[PATCH v2 3/6] kexec_file: Don't opencode appended signature verification.
From: Michal Suchanek <hidden>
Date: 2021-11-25 18:06:01
Also in:
kexec, keyrings, linux-crypto, linux-integrity, linux-s390, linux-security-module, lkml
Subsystem:
asymmetric keys, linux for powerpc (32-bit and 64-bit), s390 architecture, the rest · Maintainers:
David Howells, Lukas Wunner, Ignat Korchagin, Madhavan Srinivasan, Michael Ellerman, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
Module verification already implements appeded signature verification. Reuse it for kexec_file. Signed-off-by: Michal Suchanek <redacted> --- arch/powerpc/kexec/elf_64.c | 21 ++++----------------- arch/s390/kernel/machine_kexec_file.c | 21 ++++----------------- include/linux/verification.h | 3 +++ kernel/module-internal.h | 2 -- kernel/module.c | 4 +++- kernel/module_signing.c | 24 +++++++++++++++--------- 6 files changed, 29 insertions(+), 46 deletions(-)
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 25dc1071feec..266cb26d3ca0 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c@@ -153,12 +153,10 @@ 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) +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; - struct module_signature *ms; - unsigned long sig_len; - int ret; if (marker_len > kernel_len) return -EKEYREJECTED;
@@ -168,19 +166,8 @@ int elf64_verify_sig(const char *kernel, unsigned long kernel_len) return -EKEYREJECTED; kernel_len -= marker_len; - ms = (void *)kernel + kernel_len - sizeof(*ms); - ret = mod_check_sig(ms, kernel_len, "kexec"); - if (ret) - return ret; - - sig_len = be32_to_cpu(ms->sig_len); - kernel_len -= sizeof(*ms) + sig_len; - - return verify_pkcs7_signature(kernel, kernel_len, - kernel + kernel_len, sig_len, - VERIFY_USE_PLATFORM_KEYRING, - VERIFYING_MODULE_SIGNATURE, - NULL, NULL); + return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING, + "kexec_file"); } #endif /* CONFIG_KEXEC_SIG */
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 43a9abe48abd..432797249db3 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c@@ -24,12 +24,10 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { }; #ifdef CONFIG_KEXEC_SIG -int s390_verify_sig(const char *kernel, unsigned long kernel_len) +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; - struct module_signature *ms; - unsigned long sig_len; - int ret; /* Skip signature verification when not secure IPLed. */ if (!ipl_secure_flag)
@@ -43,19 +41,8 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len) return -EKEYREJECTED; kernel_len -= marker_len; - ms = (void *)kernel + kernel_len - sizeof(*ms); - ret = mod_check_sig(ms, kernel_len, "kexec"); - if (ret) - return ret; - - sig_len = be32_to_cpu(ms->sig_len); - kernel_len -= sizeof(*ms) + sig_len; - - return verify_pkcs7_signature(kernel, kernel_len, - kernel + kernel_len, sig_len, - VERIFY_USE_PLATFORM_KEYRING, - VERIFYING_MODULE_SIGNATURE, - NULL, NULL); + return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING, + "kexec_file"); } #endif /* CONFIG_KEXEC_SIG */
diff --git a/include/linux/verification.h b/include/linux/verification.h
index a655923335ae..c1cf0582012a 100644
--- a/include/linux/verification.h
+++ b/include/linux/verification.h@@ -60,5 +60,8 @@ extern int verify_pefile_signature(const void *pebuf, unsigned pelen, enum key_being_used_for usage); #endif +int verify_appended_signature(const void *data, size_t *len, struct key *trusted_keys, + const char *what); + #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ #endif /* _LINUX_VERIFY_PEFILE_H */
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 33783abc377b..80461e14bf29 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h@@ -27,5 +27,3 @@ struct load_info { unsigned int sym, str, mod, vers, info, pcpu; } index; }; - -extern int mod_verify_sig(const void *mod, struct load_info *info);
diff --git a/kernel/module.c b/kernel/module.c
index 84a9141a5e15..8481933dfa92 100644
--- a/kernel/module.c
+++ b/kernel/module.c@@ -57,6 +57,7 @@ #include <linux/bsearch.h> #include <linux/dynamic_debug.h> #include <linux/audit.h> +#include <linux/verification.h> #include <uapi/linux/module.h> #include "module-internal.h"
@@ -2894,7 +2895,8 @@ static int module_sig_check(struct load_info *info, int flags) memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { /* We truncate the module to discard the signature */ info->len -= markerlen; - err = mod_verify_sig(mod, info); + err = verify_appended_signature(mod, &info->len, + VERIFY_USE_SECONDARY_KEYRING, "module"); if (!err) { info->sig_ok = true; return 0;
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 8723ae70ea1f..f492e410564d 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c@@ -14,13 +14,19 @@ #include <crypto/public_key.h> #include "module-internal.h" -/* - * Verify the signature on a module. +/** + * verify_appended_signature - Verify the signature on a module with the + * signature marker stripped. + * @data: The data to be verified + * @len: Size of @data. + * @trusted_keys: Keyring to use for verification + * @what: Informational string for log messages */ -int mod_verify_sig(const void *mod, struct load_info *info) +int verify_appended_signature(const void *data, size_t *len, + struct key *trusted_keys, const char *what) { struct module_signature ms; - size_t sig_len, modlen = info->len; + size_t sig_len, modlen = *len; int ret; pr_devel("==>%s(,%zu)\n", __func__, modlen);
@@ -28,18 +34,18 @@ int mod_verify_sig(const void *mod, struct load_info *info) if (modlen <= sizeof(ms)) return -EBADMSG; - memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); + memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); - ret = mod_check_sig(&ms, modlen, "module"); + ret = mod_check_sig(&ms, modlen, what); if (ret) return ret; sig_len = be32_to_cpu(ms.sig_len); modlen -= sig_len + sizeof(ms); - info->len = modlen; + *len = modlen; - return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len, - VERIFY_USE_SECONDARY_KEYRING, + return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, + trusted_keys, VERIFYING_MODULE_SIGNATURE, NULL, NULL); }
--
2.31.1