test_kuid_r...with_mapping(9)

🎀 test_kuid_root_in_ns_with_mapping — Kernel API Manual 🎀

Okay bestie, let's get into this Kernel API Manual page. The manual name is Kernel API Manual, and the header title is test_kuid_r...with_mapping(9) — yes, that's the shortened header vibe. The actual function is test_kuid_root_in_ns_with_mapping. 💅

🌸 NAME 🌸

test_kuid_root_in_ns_with_mapping — Test kuid_root_in_ns with a namespace where uid 0 maps to a different kuid. ✨

✨ SYNOPSIS ✨

void test_kuid_root_in_ns_with_mapping (struct kunit *test );

🫶 ARGUMENTS 🫶

• test — KUnit test context. 🧚

💖 DESCRIPTION 💖

So this test creates a user namespace where uid 0 maps to kuid 1000 in the parent namespace. Then it verifies that kuid_root_in_ns correctly identifies kuid 1000 as owning the namespace. Slay. 👑

👑 NOTE 👑

Heads up, bestie: kuid_root_in_ns walks up the namespace hierarchy, so it checks the current namespace first, then parent, then parent's parent, etc. So:

• kuid 1000 owns test_ns because from_kuid(test_ns, 1000) == 0
• kuid 0 also owns test_ns because from_kuid(init_user_ns, 0) == 0 (checked in parent)

This tests the actual functionality as requested: creating namespaces with different values for the namespace's uid 0. No cap, fr fr. 🦋

🌈 SEE ALSO 🌈

• Kernel file ./security/commoncap_test.c
• test_vfsuid_root_in_currentns_init_ns(9)
• test_vfsuid_root_in_currentns_invalid(9)
• test_vfsuid_root_in_currentns_nonzero(9)
• test_kuid_root_in_ns_init_ns_uid0(9)
• test_kuid_root_in_ns_init_ns_nonzero(9)
• create_test_user_ns_with_mapping(9)
• test_kuid_root_in_ns_with_different_mappings(9)

Cute little sign-off: this page is from the Kernel API Manual, source/version ./security, dated October 2026, and the header name is test_kuid_r...with_mapping(9). Byeee, ily, go read those tests. 💖🎀