119 lines
2.7 KiB
C
119 lines
2.7 KiB
C
/* $OpenBSD: shm_open.c,v 1.9 2017/09/10 18:20:00 guenther Exp $ */
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/*
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* Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <sha2.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/* SHA256_DIGEST_STRING_LENGTH includes nul */
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/* "/tmp/" + sha256 + ".shm" */
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#define SHM_PATH_SIZE (5 + SHA256_DIGEST_STRING_LENGTH + 4)
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/* O_CLOEXEC and O_NOFOLLOW are extensions to POSIX */
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#define OK_FLAGS (O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC | O_NOFOLLOW)
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static void
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makeshmpath(const char *origpath, char *shmpath, size_t len)
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{
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char buf[SHA256_DIGEST_STRING_LENGTH];
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SHA256Data(origpath, strlen(origpath), buf);
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snprintf(shmpath, len, "/tmp/%s.shm", buf);
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}
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int
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shm_open(const char *path, int flags, mode_t mode)
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{
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char shmpath[SHM_PATH_SIZE];
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struct stat sb;
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int fd;
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if (((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
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|| (flags & ~(O_ACCMODE | OK_FLAGS))) {
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errno = EINVAL;
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return -1;
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}
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flags |= O_CLOEXEC | O_NOFOLLOW;
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mode = mode & 0600;
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makeshmpath(path, shmpath, sizeof(shmpath));
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fd = HIDDEN(open)(shmpath, flags, mode);
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if (fd == -1)
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return -1;
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if (fstat(fd, &sb) == -1 || !S_ISREG(sb.st_mode)) {
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HIDDEN(close)(fd);
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errno = EINVAL;
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return -1;
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}
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if (sb.st_uid != geteuid()) {
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HIDDEN(close)(fd);
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errno = EPERM;
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return -1;
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}
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return fd;
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}
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DEF_WEAK(shm_open);
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int
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shm_unlink(const char *path)
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{
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char shmpath[SHM_PATH_SIZE];
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makeshmpath(path, shmpath, sizeof(shmpath));
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return unlink(shmpath);
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}
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int
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shm_mkstemp(char *template)
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{
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size_t templatelen;
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char *t;
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int i, fd;
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templatelen = strlen(template);
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t = malloc(templatelen + 1);
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if (!t)
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return -1;
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t[templatelen] = '\0';
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fd = -1;
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for (i = 0; i < INT_MAX; i++) {
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memcpy(t, template, templatelen);
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if (!_mktemp(t))
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break;
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fd = shm_open(t, O_RDWR | O_EXCL | O_CREAT, 0600);
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if (fd != -1) {
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memcpy(template, t, templatelen);
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break;
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}
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}
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free(t);
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return fd;
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}
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