@@ -1,5 +1,6 @@
/* Temporary file handling for tests.
Copyright (C) 1998-2022 Free Software Foundation, Inc.
+ Copyright The GNU Tools Authors.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -20,15 +21,17 @@
some 32-bit platforms. */
#define _FILE_OFFSET_BITS 64
+#include <support/check.h>
#include <support/temp_file.h>
#include <support/temp_file-internal.h>
#include <support/support.h>
+#include <errno.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
-#include <unistd.h>
+#include <xunistd.h>
/* List of temporary files. */
static struct temp_name_list
@@ -36,14 +39,20 @@ static struct temp_name_list
struct temp_name_list *next;
char *name;
pid_t owner;
+ bool toolong;
} *temp_name_list;
/* Location of the temporary files. Set by the test skeleton via
support_set_test_dir. The string is not be freed. */
static const char *test_dir = _PATH_TMP;
-void
-add_temp_file (const char *name)
+/* Name of subdirectories in a too long temporary directory tree. */
+static char toolong_subdir[NAME_MAX + 1];
+static bool toolong_initialized;
+static size_t toolong_path_max;
+
+static void
+add_temp_file_internal (const char *name, bool toolong)
{
struct temp_name_list *newp
= (struct temp_name_list *) xcalloc (sizeof (*newp), 1);
@@ -53,12 +62,19 @@ add_temp_file (const char *name)
newp->name = newname;
newp->next = temp_name_list;
newp->owner = getpid ();
+ newp->toolong = toolong;
temp_name_list = newp;
}
else
free (newp);
}
+void
+add_temp_file (const char *name)
+{
+ add_temp_file_internal (name, false);
+}
+
int
create_temp_file_in_dir (const char *base, const char *dir, char **filename)
{
@@ -90,8 +106,8 @@ create_temp_file (const char *base, char **filename)
return create_temp_file_in_dir (base, test_dir, filename);
}
-char *
-support_create_temp_directory (const char *base)
+static char *
+create_temp_directory_internal (const char *base, bool toolong)
{
char *path = xasprintf ("%s/%sXXXXXX", test_dir, base);
if (mkdtemp (path) == NULL)
@@ -99,16 +115,145 @@ support_create_temp_directory (const char *base)
printf ("error: mkdtemp (\"%s\"): %m", path);
exit (1);
}
- add_temp_file (path);
+ add_temp_file_internal (path, toolong);
return path;
}
-/* Helper functions called by the test skeleton follow. */
+char *
+support_create_temp_directory (const char *base)
+{
+ return create_temp_directory_internal (base, false);
+}
+
+static void
+ensure_toolong_initialized (void)
+{
+ if (!toolong_initialized)
+ FAIL_EXIT1 ("uninitialized toolong directory tree\n");
+}
+
+static void
+initialize_toolong (const char *base)
+{
+ long name_max = pathconf (base, _PC_NAME_MAX);
+ name_max = (name_max < 0 ? 64
+ : (name_max < sizeof (toolong_subdir) ? name_max
+ : sizeof (toolong_subdir) - 1));
+
+ long path_max = pathconf (base, _PC_PATH_MAX);
+ path_max = (path_max < 0 ? 1024
+ : path_max <= PTRDIFF_MAX ? path_max : PTRDIFF_MAX);
+
+ /* Sanity check to ensure that the test does not create temporary directories
+ in different filesystems because this API doesn't support it. */
+ if (toolong_initialized)
+ {
+ if (name_max != strlen (toolong_subdir))
+ FAIL_UNSUPPORTED ("name_max: Temporary directories in different"
+ " filesystems not supported yet\n");
+ if (path_max != toolong_path_max)
+ FAIL_UNSUPPORTED ("path_max: Temporary directories in different"
+ " filesystems not supported yet\n");
+ return;
+ }
+
+ toolong_path_max = path_max;
+
+ size_t len = name_max;
+ memset (toolong_subdir, 'X', len);
+
+ /* Some broken filesystems lie about NAME_MAX, so try to arrive at a size
+ that actually works and if we don't find one, bail out. */
+ int ret;
+ do
+ {
+ toolong_subdir[len] = '\0';
+ ret = mkdir (toolong_subdir, S_IRWXU);
+ }
+ while (ret != 0 && errno == ENAMETOOLONG && (len = len - 8) > 8);
+
+ if (ret != 0)
+ FAIL_EXIT1 ("Unable to create a directory tree\n");
+
+ xchdir (toolong_subdir);
+ toolong_initialized = true;
+}
+
+char *
+support_create_and_chdir_toolong_temp_directory (const char *basename)
+{
+ char *base = create_temp_directory_internal (basename, true);
+ xchdir (base);
+
+ initialize_toolong (base);
+
+ size_t sz = strlen (toolong_subdir);
+
+ /* Create directories and descend into them so that the final path is larger
+ than PATH_MAX. */
+ size_t max = toolong_path_max / sz;
+ for (size_t i = 0; i <= max; i++)
+ {
+ xmkdir (toolong_subdir, S_IRWXU);
+ xchdir (toolong_subdir);
+ }
+ return base;
+}
void
-support_set_test_dir (const char *path)
+support_chdir_toolong_temp_directory (const char *base)
{
- test_dir = path;
+ ensure_toolong_initialized ();
+
+ xchdir (base);
+
+ size_t sz = strlen (toolong_subdir);
+ size_t max = toolong_path_max / sz + 1;
+ for (size_t i = 0; i <= max; i++)
+ xchdir (toolong_subdir);
+}
+
+/* Helper functions called by the test skeleton follow. */
+
+static void
+remove_toolong_subdirs (const char *base)
+{
+ ensure_toolong_initialized ();
+
+ if (chdir (base) != 0)
+ {
+ printf ("warning: toolong cleanup base failed: chdir (\"%s\"): %m\n",
+ base);
+ return;
+ }
+
+ /* Descend. */
+ int levels = 0;
+ size_t sz = strlen (toolong_subdir);
+ size_t max = toolong_path_max / sz + 1;
+ for (levels = 0; levels <= max; levels++)
+ if (chdir (toolong_subdir) != 0)
+ {
+ printf ("warning: toolong cleanup failed: chdir (\"%s\"): %m\n",
+ toolong_subdir);
+ return;
+ }
+
+ /* Ascend and remove. */
+ while (--levels >= 0)
+ {
+ if (chdir ("..") != 0)
+ {
+ printf ("warning: toolong cleanup failed: chdir (\"..\"): %m\n");
+ return;
+ }
+ if (remove (toolong_subdir) != 0)
+ {
+ printf ("warning: could not remove subdirectory: %s: %m\n",
+ toolong_subdir);
+ return;
+ }
+ }
}
void
@@ -123,6 +268,9 @@ support_delete_temp_files (void)
around, to prevent PID reuse.) */
if (temp_name_list->owner == pid)
{
+ if (temp_name_list->toolong)
+ remove_toolong_subdirs (temp_name_list->name);
+
if (remove (temp_name_list->name) != 0)
printf ("warning: could not remove temporary file: %s: %m\n",
temp_name_list->name);
@@ -147,3 +295,9 @@ support_print_temp_files (FILE *f)
fprintf (f, ")\n");
}
}
+
+void
+support_set_test_dir (const char *path)
+{
+ test_dir = path;
+}
@@ -44,6 +44,15 @@ int create_temp_file_in_dir (const char *base, const char *dir,
returns. The caller should free this string. */
char *support_create_temp_directory (const char *base);
+/* Create a temporary directory tree that is longer than PATH_MAX and schedule
+ it for deletion. BASENAME is used as a prefix for the unique directory
+ name, which the function returns. The caller should free this string. */
+char *support_create_and_chdir_toolong_temp_directory (const char *basename);
+
+/* Change into the innermost directory of the directory tree BASE, which was
+ created using support_create_and_chdir_toolong_temp_directory. */
+void support_chdir_toolong_temp_directory (const char *base);
+
__END_DECLS
#endif /* SUPPORT_TEMP_FILE_H */
@@ -187,6 +187,13 @@ __getcwd_generic (char *buf, size_t size)
size_t allocated = size;
size_t used;
+ /* A size of 1 byte is never useful. */
+ if (allocated == 1)
+ {
+ __set_errno (ERANGE);
+ return NULL;
+ }
+
#if HAVE_MINIMALLY_WORKING_GETCWD
/* If AT_FDCWD is not defined, the algorithm below is O(N**2) and
this is much slower than the system getcwd (at least on
@@ -346,7 +346,12 @@ sysdep_routines += xstatconv internal_statvfs \
sysdep_headers += bits/fcntl-linux.h
-tests += tst-fallocate tst-fallocate64 tst-o_path-locks
+tests += \
+ tst-fallocate \
+ tst-fallocate64 \
+ tst-getcwd-smallbuff \
+ tst-o_path-locks \
+# tests
endif
ifeq ($(subdir),elf)
new file mode 100644
@@ -0,0 +1,245 @@
+/* Verify that getcwd returns ERANGE for size 1 byte and does not underflow
+ buffer when the CWD is too long and is also a mount target of /. See bug
+ #28769 or CVE-2021-3999 for more context.
+ Copyright The GNU Toolchain Authors.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <support/check.h>
+#include <support/temp_file.h>
+#include <support/xsched.h>
+#include <support/xunistd.h>
+
+#ifndef PATH_MAX
+# define PATH_MAX 1024
+#endif
+
+static char *base;
+#define BASENAME "tst-getcwd-smallbuff"
+#define MOUNT_NAME "mpoint"
+static int sockfd[2];
+
+static void
+do_cleanup (void)
+{
+ support_chdir_toolong_temp_directory (base);
+ TEST_VERIFY_EXIT (rmdir (MOUNT_NAME) == 0);
+ free (base);
+}
+
+static void
+send_fd (const int sock, const int fd)
+{
+ struct msghdr msg;
+ union
+ {
+ struct cmsghdr hdr;
+ char buf[CMSG_SPACE (sizeof (int))];
+ } cmsgbuf;
+ struct cmsghdr *cmsg;
+ struct iovec vec;
+ char ch = 'A';
+ ssize_t n;
+
+ memset (&msg, 0, sizeof (msg));
+ memset (&cmsgbuf, 0, sizeof (cmsgbuf));
+ msg.msg_control = &cmsgbuf.buf;
+ msg.msg_controllen = sizeof (cmsgbuf.buf);
+
+ cmsg = CMSG_FIRSTHDR (&msg);
+ cmsg->cmsg_len = CMSG_LEN (sizeof (int));
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ *(int *) CMSG_DATA (cmsg) = fd;
+
+ vec.iov_base = &ch;
+ vec.iov_len = 1;
+ msg.msg_iov = &vec;
+ msg.msg_iovlen = 1;
+
+ while ((n = sendmsg (sock, &msg, 0)) == -1 && errno == EINTR);
+
+ TEST_VERIFY_EXIT (n == 1);
+}
+
+static int
+recv_fd (const int sock)
+{
+ struct msghdr msg;
+ union
+ {
+ struct cmsghdr hdr;
+ char buf[CMSG_SPACE(sizeof(int))];
+ } cmsgbuf;
+ struct cmsghdr *cmsg;
+ struct iovec vec;
+ ssize_t n;
+ char ch = '\0';
+ int fd = -1;
+
+ memset (&msg, 0, sizeof (msg));
+ vec.iov_base = &ch;
+ vec.iov_len = 1;
+ msg.msg_iov = &vec;
+ msg.msg_iovlen = 1;
+
+ memset (&cmsgbuf, 0, sizeof (cmsgbuf));
+ msg.msg_control = &cmsgbuf.buf;
+ msg.msg_controllen = sizeof (cmsgbuf.buf);
+
+ while ((n = recvmsg (sock, &msg, 0)) == -1 && errno == EINTR);
+ if (n != 1 || ch != 'A')
+ return -1;
+
+ cmsg = CMSG_FIRSTHDR (&msg);
+ if (cmsg == NULL)
+ return -1;
+ if (cmsg->cmsg_type != SCM_RIGHTS)
+ return -1;
+ fd = *(const int *) CMSG_DATA (cmsg);
+ if (fd < 0)
+ return -1;
+ return fd;
+}
+
+static int
+child_func (void * const arg)
+{
+ xclose (sockfd[0]);
+ const int sock = sockfd[1];
+ char ch;
+
+ TEST_VERIFY_EXIT (read (sock, &ch, 1) == 1);
+ TEST_VERIFY_EXIT (ch == '1');
+
+ if (mount ("/", MOUNT_NAME, NULL, MS_BIND | MS_REC, NULL))
+ FAIL_EXIT1 ("mount failed: %m\n");
+ const int fd = xopen ("mpoint",
+ O_RDONLY | O_PATH | O_DIRECTORY | O_NOFOLLOW, 0);
+
+ send_fd (sock, fd);
+ xclose (fd);
+
+ TEST_VERIFY_EXIT (read (sock, &ch, 1) == 1);
+ TEST_VERIFY_EXIT (ch == 'a');
+
+ xclose (sock);
+ return 0;
+}
+
+static void
+update_map (char * const mapping, const char * const map_file)
+{
+ const size_t map_len = strlen (mapping);
+
+ const int fd = xopen (map_file, O_WRONLY, 0);
+ xwrite (fd, mapping, map_len);
+ xclose (fd);
+}
+
+static void
+proc_setgroups_write (const long child_pid, const char * const str)
+{
+ const size_t str_len = strlen(str);
+
+ char setgroups_path[64];
+ snprintf (setgroups_path, sizeof (setgroups_path),
+ "/proc/%ld/setgroups", child_pid);
+
+ const int fd = open (setgroups_path, O_WRONLY);
+
+ if (fd < 0)
+ {
+ TEST_VERIFY_EXIT (errno == ENOENT);
+ FAIL_UNSUPPORTED ("/proc/%ld/setgroups not found\n", child_pid);
+ }
+
+ xwrite (fd, str, str_len);
+ xclose(fd);
+}
+
+static char child_stack[1024 * 1024];
+
+int
+do_test (void)
+{
+ base = support_create_and_chdir_toolong_temp_directory (BASENAME);
+
+ xmkdir (MOUNT_NAME, S_IRWXU);
+ atexit (do_cleanup);
+
+ TEST_VERIFY_EXIT (socketpair (AF_UNIX, SOCK_STREAM, 0, sockfd) == 0);
+ pid_t child_pid = xclone (child_func, NULL, child_stack,
+ sizeof (child_stack),
+ CLONE_NEWUSER | CLONE_NEWNS | SIGCHLD);
+
+ xclose (sockfd[1]);
+ const int sock = sockfd[0];
+
+ char map_path[64], map_buf[64];
+ snprintf (map_path, sizeof (map_path), "/proc/%ld/uid_map",
+ (long) child_pid);
+ snprintf (map_buf, sizeof (map_buf), "0 %ld 1", (long) getuid());
+ update_map (map_buf, map_path);
+
+ proc_setgroups_write ((long) child_pid, "deny");
+ snprintf (map_path, sizeof (map_path), "/proc/%ld/gid_map",
+ (long) child_pid);
+ snprintf (map_buf, sizeof (map_buf), "0 %ld 1", (long) getgid());
+ update_map (map_buf, map_path);
+
+ TEST_VERIFY_EXIT (send (sock, "1", 1, MSG_NOSIGNAL) == 1);
+ const int fd = recv_fd (sock);
+ TEST_VERIFY_EXIT (fd >= 0);
+ TEST_VERIFY_EXIT (fchdir (fd) == 0);
+
+ static char buf[2 * 10 + 1];
+ memset (buf, 'A', sizeof(buf));
+
+ /* Finally, call getcwd and check if it resulted in a buffer underflow. */
+ char * cwd = getcwd (buf + sizeof(buf) / 2, 1);
+ TEST_VERIFY (cwd == NULL);
+ TEST_VERIFY (errno == ERANGE);
+
+ for (int i = 0; i < sizeof (buf); i++)
+ if (buf[i] != 'A')
+ {
+ printf ("buf[%d] = %02x\n", i, (unsigned int) buf[i]);
+ support_record_failure ();
+ }
+
+ TEST_VERIFY_EXIT (send (sock, "a", 1, MSG_NOSIGNAL) == 1);
+ xclose (sock);
+ TEST_VERIFY_EXIT (xwaitpid (child_pid, NULL, 0) == child_pid);
+
+ return 0;
+}
+
+#define CLEANUP_HANDLER do_cleanup
+#include <support/test-driver.c>