1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 /* 3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. 4 * 5 * Based on public domain code from Daniel J. Bernstein and Peter Schwabe. This 6 * began from SUPERCOP's curve25519/neon2/scalarmult.s, but has subsequently been 7 * manually reworked for use in kernel space. 8 */ 9 10 #include <asm/hwcap.h> 11 #include <asm/neon.h> 12 #include <asm/simd.h> 13 #include <crypto/internal/kpp.h> 14 #include <crypto/internal/simd.h> 15 #include <linux/types.h> 16 #include <linux/module.h> 17 #include <linux/init.h> 18 #include <linux/jump_label.h> 19 #include <crypto/curve25519.h> 20 21 asmlinkage void curve25519_neon(u8 mypublic[CURVE25519_KEY_SIZE], 22 const u8 secret[CURVE25519_KEY_SIZE], 23 const u8 basepoint[CURVE25519_KEY_SIZE]); 24 25 static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon); 26 27 void curve25519_arch(u8 out[CURVE25519_KEY_SIZE], 28 const u8 scalar[CURVE25519_KEY_SIZE], 29 const u8 point[CURVE25519_KEY_SIZE]) 30 { 31 if (static_branch_likely(&have_neon) && crypto_simd_usable()) { 32 kernel_neon_begin(); 33 curve25519_neon(out, scalar, point); 34 kernel_neon_end(); 35 } else { 36 curve25519_generic(out, scalar, point); 37 } 38 } 39 EXPORT_SYMBOL(curve25519_arch); 40 41 void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE], 42 const u8 secret[CURVE25519_KEY_SIZE]) 43 { 44 return curve25519_arch(pub, secret, curve25519_base_point); 45 } 46 EXPORT_SYMBOL(curve25519_base_arch); 47 48 static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf, 49 unsigned int len) 50 { 51 u8 *secret = kpp_tfm_ctx(tfm); 52 53 if (!len) 54 curve25519_generate_secret(secret); 55 else if (len == CURVE25519_KEY_SIZE && 56 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE)) 57 memcpy(secret, buf, CURVE25519_KEY_SIZE); 58 else 59 return -EINVAL; 60 return 0; 61 } 62 63 static int curve25519_compute_value(struct kpp_request *req) 64 { 65 struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); 66 const u8 *secret = kpp_tfm_ctx(tfm); 67 u8 public_key[CURVE25519_KEY_SIZE]; 68 u8 buf[CURVE25519_KEY_SIZE]; 69 int copied, nbytes; 70 u8 const *bp; 71 72 if (req->src) { 73 copied = sg_copy_to_buffer(req->src, 74 sg_nents_for_len(req->src, 75 CURVE25519_KEY_SIZE), 76 public_key, CURVE25519_KEY_SIZE); 77 if (copied != CURVE25519_KEY_SIZE) 78 return -EINVAL; 79 bp = public_key; 80 } else { 81 bp = curve25519_base_point; 82 } 83 84 curve25519_arch(buf, secret, bp); 85 86 /* might want less than we've got */ 87 nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len); 88 copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, 89 nbytes), 90 buf, nbytes); 91 if (copied != nbytes) 92 return -EINVAL; 93 return 0; 94 } 95 96 static unsigned int curve25519_max_size(struct crypto_kpp *tfm) 97 { 98 return CURVE25519_KEY_SIZE; 99 } 100 101 static struct kpp_alg curve25519_alg = { 102 .base.cra_name = "curve25519", 103 .base.cra_driver_name = "curve25519-neon", 104 .base.cra_priority = 200, 105 .base.cra_module = THIS_MODULE, 106 .base.cra_ctxsize = CURVE25519_KEY_SIZE, 107 108 .set_secret = curve25519_set_secret, 109 .generate_public_key = curve25519_compute_value, 110 .compute_shared_secret = curve25519_compute_value, 111 .max_size = curve25519_max_size, 112 }; 113 114 static int __init mod_init(void) 115 { 116 if (elf_hwcap & HWCAP_NEON) { 117 static_branch_enable(&have_neon); 118 return IS_REACHABLE(CONFIG_CRYPTO_KPP) ? 119 crypto_register_kpp(&curve25519_alg) : 0; 120 } 121 return 0; 122 } 123 124 static void __exit mod_exit(void) 125 { 126 if (IS_REACHABLE(CONFIG_CRYPTO_KPP) && elf_hwcap & HWCAP_NEON) 127 crypto_unregister_kpp(&curve25519_alg); 128 } 129 130 module_init(mod_init); 131 module_exit(mod_exit); 132 133 MODULE_ALIAS_CRYPTO("curve25519"); 134 MODULE_ALIAS_CRYPTO("curve25519-neon"); 135 MODULE_LICENSE("GPL v2"); 136