apparmor/kernel-patches/for-mainline/expand-dfa.diff

Allow the dfa to return its state, which will allow for pair matches.

---
 security/apparmor/apparmor.h |    7 ++-
 security/apparmor/inline.h   |    2 
 security/apparmor/match.c    |   99 ++++++++++++++++++++++++++++++++++++++-----
 security/apparmor/match.h    |    2 
 4 files changed, 99 insertions(+), 11 deletions(-)

--- a/security/apparmor/apparmor.h
+++ b/security/apparmor/apparmor.h
@@ -45,7 +45,6 @@
 
 #define AA_SECURE_EXEC_NEEDED		1
 
-
 /* Control parameters (0 or 1), settable thru module/boot flags or
  * via /sys/kernel/security/apparmor/control */
 extern int apparmor_complain;
@@ -260,5 +259,11 @@ extern void aa_match_free(struct aa_dfa 
 extern int unpack_dfa(struct aa_dfa *dfa, void *blob, size_t size);
 extern int verify_dfa(struct aa_dfa *dfa);
 extern unsigned int aa_dfa_match(struct aa_dfa *dfa, const char *str);
+extern unsigned int aa_dfa_next_state(struct aa_dfa *dfa, unsigned int start,
+				      const char *str);
+extern unsigned int aa_match_state(struct aa_dfa *dfa, unsigned int start,
+				   const char *str, unsigned int *final);
+extern unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
+					   unsigned int start);
 
 #endif  /* __APPARMOR_H */
--- a/security/apparmor/inline.h
+++ b/security/apparmor/inline.h
@@ -12,6 +12,8 @@
 
 #include <linux/sched.h>
 
+#include "match.h"
+
 static inline int mediated_filesystem(struct inode *inode)
 {
 	return !(inode->i_sb->s_flags & MS_NOUSER);
--- a/security/apparmor/match.c
+++ b/security/apparmor/match.c
@@ -208,22 +208,26 @@ void aa_match_free(struct aa_dfa *dfa)
 }
 
 /**
- * aa_dfa_match - match @path against @dfa starting in @state
- * @dfa: the dfa to match @path against
- * @state: the state to start matching in
- * @path: the path to match against the dfa
+ * aa_dfa_next_state - traverse @dfa to find state @str stops at
+ * @dfa: the dfa to match @str against
+ * @start: the state of the dfa to start matching in
+ * @str: the string to match against the dfa
  *
- * aa_dfa_match will match the full path length and return the state it
- * finished matching in. The final state is used to look up the accepting
- * label.
+ * 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.
  */
-unsigned int aa_dfa_match(struct aa_dfa *dfa, const char *str)
+unsigned int aa_dfa_next_state(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 = 1, pos;
+	unsigned int state = start, pos;
+
+	if (state == 0)
+		return 0;
 
 	/* current state is <state>, matching character *str */
 	if (dfa->tables[YYTD_ID_EC - 1]) {
@@ -244,5 +248,80 @@ unsigned int aa_dfa_match(struct aa_dfa 
 				state = def[state];
 		}
 	}
-	return ACCEPT_TABLE(dfa)[state];
+	return state;
+}
+
+/**
+ * aa_dfa_null_transition - step to next state after null character
+ * @dfa: the dfa to match against
+ * @start: the state of the dfa to start matching in
+ *
+ * aa_dfa_null_transition transitions to the next state after a null
+ * character which is not used in standard matching and is only
+ * used to seperate pairs.
+ */
+unsigned int aa_dfa_null_transition(struct aa_dfa *dfa, unsigned int start)
+{
+	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;
+
+	/* current state is <state>, matching character *str */
+	if (dfa->tables[YYTD_ID_EC - 1]) {
+		u8 *equiv = EQUIV_TABLE(dfa);
+		pos = base[state] + equiv[0];
+		if (check[pos] == state)
+			state = next[pos];
+		else
+			state = def[state];
+	} else {
+		pos = base[state] + 0;
+		if (check[pos] == state)
+			state = next[pos];
+		else
+			state = def[state];
+	}
+
+	return state;
+}
+
+/**
+ * aa_dfa_match - find accept perm for @str in @dfa
+ * @dfa: the dfa to match @str against
+ * @str: the string to match against the dfa
+ *
+ * aa_dfa_match will match @str and return the accept perms for the
+ * final state.
+ */
+unsigned int aa_dfa_match(struct aa_dfa *dfa, const char *str)
+{
+	return ACCEPT_TABLE(dfa)[aa_dfa_next_state(dfa, DFA_START, str)];
 }
+
+/**
+ * aa_match_state - find accept perm and state for @str in @dfa
+ * @dfa: the dfa to match @str against
+ * @start: the state to start the match from
+ * @str: the string to match against the dfa
+ * @final: the state that the match finished in
+ *
+ * aa_match_state will match @str and return the accept perms, and @final
+ * state, the match occured in.
+ */
+unsigned int aa_match_state(struct aa_dfa *dfa, unsigned int start,
+			    const char *str, unsigned int *final)
+{
+	unsigned int state;
+	if (dfa) {
+		state = aa_dfa_next_state(dfa, start, str);
+		if (final)
+			*final = state;
+		return ACCEPT_TABLE(dfa)[state];
+	}
+	if (final)
+		*final = 0;
+	return 0;
+}
+
--- a/security/apparmor/match.h
+++ b/security/apparmor/match.h
@@ -12,6 +12,8 @@
 #ifndef __MATCH_H
 #define __MATCH_H
 
+#define DFA_START			1
+
 /**
  * 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