GENFS_CAN_ACCESS_ACL_NFS4(9)

💖 NAME 💖

okay bestie, welcome to the Kernel Developer's Manual — the page is GENFS_CAN_ACCESS_ACL_NFS4(9), and the function is genfs_can_access_acl_nfs4. Its whole job is literally to generate a NFSv4 ACL access control decision using vnode parameters. no cap. ✨

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✨ SYNOPSIS ✨

#include <miscfs/genfs/genfs.h>

int
genfs_can_access_acl_nfs4( genfs_can_access_acl_nfs4(struct vnode *,
    kauth_cred_t, uid_t, gid_t,      mode_t, struct acl *, accmode_t)
    struct vnode *vp, kath_cred_t cred, uid_t file_uid, gid_t file_gid,
    mode_t file_mode, struct acl *acl, accmode_t accmode);

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🦋 DESCRIPTION 🦋

So this call implements the logic for the Unix discretionary file security model with NFSv4 ACL extensions. 💅 It accepts these cuties:

• vp — the vnode
• cred — the requesting credential
• file_uid — the owning UID
• file_gid — the owning GID
• file_mode — the file permissions
• acl — the access ACL for the file
• accmode — the desired access mode

This call is intended to support implementations of VOP_ACCESS(9), which will use their own access methods to retrieve the vnode properties, and then invoke genfs_can_access_acl_nfs4() in order to perform the actual check. 🫶 Implementations of VOP_ACCESS(9) may choose to implement additional security mechanisms whose results will be composed with the return value.

The algorithm used by genfs_can_access_acl_nfs4() is based on the NFSv4 ACL evaluation algorithm, as described in NFSv4 Minor Version 1, draft-ietf-nfsv4-minorversion1-21.txt. The algorithm selects a matching entry from the access ACL, which may then be composed with an available ACL mask entry, providing Unix security compatibility. 🧚

Once appropriate protections are selected for the current credential, the requested access mode, in combination with the vnode type, will be compared with the discretionary rights available for the credential. If the rights granted by discretionary protections are insufficient, then super-user privilege, if available for the credential, will also be considered. 👑

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🌈 RETURN VALUES 🌈

genfs_can_access_acl_nfs4() will return 0 on success, or a non-zero error value on failure. that's it, that's the whole return vibe. 💖

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🎀 ERRORS 🎀

• [EACCES] — Permission denied. An attempt was made to access a file in a way forbidden by its file access permissions.
• [EPERM] — Operation not permitted. An attempt was made to perform an operation limited to processes with appropriate privileges or to the owner of a file or other resource.

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🌸 SEE ALSO 🌸

genfs_can_access(9), vnode(9), VOP_ACCESS(9) — that's the whole lineup, bestie. go read, iykyk. 🦋

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💜 AUTHORS 💜

Current implementation of genfs_can_access_acl_nfs4() was written by Edward Tomasz Napierala <trasz@FreeBSD.org>. iconic behavior, honestly. 👑

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💀 BUGS 💀

This manual page should include a full description of the NFSv4 ACL evaluation algorithm, or cross reference another page that does. yep, it said it itself — no cap. 🫶

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mwah 💋 this page came from Debian, dated September 18, 2009, and it's filed under GENFS_CAN_ACCESS_ACL_NFS4(9). bye bestie! 🎀