/**
* 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;
}
/**
* aa_dfa_matchn_until - traverse @dfa until accept or @n bytes consumed
* @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)
* @n: length of the string of bytes to match
* @retpos: first character in str after match OR str + n
*
* 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 @n input is consumed.
*
* Returns: final state reached after input is consumed
*/
unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
const char *str, int n, const char **retpos)
{
u16 *def = DEFAULT_TABLE(dfa);
u32 *base = BASE_TABLE(dfa);
u16 *next = NEXT_TABLE(dfa);
u16 *check = CHECK_TABLE(dfa);
u32 *accept = ACCEPT_TABLE(dfa);
unsigned int state = start, pos;
*retpos = NULL;
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 (; n; n--) {
pos = base_idx(base[state]) + equiv[(u8) *str++];
if (check[pos] == state)
state = next[pos];
else
state = def[state];
if (accept[state])
break;
}
} else {
/* default is direct to next state */
for (; n; n--) {
pos = base_idx(base[state]) + (u8) *str++;
if (check[pos] == state)
state = next[pos];
else
state = def[state];
if (accept[state])
break;
}
}
*retpos = str;
return state;
}
/**
* verify_dfa - verify that transitions and states in the tables are in bounds.
* @dfa: dfa to test (NOT NULL)
*
* 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)
{
size_t i, state_count, trans_count;
int error = -EPROTO;
state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
for (i = 0; i < state_count; i++) {
if (!(BASE_TABLE(dfa)[i] & MATCH_FLAG_DIFF_ENCODE) &&
(DEFAULT_TABLE(dfa)[i] >= state_count))
goto out;
if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
pr_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;
}
/* Now that all the other tables are verified, verify diffencoding */
for (i = 0; i < state_count; i++) {
size_t j, k;
for (j = i;
(BASE_TABLE(dfa)[j] & MATCH_FLAG_DIFF_ENCODE) &&
!(BASE_TABLE(dfa)[j] & MARK_DIFF_ENCODE);
j = k) {
k = DEFAULT_TABLE(dfa)[j];
if (j == k)
goto out;
if (k < j)
break; /* already verified */
BASE_TABLE(dfa)[j] |= MARK_DIFF_ENCODE;
}
}
error = 0;
out:
return error;
}
static unsigned int leftmatch_fb(struct aa_dfa *dfa, unsigned int start,
const char *str, struct match_workbuf *wb,
unsigned int *count)
{
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;
AA_BUG(!dfa);
AA_BUG(!str);
AA_BUG(!wb);
AA_BUG(!count);
*count = 0;
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) {
unsigned int adjust;
wb->history[wb->pos] = state;
pos = base_idx(base[state]) + equiv[(u8) *str++];
if (check[pos] == state)
state = next[pos];
else
state = def[state];
if (is_loop(wb, state, &adjust)) {
state = aa_dfa_match(dfa, state, str);
*count -= adjust;
goto out;
}
inc_wb_pos(wb);
(*count)++;
}
} else {
/* default is direct to next state */
while (*str) {
unsigned int adjust;
wb->history[wb->pos] = state;
pos = base_idx(base[state]) + (u8) *str++;
if (check[pos] == state)
state = next[pos];
else
state = def[state];
if (is_loop(wb, state, &adjust)) {
state = aa_dfa_match(dfa, state, str);
*count -= adjust;
goto out;
}
inc_wb_pos(wb);
(*count)++;
}
}
out:
if (!state)
*count = 0;
return state;
}
/**
* 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;
}
