1 /* $OpenBSD: evp_aead.c,v 1.7 2022/01/07 21:58:17 tb Exp $ */
2 /*
3 * Copyright (c) 2014, Google Inc.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <limits.h>
19 #include <string.h>
20
21 #include <openssl/evp.h>
22 #include <openssl/err.h>
23
24 #include "evp_locl.h"
25
26 size_t
EVP_AEAD_key_length(const EVP_AEAD * aead)27 EVP_AEAD_key_length(const EVP_AEAD *aead)
28 {
29 return aead->key_len;
30 }
31
32 size_t
EVP_AEAD_nonce_length(const EVP_AEAD * aead)33 EVP_AEAD_nonce_length(const EVP_AEAD *aead)
34 {
35 return aead->nonce_len;
36 }
37
38 size_t
EVP_AEAD_max_overhead(const EVP_AEAD * aead)39 EVP_AEAD_max_overhead(const EVP_AEAD *aead)
40 {
41 return aead->overhead;
42 }
43
44 size_t
EVP_AEAD_max_tag_len(const EVP_AEAD * aead)45 EVP_AEAD_max_tag_len(const EVP_AEAD *aead)
46 {
47 return aead->max_tag_len;
48 }
49
50 int
EVP_AEAD_CTX_init(EVP_AEAD_CTX * ctx,const EVP_AEAD * aead,const unsigned char * key,size_t key_len,size_t tag_len,ENGINE * impl)51 EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead,
52 const unsigned char *key, size_t key_len, size_t tag_len, ENGINE *impl)
53 {
54 ctx->aead = aead;
55 if (key_len != aead->key_len) {
56 EVPerror(EVP_R_UNSUPPORTED_KEY_SIZE);
57 return 0;
58 }
59 return aead->init(ctx, key, key_len, tag_len);
60 }
61
62 void
EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX * ctx)63 EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx)
64 {
65 if (ctx->aead == NULL)
66 return;
67 ctx->aead->cleanup(ctx);
68 ctx->aead = NULL;
69 }
70
71 EVP_AEAD_CTX *
EVP_AEAD_CTX_new(void)72 EVP_AEAD_CTX_new(void)
73 {
74 return calloc(1, sizeof(EVP_AEAD_CTX));
75 }
76
77 void
EVP_AEAD_CTX_free(EVP_AEAD_CTX * ctx)78 EVP_AEAD_CTX_free(EVP_AEAD_CTX *ctx)
79 {
80 if (ctx == NULL)
81 return;
82
83 EVP_AEAD_CTX_cleanup(ctx);
84 free(ctx);
85 }
86
87 /* check_alias returns 0 if out points within the buffer determined by in
88 * and in_len and 1 otherwise.
89 *
90 * When processing, there's only an issue if out points within in[:in_len]
91 * and isn't equal to in. If that's the case then writing the output will
92 * stomp input that hasn't been read yet.
93 *
94 * This function checks for that case. */
95 static int
check_alias(const unsigned char * in,size_t in_len,const unsigned char * out)96 check_alias(const unsigned char *in, size_t in_len, const unsigned char *out)
97 {
98 if (out <= in)
99 return 1;
100 if (in + in_len <= out)
101 return 1;
102 return 0;
103 }
104
105 int
EVP_AEAD_CTX_seal(const EVP_AEAD_CTX * ctx,unsigned char * out,size_t * out_len,size_t max_out_len,const unsigned char * nonce,size_t nonce_len,const unsigned char * in,size_t in_len,const unsigned char * ad,size_t ad_len)106 EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, unsigned char *out, size_t *out_len,
107 size_t max_out_len, const unsigned char *nonce, size_t nonce_len,
108 const unsigned char *in, size_t in_len, const unsigned char *ad,
109 size_t ad_len)
110 {
111 size_t possible_out_len = in_len + ctx->aead->overhead;
112
113 /* Overflow. */
114 if (possible_out_len < in_len) {
115 EVPerror(EVP_R_TOO_LARGE);
116 goto error;
117 }
118
119 if (!check_alias(in, in_len, out)) {
120 EVPerror(EVP_R_OUTPUT_ALIASES_INPUT);
121 goto error;
122 }
123
124 if (ctx->aead->seal(ctx, out, out_len, max_out_len, nonce, nonce_len,
125 in, in_len, ad, ad_len)) {
126 return 1;
127 }
128
129 error:
130 /* In the event of an error, clear the output buffer so that a caller
131 * that doesn't check the return value doesn't send raw data. */
132 memset(out, 0, max_out_len);
133 *out_len = 0;
134 return 0;
135 }
136
137 int
EVP_AEAD_CTX_open(const EVP_AEAD_CTX * ctx,unsigned char * out,size_t * out_len,size_t max_out_len,const unsigned char * nonce,size_t nonce_len,const unsigned char * in,size_t in_len,const unsigned char * ad,size_t ad_len)138 EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, unsigned char *out, size_t *out_len,
139 size_t max_out_len, const unsigned char *nonce, size_t nonce_len,
140 const unsigned char *in, size_t in_len, const unsigned char *ad,
141 size_t ad_len)
142 {
143 if (!check_alias(in, in_len, out)) {
144 EVPerror(EVP_R_OUTPUT_ALIASES_INPUT);
145 goto error;
146 }
147
148 if (ctx->aead->open(ctx, out, out_len, max_out_len, nonce, nonce_len,
149 in, in_len, ad, ad_len)) {
150 return 1;
151 }
152
153 error:
154 /* In the event of an error, clear the output buffer so that a caller
155 * that doesn't check the return value doesn't try and process bad
156 * data. */
157 memset(out, 0, max_out_len);
158 *out_len = 0;
159 return 0;
160 }
161