8 files changed, 832 insertions, 0 deletions

diff --git a/crypto/asymmetric_keys/.gitignore b/crypto/asymmetric_keys/.gitignore
new file mode 100644
index 000000000000..ee328374dba8
--- /dev/null
+++ b/crypto/asymmetric_keys/.gitignore
@@ -0,0 +1 @@
+*-asn1.[ch]
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 561759d6a65f..6d2c2ea12559 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -25,4 +25,14 @@ config PUBLIC_KEY_ALGO_RSA
         help
           This option enables support for the RSA algorithm (PKCS#1, RFC3447).
 
+config X509_CERTIFICATE_PARSER
+        tristate "X.509 certificate parser"
+        depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+        select ASN1
+        select OID_REGISTRY
+        help
+          This option procides support for parsing X.509 format blobs for key
+          data and provides the ability to instantiate a crypto key from a
+          public key packet found inside the certificate.
+
 endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 7c92691a45eb..0727204aab68 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -8,3 +8,20 @@ asymmetric_keys-y := asymmetric_type.o signature.o
 
 obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
 obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
+
+#
+# X.509 Certificate handling
+#
+obj-$(CONFIG_X509_CERTIFICATE_PARSER) += x509_key_parser.o
+x509_key_parser-y := \
+        x509-asn1.o \
+        x509_rsakey-asn1.o \
+        x509_cert_parser.o \
+        x509_public_key.o
+
+$(obj)/x509_cert_parser.o: $(obj)/x509-asn1.h $(obj)/x509_rsakey-asn1.h
+$(obj)/x509-asn1.o: $(obj)/x509-asn1.c $(obj)/x509-asn1.h
+$(obj)/x509_rsakey-asn1.o: $(obj)/x509_rsakey-asn1.c $(obj)/x509_rsakey-asn1.h
+
+clean-files     += x509-asn1.c x509-asn1.h
+clean-files     += x509_rsakey-asn1.c x509_rsakey-asn1.h
diff --git a/crypto/asymmetric_keys/x509.asn1 b/crypto/asymmetric_keys/x509.asn1
new file mode 100644
index 000000000000..bf32b3dff088
--- /dev/null
+++ b/crypto/asymmetric_keys/x509.asn1
@@ -0,0 +1,60 @@
+Certificate ::= SEQUENCE {
+        tbsCertificate          TBSCertificate ({ x509_note_tbs_certificate }),
+        signatureAlgorithm      AlgorithmIdentifier,
+        signature               BIT STRING ({ x509_note_signature })
+        }
+
+TBSCertificate ::= SEQUENCE {
+        version           [ 0 ] Version DEFAULT,
+        serialNumber            CertificateSerialNumber,
+        signature               AlgorithmIdentifier ({ x509_note_pkey_algo }),
+        issuer                  Name ({ x509_note_issuer }),
+        validity                Validity,
+        subject                 Name ({ x509_note_subject }),
+        subjectPublicKeyInfo    SubjectPublicKeyInfo,
+        issuerUniqueID    [ 1 ] IMPLICIT UniqueIdentifier OPTIONAL,
+        subjectUniqueID   [ 2 ] IMPLICIT UniqueIdentifier OPTIONAL,
+        extensions        [ 3 ] Extensions OPTIONAL
+        }
+
+Version ::= INTEGER
+CertificateSerialNumber ::= INTEGER
+
+AlgorithmIdentifier ::= SEQUENCE {
+        algorithm               OBJECT IDENTIFIER ({ x509_note_OID }),
+        parameters              ANY OPTIONAL
+}
+
+Name ::= SEQUENCE OF RelativeDistinguishedName
+
+RelativeDistinguishedName ::= SET OF AttributeValueAssertion
+
+AttributeValueAssertion ::= SEQUENCE {
+        attributeType           OBJECT IDENTIFIER ({ x509_note_OID }),
+        attributeValue          ANY ({ x509_extract_name_segment })
+        }
+
+Validity ::= SEQUENCE {
+        notBefore               Time ({ x509_note_not_before }),
+        notAfter                Time ({ x509_note_not_after })
+        }
+
+Time ::= CHOICE {
+        utcTime                 UTCTime,
+        generalTime             GeneralizedTime
+        }
+
+SubjectPublicKeyInfo ::= SEQUENCE {
+        algorithm               AlgorithmIdentifier,
+        subjectPublicKey        BIT STRING ({ x509_extract_key_data })
+        }
+
+UniqueIdentifier ::= BIT STRING
+
+Extensions ::= SEQUENCE OF Extension
+
+Extension ::= SEQUENCE {
+        extnid                  OBJECT IDENTIFIER ({ x509_note_OID }),
+        critical                BOOLEAN DEFAULT,
+        extnValue               OCTET STRING ({ x509_process_extension })
+        }
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
new file mode 100644
index 000000000000..8fcac9493b7a
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -0,0 +1,497 @@
+/* X.509 certificate parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "X.509: "fmt
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/oid_registry.h>
+#include "public_key.h"
+#include "x509_parser.h"
+#include "x509-asn1.h"
+#include "x509_rsakey-asn1.h"
+
+struct x509_parse_context {
+        struct x509_certificate *cert;          /* Certificate being constructed */
+        unsigned long   data;                   /* Start of data */
+        const void      *cert_start;            /* Start of cert content */
+        const void      *key;                   /* Key data */
+        size_t          key_size;               /* Size of key data */
+        enum OID        last_oid;               /* Last OID encountered */
+        enum OID        algo_oid;               /* Algorithm OID */
+        unsigned char   nr_mpi;                 /* Number of MPIs stored */
+        u8              o_size;                 /* Size of organizationName (O) */
+        u8              cn_size;                /* Size of commonName (CN) */
+        u8              email_size;             /* Size of emailAddress */
+        u16             o_offset;               /* Offset of organizationName (O) */
+        u16             cn_offset;              /* Offset of commonName (CN) */
+        u16             email_offset;           /* Offset of emailAddress */
+};
+
+/*
+ * Free an X.509 certificate
+ */
+void x509_free_certificate(struct x509_certificate *cert)
+{
+        if (cert) {
+                public_key_destroy(cert->pub);
+                kfree(cert->issuer);
+                kfree(cert->subject);
+                kfree(cert->fingerprint);
+                kfree(cert->authority);
+                kfree(cert);
+        }
+}
+
+/*
+ * Parse an X.509 certificate
+ */
+struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
+{
+        struct x509_certificate *cert;
+        struct x509_parse_context *ctx;
+        long ret;
+
+        ret = -ENOMEM;
+        cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
+        if (!cert)
+                goto error_no_cert;
+        cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
+        if (!cert->pub)
+                goto error_no_ctx;
+        ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
+        if (!ctx)
+                goto error_no_ctx;
+
+        ctx->cert = cert;
+        ctx->data = (unsigned long)data;
+
+        /* Attempt to decode the certificate */
+        ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
+        if (ret < 0)
+                goto error_decode;
+
+        /* Decode the public key */
+        ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
+                               ctx->key, ctx->key_size);
+        if (ret < 0)
+                goto error_decode;
+
+        kfree(ctx);
+        return cert;
+
+error_decode:
+        kfree(ctx);
+error_no_ctx:
+        x509_free_certificate(cert);
+error_no_cert:
+        return ERR_PTR(ret);
+}
+
+/*
+ * Note an OID when we find one for later processing when we know how
+ * to interpret it.
+ */
+int x509_note_OID(void *context, size_t hdrlen,
+             unsigned char tag,
+             const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        ctx->last_oid = look_up_OID(value, vlen);
+        if (ctx->last_oid == OID__NR) {
+                char buffer[50];
+                sprint_oid(value, vlen, buffer, sizeof(buffer));
+                pr_debug("Unknown OID: [%zu] %s\n",
+                         (unsigned long)value - ctx->data, buffer);
+        }
+        return 0;
+}
+
+/*
+ * Save the position of the TBS data so that we can check the signature over it
+ * later.
+ */
+int x509_note_tbs_certificate(void *context, size_t hdrlen,
+                              unsigned char tag,
+                              const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
+                 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
+
+        ctx->cert->tbs = value - hdrlen;
+        ctx->cert->tbs_size = vlen + hdrlen;
+        return 0;
+}
+
+/*
+ * Record the public key algorithm
+ */
+int x509_note_pkey_algo(void *context, size_t hdrlen,
+                        unsigned char tag,
+                        const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        pr_debug("PubKey Algo: %u\n", ctx->last_oid);
+
+        switch (ctx->last_oid) {
+        case OID_md2WithRSAEncryption:
+        case OID_md3WithRSAEncryption:
+        default:
+                return -ENOPKG; /* Unsupported combination */
+
+        case OID_md4WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_MD5;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+
+        case OID_sha1WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_SHA1;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+
+        case OID_sha256WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_SHA256;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+
+        case OID_sha384WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_SHA384;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+
+        case OID_sha512WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_SHA512;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+
+        case OID_sha224WithRSAEncryption:
+                ctx->cert->sig_hash_algo = PKEY_HASH_SHA224;
+                ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+                break;
+        }
+
+        ctx->algo_oid = ctx->last_oid;
+        return 0;
+}
+
+/*
+ * Note the whereabouts and type of the signature.
+ */
+int x509_note_signature(void *context, size_t hdrlen,
+                        unsigned char tag,
+                        const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
+
+        if (ctx->last_oid != ctx->algo_oid) {
+                pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
+                        ctx->algo_oid, ctx->last_oid);
+                return -EINVAL;
+        }
+
+        ctx->cert->sig = value;
+        ctx->cert->sig_size = vlen;
+        return 0;
+}
+
+/*
+ * Note some of the name segments from which we'll fabricate a name.
+ */
+int x509_extract_name_segment(void *context, size_t hdrlen,
+                              unsigned char tag,
+                              const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        switch (ctx->last_oid) {
+        case OID_commonName:
+                ctx->cn_size = vlen;
+                ctx->cn_offset = (unsigned long)value - ctx->data;
+                break;
+        case OID_organizationName:
+                ctx->o_size = vlen;
+                ctx->o_offset = (unsigned long)value - ctx->data;
+                break;
+        case OID_email_address:
+                ctx->email_size = vlen;
+                ctx->email_offset = (unsigned long)value - ctx->data;
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
+/*
+ * Fabricate and save the issuer and subject names
+ */
+static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
+                               unsigned char tag,
+                               char **_name, size_t vlen)
+{
+        const void *name, *data = (const void *)ctx->data;
+        size_t namesize;
+        char *buffer;
+
+        if (*_name)
+                return -EINVAL;
+
+        /* Empty name string if no material */
+        if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
+                buffer = kmalloc(1, GFP_KERNEL);
+                if (!buffer)
+                        return -ENOMEM;
+                buffer[0] = 0;
+                goto done;
+        }
+
+        if (ctx->cn_size && ctx->o_size) {
+                /* Consider combining O and CN, but use only the CN if it is
+                 * prefixed by the O, or a significant portion thereof.
+                 */
+                namesize = ctx->cn_size;
+                name = data + ctx->cn_offset;
+                if (ctx->cn_size >= ctx->o_size &&
+                    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
+                           ctx->o_size) == 0)
+                        goto single_component;
+                if (ctx->cn_size >= 7 &&
+                    ctx->o_size >= 7 &&
+                    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
+                        goto single_component;
+
+                buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
+                                 GFP_KERNEL);
+                if (!buffer)
+                        return -ENOMEM;
+
+                memcpy(buffer,
+                       data + ctx->o_offset, ctx->o_size);
+                buffer[ctx->o_size + 0] = ':';
+                buffer[ctx->o_size + 1] = ' ';
+                memcpy(buffer + ctx->o_size + 2,
+                       data + ctx->cn_offset, ctx->cn_size);
+                buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
+                goto done;
+
+        } else if (ctx->cn_size) {
+                namesize = ctx->cn_size;
+                name = data + ctx->cn_offset;
+        } else if (ctx->o_size) {
+                namesize = ctx->o_size;
+                name = data + ctx->o_offset;
+        } else {
+                namesize = ctx->email_size;
+                name = data + ctx->email_offset;
+        }
+
+single_component:
+        buffer = kmalloc(namesize + 1, GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
+        memcpy(buffer, name, namesize);
+        buffer[namesize] = 0;
+
+done:
+        *_name = buffer;
+        ctx->cn_size = 0;
+        ctx->o_size = 0;
+        ctx->email_size = 0;
+        return 0;
+}
+
+int x509_note_issuer(void *context, size_t hdrlen,
+                     unsigned char tag,
+                     const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
+}
+
+int x509_note_subject(void *context, size_t hdrlen,
+                      unsigned char tag,
+                      const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
+}
+
+/*
+ * Extract the data for the public key algorithm
+ */
+int x509_extract_key_data(void *context, size_t hdrlen,
+                          unsigned char tag,
+                          const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+
+        if (ctx->last_oid != OID_rsaEncryption)
+                return -ENOPKG;
+
+        /* There seems to be an extraneous 0 byte on the front of the data */
+        ctx->cert->pkey_algo = PKEY_ALGO_RSA;
+        ctx->key = value + 1;
+        ctx->key_size = vlen - 1;
+        return 0;
+}
+
+/*
+ * Extract a RSA public key value
+ */
+int rsa_extract_mpi(void *context, size_t hdrlen,
+                    unsigned char tag,
+                    const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        MPI mpi;
+
+        if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
+                pr_err("Too many public key MPIs in certificate\n");
+                return -EBADMSG;
+        }
+
+        mpi = mpi_read_raw_data(value, vlen);
+        if (!mpi)
+                return -ENOMEM;
+
+        ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
+        return 0;
+}
+
+/*
+ * Process certificate extensions that are used to qualify the certificate.
+ */
+int x509_process_extension(void *context, size_t hdrlen,
+                           unsigned char tag,
+                           const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        const unsigned char *v = value;
+        char *f;
+        int i;
+
+        pr_debug("Extension: %u\n", ctx->last_oid);
+
+        if (ctx->last_oid == OID_subjectKeyIdentifier) {
+                /* Get hold of the key fingerprint */
+                if (vlen < 3)
+                        return -EBADMSG;
+                if (v[0] != ASN1_OTS || v[1] != vlen - 2)
+                        return -EBADMSG;
+                v += 2;
+                vlen -= 2;
+
+                f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
+                if (!f)
+                        return -ENOMEM;
+                for (i = 0; i < vlen; i++)
+                        sprintf(f + i * 2, "%02x", v[i]);
+                pr_debug("fingerprint %s\n", f);
+                ctx->cert->fingerprint = f;
+                return 0;
+        }
+
+        if (ctx->last_oid == OID_authorityKeyIdentifier) {
+                /* Get hold of the CA key fingerprint */
+                if (vlen < 5)
+                        return -EBADMSG;
+                if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)) ||
+                    v[1] != vlen - 2 ||
+                    v[2] != (ASN1_CONT << 6) ||
+                    v[3] != vlen - 4)
+                        return -EBADMSG;
+                v += 4;
+                vlen -= 4;
+
+                f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
+                if (!f)
+                        return -ENOMEM;
+                for (i = 0; i < vlen; i++)
+                        sprintf(f + i * 2, "%02x", v[i]);
+                pr_debug("authority   %s\n", f);
+                ctx->cert->authority = f;
+                return 0;
+        }
+
+        return 0;
+}
+
+/*
+ * Record a certificate time.
+ */
+static int x509_note_time(time_t *_time,  size_t hdrlen,
+                          unsigned char tag,
+                          const unsigned char *value, size_t vlen)
+{
+        unsigned YY, MM, DD, hh, mm, ss;
+        const unsigned char *p = value;
+
+#define dec2bin(X) ((X) - '0')
+#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
+
+        if (tag == ASN1_UNITIM) {
+                /* UTCTime: YYMMDDHHMMSSZ */
+                if (vlen != 13)
+                        goto unsupported_time;
+                YY = DD2bin(p);
+                if (YY > 50)
+                        YY += 1900;
+                else
+                        YY += 2000;
+        } else if (tag == ASN1_GENTIM) {
+                /* GenTime: YYYYMMDDHHMMSSZ */
+                if (vlen != 15)
+                        goto unsupported_time;
+                YY = DD2bin(p) * 100 + DD2bin(p);
+        } else {
+                goto unsupported_time;
+        }
+
+        MM = DD2bin(p);
+        DD = DD2bin(p);
+        hh = DD2bin(p);
+        mm = DD2bin(p);
+        ss = DD2bin(p);
+
+        if (*p != 'Z')
+                goto unsupported_time;
+
+        *_time = mktime(YY, MM, DD, hh, mm, ss);
+        return 0;
+
+unsupported_time:
+        pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
+                 tag, (int)vlen, (int)vlen, value);
+        return -EBADMSG;
+}
+
+int x509_note_not_before(void *context, size_t hdrlen,
+                         unsigned char tag,
+                         const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
+}
+
+int x509_note_not_after(void *context, size_t hdrlen,
+                        unsigned char tag,
+                        const void *value, size_t vlen)
+{
+        struct x509_parse_context *ctx = context;
+        return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
+}
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
new file mode 100644
index 000000000000..635053f7e962
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -0,0 +1,36 @@
+/* X.509 certificate parser internal definitions
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <crypto/public_key.h>
+
+struct x509_certificate {
+        struct x509_certificate *next;
+        struct public_key *pub;                 /* Public key details */
+        char            *issuer;                /* Name of certificate issuer */
+        char            *subject;               /* Name of certificate subject */
+        char            *fingerprint;           /* Key fingerprint as hex */
+        char            *authority;             /* Authority key fingerprint as hex */
+        time_t          valid_from;
+        time_t          valid_to;
+        enum pkey_algo  pkey_algo : 8;          /* Public key algorithm */
+        enum pkey_algo  sig_pkey_algo : 8;      /* Signature public key algorithm */
+        enum pkey_hash_algo sig_hash_algo : 8;  /* Signature hash algorithm */
+        const void      *tbs;                   /* Signed data */
+        size_t          tbs_size;               /* Size of signed data */
+        const void      *sig;                   /* Signature data */
+        size_t          sig_size;               /* Size of sigature */
+};
+
+/*
+ * x509_cert_parser.c
+ */
+extern void x509_free_certificate(struct x509_certificate *cert);
+extern struct x509_certificate *x509_cert_parse(const void *data, size_t datalen);
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
new file mode 100644
index 000000000000..716917ce0907
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -0,0 +1,207 @@
+/* Instantiate a public key crypto key from an X.509 Certificate
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "X.509: "fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/mpi.h>
+#include <linux/asn1_decoder.h>
+#include <keys/asymmetric-subtype.h>
+#include <keys/asymmetric-parser.h>
+#include <crypto/hash.h>
+#include "asymmetric_keys.h"
+#include "public_key.h"
+#include "x509_parser.h"
+
+static const
+struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = {
+        [PKEY_ALGO_DSA]         = NULL,
+#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
+        defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
+        [PKEY_ALGO_RSA]         = &RSA_public_key_algorithm,
+#endif
+};
+
+/*
+ * Check the signature on a certificate using the provided public key
+ */
+static int x509_check_signature(const struct public_key *pub,
+                                const struct x509_certificate *cert)
+{
+        struct public_key_signature *sig;
+        struct crypto_shash *tfm;
+        struct shash_desc *desc;
+        size_t digest_size, desc_size;
+        int ret;
+
+        pr_devel("==>%s()\n", __func__);
+        
+        /* Allocate the hashing algorithm we're going to need and find out how
+         * big the hash operational data will be.
+         */
+        tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_hash_algo], 0, 0);
+        if (IS_ERR(tfm))
+                return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
+
+        desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
+        digest_size = crypto_shash_digestsize(tfm);
+
+        /* We allocate the hash operational data storage on the end of our
+         * context data.
+         */
+        ret = -ENOMEM;
+        sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL);
+        if (!sig)
+                goto error_no_sig;
+
+        sig->pkey_hash_algo     = cert->sig_hash_algo;
+        sig->digest             = (u8 *)sig + sizeof(*sig) + desc_size;
+        sig->digest_size        = digest_size;
+
+        desc = (void *)sig + sizeof(*sig);
+        desc->tfm       = tfm;
+        desc->flags     = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+        ret = crypto_shash_init(desc);
+        if (ret < 0)
+                goto error;
+
+        ret = -ENOMEM;
+        sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size);
+        if (!sig->rsa.s)
+                goto error;
+
+        ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);
+        if (ret < 0)
+                goto error_mpi;
+
+        ret = pub->algo->verify_signature(pub, sig);
+
+        pr_debug("Cert Verification: %d\n", ret);
+
+error_mpi:
+        mpi_free(sig->rsa.s);
+error:
+        kfree(sig);
+error_no_sig:
+        crypto_free_shash(tfm);
+
+        pr_devel("<==%s() = %d\n", __func__, ret);
+        return ret;
+}
+
+/*
+ * Attempt to parse a data blob for a key as an X509 certificate.
+ */
+static int x509_key_preparse(struct key_preparsed_payload *prep)
+{
+        struct x509_certificate *cert;
+        time_t now;
+        size_t srlen, sulen;
+        char *desc = NULL;
+        int ret;
+
+        cert = x509_cert_parse(prep->data, prep->datalen);
+        if (IS_ERR(cert))
+                return PTR_ERR(cert);
+
+        pr_devel("Cert Issuer: %s\n", cert->issuer);
+        pr_devel("Cert Subject: %s\n", cert->subject);
+        pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]);
+        pr_devel("Cert Valid: %lu - %lu\n", cert->valid_from, cert->valid_to);
+        pr_devel("Cert Signature: %s + %s\n",
+                 pkey_algo[cert->sig_pkey_algo],
+                 pkey_hash_algo[cert->sig_hash_algo]);
+
+        if (!cert->fingerprint || !cert->authority) {
+                pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n",
+                        cert->subject);
+                ret = -EKEYREJECTED;
+                goto error_free_cert;
+        }
+
+        now = CURRENT_TIME.tv_sec;
+        if (now < cert->valid_from) {
+                pr_warn("Cert %s is not yet valid\n", cert->fingerprint);
+                ret = -EKEYREJECTED;
+                goto error_free_cert;
+        }
+        if (now >= cert->valid_to) {
+                pr_warn("Cert %s has expired\n", cert->fingerprint);
+                ret = -EKEYEXPIRED;
+                goto error_free_cert;
+        }
+
+        cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo];
+        cert->pub->id_type = PKEY_ID_X509;
+
+        /* Check the signature on the key */
+        if (strcmp(cert->fingerprint, cert->authority) == 0) {
+                ret = x509_check_signature(cert->pub, cert);
+                if (ret < 0)
+                        goto error_free_cert;
+        }
+
+        /* Propose a description */
+        sulen = strlen(cert->subject);
+        srlen = strlen(cert->fingerprint);
+        ret = -ENOMEM;
+        desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL);
+        if (!desc)
+                goto error_free_cert;
+        memcpy(desc, cert->subject, sulen);
+        desc[sulen] = ':';
+        desc[sulen + 1] = ' ';
+        memcpy(desc + sulen + 2, cert->fingerprint, srlen);
+        desc[sulen + 2 + srlen] = 0;
+
+        /* We're pinning the module by being linked against it */
+        __module_get(public_key_subtype.owner);
+        prep->type_data[0] = &public_key_subtype;
+        prep->type_data[1] = cert->fingerprint;
+        prep->payload = cert->pub;
+        prep->description = desc;
+        prep->quotalen = 100;
+
+        /* We've finished with the certificate */
+        cert->pub = NULL;
+        cert->fingerprint = NULL;
+        desc = NULL;
+        ret = 0;
+
+error_free_cert:
+        x509_free_certificate(cert);
+        return ret;
+}
+
+static struct asymmetric_key_parser x509_key_parser = {
+        .owner  = THIS_MODULE,
+        .name   = "x509",
+        .parse  = x509_key_preparse,
+};
+
+/*
+ * Module stuff
+ */
+static int __init x509_key_init(void)
+{
+        return register_asymmetric_key_parser(&x509_key_parser);
+}
+
+static void __exit x509_key_exit(void)
+{
+        unregister_asymmetric_key_parser(&x509_key_parser);
+}
+
+module_init(x509_key_init);
+module_exit(x509_key_exit);
diff --git a/crypto/asymmetric_keys/x509_rsakey.asn1 b/crypto/asymmetric_keys/x509_rsakey.asn1
new file mode 100644
index 000000000000..4ec7cc6532c1
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_rsakey.asn1
@@ -0,0 +1,4 @@
+RSAPublicKey ::= SEQUENCE {
+        modulus                 INTEGER ({ rsa_extract_mpi }),  -- n
+        publicExponent          INTEGER ({ rsa_extract_mpi })   -- e
+        }