apparmor: add the base fns() for domain labels

Begin moving apparmor to using broader domain labels, that will allow
run time computation of domain type splitting via "stacking" of
profiles into a domain label vec.
Signed-off-by: NJohn Johansen <john.johansen@canonical.com>

security/apparmor/include/label.h

+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor label definitions
+ *
+ * Copyright 2017 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_LABEL_H
+#define __AA_LABEL_H
+
+#include <linux/atomic.h>
+#include <linux/audit.h>
+#include <linux/rbtree.h>
+#include <linux/rcupdate.h>
+
+#include "apparmor.h"
+#include "lib.h"
+
+struct aa_ns;
+
+#define LOCAL_VEC_ENTRIES 8
+#define DEFINE_VEC(T, V)						\
+	struct aa_ ## T *(_ ## V ## _localtmp)[LOCAL_VEC_ENTRIES];	\
+	struct aa_ ## T **(V)
+
+#define vec_setup(T, V, N, GFP)						\
+({									\
+	if ((N) <= LOCAL_VEC_ENTRIES) {					\
+		typeof(N) i;						\
+		(V) = (_ ## V ## _localtmp);				\
+		for (i = 0; i < (N); i++)				\
+			(V)[i] = NULL;					\
+	} else								\
+		(V) = kzalloc(sizeof(struct aa_ ## T *) * (N), (GFP));	\
+	(V) ? 0 : -ENOMEM;						\
+})
+
+#define vec_cleanup(T, V, N)						\
+do {									\
+	int i;								\
+	for (i = 0; i < (N); i++) {					\
+		if (!IS_ERR_OR_NULL((V)[i]))				\
+			aa_put_ ## T((V)[i]);				\
+	}								\
+	if ((V) != _ ## V ## _localtmp)					\
+		kfree(V);						\
+} while (0)
+
+#define vec_last(VEC, SIZE) ((VEC)[(SIZE) - 1])
+#define vec_ns(VEC, SIZE) (vec_last((VEC), (SIZE))->ns)
+#define vec_labelset(VEC, SIZE) (&vec_ns((VEC), (SIZE))->labels)
+#define cleanup_domain_vec(V, L) cleanup_label_vec((V), (L)->size)
+
+struct aa_profile;
+#define VEC_FLAG_TERMINATE 1
+int aa_vec_unique(struct aa_profile **vec, int n, int flags);
+struct aa_label *aa_vec_find_or_create_label(struct aa_profile **vec, int len,
+					     gfp_t gfp);
+#define aa_sort_and_merge_vec(N, V) \
+	aa_sort_and_merge_profiles((N), (struct aa_profile **)(V))
+
+
+/* struct aa_labelset - set of labels for a namespace
+ *
+ * Labels are reference counted; aa_labelset does not contribute to label
+ * reference counts. Once a label's last refcount is put it is removed from
+ * the set.
+ */
+struct aa_labelset {
+	rwlock_t lock;
+
+	struct rb_root root;
+};
+
+#define __labelset_for_each(LS, N) \
+	for ((N) = rb_first(&(LS)->root); (N); (N) = rb_next(N))
+
+void aa_labelset_destroy(struct aa_labelset *ls);
+void aa_labelset_init(struct aa_labelset *ls);
+
+
+enum label_flags {
+	FLAG_HAT = 1,			/* profile is a hat */
+	FLAG_UNCONFINED = 2,		/* label unconfined only if all */
+	FLAG_NULL = 4,			/* profile is null learning profile */
+	FLAG_IX_ON_NAME_ERROR = 8,	/* fallback to ix on name lookup fail */
+	FLAG_IMMUTIBLE = 0x10,		/* don't allow changes/replacement */
+	FLAG_USER_DEFINED = 0x20,	/* user based profile - lower privs */
+	FLAG_NO_LIST_REF = 0x40,	/* list doesn't keep profile ref */
+	FLAG_NS_COUNT = 0x80,		/* carries NS ref count */
+	FLAG_IN_TREE = 0x100,		/* label is in tree */
+	FLAG_PROFILE = 0x200,		/* label is a profile */
+	FLAG_EXPLICIT = 0x400,		/* explicit static label */
+	FLAG_STALE = 0x800,		/* replaced/removed */
+	FLAG_RENAMED = 0x1000,		/* label has renaming in it */
+	FLAG_REVOKED = 0x2000,		/* label has revocation in it */
+
+	/* These flags must correspond with PATH_flags */
+	/* TODO: add new path flags */
+};
+
+struct aa_label;
+struct aa_proxy {
+	struct kref count;
+	struct aa_label __rcu *label;
+};
+
+struct label_it {
+	int i, j;
+};
+
+/* struct aa_label - lazy labeling struct
+ * @count: ref count of active users
+ * @node: rbtree position
+ * @rcu: rcu callback struct
+ * @proxy: is set to the label that replaced this label
+ * @hname: text representation of the label (MAYBE_NULL)
+ * @flags: stale and other flags - values may change under label set lock
+ * @secid: secid that references this label
+ * @size: number of entries in @ent[]
+ * @ent: set of profiles for label, actual size determined by @size
+ */
+struct aa_label {
+	struct kref count;
+	struct rb_node node;
+	struct rcu_head rcu;
+	struct aa_proxy *proxy;
+	__counted char *hname;
+	long flags;
+	u32 secid;
+	int size;
+	struct aa_profile *vec[];
+};
+
+#define last_error(E, FN)				\
+do {							\
+	int __subE = (FN);				\
+	if (__subE)					\
+		(E) = __subE;				\
+} while (0)
+
+#define label_isprofile(X) ((X)->flags & FLAG_PROFILE)
+#define label_unconfined(X) ((X)->flags & FLAG_UNCONFINED)
+#define unconfined(X) label_unconfined(X)
+#define label_is_stale(X) ((X)->flags & FLAG_STALE)
+#define __label_make_stale(X) ((X)->flags |= FLAG_STALE)
+#define labels_ns(X) (vec_ns(&((X)->vec[0]), (X)->size))
+#define labels_set(X) (&labels_ns(X)->labels)
+#define labels_profile(X) ((X)->vec[(X)->size - 1])
+
+
+int aa_label_next_confined(struct aa_label *l, int i);
+
+/* for each profile in a label */
+#define label_for_each(I, L, P)						\
+	for ((I).i = 0; ((P) = (L)->vec[(I).i]); ++((I).i))
+
+/* assumes break/goto ended label_for_each */
+#define label_for_each_cont(I, L, P)					\
+	for (++((I).i); ((P) = (L)->vec[(I).i]); ++((I).i))
+
+#define next_comb(I, L1, L2)						\
+do {									\
+	(I).j++;							\
+	if ((I).j >= (L2)->size) {					\
+		(I).i++;						\
+		(I).j = 0;						\
+	}								\
+} while (0)
+
+
+/* for each combination of P1 in L1, and P2 in L2 */
+#define label_for_each_comb(I, L1, L2, P1, P2)				\
+for ((I).i = (I).j = 0;							\
+	((P1) = (L1)->vec[(I).i]) && ((P2) = (L2)->vec[(I).j]);		\
+	(I) = next_comb(I, L1, L2))
+
+#define fn_for_each_comb(L1, L2, P1, P2, FN)				\
+({									\
+	struct label_it i;						\
+	int __E = 0;							\
+	label_for_each_comb(i, (L1), (L2), (P1), (P2)) {		\
+		last_error(__E, (FN));					\
+	}								\
+	__E;								\
+})
+
+/* for each profile that is enforcing confinement in a label */
+#define label_for_each_confined(I, L, P)				\
+	for ((I).i = aa_label_next_confined((L), 0);			\
+	     ((P) = (L)->vec[(I).i]);					\
+	     (I).i = aa_label_next_confined((L), (I).i + 1))
+
+#define label_for_each_in_merge(I, A, B, P)				\
+	for ((I).i = (I).j = 0;						\
+	     ((P) = aa_label_next_in_merge(&(I), (A), (B)));		\
+	     )
+
+#define label_for_each_not_in_set(I, SET, SUB, P)			\
+	for ((I).i = (I).j = 0;						\
+	     ((P) = __aa_label_next_not_in_set(&(I), (SET), (SUB)));	\
+	     )
+
+#define next_in_ns(i, NS, L)						\
+({									\
+	typeof(i) ___i = (i);						\
+	while ((L)->vec[___i] && (L)->vec[___i]->ns != (NS))		\
+		(___i)++;						\
+	(___i);								\
+})
+
+#define label_for_each_in_ns(I, NS, L, P)				\
+	for ((I).i = next_in_ns(0, (NS), (L));				\
+	     ((P) = (L)->vec[(I).i]);					\
+	     (I).i = next_in_ns((I).i + 1, (NS), (L)))
+
+#define fn_for_each_in_ns(L, P, FN)					\
+({									\
+	struct label_it __i;						\
+	struct aa_ns *__ns = labels_ns(L);				\
+	int __E = 0;							\
+	label_for_each_in_ns(__i, __ns, (L), (P)) {			\
+		last_error(__E, (FN));					\
+	}								\
+	__E;								\
+})
+
+
+#define fn_for_each_XXX(L, P, FN, ...)					\
+({									\
+	struct label_it i;						\
+	int __E = 0;							\
+	label_for_each ## __VA_ARGS__(i, (L), (P)) {			\
+		last_error(__E, (FN));					\
+	}								\
+	__E;								\
+})
+
+#define fn_for_each(L, P, FN) fn_for_each_XXX(L, P, FN)
+#define fn_for_each_confined(L, P, FN) fn_for_each_XXX(L, P, FN, _confined)
+
+#define fn_for_each2_XXX(L1, L2, P, FN, ...)				\
+({									\
+	struct label_it i;						\
+	int __E = 0;							\
+	label_for_each ## __VA_ARGS__(i, (L1), (L2), (P)) {		\
+		last_error(__E, (FN));					\
+	}								\
+	__E;								\
+})
+
+#define fn_for_each_in_merge(L1, L2, P, FN)				\
+	fn_for_each2_XXX((L1), (L2), P, FN, _in_merge)
+#define fn_for_each_not_in_set(L1, L2, P, FN)				\
+	fn_for_each2_XXX((L1), (L2), P, FN, _not_in_set)
+
+#define LABEL_MEDIATES(L, C)						\
+({									\
+	struct aa_profile *profile;					\
+	struct label_it i;						\
+	int ret = 0;							\
+	label_for_each(i, (L), profile) {				\
+		if (PROFILE_MEDIATES(profile, (C))) {			\
+			ret = 1;					\
+			break;						\
+		}							\
+	}								\
+	ret;								\
+})
+
+
+void aa_labelset_destroy(struct aa_labelset *ls);
+void aa_labelset_init(struct aa_labelset *ls);
+void __aa_labelset_update_subtree(struct aa_ns *ns);
+
+void aa_label_free(struct aa_label *label);
+void aa_label_kref(struct kref *kref);
+bool aa_label_init(struct aa_label *label, int size);
+struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp);
+
+bool aa_label_is_subset(struct aa_label *set, struct aa_label *sub);
+struct aa_profile *__aa_label_next_not_in_set(struct label_it *I,
+					     struct aa_label *set,
+					     struct aa_label *sub);
+bool aa_label_remove(struct aa_label *label);
+struct aa_label *aa_label_insert(struct aa_labelset *ls, struct aa_label *l);
+bool aa_label_replace(struct aa_label *old, struct aa_label *new);
+bool aa_label_make_newest(struct aa_labelset *ls, struct aa_label *old,
+			  struct aa_label *new);
+
+struct aa_label *aa_label_find(struct aa_label *l);
+
+struct aa_profile *aa_label_next_in_merge(struct label_it *I,
+					  struct aa_label *a,
+					  struct aa_label *b);
+struct aa_label *aa_label_find_merge(struct aa_label *a, struct aa_label *b);
+struct aa_label *aa_label_merge(struct aa_label *a, struct aa_label *b,
+				gfp_t gfp);
+
+
+bool aa_update_label_name(struct aa_ns *ns, struct aa_label *label, gfp_t gfp);
+
+#define FLAGS_NONE 0
+#define FLAG_SHOW_MODE 1
+#define FLAG_VIEW_SUBNS 2
+#define FLAG_HIDDEN_UNCONFINED 4
+int aa_label_snxprint(char *str, size_t size, struct aa_ns *view,
+		      struct aa_label *label, int flags);
+int aa_label_asxprint(char **strp, struct aa_ns *ns, struct aa_label *label,
+		      int flags, gfp_t gfp);
+int aa_label_acntsxprint(char __counted **strp, struct aa_ns *ns,
+			 struct aa_label *label, int flags, gfp_t gfp);
+void aa_label_xaudit(struct audit_buffer *ab, struct aa_ns *ns,
+		     struct aa_label *label, int flags, gfp_t gfp);
+void aa_label_seq_xprint(struct seq_file *f, struct aa_ns *ns,
+			 struct aa_label *label, int flags, gfp_t gfp);
+void aa_label_xprintk(struct aa_ns *ns, struct aa_label *label, int flags,
+		      gfp_t gfp);
+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_parse(struct aa_label *base, const char *str,
+				gfp_t gfp, bool create, bool force_stack);
+
+
+struct aa_perms;
+int aa_label_match(struct aa_profile *profile, struct aa_label *label,
+		   unsigned int state, bool subns, u32 request,
+		   struct aa_perms *perms);
+
+
+/**
+ * __aa_get_label - get a reference count to uncounted label reference
+ * @l: reference to get a count on
+ *
+ * Returns: pointer to reference OR NULL if race is lost and reference is
+ *          being repeated.
+ * Requires: lock held, and the return code MUST be checked
+ */
+static inline struct aa_label *__aa_get_label(struct aa_label *l)
+{
+	if (l && kref_get_unless_zero(&l->count))
+		return l;
+
+	return NULL;
+}
+
+static inline struct aa_label *aa_get_label(struct aa_label *l)
+{
+	if (l)
+		kref_get(&(l->count));
+
+	return l;
+}
+
+
+/**
+ * aa_get_label_rcu - increment refcount on a label that can be replaced
+ * @l: pointer to label that can be replaced (NOT NULL)
+ *
+ * Returns: pointer to a refcounted label.
+ *     else NULL if no label
+ */
+static inline struct aa_label *aa_get_label_rcu(struct aa_label __rcu **l)
+{
+	struct aa_label *c;
+
+	rcu_read_lock();
+	do {
+		c = rcu_dereference(*l);
+	} while (c && !kref_get_unless_zero(&c->count));
+	rcu_read_unlock();
+
+	return c;
+}
+
+/**
+ * aa_get_newest_label - find the newest version of @l
+ * @l: the label to check for newer versions of
+ *
+ * Returns: refcounted newest version of @l taking into account
+ *          replacement, renames and removals
+ *          return @l.
+ */
+static inline struct aa_label *aa_get_newest_label(struct aa_label *l)
+{
+	if (!l)
+		return NULL;
+
+	if (label_is_stale(l)) {
+		struct aa_label *tmp;
+
+		AA_BUG(!l->proxy);
+		AA_BUG(!l->proxy->label);
+		/* BUG: only way this can happen is @l ref count and its
+		 * replacement count have gone to 0 and are on their way
+		 * to destruction. ie. we have a refcounting error
+		 */
+		tmp = aa_get_label_rcu(&l->proxy->label);
+		AA_BUG(!tmp);
+
+		return tmp;
+	}
+
+	return aa_get_label(l);
+}
+
+static inline void aa_put_label(struct aa_label *l)
+{
+	if (l)
+		kref_put(&l->count, aa_label_kref);
+}
+
+
+struct aa_proxy *aa_alloc_proxy(struct aa_label *l, gfp_t gfp);
+void aa_proxy_kref(struct kref *kref);
+
+static inline struct aa_proxy *aa_get_proxy(struct aa_proxy *proxy)
+{
+	if (proxy)
+		kref_get(&(proxy->count));
+
+	return proxy;
+}
+
+static inline void aa_put_proxy(struct aa_proxy *proxy)
+{
+	if (proxy)
+		kref_put(&proxy->count, aa_proxy_kref);
+}
+
+void __aa_proxy_redirect(struct aa_label *orig, struct aa_label *new);
+
+#endif /* __AA_LABEL_H */