apparmor: add the profile introspection file to interface

Add the dynamic namespace relative profiles file to the interace, to allow
introspection of loaded profiles and their modes.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>

security/apparmor/apparmorfs.c

@@ -20,6 +20,7 @@
 #include <linux/uaccess.h>
 #include <linux/namei.h>
 #include <linux/capability.h>
+#include <linux/rcupdate.h>
 
 #include "include/apparmor.h"
 #include "include/apparmorfs.h"
@@ -512,6 +513,240 @@ int __aa_fs_namespace_mkdir(struct aa_namespace *ns, struct dentry *parent,
 }
 
 
+#define list_entry_next(pos, member) \
+	list_entry(pos->member.next, typeof(*pos), member)
+#define list_entry_is_head(pos, head, member) (&pos->member == (head))
+
+/**
+ * __next_namespace - find the next namespace to list
+ * @root: root namespace to stop search at (NOT NULL)
+ * @ns: current ns position (NOT NULL)
+ *
+ * Find the next namespace from @ns under @root and handle all locking needed
+ * while switching current namespace.
+ *
+ * Returns: next namespace or NULL if at last namespace under @root
+ * Requires: ns->parent->lock to be held
+ * NOTE: will not unlock root->lock
+ */
+static struct aa_namespace *__next_namespace(struct aa_namespace *root,
+					     struct aa_namespace *ns)
+{
+	struct aa_namespace *parent, *next;
+
+	/* is next namespace a child */
+	if (!list_empty(&ns->sub_ns)) {
+		next = list_first_entry(&ns->sub_ns, typeof(*ns), base.list);
+		mutex_lock(&next->lock);
+		return next;
+	}
+
+	/* check if the next ns is a sibling, parent, gp, .. */
+	parent = ns->parent;
+	while (parent) {
+		mutex_unlock(&ns->lock);
+		next = list_entry_next(ns, base.list);
+		if (!list_entry_is_head(next, &parent->sub_ns, base.list)) {
+			mutex_lock(&next->lock);
+			return next;
+		}
+		if (parent == root)
+			return NULL;
+		ns = parent;
+		parent = parent->parent;
+	}
+
+	return NULL;
+}
+
+/**
+ * __first_profile - find the first profile in a namespace
+ * @root: namespace that is root of profiles being displayed (NOT NULL)
+ * @ns: namespace to start in   (NOT NULL)
+ *
+ * Returns: unrefcounted profile or NULL if no profile
+ * Requires: profile->ns.lock to be held
+ */
+static struct aa_profile *__first_profile(struct aa_namespace *root,
+					  struct aa_namespace *ns)
+{
+	for (; ns; ns = __next_namespace(root, ns)) {
+		if (!list_empty(&ns->base.profiles))
+			return list_first_entry(&ns->base.profiles,
+						struct aa_profile, base.list);
+	}
+	return NULL;
+}
+
+/**
+ * __next_profile - step to the next profile in a profile tree
+ * @profile: current profile in tree (NOT NULL)
+ *
+ * Perform a depth first traversal on the profile tree in a namespace
+ *
+ * Returns: next profile or NULL if done
+ * Requires: profile->ns.lock to be held
+ */
+static struct aa_profile *__next_profile(struct aa_profile *p)
+{
+	struct aa_profile *parent;
+	struct aa_namespace *ns = p->ns;
+
+	/* is next profile a child */
+	if (!list_empty(&p->base.profiles))
+		return list_first_entry(&p->base.profiles, typeof(*p),
+					base.list);
+
+	/* is next profile a sibling, parent sibling, gp, sibling, .. */
+	parent = rcu_dereference_protected(p->parent,
+					   mutex_is_locked(&p->ns->lock));
+	while (parent) {
+		p = list_entry_next(p, base.list);
+		if (!list_entry_is_head(p, &parent->base.profiles, base.list))
+			return p;
+		p = parent;
+		parent = rcu_dereference_protected(parent->parent,
+					    mutex_is_locked(&parent->ns->lock));
+	}
+
+	/* is next another profile in the namespace */
+	p = list_entry_next(p, base.list);
+	if (!list_entry_is_head(p, &ns->base.profiles, base.list))
+		return p;
+
+	return NULL;
+}
+
+/**
+ * next_profile - step to the next profile in where ever it may be
+ * @root: root namespace  (NOT NULL)
+ * @profile: current profile  (NOT NULL)
+ *
+ * Returns: next profile or NULL if there isn't one
+ */
+static struct aa_profile *next_profile(struct aa_namespace *root,
+				       struct aa_profile *profile)
+{
+	struct aa_profile *next = __next_profile(profile);
+	if (next)
+		return next;
+
+	/* finished all profiles in namespace move to next namespace */
+	return __first_profile(root, __next_namespace(root, profile->ns));
+}
+
+/**
+ * p_start - start a depth first traversal of profile tree
+ * @f: seq_file to fill
+ * @pos: current position
+ *
+ * Returns: first profile under current namespace or NULL if none found
+ *
+ * acquires first ns->lock
+ */
+static void *p_start(struct seq_file *f, loff_t *pos)
+{
+	struct aa_profile *profile = NULL;
+	struct aa_namespace *root = aa_current_profile()->ns;
+	loff_t l = *pos;
+	f->private = aa_get_namespace(root);
+
+
+	/* find the first profile */
+	mutex_lock(&root->lock);
+	profile = __first_profile(root, root);
+
+	/* skip to position */
+	for (; profile && l > 0; l--)
+		profile = next_profile(root, profile);
+
+	return profile;
+}
+
+/**
+ * p_next - read the next profile entry
+ * @f: seq_file to fill
+ * @p: profile previously returned
+ * @pos: current position
+ *
+ * Returns: next profile after @p or NULL if none
+ *
+ * may acquire/release locks in namespace tree as necessary
+ */
+static void *p_next(struct seq_file *f, void *p, loff_t *pos)
+{
+	struct aa_profile *profile = p;
+	struct aa_namespace *ns = f->private;
+	(*pos)++;
+
+	return next_profile(ns, profile);
+}
+
+/**
+ * p_stop - stop depth first traversal
+ * @f: seq_file we are filling
+ * @p: the last profile writen
+ *
+ * Release all locking done by p_start/p_next on namespace tree
+ */
+static void p_stop(struct seq_file *f, void *p)
+{
+	struct aa_profile *profile = p;
+	struct aa_namespace *root = f->private, *ns;
+
+	if (profile) {
+		for (ns = profile->ns; ns && ns != root; ns = ns->parent)
+			mutex_unlock(&ns->lock);
+	}
+	mutex_unlock(&root->lock);
+	aa_put_namespace(root);
+}
+
+/**
+ * seq_show_profile - show a profile entry
+ * @f: seq_file to file
+ * @p: current position (profile)    (NOT NULL)
+ *
+ * Returns: error on failure
+ */
+static int seq_show_profile(struct seq_file *f, void *p)
+{
+	struct aa_profile *profile = (struct aa_profile *)p;
+	struct aa_namespace *root = f->private;
+
+	if (profile->ns != root)
+		seq_printf(f, ":%s://", aa_ns_name(root, profile->ns));
+	seq_printf(f, "%s (%s)\n", profile->base.hname,
+		   aa_profile_mode_names[profile->mode]);
+
+	return 0;
+}
+
+static const struct seq_operations aa_fs_profiles_op = {
+	.start = p_start,
+	.next = p_next,
+	.stop = p_stop,
+	.show = seq_show_profile,
+};
+
+static int profiles_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &aa_fs_profiles_op);
+}
+
+static int profiles_release(struct inode *inode, struct file *file)
+{
+	return seq_release(inode, file);
+}
+
+static const struct file_operations aa_fs_profiles_fops = {
+	.open = profiles_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = profiles_release,
+};
+
+
 /** Base file system setup **/
 static struct aa_fs_entry aa_fs_entry_file[] = {
 	AA_FS_FILE_STRING("mask", "create read write exec append mmap_exec " \
@@ -545,6 +780,7 @@ static struct aa_fs_entry aa_fs_entry_apparmor[] = {
 	AA_FS_FILE_FOPS(".load", 0640, &aa_fs_profile_load),
 	AA_FS_FILE_FOPS(".replace", 0640, &aa_fs_profile_replace),
 	AA_FS_FILE_FOPS(".remove", 0640, &aa_fs_profile_remove),
+	AA_FS_FILE_FOPS("profiles", 0640, &aa_fs_profiles_fops),
 	AA_FS_DIR("features", aa_fs_entry_features),
 	{ }
 };