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-rw-r--r--src/preserve_fds.c222
1 files changed, 222 insertions, 0 deletions
diff --git a/src/preserve_fds.c b/src/preserve_fds.c
new file mode 100644
index 0000000..1de01ad
--- /dev/null
+++ b/src/preserve_fds.c
@@ -0,0 +1,222 @@
+/*
+ * Copyright (c) 2013-2015 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/types.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#include "sudo.h"
+
+/*
+ * Add an fd to preserve.
+ */
+int
+add_preserved_fd(struct preserved_fd_list *pfds, int fd)
+{
+ struct preserved_fd *pfd, *pfd_new;
+ debug_decl(add_preserved_fd, SUDO_DEBUG_UTIL)
+
+ pfd_new = malloc(sizeof(*pfd));
+ if (pfd_new == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ pfd_new->lowfd = fd;
+ pfd_new->highfd = fd;
+ pfd_new->flags = fcntl(fd, F_GETFD);
+ if (pfd_new->flags == -1) {
+ free(pfd_new);
+ debug_return_int(-1);
+ }
+
+ TAILQ_FOREACH(pfd, pfds, entries) {
+ if (fd == pfd->highfd) {
+ /* already preserved */
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "fd %d already preserved", fd);
+ free(pfd_new);
+ pfd_new = NULL;
+ break;
+ }
+ if (fd < pfd->highfd) {
+ TAILQ_INSERT_BEFORE(pfd, pfd_new, entries);
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "preserving fd %d", fd);
+ pfd_new = NULL;
+ break;
+ }
+ }
+ if (pfd_new != NULL) {
+ TAILQ_INSERT_TAIL(pfds, pfd_new, entries);
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "preserving fd %d", fd);
+ }
+
+ debug_return_int(0);
+}
+
+/*
+ * Close all descriptors, startfd and higher except those listed
+ * in pfds.
+ */
+void
+closefrom_except(int startfd, struct preserved_fd_list *pfds)
+{
+ int fd, lastfd = -1;
+ struct preserved_fd *pfd, *pfd_next;
+ unsigned char *fdbits;
+ debug_decl(closefrom_except, SUDO_DEBUG_UTIL)
+
+ /* First, relocate preserved fds to be as contiguous as possible. */
+ TAILQ_FOREACH_REVERSE_SAFE(pfd, pfds, preserved_fd_list, entries, pfd_next) {
+ if (pfd->highfd < startfd)
+ continue;
+ fd = dup(pfd->highfd);
+ if (fd == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
+ "dup %d", pfd->highfd);
+ if (errno == EBADF) {
+ TAILQ_REMOVE(pfds, pfd, entries);
+ continue;
+ }
+ /* NOTE: still need to adjust lastfd below with unchanged lowfd. */
+ } else if (fd < pfd->highfd) {
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "dup %d -> %d", pfd->highfd, pfd->lowfd);
+ sudo_debug_update_fd(pfd->highfd, pfd->lowfd);
+ pfd->lowfd = fd;
+ fd = pfd->highfd;
+ }
+ if (fd != -1)
+ (void) close(fd);
+
+ if (pfd->lowfd > lastfd)
+ lastfd = pfd->lowfd; /* highest (relocated) preserved fd */
+ }
+
+ if (lastfd == -1) {
+ /* No fds to preserve. */
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "closefrom(%d)", startfd);
+ closefrom(startfd);
+ debug_return;
+ }
+
+ /* Create bitmap of preserved (relocated) fds. */
+ fdbits = calloc((lastfd + NBBY) / NBBY, 1);
+ if (fdbits == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ TAILQ_FOREACH(pfd, pfds, entries) {
+ sudo_setbit(fdbits, pfd->lowfd);
+ }
+
+ /*
+ * Close any unpreserved fds [startfd,lastfd]
+ */
+ for (fd = startfd; fd <= lastfd; fd++) {
+ if (!sudo_isset(fdbits, fd)) {
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "closing fd %d", fd);
+#ifdef __APPLE__
+ /* Avoid potential libdispatch crash when we close its fds. */
+ (void) fcntl(fd, F_SETFD, FD_CLOEXEC);
+#else
+ (void) close(fd);
+#endif
+ }
+ }
+ free(fdbits);
+
+ /* Let closefrom() do the rest for us. */
+ if (lastfd + 1 > startfd)
+ startfd = lastfd + 1;
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "closefrom(%d)", startfd);
+ closefrom(startfd);
+
+ /* Restore preserved fds and set flags. */
+ TAILQ_FOREACH_REVERSE(pfd, pfds, preserved_fd_list, entries) {
+ if (pfd->lowfd != pfd->highfd) {
+ if (dup2(pfd->lowfd, pfd->highfd) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "dup2(%d, %d): %s", pfd->lowfd, pfd->highfd,
+ strerror(errno));
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "dup2(%d, %d)", pfd->lowfd, pfd->highfd);
+ }
+ if (fcntl(pfd->highfd, F_SETFD, pfd->flags) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "fcntl(%d, F_SETFD, %d): %s", pfd->highfd,
+ pfd->flags, strerror(errno));
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
+ "fcntl(%d, F_SETFD, %d)", pfd->highfd, pfd->flags);
+ }
+ sudo_debug_update_fd(pfd->lowfd, pfd->highfd);
+ (void) close(pfd->lowfd);
+ pfd->lowfd = pfd->highfd;
+ }
+ }
+ debug_return;
+}
+
+/*
+ * Parse a comma-separated list of fds and add them to preserved_fds.
+ */
+void
+parse_preserved_fds(struct preserved_fd_list *pfds, const char *fdstr)
+{
+ const char *cp = fdstr;
+ long lval;
+ char *ep;
+ debug_decl(parse_preserved_fds, SUDO_DEBUG_UTIL)
+
+ do {
+ errno = 0;
+ lval = strtol(cp, &ep, 10);
+ if (ep == cp || (*ep != ',' && *ep != '\0')) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "unable to parse fd string %s", cp);
+ break;
+ }
+ if ((errno == ERANGE && lval == LONG_MAX) || lval < 0 || lval > INT_MAX) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+ "range error parsing fd string %s", cp);
+ } else {
+ add_preserved_fd(pfds, (int)lval);
+ }
+ cp = ep + 1;
+ } while (*ep != '\0');
+
+ debug_return;
+}