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v1.9.16
plugins/sudoers/timestamp.c
1 275 строк
37 KB
Todd C. Miller
Automatically migrate lecture file path from name-based to uid-based.
22 дек 2023, 19:39
22 дек 2023, 19:39
ad4dc22
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/* * SPDX-License-Identifier: ISC * * Copyright (c) 2014-2023 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 <sys/ioctl.h> #include <stddef.h> #include <stdio.h> #include <stdlib.h> #if defined(HAVE_STDINT_H) # include <stdint.h> #elif defined(HAVE_INTTYPES_H) # include <inttypes.h> #endif #include <string.h> #include <unistd.h> #include <time.h> #include <errno.h> #include <fcntl.h> #include <pwd.h> #include <signal.h> #include <sudoers.h> #include <timestamp.h> #define TIMESTAMP_OPEN_ERROR -1 #define TIMESTAMP_PERM_ERROR -2 /* * Each user has a single time stamp file that contains multiple records. * Records are locked to ensure that changes are serialized. * * The first record is of type TS_LOCKEXCL and is used to gain exclusive * access to create new records. This is a short-term lock and sudo * should not sleep while holding it (or the user will not be able to sudo). * The TS_LOCKEXCL entry must be unlocked before locking the actual record. */ struct ts_cookie { const struct sudoers_context *ctx; char *fname; int fd; bool locked; off_t pos; struct timestamp_entry key; }; static uid_t timestamp_uid = ROOT_UID; static gid_t timestamp_gid = ROOT_GID; uid_t timestamp_get_uid(void) { return timestamp_uid; } /* * Returns true if entry matches key, else false. * We don't match on the sid or actual time stamp. */ static bool ts_match_record(struct timestamp_entry *key, struct timestamp_entry *entry, unsigned int recno) { debug_decl(ts_match_record, SUDOERS_DEBUG_AUTH); if (entry->version != key->version) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u record version mismatch (want %u, got %u)", __func__, recno, key->version, entry->version); debug_return_bool(false); } if (!ISSET(key->flags, TS_ANYUID) && entry->auth_uid != key->auth_uid) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u record uid mismatch (want %u, got %u)", __func__, recno, (unsigned int)key->auth_uid, (unsigned int)entry->auth_uid); debug_return_bool(false); } if (entry->type != key->type) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u record type mismatch (want %u, got %u)", __func__, recno, key->type, entry->type); debug_return_bool(false); } switch (entry->type) { case TS_GLOBAL: /* no ppid or tty to match */ break; case TS_PPID: /* verify parent pid */ if (entry->u.ppid != key->u.ppid) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u record ppid mismatch (want %d, got %d)", __func__, recno, (int)key->u.ppid, (int)entry->u.ppid); debug_return_bool(false); } if (sudo_timespeccmp(&entry->start_time, &key->start_time, !=)) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u ppid start time mismatch", __func__, recno); debug_return_bool(false); } break; case TS_TTY: if (entry->u.ttydev != key->u.ttydev) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u record tty mismatch (want 0x%x, got 0x%x)", __func__, recno, (unsigned int)key->u.ttydev, (unsigned int)entry->u.ttydev); debug_return_bool(false); } if (sudo_timespeccmp(&entry->start_time, &key->start_time, !=)) { sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s:%u session leader start time mismatch", __func__, recno); debug_return_bool(false); } break; default: /* unknown record type, ignore it */ sudo_debug_printf(SUDO_DEBUG_WARN|SUDO_DEBUG_LINENO, "%s:%u unknown time stamp record type %d", __func__, recno, entry->type); debug_return_bool(false); } debug_return_bool(true); } /* * Searches the time stamp file descriptor for a record that matches key. * On success, fills in entry with the matching record and returns true. * On failure, returns false. * * Note that records are searched starting at the current file offset, * which may not be the beginning of the file. */ static bool ts_find_record(int fd, struct timestamp_entry *key, struct timestamp_entry *entry) { struct timestamp_entry cur; unsigned int recno = 0; debug_decl(ts_find_record, SUDOERS_DEBUG_AUTH); /* * Find a matching record (does not match sid or time stamp value). */ while (read(fd, &cur, sizeof(cur)) == sizeof(cur)) { recno++; if (cur.size != sizeof(cur)) { /* wrong size, seek to start of next record */ sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO, "wrong sized record, got %hu, expected %zu", cur.size, sizeof(cur)); if (lseek(fd, (off_t)cur.size - (off_t)sizeof(cur), SEEK_CUR) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "unable to seek forward %zd", cur.size - ssizeof(cur)); break; } if (cur.size == 0) break; /* size must be non-zero */ continue; } if (ts_match_record(key, &cur, recno)) { memcpy(entry, &cur, sizeof(struct timestamp_entry)); debug_return_bool(true); } } debug_return_bool(false); } /* * Create a directory and any missing parent directories with the * specified mode. * Returns an fd usable with the *at() functions on success. * Returns -1 on failure, setting errno. */ static int ts_mkdirs(const char *path, uid_t owner, gid_t group, mode_t mode, mode_t parent_mode, bool quiet) { int parentfd, fd = -1; const char *base; mode_t omask; debug_decl(ts_mkdirs, SUDOERS_DEBUG_AUTH); /* Child directory we will create. */ base = sudo_basename(path); /* umask must not be more restrictive than the file modes. */ omask = umask(ACCESSPERMS & ~(mode|parent_mode)); parentfd = sudo_open_parent_dir(path, owner, group, parent_mode, quiet); if (parentfd != -1) { /* Create final path component. */ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "mkdir %s, mode 0%o, uid %d, gid %d", path, (unsigned int)mode, (int)owner, (int)group); if (mkdirat(parentfd, base, mode) != 0 && errno != EEXIST) { if (!quiet) sudo_warn(U_("unable to mkdir %s"), path); } else { fd = openat(parentfd, base, O_RDONLY|O_NONBLOCK, 0); if (fd == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, "%s: unable to open %s", __func__, path); } else if (fchown(fd, owner, group) != 0) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, "%s: unable to chown %d:%d %s", __func__, (int)owner, (int)group, path); } } close(parentfd); } umask(omask); debug_return_int(fd); } /* * Check that path is owned by timestamp_uid and not writable by * group or other. If path is missing and make_it is true, create * the directory and its parent dirs. * * Returns an fd usable with the *at() functions on success. * Returns -1 on failure, setting errno. */ static int ts_secure_opendir(const char *path, bool make_it, bool quiet) { int error, fd; struct stat sb; debug_decl(ts_secure_opendir, SUDOERS_DEBUG_AUTH); sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO, "checking %s", path); fd = sudo_secure_open_dir(path, timestamp_uid, timestamp_gid, &sb, &error); if (fd == -1) { switch (error) { case SUDO_PATH_MISSING: if (make_it) { fd = ts_mkdirs(path, timestamp_uid, timestamp_gid, S_IRWXU, S_IRWXU|S_IXGRP|S_IXOTH, quiet); if (fd != -1) break; } if (!quiet) sudo_warn("%s", path); break; case SUDO_PATH_BAD_TYPE: errno = ENOTDIR; if (!quiet) sudo_warn("%s", path); break; case SUDO_PATH_WRONG_OWNER: if (!quiet) { sudo_warnx(U_("%s is owned by uid %u, should be %u"), path, (unsigned int)sb.st_uid, (unsigned int)timestamp_uid); } errno = EACCES; break; case SUDO_PATH_WORLD_WRITABLE: if (!quiet) sudo_warnx(U_("%s is world writable"), path); errno = EACCES; break; case SUDO_PATH_GROUP_WRITABLE: if (!quiet) { sudo_warnx(U_("%s is owned by gid %u, should be %u"), path, (unsigned int)sb.st_gid, (unsigned int)timestamp_gid); } errno = EACCES; break; default: if (!quiet) { sudo_warnx("%s: internal error, unexpected error %d", __func__, error); errno = EINVAL; } break; } } debug_return_int(fd); } /* * Open the specified timestamp or lecture file and set the * close on exec flag. * Returns open file descriptor on success. * Returns TIMESTAMP_OPEN_ERROR or TIMESTAMP_PERM_ERROR on error. */ static int ts_openat(int dfd, const char *path, int flags) { bool uid_changed = false; int fd; debug_decl(ts_openat, SUDOERS_DEBUG_AUTH); if (timestamp_uid != 0) uid_changed = set_perms(NULL, PERM_TIMESTAMP); fd = openat(dfd, path, flags, S_IRUSR|S_IWUSR); if (uid_changed && !restore_perms()) { /* Unable to restore permissions, should not happen. */ if (fd != -1) { int serrno = errno; close(fd); errno = serrno; fd = TIMESTAMP_PERM_ERROR; } } if (fd >= 0) (void)fcntl(fd, F_SETFD, FD_CLOEXEC); debug_return_int(fd); } static ssize_t ts_write(const struct sudoers_context *ctx, int fd, const char *fname, struct timestamp_entry *entry, off_t offset) { ssize_t nwritten; off_t old_eof; debug_decl(ts_write, SUDOERS_DEBUG_AUTH); if (offset == -1) { old_eof = lseek(fd, 0, SEEK_CUR); if (old_eof == -1) debug_return_ssize_t(-1); nwritten = write(fd, entry, entry->size); } else { old_eof = offset; nwritten = pwrite(fd, entry, entry->size, offset); } if ((size_t)nwritten != entry->size) { if (nwritten == -1) { log_warning(ctx, SLOG_SEND_MAIL, N_("unable to write to %s"), fname); } else { log_warningx(ctx, SLOG_SEND_MAIL, N_("unable to write to %s"), fname); } /* Truncate on partial write to be safe (assumes end of file). */ if (nwritten > 0) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "short write, truncating partial time stamp record"); if (ftruncate(fd, old_eof) != 0) { sudo_warn(U_("unable to truncate time stamp file to %lld bytes"), (long long)old_eof); } } debug_return_ssize_t(-1); } debug_return_ssize_t(nwritten); } /* * Full in struct timestamp_entry with the specified flags * based on auth user pw. Does not set the time stamp. */ static void ts_init_key(const struct sudoers_context *ctx, struct timestamp_entry *entry, struct passwd *pw, unsigned short flags, enum def_tuple ticket_type) { debug_decl(ts_init_key, SUDOERS_DEBUG_AUTH); memset(entry, 0, sizeof(*entry)); entry->version = TS_VERSION; entry->size = sizeof(*entry); entry->flags = flags; if (pw != NULL) { entry->auth_uid = pw->pw_uid; } else { entry->flags |= TS_ANYUID; } entry->sid = ctx->user.sid; switch (ticket_type) { default: /* Unknown time stamp ticket type, treat as tty (should not happen). */ sudo_warnx("unknown time stamp ticket type %d", ticket_type); FALLTHROUGH; case tty: if (ctx->user.ttydev != (dev_t)-1) { /* tty-based time stamp */ entry->type = TS_TTY; entry->u.ttydev = ctx->user.ttydev; if (entry->sid != -1) get_starttime(entry->sid, &entry->start_time); break; } FALLTHROUGH; case kernel: case ppid: /* ppid-based time stamp */ entry->type = TS_PPID; entry->u.ppid = ctx->user.ppid; get_starttime(entry->u.ppid, &entry->start_time); break; case global: /* global time stamp */ entry->type = TS_GLOBAL; break; } debug_return; } static void ts_init_key_nonglobal(const struct sudoers_context *ctx, struct timestamp_entry *entry, struct passwd *pw, unsigned short flags) { /* * Even if the timestamp type is global or kernel we still want to do * per-tty or per-ppid locking so sudo works predictably in a pipeline. */ ts_init_key(ctx, entry, pw, flags, def_timestamp_type == ppid ? ppid : tty); } /* * Open the user's time stamp file. * Returns a cookie or NULL on error, does not lock the file. */ void * timestamp_open(const struct sudoers_context *ctx) { int tries, len, dfd = -1, fd = -1; char uidstr[STRLEN_MAX_UNSIGNED(uid_t) + 1]; struct ts_cookie *cookie; char *fname = NULL; debug_decl(timestamp_open, SUDOERS_DEBUG_AUTH); /* Zero timeout means don't use the time stamp file. */ if (!sudo_timespecisset(&def_timestamp_timeout)) { errno = ENOENT; goto bad; } /* Check the validity of timestamp dir and create if missing. */ dfd = ts_secure_opendir(def_timestampdir, true, false); if (dfd == -1) goto bad; /* Open time stamp file. */ len = snprintf(uidstr, sizeof(uidstr), "%u", (unsigned int)ctx->user.uid); if (len < 0 || len >= ssizeof(uidstr)) { errno = EINVAL; goto bad; } if (asprintf(&fname, "%s/%s", def_timestampdir, uidstr) == -1) { sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory")); goto bad; } for (tries = 1; ; tries++) { struct stat sb; fd = ts_openat(dfd, uidstr, O_RDWR|O_CREAT); switch (fd) { case TIMESTAMP_OPEN_ERROR: log_warning(ctx, SLOG_SEND_MAIL, N_("unable to open %s"), fname); goto bad; case TIMESTAMP_PERM_ERROR: /* Already logged set_perms/restore_perms error. */ goto bad; } sudo_debug_printf(SUDO_DEBUG_INFO, "%s: opened time stamp file %s", __func__, fname); /* Remove time stamp file if its mtime predates boot time. */ if (tries == 1 && fstat(fd, &sb) == 0) { struct timespec boottime, mtime, now; if (sudo_gettime_real(&now) == 0 && get_boottime(&boottime)) { /* Ignore a boot time that is in the future. */ if (sudo_timespeccmp(&now, &boottime, <)) { sudo_debug_printf(SUDO_DEBUG_WARN|SUDO_DEBUG_LINENO, "ignoring boot time that is in the future"); } else { mtim_get(&sb, mtime); if (sudo_timespeccmp(&mtime, &boottime, <)) { /* Time stamp file too old, remove it. */ sudo_debug_printf(SUDO_DEBUG_WARN|SUDO_DEBUG_LINENO, "removing time stamp file that predates boot time"); close(fd); unlinkat(dfd, uidstr, 0); continue; } } } } break; } /* Allocate and fill in cookie to store state. */ cookie = malloc(sizeof(*cookie)); if (cookie == NULL) { sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory")); goto bad; } cookie->ctx = ctx; cookie->fd = fd; cookie->fname = fname; cookie->pos = -1; close(dfd); debug_return_ptr(cookie); bad: sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, "%s: unable to open time stamp file %s", __func__, fname); if (dfd != -1) close(dfd); if (fd >= 0) close(fd); free(fname); debug_return_ptr(NULL); } static volatile sig_atomic_t got_signal; static void timestamp_handler(int s) { got_signal = s; } /* * Wrapper for sudo_lock_region() that is interruptible. */ static bool timestamp_lock_record(int fd, off_t pos, off_t len) { struct sigaction sa, saveint, savequit; sigset_t mask, omask; bool ret; debug_decl(timestamp_lock_record, SUDOERS_DEBUG_AUTH); if (pos >= 0 && lseek(fd, pos, SEEK_SET) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "unable to seek to %lld", (long long)pos); debug_return_bool(false); } /* Allow SIGINT and SIGQUIT to interrupt a lock. */ got_signal = 0; memset(&sa, 0, sizeof(sa)); sigemptyset(&sa.sa_mask); sa.sa_flags = 0; /* don't restart system calls */ sa.sa_handler = timestamp_handler; (void) sigaction(SIGINT, &sa, &saveint); (void) sigaction(SIGQUIT, &sa, &savequit); sigemptyset(&mask); sigaddset(&mask, SIGINT); sigaddset(&mask, SIGQUIT); (void) sigprocmask(SIG_UNBLOCK, &mask, &omask); ret = sudo_lock_region(fd, SUDO_LOCK, len); if (!ret) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "failed to lock fd %d [%lld, %lld]", fd, (long long)pos, (long long)len); } /* Restore the old mask (SIGINT and SIGQUIT blocked) and handlers. */ (void) sigprocmask(SIG_SETMASK, &omask, NULL); (void) sigaction(SIGINT, &saveint, NULL); (void) sigaction(SIGQUIT, &savequit, NULL); /* Re-deliver the signal that interrupted the lock, if any. */ if (!ret && got_signal) kill(getpid(), got_signal); debug_return_bool(ret); } static bool timestamp_unlock_record(int fd, off_t pos, off_t len) { debug_decl(timestamp_unlock_record, SUDOERS_DEBUG_AUTH); if (pos >= 0 && lseek(fd, pos, SEEK_SET) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "unable to seek to %lld", (long long)pos); debug_return_bool(false); } debug_return_bool(sudo_lock_region(fd, SUDO_UNLOCK, len)); } /* * Seek to the record's position and read it, locking as needed. */ static ssize_t ts_read(struct ts_cookie *cookie, struct timestamp_entry *entry) { ssize_t nread = -1; bool should_unlock = false; debug_decl(ts_read, SUDOERS_DEBUG_AUTH); /* If the record is not already locked, lock it now. */ if (!cookie->locked) { if (!timestamp_lock_record(cookie->fd, cookie->pos, sizeof(*entry))) goto done; should_unlock = true; } /* Seek to the record position and read it. */ nread = pread(cookie->fd, entry, sizeof(*entry), cookie->pos); if (nread != sizeof(*entry)) { /* short read, should not happen */ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, "short read (%zd vs %zu), truncated time stamp file?", nread, sizeof(*entry)); goto done; } sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "read %zd byte record at %lld", nread, (long long)cookie->pos); done: /* If the record was not locked initially, unlock it. */ if (should_unlock) timestamp_unlock_record(cookie->fd, cookie->pos, sizeof(*entry)); debug_return_ssize_t(nread); } /* * Write a TS_LOCKEXCL record at the beginning of the time stamp file. */ static bool timestamp_lock_write(struct ts_cookie *cookie) { struct timestamp_entry entry; bool ret = true; debug_decl(timestamp_lock_write, SUDOERS_DEBUG_AUTH); memset(&entry, 0, sizeof(entry)); entry.version = TS_VERSION; entry.size = sizeof(entry); entry.type = TS_LOCKEXCL; if (ts_write(cookie->ctx, cookie->fd, cookie->fname, &entry, -1) == -1) ret = false; debug_return_bool(ret); } /* * Lock a record in the time stamp file for exclusive access. * If the record does not exist, it is created (as disabled). */ bool timestamp_lock(void *vcookie, struct passwd *pw) { struct ts_cookie *cookie = vcookie; struct timestamp_entry entry; bool overwrite = false; off_t lock_pos; ssize_t nread; debug_decl(timestamp_lock, SUDOERS_DEBUG_AUTH); if (cookie == NULL) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "called with a NULL cookie!"); debug_return_bool(false); } /* * Take a lock on the "write" record (the first record in the file). * This will let us seek for the record or extend as needed * without colliding with anyone else. */ if (!timestamp_lock_record(cookie->fd, 0, sizeof(struct timestamp_entry))) debug_return_bool(false); /* Make sure the first record is of type TS_LOCKEXCL. */ memset(&entry, 0, sizeof(entry)); nread = read(cookie->fd, &entry, sizeof(entry)); if (nread < ssizeof(struct timestamp_entry_v1)) { /* New or invalid time stamp file. */ overwrite = true; } else if (entry.type != TS_LOCKEXCL) { if (entry.size == sizeof(struct timestamp_entry_v1)) { /* Old sudo record, convert it to TS_LOCKEXCL. */ entry.type = TS_LOCKEXCL; memset((char *)&entry + offsetof(struct timestamp_entry, flags), 0, (size_t)nread - offsetof(struct timestamp_entry, flags)); if (ts_write(cookie->ctx, cookie->fd, cookie->fname, &entry, 0) == -1) debug_return_bool(false); } else { /* Corrupted time stamp file? Just overwrite it. */ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "corrupt initial record, type: %hu, size: %hu (expected %zu)", entry.type, entry.size, sizeof(struct timestamp_entry_v1)); overwrite = true; } } if (overwrite) { /* Rewrite existing time stamp file or create new one. */ if (ftruncate(cookie->fd, 0) != 0) { sudo_warn(U_("unable to truncate time stamp file to %lld bytes"), 0LL); debug_return_bool(false); } if (!timestamp_lock_write(cookie)) debug_return_bool(false); } else if (entry.size != sizeof(entry)) { /* Reset position if the lock record has an unexpected size. */ if (lseek(cookie->fd, entry.size, SEEK_SET) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "unable to seek to %hu", entry.size); debug_return_bool(false); } } /* Search for a tty/ppid-based record or append a new one. */ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "searching for %s time stamp record", def_timestamp_type == ppid ? "ppid" : "tty"); ts_init_key_nonglobal(cookie->ctx, &cookie->key, pw, TS_DISABLED); if (ts_find_record(cookie->fd, &cookie->key, &entry)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "found existing %s time stamp record", def_timestamp_type == ppid ? "ppid" : "tty"); lock_pos = lseek(cookie->fd, 0, SEEK_CUR) - (off_t)entry.size; } else { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "appending new %s time stamp record", def_timestamp_type == ppid ? "ppid" : "tty"); lock_pos = lseek(cookie->fd, 0, SEEK_CUR); if (ts_write(cookie->ctx, cookie->fd, cookie->fname, &cookie->key, -1) == -1) debug_return_bool(false); } sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "%s time stamp position is %lld", def_timestamp_type == ppid ? "ppid" : "tty", (long long)lock_pos); if (def_timestamp_type == global) { /* * For global tickets we use a separate record lock that we * cannot hold long-term since it is shared between all ttys. */ cookie->locked = false; cookie->key.type = TS_GLOBAL; /* find a global record */ if (lseek(cookie->fd, 0, SEEK_SET) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO, "unable to rewind fd"); debug_return_bool(false); } if (ts_find_record(cookie->fd, &cookie->key, &entry)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "found existing global record"); cookie->pos = lseek(cookie->fd, 0, SEEK_CUR) - (off_t)entry.size; } else { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "appending new global record"); cookie->pos = lseek(cookie->fd, 0, SEEK_CUR); if (ts_write(cookie->ctx, cookie->fd, cookie->fname, &cookie->key, -1) == -1) debug_return_bool(false); } } else { /* For tty/ppid tickets the tty lock is the same as the record lock. */ cookie->pos = lock_pos; cookie->locked = true; } /* Unlock the TS_LOCKEXCL record. */ timestamp_unlock_record(cookie->fd, 0, sizeof(struct timestamp_entry)); /* Lock the per-tty record (may sleep). */ if (!timestamp_lock_record(cookie->fd, lock_pos, sizeof(struct timestamp_entry))) debug_return_bool(false); debug_return_bool(true); } void timestamp_close(void *vcookie) { struct ts_cookie *cookie = vcookie; debug_decl(timestamp_close, SUDOERS_DEBUG_AUTH); if (cookie != NULL) { close(cookie->fd); free(cookie->fname); free(cookie); } debug_return; } #define TIMESPEC_VALID(ts) \ ((ts)->tv_sec >= 0 && (ts)->tv_nsec >= 0 && (ts)->tv_nsec < 1000000000L) /* * Check the time stamp file and directory and return their status. * Called with the file position before the locked record to read. * Returns one of TS_CURRENT, TS_OLD, TS_MISSING, TS_ERROR, TS_FATAL. * Fills in fdp with an open file descriptor positioned at the * appropriate (and locked) record. */ int timestamp_status(void *vcookie, struct passwd *pw) { struct ts_cookie *cookie = vcookie; struct timestamp_entry entry; struct timespec diff, now; int status = TS_ERROR; /* assume the worst */ ssize_t nread; debug_decl(timestamp_status, SUDOERS_DEBUG_AUTH); /* Zero timeout means don't use time stamp files. */ if (!sudo_timespecisset(&def_timestamp_timeout)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "timestamps disabled"); status = TS_OLD; goto done; } if (cookie == NULL || cookie->pos < 0) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "NULL cookie or invalid position"); status = TS_OLD; goto done; } #ifdef TIOCCHKVERAUTH if (def_timestamp_type == kernel) { int fd = open(_PATH_TTY, O_RDWR); if (fd != -1) { if (ioctl(fd, TIOCCHKVERAUTH) == 0) status = TS_CURRENT; else status = TS_OLD; close(fd); goto done; } } #endif /* Read the record at the correct position. */ if ((nread = ts_read(cookie, &entry)) != sizeof(entry)) goto done; /* Make sure what we read matched the expected record. */ if (entry.version != TS_VERSION || entry.size != nread) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, "invalid time stamp file @ %lld", (long long)cookie->pos); status = TS_OLD; goto done; } /* Sanity check time stamps. */ if (!TIMESPEC_VALID(&entry.start_time) || !TIMESPEC_VALID(&entry.ts)) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO, "invalid timespec in time stamp file @ %lld", (long long)cookie->pos); status = TS_OLD; goto done; } if (ISSET(entry.flags, TS_DISABLED)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "time stamp record disabled"); status = TS_OLD; /* disabled via sudo -k */ goto done; } if (entry.type != TS_GLOBAL && entry.sid != cookie->ctx->user.sid) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "time stamp record sid mismatch"); status = TS_OLD; /* belongs to different session */ goto done; } /* Negative timeouts only expire manually (sudo -k). */ sudo_timespecclear(&diff); if (sudo_timespeccmp(&def_timestamp_timeout, &diff, <)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "time stamp record does not expire"); status = TS_CURRENT; goto done; } /* Compare stored time stamp with current time. */ if (sudo_gettime_mono(&now) == -1) { log_warning(cookie->ctx, 0, N_("unable to read the clock")); status = TS_ERROR; goto done; } sudo_timespecsub(&now, &entry.ts, &diff); if (sudo_timespeccmp(&diff, &def_timestamp_timeout, <)) { status = TS_CURRENT; #if defined(CLOCK_MONOTONIC) || defined(__MACH__) /* A monotonic clock should never run backwards. */ if (diff.tv_sec < 0) { log_warningx(cookie->ctx, SLOG_SEND_MAIL, N_("ignoring time stamp from the future")); status = TS_OLD; SET(entry.flags, TS_DISABLED); (void)ts_write(cookie->ctx, cookie->fd, cookie->fname, &entry, cookie->pos); } #else /* * Check for bogus (future) time in the stampfile. * If diff / 2 > timeout, someone has been fooling with the clock. */ sudo_timespecsub(&entry.ts, &now, &diff); diff.tv_nsec /= 2; if (diff.tv_sec & 1) diff.tv_nsec += 500000000; diff.tv_sec /= 2; while (diff.tv_nsec >= 1000000000) { diff.tv_sec++; diff.tv_nsec -= 1000000000; } if (sudo_timespeccmp(&diff, &def_timestamp_timeout, >)) { time_t tv_sec = (time_t)entry.ts.tv_sec; log_warningx(cookie->ctx, SLOG_SEND_MAIL, N_("time stamp too far in the future: %20.20s"), 4 + ctime(&tv_sec)); status = TS_OLD; SET(entry.flags, TS_DISABLED); (void)ts_write(cookie->ctx, cookie->fd, cookie->fname, &entry, cookie->pos); } #endif /* CLOCK_MONOTONIC */ } else { status = TS_OLD; } done: debug_return_int(status); } /* * Update the time on the time stamp file/dir or create it if necessary. * Returns true on success, false on failure or -1 on setuid failure. */ bool timestamp_update(void *vcookie, struct passwd *pw) { struct ts_cookie *cookie = vcookie; bool ret = false; debug_decl(timestamp_update, SUDOERS_DEBUG_AUTH); /* Zero timeout means don't use time stamp files. */ if (!sudo_timespecisset(&def_timestamp_timeout)) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "timestamps disabled"); goto done; } if (cookie == NULL || cookie->pos < 0) { sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "NULL cookie or invalid position"); goto done; } #ifdef TIOCSETVERAUTH if (def_timestamp_type == kernel) { int fd = open(_PATH_TTY, O_RDWR); if (fd != -1) { int secs = (int)def_timestamp_timeout.tv_sec; if (secs > 0) { if (secs > 3600) secs = 3600; /* OpenBSD limitation */ if (ioctl(fd, TIOCSETVERAUTH, &secs) != 0) sudo_warn("TIOCSETVERAUTH"); } close(fd); goto done; } } #endif /* Update timestamp in key and enable it. */ CLR(cookie->key.flags, TS_DISABLED); if (sudo_gettime_mono(&cookie->key.ts) == -1) { log_warning(cookie->ctx, 0, N_("unable to read the clock")); goto done; } /* Write out the locked record. */ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO, "writing %zu byte record at %lld", sizeof(cookie->key), (long long)cookie->pos); if (ts_write(cookie->ctx, cookie->fd, cookie->fname, &cookie->key, cookie->pos) != -1) ret = true; done: debug_return_bool(ret); } /* * Remove the timestamp entry or file if unlink_it is set. * Returns true on success, false on failure or -1 on setuid failure. * A missing timestamp entry is not considered an error. */ int timestamp_remove(const struct sudoers_context *ctx, bool unlink_it) { struct timestamp_entry key, entry; int len, dfd = -1, fd = -1, ret = true; char uidstr[STRLEN_MAX_UNSIGNED(uid_t) + 1]; char *fname = NULL; debug_decl(timestamp_remove, SUDOERS_DEBUG_AUTH); #ifdef TIOCCLRVERAUTH if (def_timestamp_type == kernel) { fd = open(_PATH_TTY, O_RDWR); if (fd != -1) { ioctl(fd, TIOCCLRVERAUTH); goto done; } } #endif dfd = open(def_timestampdir, O_RDONLY|O_NONBLOCK); if (dfd == -1) { if (errno != ENOENT) ret = -1; goto done; } len = snprintf(uidstr, sizeof(uidstr), "%u", (unsigned int)ctx->user.uid); if (len < 0 || len >= ssizeof(uidstr)) { errno = EINVAL; ret = -1; goto done; } if (asprintf(&fname, "%s/%s", def_timestampdir, uidstr) == -1) { sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory")); ret = -1; goto done; } /* For "sudo -K" simply unlink the time stamp file. */ if (unlink_it) { ret = unlinkat(dfd, uidstr, 0) ? -1 : true; goto done; } /* Open time stamp file and lock it for exclusive access. */ fd = ts_openat(dfd, uidstr, O_RDWR); switch (fd) { case TIMESTAMP_OPEN_ERROR: if (errno != ENOENT) ret = false; goto done; case TIMESTAMP_PERM_ERROR: /* Already logged set_perms/restore_perms error. */ ret = -1; goto done; } /* Lock first record to gain exclusive access. */ if (!timestamp_lock_record(fd, -1, sizeof(struct timestamp_entry))) { sudo_warn(U_("unable to lock time stamp file %s"), fname); ret = -1; goto done; } /* * Find matching entries and invalidate them. */ ts_init_key(ctx, &key, NULL, 0, def_timestamp_type); while (ts_find_record(fd, &key, &entry)) { /* Back up and disable the entry. */ if (!ISSET(entry.flags, TS_DISABLED)) { SET(entry.flags, TS_DISABLED); if (lseek(fd, 0 - (off_t)sizeof(entry), SEEK_CUR) != -1) { if (ts_write(ctx, fd, fname, &entry, -1) == -1) ret = false; } } } done: if (dfd != -1) close(dfd); if (fd >= 0) close(fd); free(fname); debug_return_int(ret); } bool cb_timestampowner(struct sudoers_context *ctx, const char *file, int line, int column, const union sudo_defs_val *sd_un, int op) { struct passwd *pw = NULL; const char *user = sd_un->str; debug_decl(cb_timestampowner, SUDOERS_DEBUG_AUTH); if (*user == '#') { const char *errstr; uid_t uid = sudo_strtoid(user + 1, &errstr); if (errstr == NULL) pw = sudo_getpwuid(uid); } if (pw == NULL) pw = sudo_getpwnam(user); if (pw == NULL) { log_warningx(ctx, SLOG_AUDIT|SLOG_PARSE_ERROR, N_("%s:%d:%d timestampowner: unknown user %s"), file, line, column, user); debug_return_bool(false); } timestamp_uid = pw->pw_uid; timestamp_gid = pw->pw_gid; sudo_pw_delref(pw); debug_return_bool(true); } /* * Returns true if the user has already been lectured. */ bool already_lectured(const struct sudoers_context *ctx) { char uidstr[STRLEN_MAX_UNSIGNED(uid_t) + 1]; bool ret = false; struct stat sb; int dfd, len; debug_decl(already_lectured, SUDOERS_DEBUG_AUTH); /* Check the existence and validity of timestamp dir. */ dfd = ts_secure_opendir(def_lecture_status_dir, false, true); if (dfd == -1) goto done; len = snprintf(uidstr, sizeof(uidstr), "%u", (unsigned int)ctx->user.uid); if (len < 0 || len >= ssizeof(uidstr)) goto done; ret = fstatat(dfd, uidstr, &sb, AT_SYMLINK_NOFOLLOW) == 0; if (!ret && errno == ENOENT && strchr(ctx->user.name, '/') == NULL) { /* No uid-based lecture path, check for username-based path. */ ret = fstatat(dfd, ctx->user.name, &sb, AT_SYMLINK_NOFOLLOW) == 0; if (ret) { /* Migrate lecture file to uid-based path. */ #ifdef HAVE_RENAMEAT if (renameat(dfd, ctx->user.name, dfd, uidstr) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, "%s: unable to rename %s/%s to %s/%s", __func__, def_lecture_status_dir, ctx->user.name, def_lecture_status_dir, uidstr); } #else char from[PATH_MAX], to[PATH_MAX]; len = snprintf(from, sizeof(from), "%s/%s", def_lecture_status_dir, ctx->user.name); if (len < 0 || len >= ssizeof(from)) goto done; len = snprintf(to, sizeof(to), "%s/%s", def_lecture_status_dir, uidstr); if (len < 0 || len >= ssizeof(to)) goto done; if (rename(from, to) == -1) { sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, "%s: unable to rename %s to %s", __func__, from, to); } #endif } } done: if (dfd != -1) close(dfd); debug_return_bool(ret); } /* * Create the lecture status file. * Returns true on success, false on failure or -1 on setuid failure. */ int set_lectured(const struct sudoers_context *ctx) { char uidstr[STRLEN_MAX_UNSIGNED(uid_t) + 1]; int dfd, fd, len, ret = false; debug_decl(set_lectured, SUDOERS_DEBUG_AUTH); /* Check the validity of timestamp dir and create if missing. */ dfd = ts_secure_opendir(def_lecture_status_dir, true, false); if (dfd == -1) goto done; len = snprintf(uidstr, sizeof(uidstr), "%u", (unsigned int)ctx->user.uid); if (len < 0 || len >= ssizeof(uidstr)) goto done; /* Create lecture file. */ fd = ts_openat(dfd, uidstr, O_WRONLY|O_CREAT|O_EXCL); switch (fd) { case TIMESTAMP_OPEN_ERROR: /* Failed to open, not a fatal error. */ break; case TIMESTAMP_PERM_ERROR: /* Already logged set_perms/restore_perms error. */ ret = -1; break; default: /* Success. */ close(fd); ret = true; break; } done: if (dfd != -1) close(dfd); debug_return_int(ret); } #ifdef _PATH_SUDO_ADMIN_FLAG int create_admin_success_flag(const struct sudoers_context *ctx) { struct passwd *pw = ctx->user.pw; char *flagfile; int ret = -1; debug_decl(create_admin_success_flag, SUDOERS_DEBUG_AUTH); /* Is the admin flag file even enabled? */ if (!def_admin_flag) debug_return_int(true); /* Check whether the user is in the sudo or admin group. */ if (!user_in_group(pw, "sudo") && !user_in_group(pw, "admin")) debug_return_int(true); /* Build path to flag file. */ if ((flagfile = strdup(def_admin_flag)) == NULL) { sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory")); debug_return_int(-1); } if (!expand_tilde(&flagfile, pw->pw_name)) { free(flagfile); debug_return_int(false); } /* Create admin flag file if it doesn't already exist. */ if (set_perms(ctx, PERM_USER)) { int fd = open(flagfile, O_CREAT|O_WRONLY|O_NONBLOCK|O_EXCL, 0644); ret = fd != -1 || errno == EEXIST; if (fd != -1) close(fd); if (!restore_perms()) ret = -1; } free(flagfile); debug_return_int(ret); } #else /* !_PATH_SUDO_ADMIN_FLAG */ int create_admin_success_flag(const struct sudoers_context *ctx) { /* STUB */ return true; } #endif /* _PATH_SUDO_ADMIN_FLAG */