On Fri, Jan 25, 2019 at 5:39 AM Yauheni Kaliuta
<yauheni.kaliuta@xxxxxxxxxx> wrote:
>
> The patch adds data fetching from the PKCS#7 certificate using
> openssl library (which is used by scripts/sign-file.c in the linux
> kernel to sign modules).
>
> In general the certificate can contain many signatures, but since
> kmod (modinfo) supports only one signature at the moment, only first
> one is taken.
>
> With the current sign-file.c certificate doesn't contain signer
> key's fingerprint, so "serial number" is used for the key id.
>
> Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@xxxxxxxxxx>
> ---
> Makefile.am | 4 +-
> configure.ac | 11 ++
> libkmod/libkmod-internal.h | 3 +
> libkmod/libkmod-module.c | 3 +
> libkmod/libkmod-signature.c | 197 +++++++++++++++++++++++++++++++++++-
> 5 files changed, 213 insertions(+), 5 deletions(-)
>
> diff --git a/Makefile.am b/Makefile.am
> index 1ab1db585316..de1026f8bd46 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -35,6 +35,8 @@ SED_PROCESS = \
> -e 's,@liblzma_LIBS\@,${liblzma_LIBS},g' \
> -e 's,@zlib_CFLAGS\@,${zlib_CFLAGS},g' \
> -e 's,@zlib_LIBS\@,${zlib_LIBS},g' \
> + -e 's,@openssl_CFLAGS\@,${openssl_CFLAGS},g' \
> + -e 's,@openssl_LIBS\@,${openssl_LIBS},g' \
> < $< > $@ || rm $@
>
> %.pc: %.pc.in Makefile
> @@ -87,7 +89,7 @@ libkmod_libkmod_la_DEPENDENCIES = \
> ${top_srcdir}/libkmod/libkmod.sym
> libkmod_libkmod_la_LIBADD = \
> shared/libshared.la \
> - ${liblzma_LIBS} ${zlib_LIBS}
> + ${liblzma_LIBS} ${zlib_LIBS} ${openssl_LIBS}
>
> noinst_LTLIBRARIES += libkmod/libkmod-internal.la
> libkmod_libkmod_internal_la_SOURCES = $(libkmod_libkmod_la_SOURCES)
> diff --git a/configure.ac b/configure.ac
> index fbc7391b2d1b..2e33380a0cc2 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -106,6 +106,17 @@ AS_IF([test "x$with_zlib" != "xno"], [
> ])
> CC_FEATURE_APPEND([with_features], [with_zlib], [ZLIB])
>
> +AC_ARG_WITH([openssl],
> + AS_HELP_STRING([--with-openssl], [handle PKCS7 signatures @<:@default=disabled@:>@]),
> + [], [with_openssl=no])
> +AS_IF([test "x$with_openssl" != "xno"], [
> + PKG_CHECK_MODULES([openssl], [openssl])
> + AC_DEFINE([ENABLE_OPENSSL], [1], [Enable openssl for modinfo.])
> +], [
> + AC_MSG_NOTICE([openssl support not requested])
> +])
> +CC_FEATURE_APPEND([with_features], [with_openssl], [OPENSSL])
> +
> AC_ARG_WITH([bashcompletiondir],
> AS_HELP_STRING([--with-bashcompletiondir=DIR], [Bash completions directory]),
> [],
> diff --git a/libkmod/libkmod-internal.h b/libkmod/libkmod-internal.h
> index 346579c71aab..a65ddd156f18 100644
> --- a/libkmod/libkmod-internal.h
> +++ b/libkmod/libkmod-internal.h
> @@ -188,5 +188,8 @@ struct kmod_signature_info {
> const char *algo, *hash_algo, *id_type;
> const char *sig;
> size_t sig_len;
> + void (*free)(void *);
> + void *private;
> };
> bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signature_info *sig_info) _must_check_ __attribute__((nonnull(1, 2)));
> +void kmod_module_signature_info_free(struct kmod_signature_info *sig_info) __attribute__((nonnull));
> diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
> index 889f26479a98..bffe715cdef4 100644
> --- a/libkmod/libkmod-module.c
> +++ b/libkmod/libkmod-module.c
> @@ -2357,6 +2357,9 @@ KMOD_EXPORT int kmod_module_get_info(const struct kmod_module *mod, struct kmod_
> ret = count;
>
> list_error:
> + /* aux structures freed in normal case also */
> + kmod_module_signature_info_free(&sig_info);
> +
> if (ret < 0) {
> kmod_module_info_free_list(*list);
> *list = NULL;
> diff --git a/libkmod/libkmod-signature.c b/libkmod/libkmod-signature.c
> index 429ffbd8a957..48d0145a7552 100644
> --- a/libkmod/libkmod-signature.c
> +++ b/libkmod/libkmod-signature.c
> @@ -19,6 +19,10 @@
>
> #include <endian.h>
> #include <inttypes.h>
> +#ifdef ENABLE_OPENSSL
> +#include <openssl/cms.h>
> +#include <openssl/ssl.h>
> +#endif
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> @@ -115,15 +119,194 @@ static bool fill_default(const char *mem, off_t size,
> return true;
> }
>
> -static bool fill_unknown(const char *mem, off_t size,
> - const struct module_signature *modsig, size_t sig_len,
> - struct kmod_signature_info *sig_info)
> +#ifdef ENABLE_OPENSSL
> +
> +struct pkcs7_private {
> + CMS_ContentInfo *cms;
> + unsigned char *key_id;
> + BIGNUM *sno;
> +};
> +
> +static void pkcs7_free(void *s)
> +{
> + struct kmod_signature_info *si = s;
> + struct pkcs7_private *pvt = si->private;
> +
> + CMS_ContentInfo_free(pvt->cms);
> + BN_free(pvt->sno);
> + free(pvt->key_id);
> + free(pvt);
> + si->private = NULL;
> +}
> +
> +static int obj_to_hash_algo(const ASN1_OBJECT *o)
> +{
> + int nid;
> +
> + nid = OBJ_obj2nid(o);
> + switch (nid) {
> + case NID_md4:
> + return PKEY_HASH_MD4;
> + case NID_md5:
> + return PKEY_HASH_MD5;
> + case NID_sha1:
> + return PKEY_HASH_SHA1;
> + case NID_ripemd160:
> + return PKEY_HASH_RIPE_MD_160;
> + case NID_sha256:
> + return PKEY_HASH_SHA256;
> + case NID_sha384:
> + return PKEY_HASH_SHA384;
> + case NID_sha512:
> + return PKEY_HASH_SHA512;
> + case NID_sha224:
> + return PKEY_HASH_SHA224;
> + default:
> + return -1;
> + }
> + return -1;
> +}
> +
> +static const char *x509_name_to_str(X509_NAME *name)
> +{
> + int i;
> + X509_NAME_ENTRY *e;
> + ASN1_STRING *d;
> + ASN1_OBJECT *o;
> + int nid = -1;
> + const char *str;
> +
> + for (i = 0; i < X509_NAME_entry_count(name); i++) {
> + e = X509_NAME_get_entry(name, i);
> + o = X509_NAME_ENTRY_get_object(e);
> + nid = OBJ_obj2nid(o);
> + if (nid == NID_commonName)
> + break;
> + }
> + if (nid == -1)
> + return NULL;
> +
> + d = X509_NAME_ENTRY_get_data(e);
> + str = (const char *)ASN1_STRING_get0_data(d);
> +
> + return str;
> +}
> +
> +static bool fill_pkcs7(const char *mem, off_t size,
> + const struct module_signature *modsig, size_t sig_len,
> + struct kmod_signature_info *sig_info)
> +{
> + const char *pkcs7_raw;
> + CMS_ContentInfo *cms;
> + STACK_OF(CMS_SignerInfo) *sis;
> + CMS_SignerInfo *si;
> + int rc;
> + ASN1_OCTET_STRING *key_id;
> + X509_NAME *issuer;
> + ASN1_INTEGER *sno;
> + ASN1_OCTET_STRING *sig;
> + BIGNUM *sno_bn;
> + X509_ALGOR *dig_alg;
> + X509_ALGOR *sig_alg;
> + const ASN1_OBJECT *o;
> + BIO *in;
> + int len;
> + unsigned char *key_id_str;
> + struct pkcs7_private *pvt;
> + const char *issuer_str;
> +
> + size -= sig_len;
> + pkcs7_raw = mem + size;
> +
> + in = BIO_new_mem_buf(pkcs7_raw, sig_len);
> +
> + cms = d2i_CMS_bio(in, NULL);
> + if (cms == NULL) {
> + BIO_free(in);
_cleanup_() on `in` would make this neater. Same for all variables in
err, err2, err3, etc.
Just remember to set it to NULL on !error-path.
> + return false;
> + }
> +
> + BIO_free(in);
> +
> + sis = CMS_get0_SignerInfos(cms);
> + if (sis == NULL)
> + goto err;
> +
> + si = sk_CMS_SignerInfo_value(sis, 0);
> + if (si == NULL)
> + goto err;
> +
> + rc = CMS_SignerInfo_get0_signer_id(si, &key_id, &issuer, &sno);
> + if (rc == 0)
> + goto err;
> +
> + sig = CMS_SignerInfo_get0_signature(si);
> + if (sig == NULL)
> + goto err;
> +
> + CMS_SignerInfo_get0_algs(si, NULL, NULL, &dig_alg, &sig_alg);
> +
> + sig_info->sig = (const char *)ASN1_STRING_get0_data(sig);
> + sig_info->sig_len = ASN1_STRING_length(sig);
> +
> + sno_bn = ASN1_INTEGER_to_BN(sno, NULL);
> + if (sno_bn == NULL)
> + goto err;
> +
> + len = BN_num_bytes(sno_bn);
> + key_id_str = malloc(len);
> + if (key_id_str == NULL)
> + goto err2;
> + BN_bn2bin(sno_bn, key_id_str);
> +
> + sig_info->key_id = (const char *)key_id_str;
> + sig_info->key_id_len = len;
> +
> + issuer_str = x509_name_to_str(issuer);
> + if (issuer_str != NULL) {
> + sig_info->signer = issuer_str;
> + sig_info->signer_len = strlen(issuer_str);
> + }
> +
> + X509_ALGOR_get0(&o, NULL, NULL, dig_alg);
> +
> + sig_info->hash_algo = pkey_hash_algo[obj_to_hash_algo(o)];
> + sig_info->id_type = pkey_id_type[modsig->id_type];
> +
> + pvt = malloc(sizeof(*pvt));
> + if (pvt == NULL)
> + goto err3;
> +
> + pvt->cms = cms;
> + pvt->key_id = key_id_str;
> + pvt->sno = sno_bn;
> + sig_info->private = pvt;
why do you keep pvt around if the only thing you will do with it later
is to free it?
AFAICS the only thing that needs to remain around is the str so we can
free it after
the user used it (because normal signature is backed in memory by the
mem object,
while these are openssl structs)
I miss a simple module in the testsuite to make sure this is working.
thanks
Lucas De Marchi
> +
> + sig_info->free = pkcs7_free;
> +
> + return true;
> +err3:
> + free(key_id_str);
> +err2:
> + BN_free(sno_bn);
> +err:
> + CMS_ContentInfo_free(cms);
> + return false;
> +}
> +
> +#else /* ENABLE OPENSSL */
> +
> +static bool fill_pkcs7(const char *mem, off_t size,
> + const struct module_signature *modsig, size_t sig_len,
> + struct kmod_signature_info *sig_info)
> {
> sig_info->hash_algo = "unknown";
> sig_info->id_type = pkey_id_type[modsig->id_type];
> return true;
> }
>
> +#endif /* ENABLE OPENSSL */
> +
> #define SIG_MAGIC "~Module signature appended~\n"
>
> /*
> @@ -167,8 +350,14 @@ bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signat
>
> switch (modsig->id_type) {
> case PKEY_ID_PKCS7:
> - return fill_unknown(mem, size, modsig, sig_len, sig_info);
> + return fill_pkcs7(mem, size, modsig, sig_len, sig_info);
> default:
> return fill_default(mem, size, modsig, sig_len, sig_info);
> }
> }
> +
> +void kmod_module_signature_info_free(struct kmod_signature_info *sig_info)
> +{
> + if (sig_info->free)
> + sig_info->free(sig_info);
> +}
> --
> 2.20.1
>
--
Lucas De Marchi
