nshlib,testing: add chroot command and ostest

nshlib/Kconfig

@@ -361,6 +361,11 @@ config NSH_DISABLE_CD
 	bool "Disable cd"
 	default DEFAULT_SMALL
 
+config NSH_DISABLE_CHROOT
+	bool "Disable chroot"
+	default DEFAULT_SMALL
+	depends on FS_CHROOT
+
 config NSH_DISABLE_CHMOD
 	bool "Disable chmod"
 	default DEFAULT_SMALL

nshlib/nsh.h

@@ -1084,6 +1084,9 @@ int cmd_irqinfo(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv);
 #ifndef CONFIG_NSH_DISABLE_CD
   int cmd_cd(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv);
 #endif
+#if defined(CONFIG_FS_CHROOT) && !defined(CONFIG_NSH_DISABLE_CHROOT)
+  int cmd_chroot(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv);
+#endif
 #ifndef CONFIG_NSH_DISABLE_PWD
   int cmd_pwd(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv);
 #endif

nshlib/nsh_command.c

@@ -168,6 +168,11 @@ static const struct cmdmap_s g_cmdmap[] =
   CMD_MAP("cd",       cmd_cd,       1, 2, "[<dir-path>|-|~|..]"),
 #endif
 
+#if defined(CONFIG_FS_CHROOT) && !defined(CONFIG_NSH_DISABLE_CHROOT)
+  CMD_MAP("chroot",   cmd_chroot,   2, CONFIG_NSH_MAXARGUMENTS,
+    "<newroot> [<command> [args...]]"),
+#endif
+
 #if defined(CONFIG_FS_PERMISSION) && !defined(CONFIG_NSH_DISABLE_CHMOD)
   CMD_MAP("chmod",    cmd_chmod,    3, 3, "<octal-mode> <path>"),
 #endif

nshlib/nsh_envcmds.c

@@ -30,6 +30,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <ctype.h>
+#include <fcntl.h>
 #include <libgen.h>
 #include <errno.h>
 
@@ -324,6 +325,99 @@ int cmd_cd(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv)
 }
 #endif
 
+/****************************************************************************
+ * Name: nsh_chroot_closefds
+ *
+ * Description:
+ *   Close descriptors above stderr that are not already O_CLOEXEC so a
+ *   jailed execvp() child cannot inherit host file descriptors.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_FS_CHROOT) && !defined(CONFIG_NSH_DISABLE_CHROOT) && \
+    defined(CONFIG_LIBC_EXECFUNCS)
+static void nsh_chroot_closefds(void)
+{
+  int fdmax;
+  int fd;
+  int flags;
+
+  fdmax = sysconf(_SC_OPEN_MAX);
+  if (fdmax <= STDERR_FILENO)
+    {
+      return;
+    }
+
+  for (fd = STDERR_FILENO + 1; fd < fdmax; fd++)
+    {
+      flags = fcntl(fd, F_GETFD);
+      if (flags >= 0 && (flags & FD_CLOEXEC) == 0)
+        {
+          close(fd);
+        }
+    }
+}
+#endif
+
+/****************************************************************************
+ * Name: cmd_chroot
+ ****************************************************************************/
+
+#if defined(CONFIG_FS_CHROOT) && !defined(CONFIG_NSH_DISABLE_CHROOT)
+int cmd_chroot(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv)
+{
+  FAR char *fullpath;
+  int ret;
+
+  fullpath = nsh_getfullpath(vtbl, argv[1]);
+  if (fullpath == NULL)
+    {
+      nsh_error(vtbl, g_fmtcmdoutofmemory, argv[0]);
+      return ERROR;
+    }
+
+  ret = chdir(fullpath);
+  nsh_freefullpath(fullpath);
+  if (ret < 0)
+    {
+      nsh_error(vtbl, g_fmtcmdfailed, argv[0], "chdir", NSH_ERRNO);
+      return ERROR;
+    }
+
+  ret = chroot(".");
+  if (ret < 0)
+    {
+      nsh_error(vtbl, g_fmtcmdfailed, argv[0], "chroot", NSH_ERRNO);
+      return ERROR;
+    }
+
+  ret = chdir("/");
+  if (ret < 0)
+    {
+      nsh_error(vtbl, g_fmtcmdfailed, argv[0], "chdir", NSH_ERRNO);
+      return ERROR;
+    }
+
+#ifdef CONFIG_LIBC_EXECFUNCS
+  if (argc > 2)
+    {
+      nsh_chroot_closefds();
+      execvp(argv[2], &argv[2]);
+      nsh_error(vtbl, g_fmtcmdfailed, argv[0], "execvp", NSH_ERRNO);
+      return ERROR;
+    }
+#else
+  if (argc > 2)
+    {
+      nsh_error(vtbl, g_fmtcmdfailed, argv[0], "execvp", NSH_ERRNO);
+      return ERROR;
+    }
+#endif
+
+  return OK;
+}
+#endif /* CONFIG_FS_CHROOT && !CONFIG_NSH_DISABLE_CHROOT */
+
 /****************************************************************************
  * Name: cmd_echo
  ****************************************************************************/

testing/ostest/CMakeLists.txt

@@ -68,6 +68,14 @@ if(CONFIG_TESTING_OSTEST)
     list(APPEND SRCS waitpid.c)
   endif()
 
+  if(CONFIG_FS_CHROOT)
+    if(CONFIG_SCHED_WAITPID)
+      if(NOT CONFIG_BUILD_KERNEL)
+        list(APPEND SRCS chroot.c)
+      endif()
+    endif()
+  endif()
+
   if(NOT CONFIG_DISABLE_PTHREAD)
     list(
       APPEND

testing/ostest/Makefile

@@ -83,6 +83,14 @@ ifeq ($(CONFIG_SCHED_WAITPID),y)
 CSRCS += waitpid.c
 endif
 
+ifeq ($(CONFIG_FS_CHROOT),y)
+ifeq ($(CONFIG_SCHED_WAITPID),y)
+ifneq ($(CONFIG_BUILD_KERNEL),y)
+CSRCS += chroot.c
+endif
+endif
+endif
+
 ifneq ($(CONFIG_DISABLE_PTHREAD),y)
 CSRCS += cancel.c cond.c mutex.c timedmutex.c sem.c semtimed.c barrier.c
 CSRCS += timedwait.c pthread_rwlock.c pthread_rwlock_cancel.c schedlock.c