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-rw-r--r--lib/iolog/iolog_nextid.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/lib/iolog/iolog_nextid.c b/lib/iolog/iolog_nextid.c
new file mode 100644
index 0000000..8977a35
--- /dev/null
+++ b/lib/iolog/iolog_nextid.c
@@ -0,0 +1,151 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * 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.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# include "compat/stdbool.h"
+#endif
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#include "sudo_compat.h"
+#include "sudo_debug.h"
+#include "sudo_fatal.h"
+#include "sudo_gettext.h"
+#include "sudo_iolog.h"
+#include "sudo_util.h"
+
+/*
+ * Read the on-disk sequence number, set sessid to the next
+ * number, and update the on-disk copy.
+ * Uses file locking to avoid sequence number collisions.
+ */
+bool
+iolog_nextid(const char *iolog_dir, char sessid[7])
+{
+ char buf[32], *ep;
+ int i, fd = -1;
+ unsigned long id = 0;
+ size_t len;
+ ssize_t nread;
+ bool ret = false;
+ char pathbuf[PATH_MAX];
+ static const char b36char[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ const uid_t iolog_uid = iolog_get_uid();
+ const gid_t iolog_gid = iolog_get_gid();
+ debug_decl(iolog_nextid, SUDO_DEBUG_UTIL);
+
+ /*
+ * Create I/O log directory if it doesn't already exist.
+ */
+ len = strlcpy(pathbuf, iolog_dir, sizeof(pathbuf));
+ if (len >= sizeof(pathbuf)) {
+ errno = ENAMETOOLONG;
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: %s", __func__, iolog_dir);
+ goto done;
+ }
+ if (!iolog_mkdirs(pathbuf))
+ goto done;
+
+ /*
+ * Open sequence file
+ */
+ len = strlcat(pathbuf, "/seq", sizeof(pathbuf));
+ if (len >= sizeof(pathbuf)) {
+ errno = ENAMETOOLONG;
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: %s/seq", __func__, iolog_dir);
+ goto done;
+ }
+ fd = iolog_openat(AT_FDCWD, pathbuf, O_RDWR|O_CREAT);
+ if (fd == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to open %s", __func__, pathbuf);
+ goto done;
+ }
+ if (!sudo_lock_file(fd, SUDO_LOCK)) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "unable to lock %s", pathbuf);
+ goto done;
+ }
+ if (fchown(fd, iolog_uid, iolog_gid) != 0) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to fchown %d:%d %s", __func__,
+ (int)iolog_uid, (int)iolog_gid, pathbuf);
+ }
+
+ /* Read current seq number (base 36). */
+ nread = read(fd, buf, sizeof(buf) - 1);
+ if (nread != 0) {
+ if (nread == -1) {
+ goto done;
+ }
+ if (buf[nread - 1] == '\n')
+ nread--;
+ buf[nread] = '\0';
+ id = strtoul(buf, &ep, 36);
+ if (ep == buf || *ep != '\0' || id >= iolog_get_maxseq()) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "%s: bad sequence number: %s", pathbuf, buf);
+ id = 0;
+ }
+ }
+ id++;
+
+ /*
+ * Convert id to a string and stash in sessid.
+ * Note that that least significant digits go at the end of the string.
+ */
+ for (i = 5; i >= 0; i--) {
+ buf[i] = b36char[id % 36];
+ id /= 36;
+ }
+ buf[6] = '\n';
+
+ /* Stash id for logging purposes. */
+ memcpy(sessid, buf, 6);
+ sessid[6] = '\0';
+
+ /* Rewind and overwrite old seq file, including the NUL byte. */
+ if (pwrite(fd, buf, 7, 0) != 7) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to write %s", __func__, pathbuf);
+ goto done;
+ }
+ ret = true;
+
+done:
+ if (fd != -1)
+ close(fd);
+ debug_return_bool(ret);
+}