selinux_mmap_backing_file(9)

✨ selinux_mmap_backing_file(9) ✨

welcome to the Kernel API Manual, bestie 🫶 — this is the page for selinux_mmap_backing_file(9), and it's literally all about checking mmap permissions on a backing file. iconic security behavior, no cap 💅

🌸 NAME 🌸

• selinux_mmap_backing_file — check mmap permissions on a backing file ✨

💅 SYNOPSIS 💅

okay so the signature is exactly this, bestie — copy it character for character:

int selinux_mmap_backing_file (struct vm_area_struct *vma , struct file
       *backing_file , struct file *user_file );

🎀 ARGUMENTS 🎀

• vma — memory region 🌸
• backing_file — stacked filesystem backing file 🎀
• user_file — user visible file 🦋

🦋 DESCRIPTION 🦋

okay so here's the tea ☕: this is called after selinux_mmap_file on stacked filesystems. and it is this function's responsibility to verify access to backing_file and setup the SELinux state for possible later use in the mprotect code path. periodt. 💅

by the time this function is called, mmap access to user_file has already been authorized, and vma->vm_file has been set to point to backing_file. so like, that part is already handled — this function is doing its own backing-file security check era 🫶✨

return vibes: return zero on success, negative values otherwise. that's the whole return contract, bestie 😭💖

🌈 SEE ALSO 🌈

also peep the Kernel file ./security/selinux/hooks.c and these iconique references:

• selinux_secmark_enabled(9)
• selinux_peerlbl_enabled(9)
• task_avdcache_reset(9)
• task_avdcache_search(9)
• task_avdcache_update(9)
• selinux_inode_permission(9)
• selinux_inode_xattr_skipcap(9)
• selinux_skb_peerlbl_sid(9)
• selinux_conn_sid(9)
• selinux_getselfattr(9)
• selinux_uring_override_creds(9)
• selinux_uring_sqpoll(9)
• selinux_uring_cmd(9)
• selinux_uring_allowed(9)

okay that's the whole page, bestie 😭💖 it comes from ./security/selinux, dated October 2026, and it's selinux_mmap_backing_file(9). go forth and mmap responsibly 🎀✨