from_kgid_munged(9)

✨ from_kgid_munged(9) ✨

okay so bestie, welcome to the kernel API manual — this one's from from_kgid_munged(9) and it's literally about turning a kernel-internal gid into one you can actually hand to userspace 💅

---

🌸 NAME 🌸

from_kgid_munged — Create a gid from a kgid user-namespace pair. fr fr that's the whole vibe 🫶

---

🎀 SYNOPSIS 🎀

gid_t from_kgid_munged (struct user_namespace *targ , kgid_t kgid );

---

💖 ARGUMENTS 💖

• targ — The user namespace we want a gid in. like, where do you want this gid to live, bestie 👀
• kgid — The kernel internal gid to start with. this is the raw ingredient ✨

---

🦋 DESCRIPTION 🦋

So the whole thing is: map kgid into the user-namespace specified by targ and return the resulting gid. That's it. That's the job. slay 💅

There is always a mapping into the initial user_namespace — like, no matter what, that one's guaranteed, periodt.

Now here's the iconic part: unlike from_kgid, from_kgid_munged never fails and always returns a valid gid. Never. Not once. This is exactly what makes from_kgid_munged appropriate for use in syscalls like stat and getgid, where failing the system call and failing to provide a valid gid are literally not options 😭 like you cannot just show up empty-handed.

and if kgid has no mapping in targ? then overflowgid is returned. that's the fallback, that's the safety net, that's the munging, iykyk 🌈

---

👑 SEE ALSO 👑

Kernel file ./kernel/user_namespace.c

• make_kuid(9)
• from_kuid(9)
• from_kuid_munged(9)
• make_kgid(9)
• from_kgid(9)
• make_kprojid(9)
• from_kprojid(9)
• from_kprojid_munged(9)
• verify_root_map(9)

go read the whole friend group, they're all iconic in their own way 🧚💜

---

and that's the page!! 🍓 this one shipped out of ./kernel back in October 2026, so yeah — old money, timeless energy. mwah 💋🌟