[PATCH v5 4/6] module: strip the signature marker in the verification function.
From: Michal Suchanek <hidden>
Date: 2022-01-11 11:38:11
Also in:
kexec, keyrings, linux-crypto, linux-integrity, linux-s390, linuxppc-dev, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), s390 architecture, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
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 <redacted>
---
v3: - Philipp Rudo [off-list ref]: 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 | 11 -----------
arch/s390/kernel/machine_kexec_file.c | 11 -----------
kernel/module.c | 7 +------
kernel/module_signing.c | 12 ++++++++++--
4 files changed, 11 insertions(+), 30 deletions(-)
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 64cd314cce0d..6dec8151ef73 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,
@@ -156,16 +155,6 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, #ifdef CONFIG_KEXEC_SIG int elf64_verify_sig(const char *kernel, unsigned long kernel_len) { - 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 345f2eab6e04..c3deccf1da83 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>
@@ -28,20 +27,10 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { #ifdef CONFIG_KEXEC_SIG int s390_verify_sig(const char *kernel, unsigned long kernel_len) { - 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 30149969f21f..39a6dd7c6dd2 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, unsigned long *len, struct key *trusted_keys, const char *what) { + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; struct module_signature *ms; unsigned long sig_len, modlen = *len; int ret; pr_devel("==>%s(,%lu)\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