1 /* 2 * Copyright (c) 2010 Philip Guenther <guenther@openbsd.org> 3 * 4 * Public domain. 5 * 6 * Verify that mkstemp() and mkstemps() doesn't overrun or underrun 7 * the template buffer and that it can generate names that don't 8 * contain any X's 9 */ 10 11 #include <sys/types.h> 12 #include <sys/mman.h> 13 #include <sys/stat.h> 14 15 #include <err.h> 16 #include <errno.h> 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <string.h> 20 #include <limits.h> 21 #include <unistd.h> 22 23 #define MAX_TEMPLATE_LEN 10 24 #define MAX_TRIES 100 25 #define MIN_Xs 6 26 27 #define SUFFIX ".suff" 28 #define SLEN (sizeof SUFFIX - 1) 29 30 long pg; 31 32 /* 33 * verify that a path generated by mkstemp() or mkstemp() looks like a 34 * reasonable expansion of the template and matches the fd. Returns true 35 * if all the X's were replaced with non-X's 36 */ 37 int 38 check(int fd, char const *path, char const *prefix, size_t plen, 39 char const *suffix, size_t slen, int tlen) 40 { 41 struct stat sb, fsb; 42 char const *p; 43 44 if (tlen < MIN_Xs) { 45 if (fd >= 0) 46 errx(1, "mkstemp(%s) succeed with too few Xs", path); 47 if (errno != EINVAL) 48 err(1, "mkstemp(%s) failed with wrong errno", path); 49 return 1; 50 } 51 if (fd < 0) 52 err(1, "mkstemp(%s)", path); 53 if (stat(path, &sb)) 54 err(1, "stat(%s)", path); 55 if (fstat(fd, &fsb)) 56 err(1, "fstat(%d==%s)", fd, path); 57 if (sb.st_dev != fsb.st_dev || sb.st_ino != fsb.st_ino) 58 errx(1, "stat mismatch"); 59 close(fd); 60 if (memcmp(path, prefix, plen) != 0) 61 errx(1, "prefix changed! %s vs %s", prefix, path); 62 if (memcmp(path + plen + tlen, suffix, slen + 1) != 0) 63 errx(1, "suffix changed! %s vs %s", suffix, path); 64 for (p = path + plen; p < path + plen + tlen; p++) 65 if (*p == '\0') 66 errx(1, "unexpected truncation"); 67 else if (*p == 'X') 68 return 0; 69 return 1; 70 } 71 72 73 void 74 try_mkstemp(char *p, char const *prefix, int len) 75 { 76 char *q; 77 size_t plen = strlen(prefix); 78 int tries, fd; 79 80 for (tries = 0; tries < MAX_TRIES; tries++) { 81 memcpy(p, prefix, plen); 82 memset(p + plen, 'X', len); 83 p[plen + len] = '\0'; 84 fd = mkstemp(p); 85 if (check(fd, p, prefix, plen, "", 0, len)) 86 return; 87 } 88 errx(1, "exceeded MAX_TRIES"); 89 } 90 91 void 92 try_mkstemps(char *p, char const *prefix, int len, char const *suffix) 93 { 94 char *q; 95 size_t plen = strlen(prefix); 96 size_t slen = strlen(suffix); 97 int tries, fd; 98 99 for (tries = 0; tries < MAX_TRIES; tries++) { 100 memcpy(p, prefix, plen); 101 memset(p + plen, 'X', len); 102 memcpy(p + plen + len, suffix, slen + 1); 103 fd = mkstemps(p, slen); 104 if (check(fd, p, prefix, plen, suffix, slen, len)) 105 return; 106 } 107 errx(1, "exceeded MAX_TRIES"); 108 } 109 110 int 111 main(void) 112 { 113 struct stat sb, fsb; 114 char cwd[PATH_MAX + 1]; 115 char *p; 116 size_t clen; 117 int i; 118 119 pg = sysconf(_SC_PAGESIZE); 120 if (getcwd(cwd, sizeof cwd - 1) == NULL) 121 err(1, "getcwd"); 122 clen = strlen(cwd); 123 cwd[clen++] = '/'; 124 cwd[clen] = '\0'; 125 p = mmap(NULL, pg * 3, PROT_READ | PROT_WRITE, MAP_ANON, -1, 0); 126 if (p == MAP_FAILED) 127 err(1, "mmap"); 128 if (mprotect(p, pg, PROT_NONE) || mprotect(p + pg * 2, pg, PROT_NONE)) 129 err(1, "mprotect"); 130 p += pg; 131 132 i = MAX_TEMPLATE_LEN + 1; 133 while (i-- > 0) { 134 /* try first at the start of a page, no prefix */ 135 try_mkstemp(p, "", i); 136 /* now at the end of the page, no prefix */ 137 try_mkstemp(p + pg - i - 1, "", i); 138 /* start of the page, prefixed with the cwd */ 139 try_mkstemp(p, cwd, i); 140 /* how about at the end of the page, prefixed with cwd? */ 141 try_mkstemp(p + pg - clen - i - 1, cwd, i); 142 143 /* again, with mkstemps() and an empty suffix */ 144 /* try first at the start of a page, no prefix */ 145 try_mkstemps(p, "", i, ""); 146 /* now at the end of the page, no prefix */ 147 try_mkstemps(p + pg - i - 1, "", i, ""); 148 /* start of the page, prefixed with the cwd */ 149 try_mkstemps(p, cwd, i, ""); 150 /* how about at the end of the page, prefixed with cwd? */ 151 try_mkstemps(p + pg - clen - i - 1, cwd, i, ""); 152 153 /* mkstemps() and a non-empty suffix */ 154 /* try first at the start of a page, no prefix */ 155 try_mkstemps(p, "", i, SUFFIX); 156 /* now at the end of the page, no prefix */ 157 try_mkstemps(p + pg - i - SLEN - 1, "", i, SUFFIX); 158 /* start of the page, prefixed with the cwd */ 159 try_mkstemps(p, cwd, i, SUFFIX); 160 /* how about at the end of the page, prefixed with cwd? */ 161 try_mkstemps(p + pg - clen - i - SLEN - 1, cwd, i, SUFFIX); 162 163 } 164 165 return 0; 166 } 167