664cceb009
The attached patch adds extra permission grants to keys for the possessor of a key in addition to the owner, group and other permissions bits. This makes SUID binaries easier to support without going as far as labelling keys and key targets using the LSM facilities. This patch adds a second "pointer type" to key structures (struct key_ref *) that can have the bottom bit of the address set to indicate the possession of a key. This is propagated through searches from the keyring to the discovered key. It has been made a separate type so that the compiler can spot attempts to dereference a potentially incorrect pointer. The "possession" attribute can't be attached to a key structure directly as it's not an intrinsic property of a key. Pointers to keys have been replaced with struct key_ref *'s wherever possession information needs to be passed through. This does assume that the bottom bit of the pointer will always be zero on return from kmem_cache_alloc(). The key reference type has been made into a typedef so that at least it can be located in the sources, even though it's basically a pointer to an undefined type. I've also renamed the accessor functions to be more useful, and all reference variables should now end in "_ref". Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
147 lines
3.6 KiB
C
147 lines
3.6 KiB
C
/* key-ui.h: key userspace interface stuff
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _LINUX_KEY_UI_H
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#define _LINUX_KEY_UI_H
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#include <linux/key.h>
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/* the key tree */
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extern struct rb_root key_serial_tree;
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extern spinlock_t key_serial_lock;
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/* required permissions */
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#define KEY_VIEW 0x01 /* require permission to view attributes */
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#define KEY_READ 0x02 /* require permission to read content */
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#define KEY_WRITE 0x04 /* require permission to update / modify */
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#define KEY_SEARCH 0x08 /* require permission to search (keyring) or find (key) */
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#define KEY_LINK 0x10 /* require permission to link */
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#define KEY_ALL 0x1f /* all the above permissions */
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/*
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* the keyring payload contains a list of the keys to which the keyring is
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* subscribed
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*/
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struct keyring_list {
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struct rcu_head rcu; /* RCU deletion hook */
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unsigned short maxkeys; /* max keys this list can hold */
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unsigned short nkeys; /* number of keys currently held */
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unsigned short delkey; /* key to be unlinked by RCU */
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struct key *keys[0];
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};
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/*
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* check to see whether permission is granted to use a key in the desired way
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*/
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static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
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{
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struct key *key = key_ref_to_ptr(key_ref);
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key_perm_t kperm;
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if (is_key_possessed(key_ref))
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kperm = key->perm >> 24;
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else if (key->uid == current->fsuid)
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kperm = key->perm >> 16;
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else if (key->gid != -1 &&
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key->perm & KEY_GRP_ALL &&
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in_group_p(key->gid)
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)
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kperm = key->perm >> 8;
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else
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kperm = key->perm;
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kperm = kperm & perm & KEY_ALL;
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return kperm == perm;
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}
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/*
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* check to see whether permission is granted to use a key in at least one of
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* the desired ways
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*/
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static inline int key_any_permission(const key_ref_t key_ref, key_perm_t perm)
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{
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struct key *key = key_ref_to_ptr(key_ref);
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key_perm_t kperm;
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if (is_key_possessed(key_ref))
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kperm = key->perm >> 24;
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else if (key->uid == current->fsuid)
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kperm = key->perm >> 16;
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else if (key->gid != -1 &&
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key->perm & KEY_GRP_ALL &&
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in_group_p(key->gid)
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)
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kperm = key->perm >> 8;
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else
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kperm = key->perm;
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kperm = kperm & perm & KEY_ALL;
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return kperm != 0;
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}
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static inline int key_task_groups_search(struct task_struct *tsk, gid_t gid)
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{
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int ret;
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task_lock(tsk);
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ret = groups_search(tsk->group_info, gid);
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task_unlock(tsk);
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return ret;
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}
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static inline int key_task_permission(const key_ref_t key_ref,
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struct task_struct *context,
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key_perm_t perm)
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{
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struct key *key = key_ref_to_ptr(key_ref);
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key_perm_t kperm;
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if (is_key_possessed(key_ref)) {
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kperm = key->perm >> 24;
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}
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else if (key->uid == context->fsuid) {
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kperm = key->perm >> 16;
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}
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else if (key->gid != -1 &&
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key->perm & KEY_GRP_ALL && (
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key->gid == context->fsgid ||
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key_task_groups_search(context, key->gid)
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)
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) {
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kperm = key->perm >> 8;
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}
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else {
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kperm = key->perm;
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}
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kperm = kperm & perm & KEY_ALL;
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return kperm == perm;
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}
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extern key_ref_t lookup_user_key(struct task_struct *context,
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key_serial_t id, int create, int partial,
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key_perm_t perm);
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extern long join_session_keyring(const char *name);
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extern struct key_type *key_type_lookup(const char *type);
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extern void key_type_put(struct key_type *ktype);
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#define key_negative_timeout 60 /* default timeout on a negative key's existence */
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#endif /* _LINUX_KEY_UI_H */
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