_ Git - BearSSL/blob - src/x509/x509_decoder.t0

   1 \ Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
   2 \
   3 \ Permission is hereby granted, free of charge, to any person obtaining
   4 \ a copy of this software and associated documentation files (the
   5 \ "Software"), to deal in the Software without restriction, including
   6 \ without limitation the rights to use, copy, modify, merge, publish,
   7 \ distribute, sublicense, and/or sell copies of the Software, and to
   8 \ permit persons to whom the Software is furnished to do so, subject to
   9 \ the following conditions:
  10 \
  11 \ The above copyright notice and this permission notice shall be
  12 \ included in all copies or substantial portions of the Software.
  13 \
  14 \ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  15 \ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16 \ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  17 \ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  18 \ BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  19 \ ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  20 \ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21 \ SOFTWARE.
  22
  23 preamble {
  24
  25 #include "inner.h"
  26
  27 #define CTX   ((br_x509_decoder_context *)(void *)((unsigned char *)t0ctx - offsetof(br_x509_decoder_context, cpu)))
  28 #define CONTEXT_NAME   br_x509_decoder_context
  29
  30 /* see bearssl_x509.h */
  31 void
  32 br_x509_decoder_init(br_x509_decoder_context *ctx,
  33         void (*append_dn)(void *ctx, const void *buf, size_t len),
  34         void *append_dn_ctx)
  35 {
  36         memset(ctx, 0, sizeof *ctx);
  37         /* obsolete
  38         ctx->err = 0;
  39         ctx->hbuf = NULL;
  40         ctx->hlen = 0;
  41         */
  42         ctx->append_dn = append_dn;
  43         ctx->append_dn_ctx = append_dn_ctx;
  44         ctx->cpu.dp = &ctx->dp_stack[0];
  45         ctx->cpu.rp = &ctx->rp_stack[0];
  46         br_x509_decoder_init_main(&ctx->cpu);
  47         br_x509_decoder_run(&ctx->cpu);
  48 }
  49
  50 /* see bearssl_x509.h */
  51 void
  52 br_x509_decoder_push(br_x509_decoder_context *ctx,
  53         const void *data, size_t len)
  54 {
  55         ctx->hbuf = data;
  56         ctx->hlen = len;
  57         br_x509_decoder_run(&ctx->cpu);
  58 }
  59
  60 }
  61
  62 addr: decoded
  63 addr: notbefore_days
  64 addr: notbefore_seconds
  65 addr: notafter_days
  66 addr: notafter_seconds
  67 addr: isCA
  68 addr: copy_dn
  69 addr: signer_key_type
  70 addr: signer_hash_id
  71
  72 cc: read8-low ( -- x ) {
  73         if (CTX->hlen == 0) {
  74                 T0_PUSHi(-1);
  75         } else {
  76                 unsigned char x = *CTX->hbuf ++;
  77                 if (CTX->copy_dn && CTX->append_dn) {
  78                         CTX->append_dn(CTX->append_dn_ctx, &x, 1);
  79                 }
  80                 CTX->hlen --;
  81                 T0_PUSH(x);
  82         }
  83 }
  84
  85 cc: read-blob-inner ( addr len -- addr len ) {
  86         uint32_t len = T0_POP();
  87         uint32_t addr = T0_POP();
  88         size_t clen = CTX->hlen;
  89         if (clen > len) {
  90                 clen = (size_t)len;
  91         }
  92         if (addr != 0) {
  93                 memcpy((unsigned char *)CTX + addr, CTX->hbuf, clen);
  94         }
  95         if (CTX->copy_dn && CTX->append_dn) {
  96                 CTX->append_dn(CTX->append_dn_ctx, CTX->hbuf, clen);
  97         }
  98         CTX->hbuf += clen;
  99         CTX->hlen -= clen;
 100         T0_PUSH(addr + clen);
 101         T0_PUSH(len - clen);
 102 }
 103
 104 \ Get the address and length for the pkey_data buffer.
 105 : addr-len-pkey_data ( -- addr len )
 106         CX 0 8191 { offsetof(br_x509_decoder_context, pkey_data) }
 107         CX 0 8191 { BR_X509_BUFSIZE_KEY } ;
 108
 109 \ Copy the public key (RSA) to the permanent buffer.
 110 cc: copy-rsa-pkey ( nlen elen -- ) {
 111         size_t elen = T0_POP();
 112         size_t nlen = T0_POP();
 113         CTX->pkey.key_type = BR_KEYTYPE_RSA;
 114         CTX->pkey.key.rsa.n = CTX->pkey_data;
 115         CTX->pkey.key.rsa.nlen = nlen;
 116         CTX->pkey.key.rsa.e = CTX->pkey_data + nlen;
 117         CTX->pkey.key.rsa.elen = elen;
 118 }
 119
 120 \ Copy the public key (EC) to the permanent buffer.
 121 cc: copy-ec-pkey ( curve qlen -- ) {
 122         size_t qlen = T0_POP();
 123         uint32_t curve = T0_POP();
 124         CTX->pkey.key_type = BR_KEYTYPE_EC;
 125         CTX->pkey.key.ec.curve = curve;
 126         CTX->pkey.key.ec.q = CTX->pkey_data;
 127         CTX->pkey.key.ec.qlen = qlen;
 128 }
 129
 130 \ Extensions with specific processing.
 131 OID: basicConstraints    2.5.29.19
 132
 133 \ Process a Basic Constraints extension. We want the "CA" flag only.
 134 : process-basicConstraints ( lim -- lim )
 135         read-sequence-open
 136         read-tag-or-end dup 0x01 = if
 137                 read-boolean 1 and addr-isCA set8
 138         else
 139                 2drop
 140         then
 141         skip-close-elt
 142         ;
 143
 144 \ Decode a certificate.
 145 : main ( -- ! )
 146
 147         \ Initialise state flags.
 148         0 addr-decoded set8
 149         0 addr-copy_dn set8
 150
 151         \ An arbitrary limit for the total certificate size.
 152         0xFFFFFF
 153
 154         \ Open the outer SEQUENCE.
 155         read-sequence-open
 156
 157         \ TBS
 158         read-sequence-open
 159
 160         \ First element may be an explicit version. We accept only
 161         \ versions 0 to 2 (certificates v1 to v3).
 162         read-tag dup 0x20 = if
 163                 drop check-constructed read-length-open-elt
 164                 read-tag
 165                 0x02 check-tag-primitive
 166                 read-small-int-value
 167                 2 > if ERR_X509_UNSUPPORTED fail then
 168                 close-elt
 169                 read-tag
 170         then
 171
 172         \ Serial number. We just check that the tag is correct.
 173         0x02 check-tag-primitive read-length-skip
 174
 175         \ Signature algorithm.
 176         read-sequence-open skip-close-elt
 177
 178         \ Issuer name.
 179         read-sequence-open skip-close-elt
 180
 181         \ Validity dates.
 182         read-sequence-open
 183         read-date addr-notbefore_seconds set32 addr-notbefore_days set32
 184         read-date addr-notafter_seconds set32 addr-notafter_days set32
 185         close-elt
 186
 187         \ Subject name.
 188         1 addr-copy_dn set8
 189         read-sequence-open skip-close-elt
 190         0 addr-copy_dn set8
 191
 192         \ Public Key.
 193         read-sequence-open
 194         \ Algorithm Identifier. Right now we are only interested in the
 195         \ OID, since we only support RSA keys.
 196         \ TODO: support EC keys
 197         read-sequence-open
 198         read-OID ifnot ERR_X509_UNSUPPORTED fail then
 199         choice
 200                 \ RSA public key.
 201                 rsaEncryption eqOID uf
 202                         skip-close-elt
 203                         \ Public key itself: the BIT STRING contains bytes
 204                         \ (no partial byte) and these bytes encode the
 205                         \ actual value.
 206                         read-bits-open
 207                                 \ RSA public key is a SEQUENCE of two
 208                                 \ INTEGER. We get both INTEGER values into
 209                                 \ the pkey_data[] buffer, if they fit.
 210                                 read-sequence-open
 211                                 addr-len-pkey_data
 212                                 read-integer { nlen }
 213                                 addr-len-pkey_data swap nlen + swap nlen -
 214                                 read-integer { elen }
 215                                 close-elt
 216                         close-elt
 217                         nlen elen copy-rsa-pkey
 218                 enduf
 219
 220                 \ EC public key.
 221                 id-ecPublicKey eqOID uf
 222                         \ We support only named curves, for which the
 223                         \ "parameters" field in the AlgorithmIdentifier
 224                         \ field should be an OID.
 225                         read-curve-ID { curve }
 226                         close-elt
 227                         read-bits-open
 228                         dup { qlen }
 229                         dup addr-len-pkey_data rot < if
 230                                 ERR_X509_LIMIT_EXCEEDED fail
 231                         then
 232                         read-blob
 233                         curve qlen copy-ec-pkey
 234                 enduf
 235                 ERR_X509_UNSUPPORTED fail
 236         endchoice
 237         close-elt
 238
 239         \ This flag will be set to true if the Basic Constraints extension
 240         \ is encountered.
 241         0 addr-isCA set8
 242
 243         \ Skip issuerUniqueID and subjectUniqueID, and process extensions
 244         \ if present. Extensions are an explicit context tag of value 3
 245         \ around a SEQUENCE OF extensions. Each extension is a SEQUENCE
 246         \ with an OID, an optional boolean, and a value; the value is
 247         \ an OCTET STRING.
 248         read-tag-or-end
 249         0x21 iftag-skip
 250         0x22 iftag-skip
 251         dup 0x23 = if
 252                 drop
 253                 check-constructed read-length-open-elt
 254                 read-sequence-open
 255                 begin dup while
 256                         read-sequence-open
 257                         read-OID drop
 258                         read-tag dup 0x01 = if
 259                                 read-boolean drop
 260                                 read-tag
 261                         then
 262                         0x04 check-tag-primitive read-length-open-elt
 263                         choice
 264                                 \ Extensions with specific processing.
 265                                 basicConstraints eqOID uf
 266                                         process-basicConstraints
 267                                 enduf
 268                                 skip-remaining
 269                         endchoice
 270                         close-elt
 271                         close-elt
 272                 repeat
 273                 close-elt
 274                 close-elt
 275         else
 276                 -1 = ifnot ERR_X509_UNEXPECTED fail then
 277                 drop
 278         then
 279
 280         close-elt
 281
 282         \ signature algorithm
 283         read-sequence-open
 284         read-OID if
 285                 choice
 286                         sha1WithRSAEncryption    eqOID uf 2 KEYTYPE_RSA enduf
 287                         sha224WithRSAEncryption  eqOID uf 3 KEYTYPE_RSA enduf
 288                         sha256WithRSAEncryption  eqOID uf 4 KEYTYPE_RSA enduf
 289                         sha384WithRSAEncryption  eqOID uf 5 KEYTYPE_RSA enduf
 290                         sha512WithRSAEncryption  eqOID uf 6 KEYTYPE_RSA enduf
 291
 292                         ecdsa-with-SHA1          eqOID uf 2 KEYTYPE_EC enduf
 293                         ecdsa-with-SHA224        eqOID uf 3 KEYTYPE_EC enduf
 294                         ecdsa-with-SHA256        eqOID uf 4 KEYTYPE_EC enduf
 295                         ecdsa-with-SHA384        eqOID uf 5 KEYTYPE_EC enduf
 296                         ecdsa-with-SHA512        eqOID uf 6 KEYTYPE_EC enduf
 297
 298                         0 0
 299                 endchoice
 300         else
 301                 0 0
 302         then
 303         addr-signer_key_type set8
 304         addr-signer_hash_id set8
 305         skip-close-elt
 306         \ read-sequence-open skip-close-elt
 307
 308         \ signature value
 309         read-bits-open skip-close-elt
 310
 311         \ Close the outer SEQUENCE.
 312         close-elt
 313         drop
 314
 315         \ Mark the decoding as successful.
 316         1 addr-decoded set8
 317
 318         \ Read one byte, then fail: if the read succeeds, then there is
 319         \ some trailing byte.
 320         read8-nc ERR_X509_EXTRA_ELEMENT fail
 321         ;