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Message-Id: <8ac1ed7dc050477c70c6fa4038ea84e56ec47815.1641555875.git.msuchanek@suse.de>
Date: Fri, 7 Jan 2022 12:53:48 +0100
From: Michal Suchanek <msuchanek@...e.de>
To: keyrings@...r.kernel.org, linux-crypto@...r.kernel.org,
linux-integrity@...r.kernel.org
Cc: Michal Suchanek <msuchanek@...e.de>, kexec@...ts.infradead.org,
Philipp Rudo <prudo@...hat.com>,
Mimi Zohar <zohar@...ux.ibm.com>,
Nayna <nayna@...ux.vnet.ibm.com>, Rob Herring <robh@...nel.org>,
linux-s390@...r.kernel.org, Vasily Gorbik <gor@...ux.ibm.com>,
Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Jessica Yu <jeyu@...nel.org>, linux-kernel@...r.kernel.org,
David Howells <dhowells@...hat.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Paul Mackerras <paulus@...ba.org>,
Hari Bathini <hbathini@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
linuxppc-dev@...ts.ozlabs.org,
Frank van der Linden <fllinden@...zon.com>,
Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
Daniel Axtens <dja@...ens.net>, buendgen@...ibm.com,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Baoquan He <bhe@...hat.com>,
linux-security-module@...r.kernel.org
Subject: [PATCH v3 4/6] module: strip the signature marker in the verification function.
It is stripped by each caller separately.
Note: this changes the error for kexec_file from EKEYREJECTED to ENODATA
when the signature marker is missing.
Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
v3: - Philipp Rudo <prudo@...hat.com>: Update the commit with note about
change of raturn value
- the module_signature.h is now no longer needed for kexec_file
---
arch/powerpc/kexec/elf_64.c | 10 ----------
arch/s390/kernel/machine_kexec_file.c | 10 ----------
kernel/module.c | 7 +------
kernel/module_signing.c | 12 ++++++++++--
4 files changed, 11 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 9442666ca69d..e8dff6b23ac5 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -24,7 +24,6 @@
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/verification.h>
-#include <linux/module_signature.h>
static void *elf64_load(struct kimage *image, char *kernel_buf,
unsigned long kernel_len, char *initrd,
@@ -157,15 +156,6 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
int elf64_verify_sig(const char *kernel, unsigned long length)
{
size_t kernel_len = length;
- const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1;
-
- if (marker_len > kernel_len)
- return -EKEYREJECTED;
-
- if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING,
- marker_len))
- return -EKEYREJECTED;
- kernel_len -= marker_len;
return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING,
"kexec_file");
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 75e0c17cf0eb..3e3bc7bcae86 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -12,7 +12,6 @@
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/kexec.h>
-#include <linux/module_signature.h>
#include <linux/verification.h>
#include <linux/vmalloc.h>
#include <asm/boot_data.h>
@@ -29,20 +28,11 @@ const struct kexec_file_ops * const kexec_file_loaders[] = {
int s390_verify_sig(const char *kernel, unsigned long length)
{
size_t kernel_len = length;
- const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1;
/* Skip signature verification when not secure IPLed. */
if (!ipl_secure_flag)
return 0;
- if (marker_len > kernel_len)
- return -EKEYREJECTED;
-
- if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING,
- marker_len))
- return -EKEYREJECTED;
- kernel_len -= marker_len;
-
return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING,
"kexec_file");
}
diff --git a/kernel/module.c b/kernel/module.c
index 8481933dfa92..d91ca0f93a40 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2882,7 +2882,6 @@ static inline void kmemleak_load_module(const struct module *mod,
static int module_sig_check(struct load_info *info, int flags)
{
int err = -ENODATA;
- const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
const char *reason;
const void *mod = info->hdr;
@@ -2890,11 +2889,7 @@ static int module_sig_check(struct load_info *info, int flags)
* Require flags == 0, as a module with version information
* removed is no longer the module that was signed
*/
- if (flags == 0 &&
- info->len > markerlen &&
- memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
- /* We truncate the module to discard the signature */
- info->len -= markerlen;
+ if (flags == 0) {
err = verify_appended_signature(mod, &info->len,
VERIFY_USE_SECONDARY_KEYRING, "module");
if (!err) {
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index f492e410564d..4c28cb55275f 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -15,8 +15,7 @@
#include "module-internal.h"
/**
- * verify_appended_signature - Verify the signature on a module with the
- * signature marker stripped.
+ * verify_appended_signature - Verify the signature on a module
* @data: The data to be verified
* @len: Size of @data.
* @trusted_keys: Keyring to use for verification
@@ -25,12 +24,21 @@
int verify_appended_signature(const void *data, size_t *len,
struct key *trusted_keys, const char *what)
{
+ const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
struct module_signature ms;
size_t sig_len, modlen = *len;
int ret;
pr_devel("==>%s(,%zu)\n", __func__, modlen);
+ if (markerlen > modlen)
+ return -ENODATA;
+
+ if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING,
+ markerlen))
+ return -ENODATA;
+ modlen -= markerlen;
+
if (modlen <= sizeof(ms))
return -EBADMSG;
--
2.31.1
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