Hello Jessica, AFAIK Mimi is happy with this patch set, but I still need acks from maintainers of other subsystems that my changes touch before she can accept it. Is this patch OK from your PoV? -- Thiago Jung Bauermann IBM Linux Technology Center Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx> writes: > 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@xxxxxxxxxxxxx> > Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> > Cc: Jessica Yu <jeyu@xxxxxxxxxx> > --- > 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" > - > /* 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@xxxxxxxxxx) > + */ > + > +#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@xxxxxxxxxx) > + */ > + > +#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 >