security/keys/keyctl_pkey.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Public-key operation keyctls
   3  *
   4  * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/err.h>
  10 #include <linux/key.h>
  11 #include <linux/keyctl.h>
  12 #include <linux/parser.h>
  13 #include <linux/uaccess.h>
  14 #include <keys/user-type.h>
  15 #include "internal.h"
  16
  17 static void keyctl_pkey_params_free(struct kernel_pkey_params *params)
  18 {
  19         kfree(params->info);
  20         key_put(params->key);
  21 }
  22
  23 enum {
  24         Opt_err,
  25         Opt_enc,                /* "enc=<encoding>" eg. "enc=oaep" */
  26         Opt_hash,               /* "hash=<digest-name>" eg. "hash=sha1" */
  27 };
  28
  29 static const match_table_t param_keys = {
  30         { Opt_enc,      "enc=%s" },
  31         { Opt_hash,     "hash=%s" },
  32         { Opt_err,      NULL }
  33 };
  34
  35 /*
  36  * Parse the information string which consists of key=val pairs.
  37  */
  38 static int keyctl_pkey_params_parse(struct kernel_pkey_params *params)
  39 {
  40         unsigned long token_mask = 0;
  41         substring_t args[MAX_OPT_ARGS];
  42         char *c = params->info, *p, *q;
  43         int token;
  44
  45         while ((p = strsep(&c, " \t"))) {
  46                 if (*p == '\0' || *p == ' ' || *p == '\t')
  47                         continue;
  48                 token = match_token(p, param_keys, args);
  49                 if (token == Opt_err)
  50                         return -EINVAL;
  51                 if (__test_and_set_bit(token, &token_mask))
  52                         return -EINVAL;
  53                 q = args[0].from;
  54                 if (!q[0])
  55                         return -EINVAL;
  56
  57                 switch (token) {
  58                 case Opt_enc:
  59                         params->encoding = q;
  60                         break;
  61
  62                 case Opt_hash:
  63                         params->hash_algo = q;
  64                         break;
  65
  66                 default:
  67                         return -EINVAL;
  68                 }
  69         }
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * Interpret parameters.  Callers must always call the free function
  76  * on params, even if an error is returned.
  77  */
  78 static int keyctl_pkey_params_get(key_serial_t id,
  79                                   const char __user *_info,
  80                                   struct kernel_pkey_params *params)
  81 {
  82         key_ref_t key_ref;
  83         void *p;
  84         int ret;
  85
  86         memset(params, 0, sizeof(*params));
  87         params->encoding = "raw";
  88
  89         p = strndup_user(_info, PAGE_SIZE);
  90         if (IS_ERR(p))
  91                 return PTR_ERR(p);
  92         params->info = p;
  93
  94         ret = keyctl_pkey_params_parse(params);
  95         if (ret < 0)
  96                 return ret;
  97
  98         key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
  99         if (IS_ERR(key_ref))
 100                 return PTR_ERR(key_ref);
 101         params->key = key_ref_to_ptr(key_ref);
 102
 103         if (!params->key->type->asym_query)
 104                 return -EOPNOTSUPP;
 105
 106         return 0;
 107 }
 108
 109 /*
 110  * Get parameters from userspace.  Callers must always call the free function
 111  * on params, even if an error is returned.
 112  */
 113 static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_params,
 114                                     const char __user *_info,
 115                                     int op,
 116                                     struct kernel_pkey_params *params)
 117 {
 118         struct keyctl_pkey_params uparams;
 119         struct kernel_pkey_query info;
 120         int ret;
 121
 122         memset(params, 0, sizeof(*params));
 123         params->encoding = "raw";
 124
 125         if (copy_from_user(&uparams, _params, sizeof(uparams)) != 0)
 126                 return -EFAULT;
 127
 128         ret = keyctl_pkey_params_get(uparams.key_id, _info, params);
 129         if (ret < 0)
 130                 return ret;
 131
 132         ret = params->key->type->asym_query(params, &info);
 133         if (ret < 0)
 134                 return ret;
 135
 136         switch (op) {
 137         case KEYCTL_PKEY_ENCRYPT:
 138         case KEYCTL_PKEY_DECRYPT:
 139                 if (uparams.in_len  > info.max_enc_size ||
 140                     uparams.out_len > info.max_dec_size)
 141                         return -EINVAL;
 142                 break;
 143         case KEYCTL_PKEY_SIGN:
 144         case KEYCTL_PKEY_VERIFY:
 145                 if (uparams.in_len  > info.max_sig_size ||
 146                     uparams.out_len > info.max_data_size)
 147                         return -EINVAL;
 148                 break;
 149         default:
 150                 BUG();
 151         }
 152
 153         params->in_len  = uparams.in_len;
 154         params->out_len = uparams.out_len;
 155         return 0;
 156 }
 157
 158 /*
 159  * Query information about an asymmetric key.
 160  */
 161 long keyctl_pkey_query(key_serial_t id,
 162                        const char __user *_info,
 163                        struct keyctl_pkey_query __user *_res)
 164 {
 165         struct kernel_pkey_params params;
 166         struct kernel_pkey_query res;
 167         long ret;
 168
 169         memset(&params, 0, sizeof(params));
 170
 171         ret = keyctl_pkey_params_get(id, _info, &params);
 172         if (ret < 0)
 173                 goto error;
 174
 175         ret = params.key->type->asym_query(&params, &res);
 176         if (ret < 0)
 177                 goto error;
 178
 179         ret = -EFAULT;
 180         if (copy_to_user(_res, &res, sizeof(res)) == 0 &&
 181             clear_user(_res->__spare, sizeof(_res->__spare)) == 0)
 182                 ret = 0;
 183
 184 error:
 185         keyctl_pkey_params_free(&params);
 186         return ret;
 187 }
 188
 189 /*
 190  * Encrypt/decrypt/sign
 191  *
 192  * Encrypt data, decrypt data or sign data using a public key.
 193  *
 194  * _info is a string of supplementary information in key=val format.  For
 195  * instance, it might contain:
 196  *
 197  *      "enc=pkcs1 hash=sha256"
 198  *
 199  * where enc= specifies the encoding and hash= selects the OID to go in that
 200  * particular encoding if required.  If enc= isn't supplied, it's assumed that
 201  * the caller is supplying raw values.
 202  *
 203  * If successful, the amount of data written into the output buffer is
 204  * returned.
 205  */
 206 long keyctl_pkey_e_d_s(int op,
 207                        const struct keyctl_pkey_params __user *_params,
 208                        const char __user *_info,
 209                        const void __user *_in,
 210                        void __user *_out)
 211 {
 212         struct kernel_pkey_params params;
 213         void *in, *out;
 214         long ret;
 215
 216         ret = keyctl_pkey_params_get_2(_params, _info, op, &params);
 217         if (ret < 0)
 218                 goto error_params;
 219
 220         ret = -EOPNOTSUPP;
 221         if (!params.key->type->asym_eds_op)
 222                 goto error_params;
 223
 224         switch (op) {
 225         case KEYCTL_PKEY_ENCRYPT:
 226                 params.op = kernel_pkey_encrypt;
 227                 break;
 228         case KEYCTL_PKEY_DECRYPT:
 229                 params.op = kernel_pkey_decrypt;
 230                 break;
 231         case KEYCTL_PKEY_SIGN:
 232                 params.op = kernel_pkey_sign;
 233                 break;
 234         default:
 235                 BUG();
 236         }
 237
 238         in = memdup_user(_in, params.in_len);
 239         if (IS_ERR(in)) {
 240                 ret = PTR_ERR(in);
 241                 goto error_params;
 242         }
 243
 244         ret = -ENOMEM;
 245         out = kmalloc(params.out_len, GFP_KERNEL);
 246         if (!out)
 247                 goto error_in;
 248
 249         ret = params.key->type->asym_eds_op(&params, in, out);
 250         if (ret < 0)
 251                 goto error_out;
 252
 253         if (copy_to_user(_out, out, ret) != 0)
 254                 ret = -EFAULT;
 255
 256 error_out:
 257         kfree(out);
 258 error_in:
 259         kfree(in);
 260 error_params:
 261         keyctl_pkey_params_free(&params);
 262         return ret;
 263 }
 264
 265 /*
 266  * Verify a signature.
 267  *
 268  * Verify a public key signature using the given key, or if not given, search
 269  * for a matching key.
 270  *
 271  * _info is a string of supplementary information in key=val format.  For
 272  * instance, it might contain:
 273  *
 274  *      "enc=pkcs1 hash=sha256"
 275  *
 276  * where enc= specifies the signature blob encoding and hash= selects the OID
 277  * to go in that particular encoding.  If enc= isn't supplied, it's assumed
 278  * that the caller is supplying raw values.
 279  *
 280  * If successful, 0 is returned.
 281  */
 282 long keyctl_pkey_verify(const struct keyctl_pkey_params __user *_params,
 283                         const char __user *_info,
 284                         const void __user *_in,
 285                         const void __user *_in2)
 286 {
 287         struct kernel_pkey_params params;
 288         void *in, *in2;
 289         long ret;
 290
 291         ret = keyctl_pkey_params_get_2(_params, _info, KEYCTL_PKEY_VERIFY,
 292                                        &params);
 293         if (ret < 0)
 294                 goto error_params;
 295
 296         ret = -EOPNOTSUPP;
 297         if (!params.key->type->asym_verify_signature)
 298                 goto error_params;
 299
 300         in = memdup_user(_in, params.in_len);
 301         if (IS_ERR(in)) {
 302                 ret = PTR_ERR(in);
 303                 goto error_params;
 304         }
 305
 306         in2 = memdup_user(_in2, params.in2_len);
 307         if (IS_ERR(in2)) {
 308                 ret = PTR_ERR(in2);
 309                 goto error_in;
 310         }
 311
 312         params.op = kernel_pkey_verify;
 313         ret = params.key->type->asym_verify_signature(&params, in, in2);
 314
 315         kfree(in2);
 316 error_in:
 317         kfree(in);
 318 error_params:
 319         keyctl_pkey_params_free(&params);
 320         return ret;
 321 }