pebuf + ctx.sig_offset, ctx.sig_len,
+                                     trusted_keys, -EKEYREJECTED, usage,
+                                     mscode_parse, &ctx);
         if (ret < 0)
                 goto error;
 
@@ -462,16 +448,8 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
          * contents.
          */
         ret = pefile_digest_pe(pebuf, pelen, &ctx);
-        if (ret < 0)
-                goto error;
-
-        ret = pkcs7_verify(pkcs7, usage);
-        if (ret < 0)
-                goto error;
-
-        ret = pkcs7_validate_trust(pkcs7, trusted_keyring, _trusted);
 
 error:
-        pkcs7_free_message(ctx.pkcs7);
+        kfree(ctx.digest);
         return ret;
 }
diff --git a/crypto/asymmetric_keys/verify_pefile.h b/crypto/asymmetric_keys/verify_pefile.h
index a133eb81a492..cd4d20930728 100644
--- a/crypto/asymmetric_keys/verify_pefile.h
+++ b/crypto/asymmetric_keys/verify_pefile.h
@@ -9,7 +9,6 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
-#include <linux/verify_pefile.h>
 #include <crypto/pkcs7.h>
 #include <crypto/hash_info.h>
 
@@ -23,7 +22,6 @@ struct pefile_context {
         unsigned        sig_offset;
         unsigned        sig_len;
         const struct section_header *secs;
-        struct pkcs7_message *pkcs7;
 
         /* PKCS#7 MS Individual Code Signing content */
         const void      *digest;                /* Digest */
@@ -39,4 +37,5 @@ struct pefile_context {
 /*
  * mscode_parser.c
  */
-extern int mscode_parse(struct pefile_context *ctx);
+extern int mscode_parse(void *_ctx, const void *content_data, size_t data_len,
+                        size_t asn1hdrlen);
diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
index 441aff9b5aa7..8323e3e57131 100644
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h
@@ -12,6 +12,7 @@
 #ifndef _CRYPTO_PKCS7_H
 #define _CRYPTO_PKCS7_H
 
+#include <linux/verification.h>
 #include <crypto/public_key.h>
 
 struct key;
@@ -26,7 +27,7 @@ extern void pkcs7_free_message(struct pkcs7_message *pkcs7);
 
 extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
                                   const void **_data, size_t *_datalen,
-                                  bool want_wrapper);
+                                  size_t *_headerlen);
 
 /*
  * pkcs7_trust.c
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 2f5de5c1a3a0..b3928e801b8c 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -15,20 +15,6 @@
 #define _LINUX_PUBLIC_KEY_H
 
 /*
- * The use to which an asymmetric key is being put.
- */
-enum key_being_used_for {
-        VERIFYING_MODULE_SIGNATURE,
-        VERIFYING_FIRMWARE_SIGNATURE,
-        VERIFYING_KEXEC_PE_SIGNATURE,
-        VERIFYING_KEY_SIGNATURE,
-        VERIFYING_KEY_SELF_SIGNATURE,
-        VERIFYING_UNSPECIFIED_SIGNATURE,
-        NR__KEY_BEING_USED_FOR
-};
-extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR];
-
-/*
  * Cryptographic data for the public-key subtype of the asymmetric key type.
  *
  * Note that this may include private part of the key as well as the public
diff --git a/include/keys/asymmetric-type.h b/include/keys/asymmetric-type.h
index 70a8775bb444..d1e23dda4363 100644
--- a/include/keys/asymmetric-type.h
+++ b/include/keys/asymmetric-type.h
@@ -15,6 +15,7 @@
 #define _KEYS_ASYMMETRIC_TYPE_H
 
 #include <linux/key-type.h>
+#include <linux/verification.h>
 
 extern struct key_type key_type_asymmetric;
 
diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
index 39fd38cfa8c9..b2d645ac35a0 100644
--- a/include/keys/system_keyring.h
+++ b/include/keys/system_keyring.h
@@ -15,6 +15,7 @@
 #ifdef CONFIG_SYSTEM_TRUSTED_KEYRING
 
 #include <linux/key.h>
+#include <linux/verification.h>
 #include <crypto/public_key.h>
 
 extern struct key *system_trusted_keyring;
@@ -29,12 +30,6 @@ static inline struct key *get_system_trusted_keyring(void)
 }
 #endif
 
-#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
-extern int system_verify_data(const void *data, unsigned long len,
-                              const void *raw_pkcs7, size_t pkcs7_len,
-                              enum key_being_used_for usage);
-#endif
-
 #ifdef CONFIG_IMA_MOK_KEYRING
 extern struct key *ima_mok_keyring;
 extern struct key *ima_blacklist_keyring;
diff --git a/include/linux/verification.h b/include/linux/verification.h
new file mode 100644
index 000000000000..bb0fcf941cb7
--- /dev/null
+++ b/include/linux/verification.h
@@ -0,0 +1,50 @@
+/* Signature verification
+ *
+ * Copyright (C) 2014 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.
+ */
+
+#ifndef _LINUX_VERIFICATION_H
+#define _LINUX_VERIFICATION_H
+
+/*
+ * The use to which an asymmetric key is being put.
+ */
+enum key_being_used_for {
+        VERIFYING_MODULE_SIGNATURE,
+        VERIFYING_FIRMWARE_SIGNATURE,
+        VERIFYING_KEXEC_PE_SIGNATURE,
+        VERIFYING_KEY_SIGNATURE,
+        VERIFYING_KEY_SELF_SIGNATURE,
+        VERIFYING_UNSPECIFIED_SIGNATURE,
+        NR__KEY_BEING_USED_FOR
+};
+extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR];
+
+#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
+
+struct key;
+
+extern int verify_pkcs7_signature(const void *data, size_t len,
+                                  const void *raw_pkcs7, size_t pkcs7_len,
+                                  struct key *trusted_keys,
+                                  int untrusted_error,
+                                  enum key_being_used_for usage,
+                                  int (*view_content)(void *ctx,
+                                                      const void *data, size_t len,
+                                                      size_t asn1hdrlen),
+                                  void *ctx);
+
+#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
+extern int verify_pefile_signature(const void *pebuf, unsigned pelen,
+                                   struct key *trusted_keys,
+                                   enum key_being_used_for usage);
+#endif
+
+#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
+#endif /* _LINUX_VERIFY_PEFILE_H */
diff --git a/include/linux/verify_pefile.h b/include/linux/verify_pefile.h
deleted file mode 100644
index da2049b5161c..000000000000
--- a/include/linux/verify_pefile.h
+++ /dev/null
@@ -1,22 +0,0 @@
-/* Signed PE file verification
- *
- * Copyright (C) 2014 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.
- */
-
-#ifndef _LINUX_VERIFY_PEFILE_H
-#define _LINUX_VERIFY_PEFILE_H
-
-#include <crypto/public_key.h>
-
-extern int verify_pefile_signature(const void *pebuf, unsigned pelen,
-                                   struct key *trusted_keyring,
-                                   enum key_being_used_for usage,
-                                   bool *_trusted);
-
-#endif /* _LINUX_VERIFY_PEFILE_H */
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 64b9dead4a07..593aace88a02 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -80,6 +80,7 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen)
                 return -EBADMSG;
         }
 
-        return system_verify_data(mod, modlen, mod + modlen, sig_len,
-                                  VERIFYING_MODULE_SIGNATURE);
+        return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len,
+                                      NULL, -ENOKEY, VERIFYING_MODULE_SIGNATURE,
+                                      NULL, NULL);
 }