2f6f0654ab
- In setxattr if we are setting a posix acl convert uids and gids from the current user namespace into the initial user namespace, before the xattrs are passed to the underlying filesystem. Untranslatable uids and gids are represented as -1 which posix_acl_from_xattr will represent as INVALID_UID or INVALID_GID. posix_acl_valid will fail if an acl from userspace has any INVALID_UID or INVALID_GID values. In net this guarantees that untranslatable posix acls will not be stored by filesystems. - In getxattr if we are reading a posix acl convert uids and gids from the initial user namespace into the current user namespace. Uids and gids that can not be tranlsated into the current user namespace will be represented as -1. - Replace e_id in struct posix_acl_entry with an anymouns union of e_uid and e_gid. For the short term retain the e_id field until all of the users are converted. - Don't set struct posix_acl.e_id in the cases where the acl type does not use e_id. Greatly reducing the use of ACL_UNDEFINED_ID. - Rework the ordering checks in posix_acl_valid so that I use kuid_t and kgid_t types throughout the code, and so that I don't need arithmetic on uid and gid types. Cc: Theodore Tso <tytso@mit.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
421 lines
9.2 KiB
C
421 lines
9.2 KiB
C
/*
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* linux/fs/posix_acl.c
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*
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* Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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*
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* Fixes from William Schumacher incorporated on 15 March 2001.
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* (Reported by Charles Bertsch, <CBertsch@microtest.com>).
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*/
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/*
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* This file contains generic functions for manipulating
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* POSIX 1003.1e draft standard 17 ACLs.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/atomic.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/posix_acl.h>
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#include <linux/export.h>
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#include <linux/errno.h>
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EXPORT_SYMBOL(posix_acl_init);
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EXPORT_SYMBOL(posix_acl_alloc);
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EXPORT_SYMBOL(posix_acl_valid);
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EXPORT_SYMBOL(posix_acl_equiv_mode);
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EXPORT_SYMBOL(posix_acl_from_mode);
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/*
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* Init a fresh posix_acl
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*/
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void
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posix_acl_init(struct posix_acl *acl, int count)
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{
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atomic_set(&acl->a_refcount, 1);
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acl->a_count = count;
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}
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/*
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* Allocate a new ACL with the specified number of entries.
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*/
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struct posix_acl *
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posix_acl_alloc(int count, gfp_t flags)
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{
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const size_t size = sizeof(struct posix_acl) +
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count * sizeof(struct posix_acl_entry);
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struct posix_acl *acl = kmalloc(size, flags);
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if (acl)
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posix_acl_init(acl, count);
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return acl;
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}
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/*
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* Clone an ACL.
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*/
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static struct posix_acl *
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posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
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{
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struct posix_acl *clone = NULL;
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if (acl) {
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int size = sizeof(struct posix_acl) + acl->a_count *
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sizeof(struct posix_acl_entry);
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clone = kmemdup(acl, size, flags);
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if (clone)
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atomic_set(&clone->a_refcount, 1);
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}
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return clone;
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}
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/*
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* Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
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*/
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int
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posix_acl_valid(const struct posix_acl *acl)
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{
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const struct posix_acl_entry *pa, *pe;
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int state = ACL_USER_OBJ;
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kuid_t prev_uid = INVALID_UID;
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kgid_t prev_gid = INVALID_GID;
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int needs_mask = 0;
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
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return -EINVAL;
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switch (pa->e_tag) {
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case ACL_USER_OBJ:
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if (state == ACL_USER_OBJ) {
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state = ACL_USER;
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break;
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}
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return -EINVAL;
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case ACL_USER:
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if (state != ACL_USER)
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return -EINVAL;
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if (!uid_valid(pa->e_uid))
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return -EINVAL;
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if (uid_valid(prev_uid) &&
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uid_lte(pa->e_uid, prev_uid))
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return -EINVAL;
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prev_uid = pa->e_uid;
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needs_mask = 1;
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break;
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case ACL_GROUP_OBJ:
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if (state == ACL_USER) {
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state = ACL_GROUP;
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break;
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}
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return -EINVAL;
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case ACL_GROUP:
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if (state != ACL_GROUP)
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return -EINVAL;
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if (!gid_valid(pa->e_gid))
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return -EINVAL;
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if (gid_valid(prev_gid) &&
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gid_lte(pa->e_gid, prev_gid))
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return -EINVAL;
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prev_gid = pa->e_gid;
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needs_mask = 1;
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break;
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case ACL_MASK:
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if (state != ACL_GROUP)
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return -EINVAL;
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state = ACL_OTHER;
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break;
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case ACL_OTHER:
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if (state == ACL_OTHER ||
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(state == ACL_GROUP && !needs_mask)) {
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state = 0;
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break;
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}
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return -EINVAL;
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default:
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return -EINVAL;
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}
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}
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if (state == 0)
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return 0;
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return -EINVAL;
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}
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/*
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* Returns 0 if the acl can be exactly represented in the traditional
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* file mode permission bits, or else 1. Returns -E... on error.
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*/
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int
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posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
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{
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const struct posix_acl_entry *pa, *pe;
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umode_t mode = 0;
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int not_equiv = 0;
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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switch (pa->e_tag) {
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case ACL_USER_OBJ:
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mode |= (pa->e_perm & S_IRWXO) << 6;
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break;
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case ACL_GROUP_OBJ:
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mode |= (pa->e_perm & S_IRWXO) << 3;
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break;
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case ACL_OTHER:
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mode |= pa->e_perm & S_IRWXO;
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break;
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case ACL_MASK:
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mode = (mode & ~S_IRWXG) |
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((pa->e_perm & S_IRWXO) << 3);
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not_equiv = 1;
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break;
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case ACL_USER:
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case ACL_GROUP:
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not_equiv = 1;
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break;
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default:
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return -EINVAL;
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}
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}
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if (mode_p)
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*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
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return not_equiv;
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}
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/*
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* Create an ACL representing the file mode permission bits of an inode.
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*/
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struct posix_acl *
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posix_acl_from_mode(umode_t mode, gfp_t flags)
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{
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struct posix_acl *acl = posix_acl_alloc(3, flags);
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if (!acl)
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return ERR_PTR(-ENOMEM);
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acl->a_entries[0].e_tag = ACL_USER_OBJ;
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acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
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acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
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acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
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acl->a_entries[2].e_tag = ACL_OTHER;
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acl->a_entries[2].e_perm = (mode & S_IRWXO);
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return acl;
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}
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/*
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* Return 0 if current is granted want access to the inode
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* by the acl. Returns -E... otherwise.
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*/
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int
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posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
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{
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const struct posix_acl_entry *pa, *pe, *mask_obj;
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int found = 0;
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want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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switch(pa->e_tag) {
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case ACL_USER_OBJ:
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/* (May have been checked already) */
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if (uid_eq(inode->i_uid, current_fsuid()))
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goto check_perm;
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break;
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case ACL_USER:
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if (uid_eq(pa->e_uid, current_fsuid()))
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goto mask;
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break;
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case ACL_GROUP_OBJ:
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if (in_group_p(inode->i_gid)) {
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found = 1;
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if ((pa->e_perm & want) == want)
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goto mask;
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}
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break;
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case ACL_GROUP:
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if (in_group_p(pa->e_gid)) {
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found = 1;
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if ((pa->e_perm & want) == want)
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goto mask;
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}
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break;
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case ACL_MASK:
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break;
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case ACL_OTHER:
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if (found)
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return -EACCES;
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else
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goto check_perm;
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default:
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return -EIO;
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}
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}
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return -EIO;
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mask:
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for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
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if (mask_obj->e_tag == ACL_MASK) {
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if ((pa->e_perm & mask_obj->e_perm & want) == want)
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return 0;
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return -EACCES;
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}
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}
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check_perm:
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if ((pa->e_perm & want) == want)
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return 0;
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return -EACCES;
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}
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/*
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* Modify acl when creating a new inode. The caller must ensure the acl is
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* only referenced once.
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*
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* mode_p initially must contain the mode parameter to the open() / creat()
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* system calls. All permissions that are not granted by the acl are removed.
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* The permissions in the acl are changed to reflect the mode_p parameter.
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*/
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static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
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{
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struct posix_acl_entry *pa, *pe;
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struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
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umode_t mode = *mode_p;
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int not_equiv = 0;
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/* assert(atomic_read(acl->a_refcount) == 1); */
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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switch(pa->e_tag) {
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case ACL_USER_OBJ:
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pa->e_perm &= (mode >> 6) | ~S_IRWXO;
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mode &= (pa->e_perm << 6) | ~S_IRWXU;
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break;
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case ACL_USER:
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case ACL_GROUP:
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not_equiv = 1;
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break;
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case ACL_GROUP_OBJ:
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group_obj = pa;
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break;
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case ACL_OTHER:
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pa->e_perm &= mode | ~S_IRWXO;
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mode &= pa->e_perm | ~S_IRWXO;
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break;
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case ACL_MASK:
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mask_obj = pa;
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not_equiv = 1;
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break;
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default:
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return -EIO;
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}
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}
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if (mask_obj) {
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mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
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mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
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} else {
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if (!group_obj)
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return -EIO;
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group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
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mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
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}
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*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
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return not_equiv;
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}
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/*
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* Modify the ACL for the chmod syscall.
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*/
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static int posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
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{
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struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
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struct posix_acl_entry *pa, *pe;
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/* assert(atomic_read(acl->a_refcount) == 1); */
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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switch(pa->e_tag) {
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case ACL_USER_OBJ:
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pa->e_perm = (mode & S_IRWXU) >> 6;
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break;
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case ACL_USER:
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case ACL_GROUP:
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break;
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case ACL_GROUP_OBJ:
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group_obj = pa;
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break;
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case ACL_MASK:
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mask_obj = pa;
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break;
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case ACL_OTHER:
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pa->e_perm = (mode & S_IRWXO);
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break;
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default:
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return -EIO;
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}
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}
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if (mask_obj) {
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mask_obj->e_perm = (mode & S_IRWXG) >> 3;
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} else {
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if (!group_obj)
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return -EIO;
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group_obj->e_perm = (mode & S_IRWXG) >> 3;
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}
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return 0;
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}
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int
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posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
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{
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struct posix_acl *clone = posix_acl_clone(*acl, gfp);
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int err = -ENOMEM;
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if (clone) {
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err = posix_acl_create_masq(clone, mode_p);
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if (err < 0) {
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posix_acl_release(clone);
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clone = NULL;
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}
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}
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posix_acl_release(*acl);
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*acl = clone;
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return err;
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}
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EXPORT_SYMBOL(posix_acl_create);
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int
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posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
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{
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struct posix_acl *clone = posix_acl_clone(*acl, gfp);
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int err = -ENOMEM;
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if (clone) {
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err = posix_acl_chmod_masq(clone, mode);
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if (err) {
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posix_acl_release(clone);
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clone = NULL;
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}
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}
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posix_acl_release(*acl);
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*acl = clone;
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return err;
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}
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EXPORT_SYMBOL(posix_acl_chmod);
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