apparmor: use the dfa to do label parse string splitting
The current split scheme is actually wrong in that it splits
///&
where that is invalid and should fail. Use the dfa to do a proper
bounded split without having to worry about getting the string
processing right in code.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h
index af22dcb..80e9ba9 100644
--- a/security/apparmor/include/label.h
+++ b/security/apparmor/include/label.h
@@ -330,6 +330,31 @@ void aa_label_printk(struct aa_label *label, gfp_t gfp);
struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
gfp_t gfp, bool create, bool force_stack);
+static inline const char *aa_label_strn_split(const char *str, int n)
+{
+ const char *pos;
+ unsigned int state;
+
+ state = aa_dfa_matchn_until(stacksplitdfa, DFA_START, str, n, &pos);
+ if (!ACCEPT_TABLE(stacksplitdfa)[state])
+ return NULL;
+
+ return pos - 3;
+}
+
+static inline const char *aa_label_str_split(const char *str)
+{
+ const char *pos;
+ unsigned int state;
+
+ state = aa_dfa_match_until(stacksplitdfa, DFA_START, str, &pos);
+ if (!ACCEPT_TABLE(stacksplitdfa)[state])
+ return NULL;
+
+ return pos - 3;
+}
+
+
struct aa_perms;
int aa_label_match(struct aa_profile *profile, struct aa_label *label,
diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h
index 72b9b896..cd8aeab 100644
--- a/security/apparmor/include/match.h
+++ b/security/apparmor/include/match.h
@@ -101,6 +101,7 @@ struct aa_dfa {
};
extern struct aa_dfa *nulldfa;
+extern struct aa_dfa *stacksplitdfa;
#define byte_to_byte(X) (X)
diff --git a/security/apparmor/label.c b/security/apparmor/label.c
index 324fe5c..31e2f70 100644
--- a/security/apparmor/label.c
+++ b/security/apparmor/label.c
@@ -1815,7 +1815,9 @@ static int label_count_str_entries(const char *str)
AA_BUG(!str);
- for (split = strstr(str, "//&"); split; split = strstr(str, "//&")) {
+ for (split = aa_label_str_split(str);
+ split;
+ split = aa_label_str_split(str)) {
count++;
str = split + 3;
}
@@ -1859,7 +1861,7 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
DEFINE_VEC(profile, vec);
struct aa_label *label, *currbase = base;
int i, len, stack = 0, error;
- char *split;
+ const char *split;
AA_BUG(!base);
AA_BUG(!str);
@@ -1883,7 +1885,8 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
for (i = 0; i < stack; i++)
vec[i] = aa_get_profile(base->vec[i]);
- for (split = strstr(str, "//&"), i = stack; split && i < len; i++) {
+ for (split = aa_label_str_split(str), i = stack;
+ split && i < len; i++) {
vec[i] = fqlookupn_profile(base, currbase, str, split - str);
if (!vec[i])
goto fail;
@@ -1894,7 +1897,7 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
if (vec[i]->ns != labels_ns(currbase))
currbase = &vec[i]->label;
str = split + 3;
- split = strstr(str, "//&");
+ split = aa_label_str_split(str);
}
/* last element doesn't have a split */
if (i < len) {
@@ -1930,7 +1933,6 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
goto out;
}
-
/**
* aa_labelset_destroy - remove all labels from the label set
* @ls: label set to cleanup (NOT NULL)
diff --git a/security/apparmor/match.c b/security/apparmor/match.c
index 6c6dc1a..5d95cae 100644
--- a/security/apparmor/match.c
+++ b/security/apparmor/match.c
@@ -30,6 +30,11 @@ static char nulldfa_src[] = {
};
struct aa_dfa *nulldfa;
+static char stacksplitdfa_src[] = {
+ #include "stacksplitdfa.in"
+};
+struct aa_dfa *stacksplitdfa;
+
int aa_setup_dfa_engine(void)
{
int error;
@@ -37,19 +42,31 @@ int aa_setup_dfa_engine(void)
nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
TO_ACCEPT1_FLAG(YYTD_DATA32) |
TO_ACCEPT2_FLAG(YYTD_DATA32));
- if (!IS_ERR(nulldfa))
- return 0;
+ if (IS_ERR(nulldfa)) {
+ error = PTR_ERR(nulldfa);
+ nulldfa = NULL;
+ return error;
+ }
- error = PTR_ERR(nulldfa);
- nulldfa = NULL;
+ stacksplitdfa = aa_dfa_unpack(stacksplitdfa_src,
+ sizeof(stacksplitdfa_src),
+ TO_ACCEPT1_FLAG(YYTD_DATA32) |
+ TO_ACCEPT2_FLAG(YYTD_DATA32));
+ if (IS_ERR(stacksplitdfa)) {
+ aa_put_dfa(nulldfa);
+ nulldfa = NULL;
+ error = PTR_ERR(stacksplitdfa);
+ stacksplitdfa = NULL;
+ return error;
+ }
- return error;
+ return 0;
}
void aa_teardown_dfa_engine(void)
{
+ aa_put_dfa(stacksplitdfa);
aa_put_dfa(nulldfa);
- nulldfa = NULL;
}
/**
diff --git a/security/apparmor/stacksplitdfa.in b/security/apparmor/stacksplitdfa.in
new file mode 100644
index 0000000..4bddd10
--- /dev/null
+++ b/security/apparmor/stacksplitdfa.in
@@ -0,0 +1,114 @@
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