apparmor: add support for mapping secids and using secctxes
Use a radix tree to provide a map between the secid and the label, and along with it a basic ability to provide secctx conversion. Shared/cached secctx will be added later. Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen
@@ -3,7 +3,7 @@
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*
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* This file contains AppArmor security identifier (secid) manipulation fns
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*
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* Copyright 2009-2010 Canonical Ltd.
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* Copyright 2009-2017 Canonical Ltd.
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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 as
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@@ -11,37 +11,218 @@
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* License.
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*
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*
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* AppArmor allocates a unique secid for every profile loaded. If a profile
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* is replaced it receives the secid of the profile it is replacing.
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*
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* The secid value of 0 is invalid.
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* AppArmor allocates a unique secid for every label used. If a label
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* is replaced it receives the secid of the label it is replacing.
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*/
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#include <linux/spinlock.h>
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include "include/cred.h"
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#include "include/lib.h"
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#include "include/secid.h"
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#include "include/label.h"
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#include "include/policy_ns.h"
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/* global counter from which secids are allocated */
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static u32 global_secid;
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/*
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* secids - do not pin labels with a refcount. They rely on the label
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* properly updating/freeing them
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*
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* A singly linked free list is used to track secids that have been
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* freed and reuse them before allocating new ones
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*/
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#define FREE_LIST_HEAD 1
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static RADIX_TREE(aa_secids_map, GFP_ATOMIC);
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static DEFINE_SPINLOCK(secid_lock);
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static u32 alloced_secid = FREE_LIST_HEAD;
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static u32 free_list = FREE_LIST_HEAD;
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static unsigned long free_count;
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/*
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* TODO: allow policy to reserve a secid range?
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* TODO: add secid pinning
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* TODO: use secid_update in label replace
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*/
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#define SECID_MAX U32_MAX
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/* TODO: mark free list as exceptional */
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static void *to_ptr(u32 secid)
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{
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return (void *)
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((((unsigned long) secid) << RADIX_TREE_EXCEPTIONAL_SHIFT));
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}
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static u32 to_secid(void *ptr)
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{
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return (u32) (((unsigned long) ptr) >> RADIX_TREE_EXCEPTIONAL_SHIFT);
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}
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/* TODO: tag free_list entries to mark them as different */
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static u32 __pop(struct aa_label *label)
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{
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u32 secid = free_list;
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void __rcu **slot;
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void *entry;
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if (free_list == FREE_LIST_HEAD)
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return AA_SECID_INVALID;
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slot = radix_tree_lookup_slot(&aa_secids_map, secid);
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AA_BUG(!slot);
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entry = radix_tree_deref_slot_protected(slot, &secid_lock);
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free_list = to_secid(entry);
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radix_tree_replace_slot(&aa_secids_map, slot, label);
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free_count--;
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return secid;
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}
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static void __push(u32 secid)
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{
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void __rcu **slot;
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slot = radix_tree_lookup_slot(&aa_secids_map, secid);
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AA_BUG(!slot);
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radix_tree_replace_slot(&aa_secids_map, slot, to_ptr(free_list));
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free_list = secid;
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free_count++;
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}
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static struct aa_label * __secid_update(u32 secid, struct aa_label *label)
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{
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struct aa_label *old;
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void __rcu **slot;
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slot = radix_tree_lookup_slot(&aa_secids_map, secid);
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AA_BUG(!slot);
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old = radix_tree_deref_slot_protected(slot, &secid_lock);
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radix_tree_replace_slot(&aa_secids_map, slot, label);
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return old;
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}
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/**
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* aa_secid_update - update a secid mapping to a new label
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* @secid: secid to update
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* @label: label the secid will now map to
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*/
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void aa_secid_update(u32 secid, struct aa_label *label)
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{
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struct aa_label *old;
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unsigned long flags;
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spin_lock_irqsave(&secid_lock, flags);
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old = __secid_update(secid, label);
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spin_unlock_irqrestore(&secid_lock, flags);
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}
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/**
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*
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* see label for inverse aa_label_to_secid
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*/
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struct aa_label *aa_secid_to_label(u32 secid)
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{
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struct aa_label *label;
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rcu_read_lock();
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label = radix_tree_lookup(&aa_secids_map, secid);
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rcu_read_unlock();
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return label;
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}
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int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
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{
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/* TODO: cache secctx and ref count so we don't have to recreate */
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struct aa_label *label = aa_secid_to_label(secid);
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AA_BUG(!secdata);
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AA_BUG(!seclen);
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if (!label)
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return -EINVAL;
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if (secdata)
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*seclen = aa_label_asxprint(secdata, root_ns, label,
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FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
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FLAG_HIDDEN_UNCONFINED |
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FLAG_ABS_ROOT, GFP_ATOMIC);
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else
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*seclen = aa_label_snxprint(NULL, 0, root_ns, label,
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FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
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FLAG_HIDDEN_UNCONFINED |
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FLAG_ABS_ROOT);
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if (*seclen < 0)
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return -ENOMEM;
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return 0;
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}
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int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
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{
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struct aa_label *label;
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label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
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seclen, GFP_KERNEL, false, false);
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if (IS_ERR(label))
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return PTR_ERR(label);
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*secid = label->secid;
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return 0;
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}
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void apparmor_release_secctx(char *secdata, u32 seclen)
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{
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kfree(secdata);
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}
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/* TODO FIXME: add secid to profile mapping, and secid recycling */
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/**
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* aa_alloc_secid - allocate a new secid for a profile
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*/
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u32 aa_alloc_secid(void)
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u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp)
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{
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unsigned long flags;
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u32 secid;
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/*
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* TODO FIXME: secid recycling - part of profile mapping table
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*/
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spin_lock(&secid_lock);
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secid = (++global_secid);
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spin_unlock(&secid_lock);
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/* racey, but at worst causes new allocation instead of reuse */
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if (free_list == FREE_LIST_HEAD) {
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bool preload = 0;
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int res;
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retry:
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if (gfpflags_allow_blocking(gfp) && !radix_tree_preload(gfp))
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preload = 1;
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spin_lock_irqsave(&secid_lock, flags);
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if (alloced_secid != SECID_MAX) {
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secid = ++alloced_secid;
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res = radix_tree_insert(&aa_secids_map, secid, label);
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AA_BUG(res == -EEXIST);
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} else {
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secid = AA_SECID_INVALID;
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}
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spin_unlock_irqrestore(&secid_lock, flags);
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if (preload)
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radix_tree_preload_end();
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} else {
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spin_lock_irqsave(&secid_lock, flags);
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/* remove entry from free list */
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secid = __pop(label);
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if (secid == AA_SECID_INVALID) {
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spin_unlock_irqrestore(&secid_lock, flags);
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goto retry;
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}
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spin_unlock_irqrestore(&secid_lock, flags);
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}
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return secid;
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}
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@@ -51,5 +232,9 @@ u32 aa_alloc_secid(void)
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*/
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void aa_free_secid(u32 secid)
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{
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; /* NOP ATM */
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unsigned long flags;
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spin_lock_irqsave(&secid_lock, flags);
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__push(secid);
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spin_unlock_irqrestore(&secid_lock, flags);
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}
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