433 lines
11 KiB
C
433 lines
11 KiB
C
|
/*
|
||
|
|
* AppArmor security module
|
||
|
|
*
|
||
|
|
* This file contains AppArmor dfa based regular expression matching engine
|
||
|
|
*
|
||
|
|
* Copyright (C) 1998-2008 Novell/SUSE
|
||
|
|
* Copyright 2009-2012 Canonical Ltd.
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License as
|
||
|
|
* published by the Free Software Foundation, version 2 of the
|
||
|
|
* License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/errno.h>
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/mm.h>
|
||
|
|
#include <linux/slab.h>
|
||
|
|
#include <linux/vmalloc.h>
|
||
|
|
#include <linux/err.h>
|
||
|
|
#include <linux/kref.h>
|
||
|
|
|
||
|
|
#include "include/apparmor.h"
|
||
|
|
#include "include/match.h"
|
||
|
|
|
||
|
|
#define base_idx(X) ((X) & 0xffffff)
|
||
|
|
|
||
|
|
/**
|
||
|
|
* unpack_table - unpack a dfa table (one of accept, default, base, next check)
|
||
|
|
* @blob: data to unpack (NOT NULL)
|
||
|
|
* @bsize: size of blob
|
||
|
|
*
|
||
|
|
* Returns: pointer to table else NULL on failure
|
||
|
|
*
|
||
|
|
* NOTE: must be freed by kvfree (not kfree)
|
||
|
|
*/
|
||
|
|
static struct table_header *unpack_table(char *blob, size_t bsize)
|
||
|
|
{
|
||
|
|
struct table_header *table = NULL;
|
||
|
|
struct table_header th;
|
||
|
|
size_t tsize;
|
||
|
|
|
||
|
|
if (bsize < sizeof(struct table_header))
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
/* loaded td_id's start at 1, subtract 1 now to avoid doing
|
||
|
|
* it every time we use td_id as an index
|
||
|
|
*/
|
||
|
|
th.td_id = be16_to_cpu(*(u16 *) (blob)) - 1;
|
||
|
|
if (th.td_id > YYTD_ID_MAX)
|
||
|
|
goto out;
|
||
|
|
th.td_flags = be16_to_cpu(*(u16 *) (blob + 2));
|
||
|
|
th.td_lolen = be32_to_cpu(*(u32 *) (blob + 8));
|
||
|
|
blob += sizeof(struct table_header);
|
||
|
|
|
||
|
|
if (!(th.td_flags == YYTD_DATA16 || th.td_flags == YYTD_DATA32 ||
|
||
|
|
th.td_flags == YYTD_DATA8))
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
tsize = table_size(th.td_lolen, th.td_flags);
|
||
|
|
if (bsize < tsize)
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
table = kvzalloc(tsize);
|
||
|
|
if (table) {
|
||
|
|
table->td_id = th.td_id;
|
||
|
|
table->td_flags = th.td_flags;
|
||
|
|
table->td_lolen = th.td_lolen;
|
||
|
|
if (th.td_flags == YYTD_DATA8)
|
||
|
|
UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
|
||
|
|
u8, byte_to_byte);
|
||
|
|
else if (th.td_flags == YYTD_DATA16)
|
||
|
|
UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
|
||
|
|
u16, be16_to_cpu);
|
||
|
|
else if (th.td_flags == YYTD_DATA32)
|
||
|
|
UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
|
||
|
|
u32, be32_to_cpu);
|
||
|
|
else
|
||
|
|
goto fail;
|
||
|
|
/* if table was vmalloced make sure the page tables are synced
|
||
|
|
* before it is used, as it goes live to all cpus.
|
||
|
|
*/
|
||
|
|
if (is_vmalloc_addr(table))
|
||
|
|
vm_unmap_aliases();
|
||
|
|
}
|
||
|
|
|
||
|
|
out:
|
||
|
|
return table;
|
||
|
|
fail:
|
||
|
|
kvfree(table);
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* verify_dfa - verify that transitions and states in the tables are in bounds.
|
||
|
|
* @dfa: dfa to test (NOT NULL)
|
||
|
|
* @flags: flags controlling what type of accept table are acceptable
|
||
|
|
*
|
||
|
|
* Assumes dfa has gone through the first pass verification done by unpacking
|
||
|
|
* NOTE: this does not valid accept table values
|
||
|
|
*
|
||
|
|
* Returns: %0 else error code on failure to verify
|
||
|
|
*/
|
||
|
|
static int verify_dfa(struct aa_dfa *dfa, int flags)
|
||
|
|
{
|
||
|
|
size_t i, state_count, trans_count;
|
||
|
|
int error = -EPROTO;
|
||
|
|
|
||
|
|
/* check that required tables exist */
|
||
|
|
if (!(dfa->tables[YYTD_ID_DEF] &&
|
||
|
|
dfa->tables[YYTD_ID_BASE] &&
|
||
|
|
dfa->tables[YYTD_ID_NXT] && dfa->tables[YYTD_ID_CHK]))
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
/* accept.size == default.size == base.size */
|
||
|
|
state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
|
||
|
|
if (ACCEPT1_FLAGS(flags)) {
|
||
|
|
if (!dfa->tables[YYTD_ID_ACCEPT])
|
||
|
|
goto out;
|
||
|
|
if (state_count != dfa->tables[YYTD_ID_ACCEPT]->td_lolen)
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
if (ACCEPT2_FLAGS(flags)) {
|
||
|
|
if (!dfa->tables[YYTD_ID_ACCEPT2])
|
||
|
|
goto out;
|
||
|
|
if (state_count != dfa->tables[YYTD_ID_ACCEPT2]->td_lolen)
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
if (state_count != dfa->tables[YYTD_ID_DEF]->td_lolen)
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
/* next.size == chk.size */
|
||
|
|
trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
|
||
|
|
if (trans_count != dfa->tables[YYTD_ID_CHK]->td_lolen)
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
/* if equivalence classes then its table size must be 256 */
|
||
|
|
if (dfa->tables[YYTD_ID_EC] &&
|
||
|
|
dfa->tables[YYTD_ID_EC]->td_lolen != 256)
|
||
|
|
goto out;
|
||
|
|
|
||
|
|
if (flags & DFA_FLAG_VERIFY_STATES) {
|
||
|
|
for (i = 0; i < state_count; i++) {
|
||
|
|
if (DEFAULT_TABLE(dfa)[i] >= state_count)
|
||
|
|
goto out;
|
||
|
|
if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
|
||
|
|
printk(KERN_ERR "AppArmor DFA next/check upper "
|
||
|
|
"bounds error\n");
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
for (i = 0; i < trans_count; i++) {
|
||
|
|
if (NEXT_TABLE(dfa)[i] >= state_count)
|
||
|
|
goto out;
|
||
|
|
if (CHECK_TABLE(dfa)[i] >= state_count)
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
error = 0;
|
||
|
|
out:
|
||
|
|
return error;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* dfa_free - free a dfa allocated by aa_dfa_unpack
|
||
|
|
* @dfa: the dfa to free (MAYBE NULL)
|
||
|
|
*
|
||
|
|
* Requires: reference count to dfa == 0
|
||
|
|
*/
|
||
|
|
static void dfa_free(struct aa_dfa *dfa)
|
||
|
|
{
|
||
|
|
if (dfa) {
|
||
|
|
int i;
|
||
|
|
|
||
|
|
for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
|
||
|
|
kvfree(dfa->tables[i]);
|
||
|
|
dfa->tables[i] = NULL;
|
||
|
|
}
|
||
|
|
kfree(dfa);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
|
||
|
|
* @kr: kref callback for freeing of a dfa (NOT NULL)
|
||
|
|
*/
|
||
|
|
void aa_dfa_free_kref(struct kref *kref)
|
||
|
|
{
|
||
|
|
struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
|
||
|
|
dfa_free(dfa);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* aa_dfa_unpack - unpack the binary tables of a serialized dfa
|
||
|
|
* @blob: aligned serialized stream of data to unpack (NOT NULL)
|
||
|
|
* @size: size of data to unpack
|
||
|
|
* @flags: flags controlling what type of accept tables are acceptable
|
||
|
|
*
|
||
|
|
* Unpack a dfa that has been serialized. To find information on the dfa
|
||
|
|
* format look in Documentation/security/apparmor.txt
|
||
|
|
* Assumes the dfa @blob stream has been aligned on a 8 byte boundary
|
||
|
|
*
|
||
|
|
* Returns: an unpacked dfa ready for matching or ERR_PTR on failure
|
||
|
|
*/
|
||
|
|
struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
|
||
|
|
{
|
||
|
|
int hsize;
|
||
|
|
int error = -ENOMEM;
|
||
|
|
char *data = blob;
|
||
|
|
struct table_header *table = NULL;
|
||
|
|
struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
|
||
|
|
if (!dfa)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
kref_init(&dfa->count);
|
||
|
|
|
||
|
|
error = -EPROTO;
|
||
|
|
|
||
|
|
/* get dfa table set header */
|
||
|
|
if (size < sizeof(struct table_set_header))
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
if (ntohl(*(u32 *) data) != YYTH_MAGIC)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
hsize = ntohl(*(u32 *) (data + 4));
|
||
|
|
if (size < hsize)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
dfa->flags = ntohs(*(u16 *) (data + 12));
|
||
|
|
data += hsize;
|
||
|
|
size -= hsize;
|
||
|
|
|
||
|
|
while (size > 0) {
|
||
|
|
table = unpack_table(data, size);
|
||
|
|
if (!table)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
switch (table->td_id) {
|
||
|
|
case YYTD_ID_ACCEPT:
|
||
|
|
if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
|
||
|
|
goto fail;
|
||
|
|
break;
|
||
|
|
case YYTD_ID_ACCEPT2:
|
||
|
|
if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
|
||
|
|
goto fail;
|
||
|
|
break;
|
||
|
|
case YYTD_ID_BASE:
|
||
|
|
if (table->td_flags != YYTD_DATA32)
|
||
|
|
goto fail;
|
||
|
|
break;
|
||
|
|
case YYTD_ID_DEF:
|
||
|
|
case YYTD_ID_NXT:
|
||
|
|
case YYTD_ID_CHK:
|
||
|
|
if (table->td_flags != YYTD_DATA16)
|
||
|
|
goto fail;
|
||
|
|
break;
|
||
|
|
case YYTD_ID_EC:
|
||
|
|
if (table->td_flags != YYTD_DATA8)
|
||
|
|
goto fail;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
/* check for duplicate table entry */
|
||
|
|
if (dfa->tables[table->td_id])
|
||
|
|
goto fail;
|
||
|
|
dfa->tables[table->td_id] = table;
|
||
|
|
data += table_size(table->td_lolen, table->td_flags);
|
||
|
|
size -= table_size(table->td_lolen, table->td_flags);
|
||
|
|
table = NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
error = verify_dfa(dfa, flags);
|
||
|
|
if (error)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
return dfa;
|
||
|
|
|
||
|
|
fail:
|
||
|
|
kvfree(table);
|
||
|
|
dfa_free(dfa);
|
||
|
|
return ERR_PTR(error);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* aa_dfa_match_len - traverse @dfa to find state @str stops at
|
||
|
|
* @dfa: the dfa to match @str against (NOT NULL)
|
||
|
|
* @start: the state of the dfa to start matching in
|
||
|
|
* @str: the string of bytes to match against the dfa (NOT NULL)
|
||
|
|
* @len: length of the string of bytes to match
|
||
|
|
*
|
||
|
|
* aa_dfa_match_len will match @str against the dfa and return the state it
|
||
|
|
* finished matching in. The final state can be used to look up the accepting
|
||
|
|
* label, or as the start state of a continuing match.
|
||
|
|
*
|
||
|
|
* This function will happily match again the 0 byte and only finishes
|
||
|
|
* when @len input is consumed.
|
||
|
|
*
|
||
|
|
* Returns: final state reached after input is consumed
|
||
|
|
*/
|
||
|
|
unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
|
||
|
|
const char *str, int len)
|
||
|
|
{
|
||
|
|
u16 *def = DEFAULT_TABLE(dfa);
|
||
|
|
u32 *base = BASE_TABLE(dfa);
|
||
|
|
u16 *next = NEXT_TABLE(dfa);
|
||
|
|
u16 *check = CHECK_TABLE(dfa);
|
||
|
|
unsigned int state = start, pos;
|
||
|
|
|
||
|
|
if (state == 0)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
/* current state is <state>, matching character *str */
|
||
|
|
if (dfa->tables[YYTD_ID_EC]) {
|
||
|
|
/* Equivalence class table defined */
|
||
|
|
u8 *equiv = EQUIV_TABLE(dfa);
|
||
|
|
/* default is direct to next state */
|
||
|
|
for (; len; len--) {
|
||
|
|
pos = base_idx(base[state]) + equiv[(u8) *str++];
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
/* default is direct to next state */
|
||
|
|
for (; len; len--) {
|
||
|
|
pos = base_idx(base[state]) + (u8) *str++;
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return state;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* aa_dfa_match - traverse @dfa to find state @str stops at
|
||
|
|
* @dfa: the dfa to match @str against (NOT NULL)
|
||
|
|
* @start: the state of the dfa to start matching in
|
||
|
|
* @str: the null terminated string of bytes to match against the dfa (NOT NULL)
|
||
|
|
*
|
||
|
|
* aa_dfa_match will match @str against the dfa and return the state it
|
||
|
|
* finished matching in. The final state can be used to look up the accepting
|
||
|
|
* label, or as the start state of a continuing match.
|
||
|
|
*
|
||
|
|
* Returns: final state reached after input is consumed
|
||
|
|
*/
|
||
|
|
unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
|
||
|
|
const char *str)
|
||
|
|
{
|
||
|
|
u16 *def = DEFAULT_TABLE(dfa);
|
||
|
|
u32 *base = BASE_TABLE(dfa);
|
||
|
|
u16 *next = NEXT_TABLE(dfa);
|
||
|
|
u16 *check = CHECK_TABLE(dfa);
|
||
|
|
unsigned int state = start, pos;
|
||
|
|
|
||
|
|
if (state == 0)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
/* current state is <state>, matching character *str */
|
||
|
|
if (dfa->tables[YYTD_ID_EC]) {
|
||
|
|
/* Equivalence class table defined */
|
||
|
|
u8 *equiv = EQUIV_TABLE(dfa);
|
||
|
|
/* default is direct to next state */
|
||
|
|
while (*str) {
|
||
|
|
pos = base_idx(base[state]) + equiv[(u8) *str++];
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
/* default is direct to next state */
|
||
|
|
while (*str) {
|
||
|
|
pos = base_idx(base[state]) + (u8) *str++;
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return state;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* aa_dfa_next - step one character to the next state in the dfa
|
||
|
|
* @dfa: the dfa to tranverse (NOT NULL)
|
||
|
|
* @state: the state to start in
|
||
|
|
* @c: the input character to transition on
|
||
|
|
*
|
||
|
|
* aa_dfa_match will step through the dfa by one input character @c
|
||
|
|
*
|
||
|
|
* Returns: state reach after input @c
|
||
|
|
*/
|
||
|
|
unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
|
||
|
|
const char c)
|
||
|
|
{
|
||
|
|
u16 *def = DEFAULT_TABLE(dfa);
|
||
|
|
u32 *base = BASE_TABLE(dfa);
|
||
|
|
u16 *next = NEXT_TABLE(dfa);
|
||
|
|
u16 *check = CHECK_TABLE(dfa);
|
||
|
|
unsigned int pos;
|
||
|
|
|
||
|
|
/* current state is <state>, matching character *str */
|
||
|
|
if (dfa->tables[YYTD_ID_EC]) {
|
||
|
|
/* Equivalence class table defined */
|
||
|
|
u8 *equiv = EQUIV_TABLE(dfa);
|
||
|
|
/* default is direct to next state */
|
||
|
|
|
||
|
|
pos = base_idx(base[state]) + equiv[(u8) c];
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
} else {
|
||
|
|
/* default is direct to next state */
|
||
|
|
pos = base_idx(base[state]) + (u8) c;
|
||
|
|
if (check[pos] == state)
|
||
|
|
state = next[pos];
|
||
|
|
else
|
||
|
|
state = def[state];
|
||
|
|
}
|
||
|
|
|
||
|
|
return state;
|
||
|
|
}
|