Messages in this thread Patch in this message | | | Date | Mon, 1 Jul 2019 16:47:53 +0200 | From | Jessica Yu <> | Subject | Re: [PATCH v12 01/11] MODSIGN: Export module signature definitions |
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+++ Thiago Jung Bauermann [27/06/19 23:19 -0300]: >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. > >Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> >Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> >Cc: Jessica Yu <jeyu@kernel.org> >--- > include/linux/module.h | 3 -- > include/linux/module_signature.h | 44 +++++++++++++++++++++++++ > init/Kconfig | 6 +++- > kernel/Makefile | 1 + > kernel/module.c | 1 + > kernel/module_signature.c | 46 ++++++++++++++++++++++++++ > kernel/module_signing.c | 56 +++++--------------------------- > scripts/Makefile | 2 +- > 8 files changed, 106 insertions(+), 53 deletions(-) > >diff --git a/include/linux/module.h b/include/linux/module.h >index 188998d3dca9..aa56f531cf1e 100644 >--- a/include/linux/module.h >+++ b/include/linux/module.h >@@ -25,9 +25,6 @@ > #include <linux/percpu.h> > #include <asm/module.h> > >-/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ >-#define MODULE_SIG_STRING "~Module signature appended~\n" >-
Hi Thiago, apologies for the delay.
It looks like arch/s390/kernel/machine_kexec_file.c also relies on MODULE_SIG_STRING being defined, so module_signature.h will need to be included there too, otherwise we'll run into a compilation error.
Other than that, the module-related changes look good to me:
Acked-by: Jessica Yu <jeyu@kernel.org>
Thanks!
Jessica
> /* Not Yet Implemented */ > #define MODULE_SUPPORTED_DEVICE(name) > >diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h >new file mode 100644 >index 000000000000..523617fc5b6a >--- /dev/null >+++ b/include/linux/module_signature.h >@@ -0,0 +1,44 @@ >+/* SPDX-License-Identifier: GPL-2.0+ */ >+/* >+ * Module signature handling. >+ * >+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. >+ * Written by David Howells (dhowells@redhat.com) >+ */ >+ >+#ifndef _LINUX_MODULE_SIGNATURE_H >+#define _LINUX_MODULE_SIGNATURE_H >+ >+/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ >+#define MODULE_SIG_STRING "~Module signature appended~\n" >+ >+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 */ >+}; >+ >+int mod_check_sig(const struct module_signature *ms, size_t file_len, >+ const char *name); >+ >+#endif /* _LINUX_MODULE_SIGNATURE_H */ >diff --git a/init/Kconfig b/init/Kconfig >index 8b9ffe236e4f..c2286a3c74c5 100644 >--- a/init/Kconfig >+++ b/init/Kconfig >@@ -1852,6 +1852,10 @@ config BASE_SMALL > default 0 if BASE_FULL > default 1 if !BASE_FULL > >+config MODULE_SIG_FORMAT >+ def_bool n >+ select SYSTEM_DATA_VERIFICATION >+ > menuconfig MODULES > bool "Enable loadable module support" > option modules >@@ -1929,7 +1933,7 @@ config MODULE_SRCVERSION_ALL > config MODULE_SIG > bool "Module signature verification" > depends on MODULES >- select SYSTEM_DATA_VERIFICATION >+ select MODULE_SIG_FORMAT > help > Check modules for valid signatures upon load: the signature > is simply appended to the module. For more information see >diff --git a/kernel/Makefile b/kernel/Makefile >index 33824f0385b3..f29ae2997a43 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 6e6712b3aaf5..2712f4d217f5 100644 >--- a/kernel/module.c >+++ b/kernel/module.c >@@ -19,6 +19,7 @@ > #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 6b9a926fd86b..cdd04a6b8074 100644 >--- a/kernel/module_signing.c >+++ b/kernel/module_signing.c >@@ -11,37 +11,13 @@ > > #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. > */ >@@ -49,6 +25,7 @@ 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); > >@@ -56,32 +33,15 @@ 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, >diff --git a/scripts/Makefile b/scripts/Makefile >index 9d442ee050bd..52098b080ab7 100644 >--- a/scripts/Makefile >+++ b/scripts/Makefile >@@ -17,7 +17,7 @@ hostprogs-$(CONFIG_VT) += conmakehash > hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount > hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable > hostprogs-$(CONFIG_ASN1) += asn1_compiler >-hostprogs-$(CONFIG_MODULE_SIG) += sign-file >+hostprogs-$(CONFIG_MODULE_SIG_FORMAT) += sign-file > hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert > hostprogs-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert >
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