seqiv.c 4.5 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * seqiv: Sequence Number IV Generator
  4. *
  5. * This generator generates an IV based on a sequence number by xoring it
  6. * with a salt. This algorithm is mainly useful for CTR and similar modes.
  7. *
  8. * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
  9. */
  10. #include <crypto/internal/geniv.h>
  11. #include <crypto/scatterwalk.h>
  12. #include <crypto/skcipher.h>
  13. #include <linux/err.h>
  14. #include <linux/init.h>
  15. #include <linux/kernel.h>
  16. #include <linux/module.h>
  17. #include <linux/slab.h>
  18. #include <linux/string.h>
  19. static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
  20. {
  21. struct aead_request *subreq = aead_request_ctx(req);
  22. struct crypto_aead *geniv;
  23. if (err == -EINPROGRESS)
  24. return;
  25. if (err)
  26. goto out;
  27. geniv = crypto_aead_reqtfm(req);
  28. memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
  29. out:
  30. kfree_sensitive(subreq->iv);
  31. }
  32. static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
  33. int err)
  34. {
  35. struct aead_request *req = base->data;
  36. seqiv_aead_encrypt_complete2(req, err);
  37. aead_request_complete(req, err);
  38. }
  39. static int seqiv_aead_encrypt(struct aead_request *req)
  40. {
  41. struct crypto_aead *geniv = crypto_aead_reqtfm(req);
  42. struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
  43. struct aead_request *subreq = aead_request_ctx(req);
  44. crypto_completion_t compl;
  45. void *data;
  46. u8 *info;
  47. unsigned int ivsize = 8;
  48. int err;
  49. if (req->cryptlen < ivsize)
  50. return -EINVAL;
  51. aead_request_set_tfm(subreq, ctx->child);
  52. compl = req->base.complete;
  53. data = req->base.data;
  54. info = req->iv;
  55. if (req->src != req->dst) {
  56. SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
  57. skcipher_request_set_sync_tfm(nreq, ctx->sknull);
  58. skcipher_request_set_callback(nreq, req->base.flags,
  59. NULL, NULL);
  60. skcipher_request_set_crypt(nreq, req->src, req->dst,
  61. req->assoclen + req->cryptlen,
  62. NULL);
  63. err = crypto_skcipher_encrypt(nreq);
  64. if (err)
  65. return err;
  66. }
  67. if (unlikely(!IS_ALIGNED((unsigned long)info,
  68. crypto_aead_alignmask(geniv) + 1))) {
  69. info = kmemdup(req->iv, ivsize, req->base.flags &
  70. CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
  71. GFP_ATOMIC);
  72. if (!info)
  73. return -ENOMEM;
  74. compl = seqiv_aead_encrypt_complete;
  75. data = req;
  76. }
  77. aead_request_set_callback(subreq, req->base.flags, compl, data);
  78. aead_request_set_crypt(subreq, req->dst, req->dst,
  79. req->cryptlen - ivsize, info);
  80. aead_request_set_ad(subreq, req->assoclen + ivsize);
  81. crypto_xor(info, ctx->salt, ivsize);
  82. scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
  83. err = crypto_aead_encrypt(subreq);
  84. if (unlikely(info != req->iv))
  85. seqiv_aead_encrypt_complete2(req, err);
  86. return err;
  87. }
  88. static int seqiv_aead_decrypt(struct aead_request *req)
  89. {
  90. struct crypto_aead *geniv = crypto_aead_reqtfm(req);
  91. struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
  92. struct aead_request *subreq = aead_request_ctx(req);
  93. crypto_completion_t compl;
  94. void *data;
  95. unsigned int ivsize = 8;
  96. if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
  97. return -EINVAL;
  98. aead_request_set_tfm(subreq, ctx->child);
  99. compl = req->base.complete;
  100. data = req->base.data;
  101. aead_request_set_callback(subreq, req->base.flags, compl, data);
  102. aead_request_set_crypt(subreq, req->src, req->dst,
  103. req->cryptlen - ivsize, req->iv);
  104. aead_request_set_ad(subreq, req->assoclen + ivsize);
  105. scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
  106. return crypto_aead_decrypt(subreq);
  107. }
  108. static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
  109. {
  110. struct aead_instance *inst;
  111. int err;
  112. inst = aead_geniv_alloc(tmpl, tb);
  113. if (IS_ERR(inst))
  114. return PTR_ERR(inst);
  115. err = -EINVAL;
  116. if (inst->alg.ivsize != sizeof(u64))
  117. goto free_inst;
  118. inst->alg.encrypt = seqiv_aead_encrypt;
  119. inst->alg.decrypt = seqiv_aead_decrypt;
  120. inst->alg.init = aead_init_geniv;
  121. inst->alg.exit = aead_exit_geniv;
  122. inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
  123. inst->alg.base.cra_ctxsize += inst->alg.ivsize;
  124. err = aead_register_instance(tmpl, inst);
  125. if (err) {
  126. free_inst:
  127. inst->free(inst);
  128. }
  129. return err;
  130. }
  131. static struct crypto_template seqiv_tmpl = {
  132. .name = "seqiv",
  133. .create = seqiv_aead_create,
  134. .module = THIS_MODULE,
  135. };
  136. static int __init seqiv_module_init(void)
  137. {
  138. return crypto_register_template(&seqiv_tmpl);
  139. }
  140. static void __exit seqiv_module_exit(void)
  141. {
  142. crypto_unregister_template(&seqiv_tmpl);
  143. }
  144. subsys_initcall(seqiv_module_init);
  145. module_exit(seqiv_module_exit);
  146. MODULE_LICENSE("GPL");
  147. MODULE_DESCRIPTION("Sequence Number IV Generator");
  148. MODULE_ALIAS_CRYPTO("seqiv");