// SPDX-License-Identifier: GPL-2.0-only
/*
* AppArmor security module
*
* This file contains AppArmor functions for unpacking policy loaded
* from userspace.
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2022 Canonical Ltd.
*
* Code to provide backwards compatibility with older policy versions,
* by converting/mapping older policy formats into the newer internal
* formats.
*/
#include <linux/ctype.h>
#include <linux/errno.h>
#include "include/lib.h"
#include "include/policy_unpack.h"
#include "include/policy_compat.h"
/* remap old accept table embedded permissions to separate permission table */
static u32 dfa_map_xindex(u16 mask)
{
u16 old_index = (mask >> 10) & 0xf;
u32 index = 0;
if (mask & 0x100)
index |= AA_X_UNSAFE;
if (mask & 0x200)
index |= AA_X_INHERIT;
if (mask & 0x80)
index |= AA_X_UNCONFINED;
if (old_index == 1) {
index |= AA_X_UNCONFINED;
} else if (old_index == 2) {
index |= AA_X_NAME;
} else if (old_index == 3) {
index |= AA_X_NAME | AA_X_CHILD;
} else if (old_index) {
index |= AA_X_TABLE;
index |= old_index - 4;
}
return index;
}
/*
* map old dfa inline permissions to new format
*/
#define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \
((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
#define dfa_user_xbits(dfa, state) (((ACCEPT_TABLE(dfa)[state]) >> 7) & 0x7f)
#define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f)
#define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f)
#define dfa_user_xindex(dfa, state) \
(dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff))
#define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \
0x7f) | \
((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
#define dfa_other_xbits(dfa, state) \
((((ACCEPT_TABLE(dfa)[state]) >> 7) >> 14) & 0x7f)
#define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f)
#define dfa_other_quiet(dfa, state) \
((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f)
#define dfa_other_xindex(dfa, state) \
dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff)
/**
* map_old_perms - map old file perms layout to the new layout
* @old: permission set in old mapping
*
* Returns: new permission mapping
*/
static u32 map_old_perms(u32 old)
{
u32 new = old & 0xf;
if (old & MAY_READ)
new |= AA_MAY_GETATTR | AA_MAY_OPEN;
if (old & MAY_WRITE)
new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
if (old & 0x10)
new |= AA_MAY_LINK;
/* the old mapping lock and link_subset flags where overlaid
* and use was determined by part of a pair that they were in
*/
if (old & 0x20)
new |= AA_MAY_LOCK | AA_LINK_SUBSET;
if (old & 0x40) /* AA_EXEC_MMAP */
new |= AA_EXEC_MMAP;
return new;
}
static void compute_fperms_allow(struct aa_perms *perms, struct aa_dfa *dfa,
aa_state_t state)
{
perms->allow |= AA_MAY_GETATTR;
/* change_profile wasn't determined by ownership in old mapping */
if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
perms->allow |= AA_MAY_CHANGE_PROFILE;
if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
perms->allow |= AA_MAY_ONEXEC;
}
static struct aa_perms compute_fperms_user(struct aa_dfa *dfa,
aa_state_t state)
{
struct aa_perms perms = { };
perms.allow = map_old_perms(dfa_user_allow(dfa, state));
perms.audit = map_old_perms(dfa_user_audit(dfa, state));
perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
perms.xindex = dfa_user_xindex(dfa, state);
compute_fperms_allow(&perms, dfa, state);
return perms;
}
static struct aa_perms compute_fperms_other(struct aa_dfa *dfa,
aa_state_t state)
{
struct aa_perms perms = { };
perms.allow = map_old_perms(dfa_other_allow(dfa, state));
perms.audit = map_old_perms(dfa_other_audit(dfa, state));
perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
perms.xindex = dfa_other_xindex(dfa, state);
compute_fperms_allow(&perms, dfa, state);
return perms;
}
/**
* compute_fperms - convert dfa compressed perms to internal perms and store
* them so they can be retrieved later.
* @dfa: a dfa using fperms to remap to internal permissions
* @size: Returns the permission table size
*
* Returns: remapped perm table
*/
static struct aa_perms *compute_fperms(struct aa_dfa *dfa,
u32 *size)
{
aa_state_t state;
unsigned int state_count;
struct aa_perms *table;
AA_BUG(!dfa);
state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
/* DFAs are restricted from having a state_count of less than 2 */
table = kvcalloc(state_count * 2, sizeof(struct aa_perms), GFP_KERNEL);
if (!table)
return NULL;
*size = state_count * 2;
for (state = 0; state < state_count; state++) {
table[state * 2] = compute_fperms_user(dfa, state);
table[state * 2 + 1] = compute_fperms_other(dfa, state);
}
return table;
}
static struct aa_perms *compute_xmatch_perms(struct aa_dfa *xmatch,
u32 *size)
{
struct aa_perms *perms;
int state;
int state_count;
AA_BUG(!xmatch);
state_count = xmatch->tables[YYTD_ID_BASE]->td_lolen;
/* DFAs are restricted from having a state_count of less than 2 */
perms = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL);
if (!perms)
return NULL;
*size = state_count;
/* zero init so skip the trap state (state == 0) */
for (state = 1; state < state_count; state++)
perms[state].allow = dfa_user_allow(xmatch, state);
return perms;
}
static u32 map_other(u32 x)
{
return ((x & 0x3) << 8) | /* SETATTR/GETATTR */
((x & 0x1c) << 18) | /* ACCEPT/BIND/LISTEN */
((x & 0x60) << 19); /* SETOPT/GETOPT */
}
static u32 map_xbits(u32 x)
{
return ((x & 0x1) << 7) |
((x & 0x7e) << 9);
}
static struct aa_perms compute_perms_entry(struct aa_dfa *dfa,
aa_state_t state,
u32 version)
{
struct aa_perms perms = { };
perms.allow = dfa_user_allow(dfa, state);
perms.audit = dfa_user_audit(dfa, state);
perms.quiet = dfa_user_quiet(dfa, state);
/*
* This mapping is convulated due to history.
* v1-v4: only file perms, which are handled by compute_fperms
* v5: added policydb which dropped user conditional to gain new
* perm bits, but had to map around the xbits because the
* userspace compiler was still munging them.
* v9: adds using the xbits in policydb because the compiler now
* supports treating policydb permission bits different.
* Unfortunately there is no way to force auditing on the
* perms represented by the xbits
*/
perms.allow |= map_other(dfa_other_allow(dfa, state));
if (VERSION_LE(version, v8))
perms.allow |= AA_MAY_LOCK;
else
perms.allow |= map_xbits(dfa_user_xbits(dfa, state));
/*
* for v5-v9 perm mapping in the policydb, the other set is used
* to extend the general perm set
*/
perms.audit |= map_other(dfa_other_audit(dfa, state));
perms.quiet |= map_other(dfa_other_quiet(dfa, state));
if (VERSION_GT(version, v8))
perms.quiet |= map_xbits(dfa_other_xbits(dfa, state));
return perms;
}
static struct aa_perms *compute_perms(struct aa_dfa *dfa, u32 version,
u32 *size)
{
unsigned int state;
unsigned int state_count;
struct aa_perms *table;
AA_BUG(!dfa);
state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
/* DFAs are restricted from having a state_count of less than 2 */
table = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL);
if (!table)
return NULL;
*size = state_count;
/* zero init so skip the trap state (state == 0) */
for (state = 1; state < state_count; state++)
table[state] = compute_perms_entry(dfa, state, version);
return table;
}
/**
* remap_dfa_accept - remap old dfa accept table to be an index
* @dfa: dfa to do the remapping on
* @factor: scaling factor for the index conversion.
*
* Used in conjunction with compute_Xperms, it converts old style perms
* that are encoded in the dfa accept tables to the new style where
* there is a permission table and the accept table is an index into
* the permission table.
*/
static void remap_dfa_accept(struct aa_dfa *dfa, unsigned int factor)
{
unsigned int state;
unsigned int state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
AA_BUG(!dfa);
for (state = 0; state < state_count; state++)
ACCEPT_TABLE(dfa)[state] = state * factor;
kvfree(dfa->tables[YYTD_ID_ACCEPT2]);
dfa->tables[YYTD_ID_ACCEPT2] = NULL;
}
/* TODO: merge different dfa mappings into single map_policy fn */
int aa_compat_map_xmatch(struct aa_policydb *policy)
{
policy->perms = compute_xmatch_perms(policy->dfa, &policy->size);
if (!policy->perms)
return -ENOMEM;
remap_dfa_accept(policy->dfa, 1);
return 0;
}
int aa_compat_map_policy(struct aa_policydb *policy, u32 version)
{
policy->perms = compute_perms(policy->dfa, version, &policy->size);
if (!policy->perms)
return -ENOMEM;
remap_dfa_accept(policy->dfa, 1);
return 0;
}
int aa_compat_map_file(struct aa_policydb *policy)
{
policy->perms = compute_fperms(policy->dfa, &policy->size);
if (!policy->perms)
return -ENOMEM;
remap_dfa_accept(policy->dfa, 2);
return 0;
}
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