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Diffstat (limited to '')
| -rw-r--r-- | lib/iolog/iolog_nextid.c | 151 |
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); +} |