AppArmor: core policy routines

The basic routines and defines for AppArmor policy.  AppArmor policy
is defined by a few basic components.
      profiles - the basic unit of confinement contain all the information
                 to enforce policy on a task

                 Profiles tend to be named after an executable that they
                 will attach to but this is not required.
      namespaces - a container for a set of profiles that will be used
                 during attachment and transitions between profiles.
      sids - which provide a unique id for each profile
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/apparmor/include/policy.h

+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy 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_POLICY_H
+#define __AA_POLICY_H
+
+#include <linux/capability.h>
+#include <linux/cred.h>
+#include <linux/kref.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/socket.h>
+
+#include "apparmor.h"
+#include "audit.h"
+#include "capability.h"
+#include "domain.h"
+#include "file.h"
+#include "resource.h"
+
+extern const char *profile_mode_names[];
+#define APPARMOR_NAMES_MAX_INDEX 3
+
+#define COMPLAIN_MODE(_profile)	\
+	((aa_g_profile_mode == APPARMOR_COMPLAIN) || \
+	 ((_profile)->mode == APPARMOR_COMPLAIN))
+
+#define KILL_MODE(_profile) \
+	((aa_g_profile_mode == APPARMOR_KILL) || \
+	 ((_profile)->mode == APPARMOR_KILL))
+
+#define PROFILE_IS_HAT(_profile) ((_profile)->flags & PFLAG_HAT)
+
+/*
+ * FIXME: currently need a clean way to replace and remove profiles as a
+ * set.  It should be done at the namespace level.
+ * Either, with a set of profiles loaded at the namespace level or via
+ * a mark and remove marked interface.
+ */
+enum profile_mode {
+	APPARMOR_ENFORCE,	/* enforce access rules */
+	APPARMOR_COMPLAIN,	/* allow and log access violations */
+	APPARMOR_KILL,		/* kill task on access violation */
+};
+
+enum profile_flags {
+	PFLAG_HAT = 1,			/* profile is a hat */
+	PFLAG_UNCONFINED = 2,		/* profile is an unconfined profile */
+	PFLAG_NULL = 4,			/* profile is null learning profile */
+	PFLAG_IX_ON_NAME_ERROR = 8,	/* fallback to ix on name lookup fail */
+	PFLAG_IMMUTABLE = 0x10,		/* don't allow changes/replacement */
+	PFLAG_USER_DEFINED = 0x20,	/* user based profile - lower privs */
+	PFLAG_NO_LIST_REF = 0x40,	/* list doesn't keep profile ref */
+	PFLAG_OLD_NULL_TRANS = 0x100,	/* use // as the null transition */
+
+	/* These flags must correspond with PATH_flags */
+	PFLAG_MEDIATE_DELETED = 0x10000, /* mediate instead delegate deleted */
+};
+
+struct aa_profile;
+
+/* struct aa_policy - common part of both namespaces and profiles
+ * @name: name of the object
+ * @hname - The hierarchical name
+ * @count: reference count of the obj
+ * @list: list policy object is on
+ * @profiles: head of the profiles list contained in the object
+ */
+struct aa_policy {
+	char *name;
+	char *hname;
+	struct kref count;
+	struct list_head list;
+	struct list_head profiles;
+};
+
+/* struct aa_ns_acct - accounting of profiles in namespace
+ * @max_size: maximum space allowed for all profiles in namespace
+ * @max_count: maximum number of profiles that can be in this namespace
+ * @size: current size of profiles
+ * @count: current count of profiles (includes null profiles)
+ */
+struct aa_ns_acct {
+	int max_size;
+	int max_count;
+	int size;
+	int count;
+};
+
+/* struct aa_namespace - namespace for a set of profiles
+ * @base: common policy
+ * @parent: parent of namespace
+ * @lock: lock for modifying the object
+ * @acct: accounting for the namespace
+ * @unconfined: special unconfined profile for the namespace
+ * @sub_ns: list of namespaces under the current namespace.
+ *
+ * An aa_namespace defines the set profiles that are searched to determine
+ * which profile to attach to a task.  Profiles can not be shared between
+ * aa_namespaces and profile names within a namespace are guaranteed to be
+ * unique.  When profiles in separate namespaces have the same name they
+ * are NOT considered to be equivalent.
+ *
+ * Namespaces are hierarchical and only namespaces and profiles below the
+ * current namespace are visible.
+ *
+ * Namespace names must be unique and can not contain the characters :/\0
+ *
+ * FIXME TODO: add vserver support of namespaces (can it all be done in
+ *             userspace?)
+ */
+struct aa_namespace {
+	struct aa_policy base;
+	struct aa_namespace *parent;
+	rwlock_t lock;
+	struct aa_ns_acct acct;
+	struct aa_profile *unconfined;
+	struct list_head sub_ns;
+};
+
+/* struct aa_profile - basic confinement data
+ * @base - base components of the profile (name, refcount, lists, lock ...)
+ * @parent: parent of profile
+ * @ns: namespace the profile is in
+ * @replacedby: is set to the profile that replaced this profile
+ * @rename: optional profile name that this profile renamed
+ * @xmatch: optional extended matching for unconfined executables names
+ * @xmatch_len: xmatch prefix len, used to determine xmatch priority
+ * @sid: the unique security id number of this profile
+ * @audit: the auditing mode of the profile
+ * @mode: the enforcement mode of the profile
+ * @flags: flags controlling profile behavior
+ * @path_flags: flags controlling path generation behavior
+ * @size: the memory consumed by this profiles rules
+ * @file: The set of rules governing basic file access and domain transitions
+ * @caps: capabilities for the profile
+ * @rlimits: rlimits for the profile
+ *
+ * The AppArmor profile contains the basic confinement data.  Each profile
+ * has a name, and exists in a namespace.  The @name and @exec_match are
+ * used to determine profile attachment against unconfined tasks.  All other
+ * attachments are determined by profile X transition rules.
+ *
+ * The @replacedby field is write protected by the profile lock.  Reads
+ * are assumed to be atomic, and are done without locking.
+ *
+ * Profiles have a hierarchy where hats and children profiles keep
+ * a reference to their parent.
+ *
+ * Profile names can not begin with a : and can not contain the \0
+ * character.  If a profile name begins with / it will be considered when
+ * determining profile attachment on "unconfined" tasks.
+ */
+struct aa_profile {
+	struct aa_policy base;
+	struct aa_profile *parent;
+
+	struct aa_namespace *ns;
+	struct aa_profile *replacedby;
+	const char *rename;
+
+	struct aa_dfa *xmatch;
+	int xmatch_len;
+	u32 sid;
+	enum audit_mode audit;
+	enum profile_mode mode;
+	u32 flags;
+	u32 path_flags;
+	int size;
+
+	struct aa_file_rules file;
+	struct aa_caps caps;
+	struct aa_rlimit rlimits;
+};
+
+extern struct aa_namespace *root_ns;
+extern enum profile_mode aa_g_profile_mode;
+
+void aa_add_profile(struct aa_policy *common, struct aa_profile *profile);
+
+bool aa_ns_visible(struct aa_namespace *curr, struct aa_namespace *view);
+const char *aa_ns_name(struct aa_namespace *parent, struct aa_namespace *child);
+int aa_alloc_root_ns(void);
+void aa_free_root_ns(void);
+void aa_free_namespace_kref(struct kref *kref);
+
+struct aa_namespace *aa_find_namespace(struct aa_namespace *root,
+				       const char *name);
+
+static inline struct aa_policy *aa_get_common(struct aa_policy *c)
+{
+	if (c)
+		kref_get(&c->count);
+
+	return c;
+}
+
+/**
+ * aa_get_namespace - increment references count on @ns
+ * @ns: namespace to increment reference count of (MAYBE NULL)
+ *
+ * Returns: pointer to @ns, if @ns is NULL returns NULL
+ * Requires: @ns must be held with valid refcount when called
+ */
+static inline struct aa_namespace *aa_get_namespace(struct aa_namespace *ns)
+{
+	if (ns)
+		kref_get(&(ns->base.count));
+
+	return ns;
+}
+
+/**
+ * aa_put_namespace - decrement refcount on @ns
+ * @ns: namespace to put reference of
+ *
+ * Decrement reference count of @ns and if no longer in use free it
+ */
+static inline void aa_put_namespace(struct aa_namespace *ns)
+{
+	if (ns)
+		kref_put(&ns->base.count, aa_free_namespace_kref);
+}
+
+struct aa_profile *aa_alloc_profile(const char *name);
+struct aa_profile *aa_new_null_profile(struct aa_profile *parent, int hat);
+void aa_free_profile_kref(struct kref *kref);
+struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name);
+struct aa_profile *aa_lookup_profile(struct aa_namespace *ns, const char *name);
+struct aa_profile *aa_match_profile(struct aa_namespace *ns, const char *name);
+
+ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace);
+ssize_t aa_remove_profiles(char *name, size_t size);
+
+#define PROF_ADD 1
+#define PROF_REPLACE 0
+
+#define unconfined(X) ((X)->flags & PFLAG_UNCONFINED)
+
+/**
+ * aa_newest_version - find the newest version of @profile
+ * @profile: the profile to check for newer versions of (NOT NULL)
+ *
+ * Returns: newest version of @profile, if @profile is the newest version
+ *          return @profile.
+ *
+ * NOTE: the profile returned is not refcounted, The refcount on @profile
+ * must be held until the caller decides what to do with the returned newest
+ * version.
+ */
+static inline struct aa_profile *aa_newest_version(struct aa_profile *profile)
+{
+	while (profile->replacedby)
+		profile = profile->replacedby;
+
+	return profile;
+}
+
+/**
+ * aa_get_profile - increment refcount on profile @p
+ * @p: profile  (MAYBE NULL)
+ *
+ * Returns: pointer to @p if @p is NULL will return NULL
+ * Requires: @p must be held with valid refcount when called
+ */
+static inline struct aa_profile *aa_get_profile(struct aa_profile *p)
+{
+	if (p)
+		kref_get(&(p->base.count));
+
+	return p;
+}
+
+/**
+ * aa_put_profile - decrement refcount on profile @p
+ * @p: profile  (MAYBE NULL)
+ */
+static inline void aa_put_profile(struct aa_profile *p)
+{
+	if (p)
+		kref_put(&p->base.count, aa_free_profile_kref);
+}
+
+static inline int AUDIT_MODE(struct aa_profile *profile)
+{
+	if (aa_g_audit != AUDIT_NORMAL)
+		return aa_g_audit;
+
+	return profile->audit;
+}
+
+bool aa_may_manage_policy(int op);
+
+#endif /* __AA_POLICY_H */

security/apparmor/include/sid.h

+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor security identifier (sid) definitions
+ *
+ * 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_SID_H
+#define __AA_SID_H
+
+#include <linux/types.h>
+
+struct aa_profile;
+
+u32 aa_alloc_sid(void);
+void aa_free_sid(u32 sid);
+
+#endif /* __AA_SID_H */

security/apparmor/sid.c

+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor security identifier (sid) manipulation fns
+ *
+ * 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.
+ *
+ *
+ * AppArmor allocates a unique sid for every profile loaded.  If a profile
+ * is replaced it receives the sid of the profile it is replacing.
+ *
+ * The sid value of 0 is invalid.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+
+#include "include/sid.h"
+
+/* global counter from which sids are allocated */
+static u32 global_sid;
+static DEFINE_SPINLOCK(sid_lock);
+
+/* TODO FIXME: add sid to profile mapping, and sid recycling */
+
+/**
+ * aa_alloc_sid - allocate a new sid for a profile
+ */
+u32 aa_alloc_sid(void)
+{
+	u32 sid;
+
+	/*
+	 * TODO FIXME: sid recycling - part of profile mapping table
+	 */
+	spin_lock(&sid_lock);
+	sid = (++global_sid);
+	spin_unlock(&sid_lock);
+	return sid;
+}
+
+/**
+ * aa_free_sid - free a sid
+ * @sid: sid to free
+ */
+void aa_free_sid(u32 sid)
+{
+	;			/* NOP ATM */
+}