cap_capable_helper(9)

💅 cap_capable_helper(9) — the Kernel API Manual, but make it group chat 🫶

okay bestie, so this page lives in the Kernel API Manual under the name cap_capable_helper(9) — say it with me, it's giving "tiny function, big security energy" ✨

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✨ NAME ✨

cap_capable_helper — literally just answers the question: does this task actually have a particular effective capability or not? 💅

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🦋 SYNOPSIS 🦋

int cap_capable_helper (const struct cred *cred , struct user_namespace
*target_ns , const struct user_namespace *cred_ns , int cap );

ngl that signature is a whole vibe check on its own, so let's break it down chapter by chapter 👑

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🎀 ARGUMENTS 🎀

• cred — the credentials you're working with, aka the receipts 💖
• target_ns — the user namespace of the resource being accessed — i.e. where the thing lives
• cred_ns — the user namespace of the credentials — i.e. who is asking
• cap — the capability you want to check for, the whole point of the function, the main character tbh 🌟

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💜 DESCRIPTION 💜

So here's the teа: this function determines whether the nominated task has the specified capability chilling in its effective set. Returns 0 if it does — slay — and -ve if it does not 😭

If you want more details (and honestly, who doesn't), see cap_capable for the full lore 🧚

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🌈 SEE ALSO 🌈

Kernel file ./security/commoncap.c and honestly the whole friend group:

• 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)
• cap_mmap_addr(9)

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💀 reminder bestie: this is effective capability we're checking, not permitted, not inheritable — effective. Don't come for me, come for the manpage.

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and that's the whole page, periodt 💅 🎀 this lil gem comes from ./security and it's dated October 2026 — so yes, she's from the future, no cap ⭐ 🦋 🌸