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jrjohansenjrjohansen
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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>
1 parent 552c69b commit c092921

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6 files changed

+224
-25
lines changed

6 files changed

+224
-25
lines changed

‎security/apparmor/include/label.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -281,7 +281,7 @@ void __aa_labelset_update_subtree(struct aa_ns *ns);
281281

282282
void aa_label_free(struct aa_label *label);
283283
void aa_label_kref(struct kref *kref);
284-
bool aa_label_init(struct aa_label *label, int size);
284+
bool aa_label_init(struct aa_label *label, int size, gfp_t gfp);
285285
struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp);
286286

287287
bool aa_label_is_subset(struct aa_label *set, struct aa_label *sub);

‎security/apparmor/include/secid.h

Lines changed: 12 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*
44
* This file contains AppArmor security identifier (secid) definitions
55
*
6-
* Copyright 2009-2010 Canonical Ltd.
6+
* Copyright 2009-2018 Canonical Ltd.
77
*
88
* This program is free software; you can redistribute it and/or
99
* modify it under the terms of the GNU General Public License as
@@ -14,13 +14,22 @@
1414
#ifndef __AA_SECID_H
1515
#define __AA_SECID_H
1616

17+
#include <linux/slab.h>
1718
#include <linux/types.h>
1819

20+
struct aa_label;
21+
1922
/* secid value that will not be allocated */
2023
#define AA_SECID_INVALID 0
21-
#define AA_SECID_ALLOC AA_SECID_INVALID
2224

23-
u32 aa_alloc_secid(void);
25+
struct aa_label *aa_secid_to_label(u32 secid);
26+
int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
27+
int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
28+
void apparmor_release_secctx(char *secdata, u32 seclen);
29+
30+
31+
u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp);
2432
void aa_free_secid(u32 secid);
33+
void aa_secid_update(u32 secid, struct aa_label *label);
2534

2635
#endif /* __AA_SECID_H */

‎security/apparmor/label.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -402,12 +402,12 @@ static void label_free_or_put_new(struct aa_label *label, struct aa_label *new)
402402
aa_put_label(new);
403403
}
404404

405-
bool aa_label_init(struct aa_label *label, int size)
405+
bool aa_label_init(struct aa_label *label, int size, gfp_t gfp)
406406
{
407407
AA_BUG(!label);
408408
AA_BUG(size < 1);
409409

410-
label->secid = aa_alloc_secid();
410+
label->secid = aa_alloc_secid(label, gfp);
411411
if (label->secid == AA_SECID_INVALID)
412412
return false;
413413

@@ -441,7 +441,7 @@ struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp)
441441
if (!new)
442442
goto fail;
443443

444-
if (!aa_label_init(new, size))
444+
if (!aa_label_init(new, size, gfp))
445445
goto fail;
446446

447447
if (!proxy) {

‎security/apparmor/lsm.c

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -39,6 +39,7 @@
3939
#include "include/policy_ns.h"
4040
#include "include/procattr.h"
4141
#include "include/mount.h"
42+
#include "include/secid.h"
4243

4344
/* Flag indicating whether initialization completed */
4445
int apparmor_initialized;
@@ -1188,6 +1189,10 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
11881189
LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
11891190
LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
11901191
LSM_HOOK_INIT(task_kill, apparmor_task_kill),
1192+
1193+
LSM_HOOK_INIT(secid_to_secctx, apparmor_secid_to_secctx),
1194+
LSM_HOOK_INIT(secctx_to_secid, apparmor_secctx_to_secid),
1195+
LSM_HOOK_INIT(release_secctx, apparmor_release_secctx),
11911196
};
11921197

11931198
/*

‎security/apparmor/policy.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -268,7 +268,7 @@ struct aa_profile *aa_alloc_profile(const char *hname, struct aa_proxy *proxy,
268268

269269
if (!aa_policy_init(&profile->base, NULL, hname, gfp))
270270
goto fail;
271-
if (!aa_label_init(&profile->label, 1))
271+
if (!aa_label_init(&profile->label, 1, gfp))
272272
goto fail;
273273

274274
/* update being set needed by fs interface */

‎security/apparmor/secid.c

Lines changed: 202 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -3,45 +3,226 @@
33
*
44
* This file contains AppArmor security identifier (secid) manipulation fns
55
*
6-
* Copyright 2009-2010 Canonical Ltd.
6+
* Copyright 2009-2017 Canonical Ltd.
77
*
88
* This program is free software; you can redistribute it and/or
99
* modify it under the terms of the GNU General Public License as
1010
* published by the Free Software Foundation, version 2 of the
1111
* License.
1212
*
1313
*
14-
* AppArmor allocates a unique secid for every profile loaded. If a profile
15-
* is replaced it receives the secid of the profile it is replacing.
16-
*
17-
* The secid value of 0 is invalid.
14+
* AppArmor allocates a unique secid for every label used. If a label
15+
* is replaced it receives the secid of the label it is replacing.
1816
*/
1917

20-
#include <linux/spinlock.h>
2118
#include <linux/errno.h>
2219
#include <linux/err.h>
20+
#include <linux/gfp.h>
21+
#include <linux/slab.h>
22+
#include <linux/spinlock.h>
2323

24+
#include "include/cred.h"
25+
#include "include/lib.h"
2426
#include "include/secid.h"
27+
#include "include/label.h"
28+
#include "include/policy_ns.h"
2529

26-
/* global counter from which secids are allocated */
27-
static u32 global_secid;
30+
/*
31+
* secids - do not pin labels with a refcount. They rely on the label
32+
* properly updating/freeing them
33+
*
34+
* A singly linked free list is used to track secids that have been
35+
* freed and reuse them before allocating new ones
36+
*/
37+
38+
#define FREE_LIST_HEAD 1
39+
40+
static RADIX_TREE(aa_secids_map, GFP_ATOMIC);
2841
static DEFINE_SPINLOCK(secid_lock);
42+
static u32 alloced_secid = FREE_LIST_HEAD;
43+
static u32 free_list = FREE_LIST_HEAD;
44+
static unsigned long free_count;
45+
46+
/*
47+
* TODO: allow policy to reserve a secid range?
48+
* TODO: add secid pinning
49+
* TODO: use secid_update in label replace
50+
*/
51+
52+
#define SECID_MAX U32_MAX
53+
54+
/* TODO: mark free list as exceptional */
55+
static void *to_ptr(u32 secid)
56+
{
57+
return (void *)
58+
((((unsigned long) secid) << RADIX_TREE_EXCEPTIONAL_SHIFT));
59+
}
60+
61+
static u32 to_secid(void *ptr)
62+
{
63+
return (u32) (((unsigned long) ptr) >> RADIX_TREE_EXCEPTIONAL_SHIFT);
64+
}
65+
66+
67+
/* TODO: tag free_list entries to mark them as different */
68+
static u32 __pop(struct aa_label *label)
69+
{
70+
u32 secid = free_list;
71+
void __rcu **slot;
72+
void *entry;
73+
74+
if (free_list == FREE_LIST_HEAD)
75+
return AA_SECID_INVALID;
76+
77+
slot = radix_tree_lookup_slot(&aa_secids_map, secid);
78+
AA_BUG(!slot);
79+
entry = radix_tree_deref_slot_protected(slot, &secid_lock);
80+
free_list = to_secid(entry);
81+
radix_tree_replace_slot(&aa_secids_map, slot, label);
82+
free_count--;
83+
84+
return secid;
85+
}
86+
87+
static void __push(u32 secid)
88+
{
89+
void __rcu **slot;
90+
91+
slot = radix_tree_lookup_slot(&aa_secids_map, secid);
92+
AA_BUG(!slot);
93+
radix_tree_replace_slot(&aa_secids_map, slot, to_ptr(free_list));
94+
free_list = secid;
95+
free_count++;
96+
}
97+
98+
static struct aa_label * __secid_update(u32 secid, struct aa_label *label)
99+
{
100+
struct aa_label *old;
101+
void __rcu **slot;
102+
103+
slot = radix_tree_lookup_slot(&aa_secids_map, secid);
104+
AA_BUG(!slot);
105+
old = radix_tree_deref_slot_protected(slot, &secid_lock);
106+
radix_tree_replace_slot(&aa_secids_map, slot, label);
107+
108+
return old;
109+
}
110+
111+
/**
112+
* aa_secid_update - update a secid mapping to a new label
113+
* @secid: secid to update
114+
* @label: label the secid will now map to
115+
*/
116+
void aa_secid_update(u32 secid, struct aa_label *label)
117+
{
118+
struct aa_label *old;
119+
unsigned long flags;
120+
121+
spin_lock_irqsave(&secid_lock, flags);
122+
old = __secid_update(secid, label);
123+
spin_unlock_irqrestore(&secid_lock, flags);
124+
}
125+
126+
/**
127+
*
128+
* see label for inverse aa_label_to_secid
129+
*/
130+
struct aa_label *aa_secid_to_label(u32 secid)
131+
{
132+
struct aa_label *label;
133+
134+
rcu_read_lock();
135+
label = radix_tree_lookup(&aa_secids_map, secid);
136+
rcu_read_unlock();
137+
138+
return label;
139+
}
140+
141+
int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
142+
{
143+
/* TODO: cache secctx and ref count so we don't have to recreate */
144+
struct aa_label *label = aa_secid_to_label(secid);
145+
146+
AA_BUG(!secdata);
147+
AA_BUG(!seclen);
148+
149+
if (!label)
150+
return -EINVAL;
151+
152+
if (secdata)
153+
*seclen = aa_label_asxprint(secdata, root_ns, label,
154+
FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
155+
FLAG_HIDDEN_UNCONFINED |
156+
FLAG_ABS_ROOT, GFP_ATOMIC);
157+
else
158+
*seclen = aa_label_snxprint(NULL, 0, root_ns, label,
159+
FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
160+
FLAG_HIDDEN_UNCONFINED |
161+
FLAG_ABS_ROOT);
162+
if (*seclen < 0)
163+
return -ENOMEM;
164+
165+
return 0;
166+
}
167+
168+
169+
int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
170+
{
171+
struct aa_label *label;
172+
173+
label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
174+
seclen, GFP_KERNEL, false, false);
175+
if (IS_ERR(label))
176+
return PTR_ERR(label);
177+
*secid = label->secid;
178+
179+
return 0;
180+
}
181+
182+
void apparmor_release_secctx(char *secdata, u32 seclen)
183+
{
184+
kfree(secdata);
185+
}
29186

30-
/* TODO FIXME: add secid to profile mapping, and secid recycling */
31187

32188
/**
33189
* aa_alloc_secid - allocate a new secid for a profile
34190
*/
35-
u32 aa_alloc_secid(void)
191+
u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp)
36192
{
193+
unsigned long flags;
37194
u32 secid;
38195

39-
/*
40-
* TODO FIXME: secid recycling - part of profile mapping table
41-
*/
42-
spin_lock(&secid_lock);
43-
secid = (++global_secid);
44-
spin_unlock(&secid_lock);
196+
/* racey, but at worst causes new allocation instead of reuse */
197+
if (free_list == FREE_LIST_HEAD) {
198+
bool preload = 0;
199+
int res;
200+
201+
retry:
202+
if (gfpflags_allow_blocking(gfp) && !radix_tree_preload(gfp))
203+
preload = 1;
204+
spin_lock_irqsave(&secid_lock, flags);
205+
if (alloced_secid != SECID_MAX) {
206+
secid = ++alloced_secid;
207+
res = radix_tree_insert(&aa_secids_map, secid, label);
208+
AA_BUG(res == -EEXIST);
209+
} else {
210+
secid = AA_SECID_INVALID;
211+
}
212+
spin_unlock_irqrestore(&secid_lock, flags);
213+
if (preload)
214+
radix_tree_preload_end();
215+
} else {
216+
spin_lock_irqsave(&secid_lock, flags);
217+
/* remove entry from free list */
218+
secid = __pop(label);
219+
if (secid == AA_SECID_INVALID) {
220+
spin_unlock_irqrestore(&secid_lock, flags);
221+
goto retry;
222+
}
223+
spin_unlock_irqrestore(&secid_lock, flags);
224+
}
225+
45226
return secid;
46227
}
47228

@@ -51,5 +232,9 @@ u32 aa_alloc_secid(void)
51232
*/
52233
void aa_free_secid(u32 secid)
53234
{
54-
; /* NOP ATM */
235+
unsigned long flags;
236+
237+
spin_lock_irqsave(&secid_lock, flags);
238+
__push(secid);
239+
spin_unlock_irqrestore(&secid_lock, flags);
55240
}

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