cap_mmap_addr(9)

💅 cap_mmap_addr (9) — a.k.a. the "can u even map here bestie" check ✨

okay so real talk, this whole page lives in the Kernel API Manual and it's genuinely one of the shorter ones, so like… enjoy the vibes while they last 🫶

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🌸 NAME 🌸

cap_mmap_addr — check if able to map given addr

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✨ SYNOPSIS ✨

int cap_mmap_addr (unsigned long addr );

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🎀 ARGUMENTS 🎀

• addr — the address that somebody's trying to map, like "excuse me can i put something right here" 🥺

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💖 DESCRIPTION 💖

okay so here's the tea: if the process is attempting to map memory below dac_mmap_min_addr, then it needs CAP_SYS_RAWIO. that's it. that's the whole check. so iconic of it, honestly 👑

and the other parameters to this function? literally unused by the capability security module. not ignored-dramatically, not "saved for later", just… unused. lowkey a little ghosted 🙈

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⭐ RETURN ⭐

• 0 — this mapping should be allowed, slay, go ahead bestie 💅
• -EPERM — nope, not today, permission said no 😭

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🦋 SEE ALSO 🦋

the kernel file ./security/commoncap.c (the mothership, iykyk) plus the whole friend group:

• cap_capable_helper(9)
• cap_capable(9)
• cap_settime(9)
• cap_ptrace_access_check(9)
• cap_ptrace_traceme(9)
• cap_capget(9)
• cap_capset(9)
• cap_inode_need_killpriv(9)
• cap_inode_killpriv(9)
• kuid_root_in_ns(9)
• rootid_from_xattr(9)
• cap_convert_nscap(9)
• get_vfs_caps_from_disk(9)
• cap_bprm_creds_from_file(9)
• cap_inode_setxattr(9)
• cap_inode_removexattr(9)
• cap_task_fix_setuid(9)
• cap_task_setscheduler(9)
• cap_task_setioprio(9)
• cap_task_setnice(9)
• cap_task_prctl(9)
• cap_vm_enough_memory(9)

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🎀 and that's the whole page, no cap. short, sweet, absolutely ate. periodt.

ok so before u go — this one's brought to u by the source ./security, dated October 2026, and it's filed under cap_mmap_addr(9). mwah, bye bestie 💜🧚‍♀️