From bcf2cd1795cfcc6068b9ecfd6dcee001e58dbdb4 Mon Sep 17 00:00:00 2001
From: Abhishek Mishra <mishra.abhishek2808@gmail.com>
Date: Wed, 19 Aug 2026 08:07:17 +0000
Subject: [PATCH] nshlib: add chroot command

chdir into the new root, call chroot("."), then chdir("/") so relative
paths stay in the jail. With a command, execvp() after the jail is set.

Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>
---
 nshlib/Kconfig       |  5 ++++
 nshlib/nsh.h         |  3 +++
 nshlib/nsh_command.c |  5 ++++
 nshlib/nsh_envcmds.c | 58 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)

diff --git a/nshlib/Kconfig b/nshlib/Kconfig
index e0259a2ac..0de85924b 100644
--- a/nshlib/Kconfig
+++ b/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
diff --git a/nshlib/nsh.h b/nshlib/nsh.h
index 295f11b94..4183fab55 100644
--- a/nshlib/nsh.h
+++ b/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
diff --git a/nshlib/nsh_command.c b/nshlib/nsh_command.c
index 988e4792d..22e43b4f4 100644
--- a/nshlib/nsh_command.c
+++ b/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
diff --git a/nshlib/nsh_envcmds.c b/nshlib/nsh_envcmds.c
index 52be0e96c..e8b0d0473 100644
--- a/nshlib/nsh_envcmds.c
+++ b/nshlib/nsh_envcmds.c
@@ -324,6 +324,64 @@ errout:
 }
 #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)
+    {
+      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
  ****************************************************************************/