/* $OpenBSD: mktemp.c,v 1.4 2019/02/16 17:59:33 deraadt Exp $ */ /* * Copyright (c) 1996-1998, 2008 Theo de Raadt * Copyright (c) 1997, 2008-2009 Todd C. Miller * Copyright (c) 2019 Florian Obser * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include #include #include #include #include #include #include #include #include #define MKTEMP_NAME 0 #define MKTEMP_FILE 1 #define MKTEMP_DIR 2 #define MKTEMP_LINK 3 #define MKTEMP_FIFO 4 #define MKTEMP_NOD 5 #define MKTEMP_SOCK 6 #define TEMPCHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" #define NUM_CHARS (sizeof(TEMPCHARS) - 1) #define MIN_X 6 #define MKOTEMP_FLAGS (O_APPEND | O_CLOEXEC | O_DSYNC | O_RSYNC | O_SYNC) #ifndef nitems #define nitems(_a) (sizeof((_a)) / sizeof((_a)[0])) #endif /* adapted from libc/stdio/mktemp.c */ static int mktemp_internalat(int pfd, char *path, int slen, int mode, int flags, const char *link, mode_t dev_type, dev_t dev) { char *start, *cp, *ep; const char tempchars[] = TEMPCHARS; unsigned int tries; struct stat sb; struct sockaddr_un sun; size_t len; int fd, saved_errno; len = strlen(path); if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) { errno = EINVAL; return(-1); } ep = path + len - slen; for (start = ep; start > path && start[-1] == 'X'; start--) ; if (ep - start < MIN_X) { errno = EINVAL; return(-1); } if (flags & ~MKOTEMP_FLAGS) { errno = EINVAL; return(-1); } flags |= O_CREAT | O_EXCL | O_RDWR; tries = INT_MAX; do { cp = start; do { unsigned short rbuf[16]; unsigned int i; /* * Avoid lots of arc4random() calls by using * a buffer sized for up to 16 Xs at a time. */ arc4random_buf(rbuf, sizeof(rbuf)); for (i = 0; i < nitems(rbuf) && cp != ep; i++) *cp++ = tempchars[rbuf[i] % NUM_CHARS]; } while (cp != ep); switch (mode) { case MKTEMP_NAME: if (fstatat(pfd, path, &sb, AT_SYMLINK_NOFOLLOW) != 0) return(errno == ENOENT ? 0 : -1); break; case MKTEMP_FILE: fd = openat(pfd, path, flags, S_IRUSR|S_IWUSR); if (fd != -1 || errno != EEXIST) return(fd); break; case MKTEMP_DIR: if (mkdirat(pfd, path, S_IRUSR|S_IWUSR|S_IXUSR) == 0) return(0); if (errno != EEXIST) return(-1); break; case MKTEMP_LINK: if (symlinkat(link, pfd, path) == 0) return(0); else if (errno != EEXIST) return(-1); break; case MKTEMP_FIFO: if (mkfifoat(pfd, path, S_IRUSR|S_IWUSR) == 0) return(0); else if (errno != EEXIST) return(-1); break; case MKTEMP_NOD: if (!(dev_type == S_IFCHR || dev_type == S_IFBLK)) { errno = EINVAL; return(-1); } if (mknodat(pfd, path, S_IRUSR|S_IWUSR|dev_type, dev) == 0) return(0); else if (errno != EEXIST) return(-1); break; case MKTEMP_SOCK: memset(&sun, 0, sizeof(sun)); sun.sun_family = AF_UNIX; if ((len = strlcpy(sun.sun_path, link, sizeof(sun.sun_path))) >= sizeof(sun.sun_path)) { errno = EINVAL; return(-1); } if (sun.sun_path[len] != '/') { if (strlcat(sun.sun_path, "/", sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) { errno = EINVAL; return(-1); } } if (strlcat(sun.sun_path, path, sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) { errno = EINVAL; return(-1); } if ((fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0)) == -1) return -1; if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == 0) { close(fd); return(0); } else if (errno != EEXIST) { saved_errno = errno; close(fd); errno = saved_errno; return -1; } close(fd); break; } } while (--tries); errno = EEXIST; return(-1); } /* * A combination of mkstemp(3) and openat(2). * On success returns a file descriptor and trailing Xs are overwritten in * path to create a unique file name. * Returns -1 on failure. */ int mkstempat(int fd, char *path) { return(mktemp_internalat(fd, path, 0, MKTEMP_FILE, 0, NULL, 0, 0)); } /* * A combination of mkstemp(3) and symlinkat(2). * On success returns path with trailing Xs overwritten to create a unique * file name. * Returns NULL on failure. */ char* mkstemplinkat(char *link, int fd, char *path) { if (mktemp_internalat(fd, path, 0, MKTEMP_LINK, 0, link, 0, 0) == -1) return(NULL); return(path); } /* * A combination of mkstemp(3) and mkfifoat(2). * On success returns path with trailing Xs overwritten to create a unique * file name. * Returns NULL on failure. */ char* mkstempfifoat(int fd, char *path) { if (mktemp_internalat(fd, path, 0, MKTEMP_FIFO, 0, NULL, 0, 0) == -1) return(NULL); return(path); } /* * A combination of mkstemp(3) and mknodat(2). * On success returns path with trailing Xs overwritten to create a unique * file name. * Returns NULL on failure. */ char* mkstempnodat(int fd, char *path, mode_t mode, dev_t dev) { if (mktemp_internalat(fd, path, 0, MKTEMP_NOD, 0, NULL, mode, dev) == -1) return(NULL); return(path); } /* * A combination of mkstemp(3) and bind(2) on a unix domain socket. * On success returns path with trailing Xs overwritten to create a unique * file name. * Returns NULL on failure. */ char* mkstempsock(const char *root, char *path) { if (mktemp_internalat(0, path, 0, MKTEMP_SOCK, 0, root, 0, 0) == -1) return(NULL); return(path); } /* * Turn path into a suitable template for mkstemp*at functions and * place it into the newly allocated string returned in ret. * The caller must free ret. * Returns -1 on failure or number of characters output to ret * (excluding the final '\0'). */ int mktemplate(char **ret, const char *path, int recursive) { int n, dirlen; const char *cp; if (recursive && (cp = strrchr(path, '/')) != NULL) { dirlen = cp - path; if ((n = asprintf(ret, "%.*s/.%s.XXXXXXXXXX", dirlen, path, path + dirlen + 1)) == -1) *ret = NULL; } else { if ((n = asprintf(ret, ".%s.XXXXXXXXXX", path)) == -1) *ret = NULL; } return(n); }