[PR #5510] [MERGED] [client] Fall back to getent/id for SSH user lookup in static builds #26031

New Issue

saavagebueno · 2026-08-05T07:06:48-04:00

saavagebueno commented

2026-08-05 07:06:48 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/5510
Author: @lixmal
Created: 3/5/2026
Status: ✅ Merged
Merged: 3/13/2026
Merged by: @lixmal

Base: main ← Head: fix/ssh-nss-user-lookup

📝 Commits (1)

9c9483b Fall back to getent/id for SSH user lookup in static builds

📊 Changes

9 files changed (+848 additions, -18 deletions)

View changed files

➕ client/ssh/server/getent_cgo_unix.go (+24 -0)
➕ client/ssh/server/getent_nocgo_unix.go (+74 -0)
➕ client/ssh/server/getent_test.go (+172 -0)
➕ client/ssh/server/getent_unix.go (+122 -0)
➕ client/ssh/server/getent_unix_test.go (+410 -0)
➕ client/ssh/server/getent_windows.go (+26 -0)
📝 client/ssh/server/shell.go (+7 -3)
📝 client/ssh/server/user_utils.go (+2 -2)
📝 client/ssh/server/userswitching_unix.go (+11 -13)

📄 Description

Describe your changes

When CGO is disabled (CGO_ENABLED=0), Go's os/user only reads /etc/passwd and /etc/group directly, bypassing the system's NSS stack. This means users provided by SSSD, LDAP, Active Directory, or other NSS modules can't be resolved.

This adds getent passwd / id -G fallback for user lookup, group resolution, and shell detection. These commands go through the host's NSS stack regardless of how the Go binary was built. The fallback is only compiled in non-CGO builds (or when osusergo tag is set), since libc handles NSS natively when CGO is enabled.

Issue ticket number and link

Closes #4919

Stack

Checklist

Is it a bug fix
Is a typo/documentation fix
Is a feature enhancement
It is a refactor
Created tests that fail without the change (if possible)

By submitting this pull request, you confirm that you have read and agree to the terms of the Contributor License Agreement.

Documentation

Select exactly one:

I added/updated documentation for this change
Documentation is not needed for this change (explain why)

No user-facing API or configuration changes. Behavior is transparent.

Docs PR URL (required if "docs added" is checked)

Paste the PR link from https://github.com/netbirdio/docs here:

https://github.com/netbirdio/docs/pull/__

Summary by CodeRabbit

New Features
- More reliable user/group lookups with platform- and build-aware fallbacks, improved input validation, 5s command timeouts, and explicit Windows behavior for shell lookup.
- Enhanced shell detection with ordered fallbacks: passwd, NSS/getent, SHELL env, then default.
Tests
- Extensive cross-platform tests covering user lookup, group resolution, shell detection, parsing, validation, timeouts, and edge cases.

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/netbirdio/netbird/pull/5510 **Author:** [@lixmal](https://github.com/lixmal) **Created:** 3/5/2026 **Status:** ✅ Merged **Merged:** 3/13/2026 **Merged by:** [@lixmal](https://github.com/lixmal) **Base:** `main` ← **Head:** `fix/ssh-nss-user-lookup` --- ### 📝 Commits (1) - [`9c9483b`](https://github.com/netbirdio/netbird/commit/9c9483b67997eb30c2b272ff9ab4f11cc13a2f10) Fall back to getent/id for SSH user lookup in static builds ### 📊 Changes **9 files changed** (+848 additions, -18 deletions) <details> <summary>View changed files</summary> ➕ `client/ssh/server/getent_cgo_unix.go` (+24 -0) ➕ `client/ssh/server/getent_nocgo_unix.go` (+74 -0) ➕ `client/ssh/server/getent_test.go` (+172 -0) ➕ `client/ssh/server/getent_unix.go` (+122 -0) ➕ `client/ssh/server/getent_unix_test.go` (+410 -0) ➕ `client/ssh/server/getent_windows.go` (+26 -0) 📝 `client/ssh/server/shell.go` (+7 -3) 📝 `client/ssh/server/user_utils.go` (+2 -2) 📝 `client/ssh/server/userswitching_unix.go` (+11 -13) </details> ### 📄 Description ## Describe your changes When CGO is disabled (`CGO_ENABLED=0`), Go's `os/user` only reads `/etc/passwd` and `/etc/group` directly, bypassing the system's NSS stack. This means users provided by SSSD, LDAP, Active Directory, or other NSS modules can't be resolved. This adds `getent passwd` / `id -G` fallback for user lookup, group resolution, and shell detection. These commands go through the host's NSS stack regardless of how the Go binary was built. The fallback is only compiled in non-CGO builds (or when `osusergo` tag is set), since libc handles NSS natively when CGO is enabled. ## Issue ticket number and link Closes #4919 ## Stack  ### Checklist - [x] Is it a bug fix - [ ] Is a typo/documentation fix - [ ] Is a feature enhancement - [ ] It is a refactor - [x] Created tests that fail without the change (if possible) > By submitting this pull request, you confirm that you have read and agree to the terms of the [Contributor License Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md). ## Documentation Select exactly one: - [ ] I added/updated documentation for this change - [x] Documentation is **not needed** for this change (explain why) No user-facing API or configuration changes. Behavior is transparent. ### Docs PR URL (required if "docs added" is checked) Paste the PR link from https://github.com/netbirdio/docs here: https://github.com/netbirdio/docs/pull/__  ## Summary by CodeRabbit * **New Features** * More reliable user/group lookups with platform- and build-aware fallbacks, improved input validation, 5s command timeouts, and explicit Windows behavior for shell lookup. * Enhanced shell detection with ordered fallbacks: passwd, NSS/getent, SHELL env, then default. * **Tests** * Extensive cross-platform tests covering user lookup, group resolution, shell detection, parsing, validation, timeouts, and edge cases.  --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

saavagebueno added the pull-request label 2026-08-05 07:06:48 -04:00

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Reference: DYNR/netbird#26031