1 files changed, 353 insertions, 0 deletions
diff --git a/security/apparmor/match.c b/security/apparmor/match.c
new file mode 100644
index 000000000000..5cb4dc1f6992
--- /dev/null
+++ b/security/apparmor/match.c
@@ -0,0 +1,353 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor dfa based regular expression matching engine
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2010 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"
+
+/**
+ * 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 kmalloc)
+ */
+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;
+	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 = kvmalloc(tsize);
+	if (table) {
+		*table = th;
+		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;
+	}
+
+out:
+	/* 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();
+	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;
+			/* TODO: do check that DEF state recursion terminates */
+			if (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/apparmor.txt
+ * Assumes the dfa @blob stream has been aligned on a 8 byte boundry
+ *
+ * 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[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[state] + (u8) *str++;
+			if (check[pos] == state)
+				state = next[pos];
+			else
+				state = def[state];
+		}
+	}
+
+	return state;
+}
+
+/**
+ * aa_dfa_next_state - 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_next_state 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)
+{
+	return aa_dfa_match_len(dfa, start, str, strlen(str));
+}