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-rw-r--r--security/apparmor/include/match.h132
-rw-r--r--security/apparmor/match.c353
2 files changed, 485 insertions, 0 deletions
diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h
new file mode 100644
index 000000000000..734a6d35112c
--- /dev/null
+++ b/security/apparmor/include/match.h
@@ -0,0 +1,132 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy dfa matching engine definitions.
+ *
+ * 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.
+ */
+
+#ifndef __AA_MATCH_H
+#define __AA_MATCH_H
+
+#include <linux/workqueue.h>
+
+#define DFA_NOMATCH 0
+#define DFA_START 1
+
+#define DFA_VALID_PERM_MASK 0xffffffff
+#define DFA_VALID_PERM2_MASK 0xffffffff
+
+/**
+ * The format used for transition tables is based on the GNU flex table
+ * file format (--tables-file option; see Table File Format in the flex
+ * info pages and the flex sources for documentation). The magic number
+ * used in the header is 0x1B5E783D insted of 0xF13C57B1 though, because
+ * the YY_ID_CHK (check) and YY_ID_DEF (default) tables are used
+ * slightly differently (see the apparmor-parser package).
+ */
+
+#define YYTH_MAGIC 0x1B5E783D
+#define YYTH_DEF_RECURSE 0x1 /* DEF Table is recursive */
+
+struct table_set_header {
+ u32 th_magic; /* YYTH_MAGIC */
+ u32 th_hsize;
+ u32 th_ssize;
+ u16 th_flags;
+ char th_version[];
+};
+
+/* The YYTD_ID are one less than flex table mappings. The flex id
+ * has 1 subtracted at table load time, this allows us to directly use the
+ * ID's as indexes.
+ */
+#define YYTD_ID_ACCEPT 0
+#define YYTD_ID_BASE 1
+#define YYTD_ID_CHK 2
+#define YYTD_ID_DEF 3
+#define YYTD_ID_EC 4
+#define YYTD_ID_META 5
+#define YYTD_ID_ACCEPT2 6
+#define YYTD_ID_NXT 7
+#define YYTD_ID_TSIZE 8
+
+#define YYTD_DATA8 1
+#define YYTD_DATA16 2
+#define YYTD_DATA32 4
+#define YYTD_DATA64 8
+
+/* Each ACCEPT2 table gets 6 dedicated flags, YYTD_DATAX define the
+ * first flags
+ */
+#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
+#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
+#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
+#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
+#define DFA_FLAG_VERIFY_STATES 0x1000
+
+struct table_header {
+ u16 td_id;
+ u16 td_flags;
+ u32 td_hilen;
+ u32 td_lolen;
+ char td_data[];
+};
+
+#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
+#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
+#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
+#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
+#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
+#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
+#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
+
+struct aa_dfa {
+ struct kref count;
+ u16 flags;
+ struct table_header *tables[YYTD_ID_TSIZE];
+};
+
+#define byte_to_byte(X) (X)
+
+#define UNPACK_ARRAY(TABLE, BLOB, LEN, TYPE, NTOHX) \
+ do { \
+ typeof(LEN) __i; \
+ TYPE *__t = (TYPE *) TABLE; \
+ TYPE *__b = (TYPE *) BLOB; \
+ for (__i = 0; __i < LEN; __i++) { \
+ __t[__i] = NTOHX(__b[__i]); \
+ } \
+ } while (0)
+
+static inline size_t table_size(size_t len, size_t el_size)
+{
+ return ALIGN(sizeof(struct table_header) + len * el_size, 8);
+}
+
+struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
+unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
+ const char *str, int len);
+unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
+ const char *str);
+void aa_dfa_free_kref(struct kref *kref);
+
+/**
+ * aa_put_dfa - put a dfa refcount
+ * @dfa: dfa to put refcount (MAYBE NULL)
+ *
+ * Requires: if @dfa != NULL that a valid refcount be held
+ */
+static inline void aa_put_dfa(struct aa_dfa *dfa)
+{
+ if (dfa)
+ kref_put(&dfa->count, aa_dfa_free_kref);
+}
+
+#endif /* __AA_MATCH_H */
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));
+}

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