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Commit 95652cac authored by John Johansen's avatar John Johansen
Browse files

apparmor: provide a bounded version of label_parse 



some label/context sources might not be guaranteed to be null terminiated
provide a size bounded version of label parse to deal with these.

Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
Acked-by: default avatarSeth Arnold <seth.arnold@canonical.com>
parent 6e0654d2

security/apparmor/include/label.h

+3 −0
Original line number Diff line number Diff line
@@ -327,6 +327,9 @@ void aa_label_audit(struct audit_buffer *ab, struct aa_label *label, gfp_t gfp); 
void aa_label_seq_print(struct seq_file *f, struct aa_label *label, gfp_t gfp);

void aa_label_printk(struct aa_label *label, gfp_t gfp);



struct aa_label *aa_label_strn_parse(struct aa_label *base, const char *str,

				     size_t n, gfp_t gfp, bool create,

				     bool force_stack);

struct aa_label *aa_label_parse(struct aa_label *base, const char *str,

				gfp_t gfp, bool create, bool force_stack);

security/apparmor/label.c

+24 −11
Original line number Diff line number Diff line
@@ -1808,16 +1808,17 @@ void aa_label_printk(struct aa_label *label, gfp_t gfp) 
	aa_put_ns(ns);

}



static int label_count_str_entries(const char *str)

static int label_count_strn_entries(const char *str, size_t n)

{

	const char *end = str + n;

	const char *split;

	int count = 1;



	AA_BUG(!str);



	for (split = aa_label_str_split(str);

	for (split = aa_label_strn_split(str, end - str);

	     split;

	     split = aa_label_str_split(str)) {

	     split = aa_label_strn_split(str, end - str)) {

		count++;

		str = split + 3;

	}
@@ -1845,9 +1846,10 @@ static struct aa_profile *fqlookupn_profile(struct aa_label *base, 
}



/**

 * aa_label_parse - parse, validate and convert a text string to a label

 * aa_label_strn_parse - parse, validate and convert a text string to a label

 * @base: base label to use for lookups (NOT NULL)

 * @str: null terminated text string (NOT NULL)

 * @n: length of str to parse, will stop at \0 if encountered before n

 * @gfp: allocation type

 * @create: true if should create compound labels if they don't exist

 * @force_stack: true if should stack even if no leading &
@@ -1855,19 +1857,23 @@ static struct aa_profile *fqlookupn_profile(struct aa_label *base, 
 * Returns: the matching refcounted label if present

 *     else ERRPTR

 */

struct aa_label *aa_label_parse(struct aa_label *base, const char *str,

				gfp_t gfp, bool create, bool force_stack)

struct aa_label *aa_label_strn_parse(struct aa_label *base, const char *str,

				     size_t n, gfp_t gfp, bool create,

				     bool force_stack)

{

	DEFINE_VEC(profile, vec);

	struct aa_label *label, *currbase = base;

	int i, len, stack = 0, error;

	const char *end = str + n;

	const char *split;



	AA_BUG(!base);

	AA_BUG(!str);



	str = skip_spaces(str);

	len = label_count_str_entries(str);

	str = skipn_spaces(str, n);

	if (str == NULL)

		return ERR_PTR(-EINVAL);

	len = label_count_strn_entries(str, end - str);

	if (*str == '&' || force_stack) {

		/* stack on top of base */

		stack = base->size;
@@ -1885,7 +1891,7 @@ 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 = aa_label_str_split(str), i = stack;

	for (split = aa_label_strn_split(str, end - str), i = stack;

	     split && i < len; i++) {

		vec[i] = fqlookupn_profile(base, currbase, str, split - str);

		if (!vec[i])
@@ -1897,11 +1903,11 @@ 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 = aa_label_str_split(str);

		split = aa_label_strn_split(str, end - str);

	}

	/* last element doesn't have a split */

	if (i < len) {

		vec[i] = fqlookupn_profile(base, currbase, str, strlen(str));

		vec[i] = fqlookupn_profile(base, currbase, str, end - str);

		if (!vec[i])

			goto fail;

	}
@@ -1933,6 +1939,13 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str, 
	goto out;

}



struct aa_label *aa_label_parse(struct aa_label *base, const char *str,

				gfp_t gfp, bool create, bool force_stack)

{

	return aa_label_strn_parse(base, str, strlen(str), gfp, create,

				   force_stack);

}



/**

 * aa_labelset_destroy - remove all labels from the label set

 * @ls: label set to cleanup (NOT NULL)