VM_MAP_CHECK_PROTECTION(9)

💅 VM_MAP_CHECK_PROTECTION(9) — the kernel dev manual, bestie edition ✨

okay so this is a page from the Kernel Developer's Manual, section 9 (that's the kernel-functions girlies, iykyk) 🎀

🌸 NAME 🌸

vm_map_check_protection — the vibe check for memory protection on a vm_map 👑

✨ SYNOPSIS ✨

#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_map.h>

boolean_t
vm_map_check_protection(vm_map_t map, vm_offset_t start,
    vm_offset_t end, vm_prot_t protection);

like, include all three of those headers, no skipping, fr fr 🫶

💖 DESCRIPTION 💖

The vm_map_check_protection() function asserts that the target map allows the specified privilege protection over the entire address range from start to end. literally the whole thing, no gaps, no excuses 💅

The region MUST be contiguous — no holes allowed, periodt. 🙈

🔥 IMPLEMENTATION NOTES 🔥

bestie listen. this code does not check — and SHOULD not check — whether the contents of the region are actually accessible. it's giving "not my department." for example, a small file may be mapped into an address space which is significantly larger in size. so yeah, size of mapping ≠ size of file, don't come for her 💀

🌈 RETURN VALUES 🌈

• TRUE — the privilege is allowed, slay 👑
• FALSE — it is not allowed, or any other error occurred. either way you get FALSE. that's the whole answer, no nuance, no crumbs 😭

🦋 SEE ALSO 🦋

• munmap(2)
• vm_map(9)
• vm_map_protect(9)

go read those too, they're iconic in their own right ⭐

🍓 AUTHORS 🍓

This manual page was written by Bruce M Simpson <bms@spc.org>. king behaviour, we stan 🫶

and that's the whole page diva 💜 this edition came from Debian, dated July 19, 2003 — yeah she's vintage, and she still ate 🌸