1 // SPDX-License-Identifier: GPL-2.0 OR MIT
2 /*
3 * Copyright (C) 2015-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 */
5
6 #include <errno.h>
7 #include <stdio.h>
8 #include <stdbool.h>
9 #include <unistd.h>
10 #include <sys/types.h>
11 #include <sys/stat.h>
12 #include <string.h>
13 #include <fcntl.h>
14 #ifdef __linux__
15 #include <sys/syscall.h>
16 #endif
17 #ifdef __APPLE__
18 #include <AvailabilityMacros.h>
19 #ifndef MAC_OS_X_VERSION_10_12
20 #define MAC_OS_X_VERSION_10_12 101200
21 #endif
22 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12
23 #include <sys/random.h>
24 #endif
25 #endif
26
27 #include "curve25519.h"
28 #include "encoding.h"
29 #include "subcommands.h"
30
31 #ifndef _WIN32
get_random_bytes(uint8_t * out,size_t len)32 static inline bool __attribute__((__warn_unused_result__)) get_random_bytes(uint8_t *out, size_t len)
33 {
34 ssize_t ret = 0;
35 size_t i;
36 int fd;
37
38 if (len > 256) {
39 errno = EOVERFLOW;
40 return false;
41 }
42
43 #if defined(__OpenBSD__) || (defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12) || (defined(__GLIBC__) && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25)))
44 if (!getentropy(out, len))
45 return true;
46 #endif
47
48 #if defined(__NR_getrandom) && defined(__linux__)
49 if (syscall(__NR_getrandom, out, len, 0) == (ssize_t)len)
50 return true;
51 #endif
52
53 fd = open("/dev/urandom", O_RDONLY);
54 if (fd < 0)
55 return false;
56 for (errno = 0, i = 0; i < len; i += ret, ret = 0) {
57 ret = read(fd, out + i, len - i);
58 if (ret <= 0) {
59 ret = errno ? -errno : -EIO;
60 break;
61 }
62 }
63 close(fd);
64 errno = -ret;
65 return i == len;
66 }
67 #else
68 #include <ntsecapi.h>
get_random_bytes(uint8_t * out,size_t len)69 static inline bool __attribute__((__warn_unused_result__)) get_random_bytes(uint8_t *out, size_t len)
70 {
71 return RtlGenRandom(out, len);
72 }
73 #endif
74
genkey_main(int argc,const char * argv[])75 int genkey_main(int argc, const char *argv[])
76 {
77 uint8_t key[WG_KEY_LEN];
78 char base64[WG_KEY_LEN_BASE64];
79 struct stat stat;
80
81 if (argc != 1) {
82 fprintf(stderr, "Usage: %s %s\n", PROG_NAME, argv[0]);
83 return 1;
84 }
85
86 if (!fstat(STDOUT_FILENO, &stat) && S_ISREG(stat.st_mode) && stat.st_mode & S_IRWXO)
87 fputs("Warning: writing to world accessible file.\nConsider setting the umask to 077 and trying again.\n", stderr);
88
89 if (!get_random_bytes(key, WG_KEY_LEN)) {
90 perror("getrandom");
91 return 1;
92 }
93 if (!strcmp(argv[0], "genkey"))
94 curve25519_clamp_secret(key);
95
96 key_to_base64(base64, key);
97 puts(base64);
98 return 0;
99 }
100