sched/nsh: Remove Hard-coded Default Password by Abhishek-2808 · Pull Request #18715 · apache/nuttx

Abhishek-2808 · 2026-04-11T16:07:49Z

Summary

This PR introduces build-time generation of the /etc/passwd file for the ROMFS image when authentication is enabled.

Instead of relying on a static etc/passwd file embedded in the source tree, the passwd entry is now generated during the build using the configuration values:

CONFIG_ETC_ROMFS_PASSWD_USER
CONFIG_ETC_ROMFS_PASSWD_PASSWORD
CONFIG_ETC_ROMFS_PASSWD_UID
CONFIG_ETC_ROMFS_PASSWD_GID
CONFIG_ETC_ROMFS_PASSWD_HOME

The generated passwd entry is written into the ROMFS staging directory and included in the firmware image.

Behavior

Authentication disabled

No passwd generation occurs.
System behavior remains unchanged.

Authentication enabled

The build generates /etc/passwd automatically.
The password is hashed before being stored in the ROMFS image.
The plaintext password is never embedded in the firmware.

Password missing

If CONFIG_ETC_ROMFS_GENPASSWD=y but the password is empty, the build fails with an explicit error.

This ensures that credentials are always explicitly configured when authentication is enabled and prevents firmware images from being built with empty passwords.

Security Improvement

Previously /etc/passwd could be included as a static file in the ROMFS source tree.
With this change, the credentials are generated at build time and must be explicitly configured, avoiding implicit or default credentials in firmware images.

Testing

General passwd entry

Plaintext passwd check

Build failure when passwd is empty

Abhishek-2808 · 2026-04-11T16:16:24Z

@acassis Please check this PR.

Note: This PR is a re-submission of a previously approved PR. The original PR became inaccessible because my GitHub account was mistakenly flagged and is under manual review. Recreating it here with the same changes for review and merge.

acassis · 2026-04-12T11:07:47Z

@Abhishek-2808 some suggestions:

Improve the error message to help the user to find where to fix the password:
Run 'make menuconfig' and select a password at: Board Selection ---> Auto-generate /etc/passwd at build time ---> Admin password

This PR is a breaking change, so, please include "!" before the commit title and include a Breaking Changes in the commit message, read https://nuttx.apache.org/docs/latest/contributing/guide.html for more info about it.

Since NuttX is a POSIX and Unix-like system, I think it make more sense to use the "root" username instead of "admin". So change the saved username from "admin" to "root" (you can keep the Admin name in the menuconfig.

@linguini1 @cederom do you agree?

cederom · 2026-04-12T13:38:24Z

@acassisL Since NuttX is a POSIX and Unix-like system, I think it make more sense to use the "root" username instead of "admin". So change the saved username from "admin" to "root" (you can keep the Admin name in the menuconfig.

Thanks Alan, yes we may switch to root and this was my first search too when looking at NuttX. We may ask about this on dev@ too :-)

Thanks for requesting breaking change mark! :-)

update: I have just asked on dev@ :-)

tools/mkpasswd.c

Introduce mkpasswd, a pure-C host tool for generating encrypted password files at build time using TEA encryption. This enables secure, credential-free firmware images while allowing build-time password configuration. Changes: * Add mkpasswd.c host tool for TEA-based password hashing and encryption * Integrate mkpasswd into Make build system (tools/Makefile.host) * Add CMake support for mkpasswd compilation and ROMFS passwd generation * Add CONFIG_BOARD_ETC_ROMFS_PASSWD_* configuration options to Kconfig * Implement credential exclusion from defconfig to prevent password leaking * Update savedefconfig.cmake to strip sensitive credentials * Fix mkdir() portability for Windows Native builds (CONFIG_WINDOWS_NATIVE) * Change default username from "admin" to "root" (POSIX convention) * Improve build-failure error message with full menuconfig navigation path BREAKING CHANGE: Boards enabling CONFIG_BOARD_ETC_ROMFS_PASSWD_ENABLE must set CONFIG_BOARD_ETC_ROMFS_PASSWD_PASSWORD to a non-empty string of at least 8 characters. The build now fails with an explicit error if this config is left empty. To fix: run 'make menuconfig' and navigate to: Board Selection ---> Auto-generate /etc/passwd at build time ---> Admin password Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>

Abhishek-2808 · 2026-04-12T16:51:24Z

@acassis, That's a very good catch!!! I have updated the PR to make root instead of admin as many folks including me liked this idea...
Also, all the commits now start with "!", and error message is improved.
Thanks. :)

acassis

@Abhishek-2808 I found many please where "admin" still used, please double check if there are more places

acassis · 2026-04-12T18:19:48Z

Documentation/platforms/renesas/rx65n/boards/rx65n-grrose/index.rst

-   USERNAME:  admin
-   PASSWORD:  Administrator
+* ``CONFIG_BOARD_ETC_ROMFS_PASSWD_ENABLE=y``
+* ``CONFIG_BOARD_ETC_ROMFS_PASSWD_USER`` (default: ``admin``)


Please update here too

Good catch! fixed this in the latest commit, please check.

acassis · 2026-04-12T18:20:03Z

Documentation/platforms/risc-v/esp32c3-legacy/boards/esp32c3-legacy-devkit/ROMFS.txt

-    nsh> cat /etc/passwd
-    admin:8Tv+Hbmr3pLVb5HHZgd26D:0:0:/
+    CONFIG_BOARD_ETC_ROMFS_PASSWD_ENABLE=y
+    CONFIG_BOARD_ETC_ROMFS_PASSWD_USER (default: admin)


acassis · 2026-04-12T18:20:14Z

Documentation/platforms/sim/sim/boards/sim/index.rst

-   admin:8Tv+Hbmr3pLVb5HHZgd26D:0:0:/
+* ``CONFIG_BOARD_ETC_ROMFS_PASSWD_ENABLE=y``
+* ``CONFIG_NSH_CONSOLE_LOGIN=y`` (required, otherwise login is not enforced)
+* ``CONFIG_BOARD_ETC_ROMFS_PASSWD_USER`` (default: ``admin``)


acassis · 2026-04-12T18:20:32Z

Documentation/platforms/sim/sim/boards/sim/index.rst

+
+   $ ./nuttx
+   NuttShell (NSH) NuttX-<version>
+   nsh login: admin


Migrate boards from static /etc/passwd files to build-time generation: * Remove static etc/passwd files from SIM and ESP32-C3-legacy boards * Update board configurations to enable BOARD_ETC_ROMFS_PASSWD_ENABLE * Configure SIM board with login demo user (root/Administrator) * Update board build rules to use newly generated passwd files * Remove CMakeLists.txt dependency on static passwd in SIM * Update MOTD string from username=admin to username=root This completes the infrastructure migration for boards supporting login functionality. BREAKING CHANGE: The static etc/passwd files have been removed from boards/sim/sim/sim/src/etc/passwd boards/risc-v/esp32c3-legacy/esp32c3-legacy-devkit/src/etc/passwd These boards now require CONFIG_BOARD_ETC_ROMFS_PASSWD_ENABLE=y and a configured password. Any board carrying a custom static passwd file must set RCRAWS to exclude etc/passwd and manage credentials via the new Kconfig options or provide their own passwd generation. To fix: run 'make menuconfig' and navigate to: Board Selection ---> Auto-generate /etc/passwd at build time ---> Admin password Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>

Document the new mkpasswd-based password generation system and its integration with the build process. Changes: * Add comprehensive mkpasswd tool documentation to components/tools * Update SIM board docs to explain generated passwd workflow * Update ESP32-C3-legacy board docs for passwd generation * Update RX65N board docs with credential handling guidance * Document how to configure and use BOARD_ETC_ROMFS_PASSWD_* options * Explain security benefits of build-time generation vs static files * Update all doc examples from default username "admin" to "root" BREAKING CHANGE: Boards using static /etc/passwd files in ETC_ROMFS must migrate to the new build-time generation workflow documented in Documentation/components/tools/index.rst. The old static passwd files are no longer present in migrated boards; boards that relied on them will fail to build until credentials are configured via Kconfig. Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>

github-actions bot added Area: Build system Size: XL The size of the change in this PR is very large. Consider breaking down the PR into smaller pieces. Board: risc-v Board: simulator labels Apr 12, 2026

acassis previously approved these changes Apr 12, 2026

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simbit18 reviewed Apr 12, 2026

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Abhishek-2808 dismissed acassis’s stale review via 171d80b April 12, 2026 16:40

Abhishek-2808 force-pushed the Issue-16822 branch from 3a68c0b to 171d80b Compare April 12, 2026 16:40

Abhishek-2808 requested review from Ouss4, anchao, btashton, fdcavalcanti, jerpelea, raiden00pl, tmedicci, xiaoxiang781216 and yamt as code owners April 12, 2026 16:40

acassis reviewed Apr 12, 2026

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Abhishek-2808 force-pushed the Issue-16822 branch from 171d80b to a8cb42b Compare April 12, 2026 18:30

Abhishek Mishra added 2 commits April 12, 2026 18:35

Abhishek-2808 force-pushed the Issue-16822 branch from a8cb42b to 40faaf6 Compare April 12, 2026 18:35

xiaoxiang781216 approved these changes Apr 13, 2026

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Abhishek-2808 commented Apr 11, 2026

Summary

Behavior

Security Improvement

Testing

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Abhishek-2808 commented Apr 11, 2026

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Abhishek-2808 commented Apr 12, 2026

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acassis commented Apr 12, 2026 •

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