[4/5] UBUNTU: SAUCE: apparmor: add policy revision file interface

Submitted by John Johansen on March 31, 2017, 12:05 p.m.

Details

Message ID 20170331120508.16255-5-john.johansen@canonical.com
State New
Headers show

Commit Message

John Johansen March 31, 2017, 12:05 p.m.
Add a policy revision file to find the current revision of a ns's policy.
There is a revision file per ns, as well as a virtualized global revision
file in the base apparmor fs directory. The global revision file when
opened will provide the revision of the opening task namespace.

The revision file can be waited on via select/poll to detect apparmor
policy changes from the last read revision of the opened file. This
means that the revision file must be read after the select/poll other
wise update data will remain ready for reading.

BugLink: http://bugs.launchpad.net/bugs/1678032
Signed-off-by: John Johansen <john.johansen@canonical.com>
---
 security/apparmor/apparmorfs.c         | 112 +++++++++++++++++++++++++++++++++
 security/apparmor/include/apparmorfs.h |   3 +
 security/apparmor/include/policy_ns.h  |   3 +
 security/apparmor/policy.c             |   3 +
 security/apparmor/policy_ns.c          |   1 +
 5 files changed, 122 insertions(+)

Patch hide | download patch | download mbox

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 2ae58fd..5c07e57 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -220,6 +220,100 @@  static const struct file_operations aa_fs_profile_remove = {
 	.llseek = default_llseek,
 };
 
+struct aa_revision {
+	struct aa_ns *ns;
+	long last_read;
+};
+
+/* revision file hook fn for policy loads */
+static int ns_revision_release(struct inode *inode, struct file *file)
+{
+	struct aa_revision *rev = file->private_data;
+
+	if (rev) {
+		aa_put_ns(rev->ns);
+		kfree(rev);
+	}
+
+	return 0;
+}
+
+static ssize_t ns_revision_read(struct file *file, char __user *buf,
+				size_t size, loff_t *ppos)
+{
+	struct aa_revision *rev = file->private_data;
+	char buffer[32];
+	long last_read;
+	int avail;
+
+	mutex_lock(&rev->ns->lock);
+	last_read = rev->last_read;
+	if (last_read == rev->ns->revision) {
+		mutex_unlock(&rev->ns->lock);
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		if (wait_event_interruptible(rev->ns->wait,
+					     last_read !=
+					     READ_ONCE(rev->ns->revision)))
+			return -ERESTARTSYS;
+		mutex_lock(&rev->ns->lock);
+	}
+
+	avail = sprintf(buffer, "%ld\n", rev->ns->revision);
+	if (*ppos + size > avail) {
+		rev->last_read = rev->ns->revision;
+		*ppos = 0;
+	}
+	mutex_unlock(&rev->ns->lock);
+
+	return simple_read_from_buffer(buf, size, ppos, buffer, avail);
+}
+
+static int ns_revision_open(struct inode *inode, struct file *file)
+{
+	struct aa_revision *rev = kzalloc(sizeof(*rev), GFP_KERNEL);
+
+	if (!rev)
+		return -ENOMEM;
+
+	rev->ns = aa_get_ns(inode->i_private);
+	if (!rev->ns)
+		rev->ns = aa_get_current_ns();
+	file->private_data = rev;
+
+	return 0;
+}
+
+static unsigned int ns_revision_poll(struct file *file, poll_table *pt)
+{
+	struct aa_revision *rev = file->private_data;
+	unsigned int mask = 0;
+
+	if (rev) {
+		mutex_lock(&rev->ns->lock);
+		poll_wait(file, &rev->ns->wait, pt);
+		if (rev->last_read < rev->ns->revision)
+			mask |= POLLIN | POLLRDNORM;
+		mutex_unlock(&rev->ns->lock);
+	}
+
+	return mask;
+}
+
+void __aa_bump_ns_revision(struct aa_ns *ns)
+{
+	ns->revision++;
+	wake_up_interruptible(&ns->wait);
+}
+
+static const struct file_operations ns_revision_fops = {
+	.owner		= THIS_MODULE,
+	.open		= ns_revision_open,
+	.poll		= ns_revision_poll,
+	.read		= ns_revision_read,
+	.llseek		= generic_file_llseek,
+	.release	= ns_revision_release,
+};
 
 static void profile_query_cb(struct aa_profile *profile, struct aa_perms *perms,
 			     const char *match_str, size_t match_len)
@@ -1153,6 +1247,10 @@  void __aa_fs_ns_rmdir(struct aa_ns *ns)
 		sub = d_inode(ns_subremove(ns))->i_private;
 		aa_put_ns(sub);
 	}
+	if (ns_subrevision(ns)) {
+		sub = d_inode(ns_subrevision(ns))->i_private;
+		aa_put_ns(sub);
+	}
 
 	for (i = AAFS_NS_SIZEOF - 1; i >= 0; --i) {
 		securityfs_remove(ns->dents[i]);
@@ -1178,6 +1276,12 @@  static int __aa_fs_ns_mkdir_entries(struct aa_ns *ns, struct dentry *dir)
 		return PTR_ERR(dent);
 	ns_subdata_dir(ns) = dent;
 
+	dent = securityfs_create_file("revision", 0444, dir, ns,
+				      &ns_revision_fops);
+	if (IS_ERR(dent))
+		return PTR_ERR(dent);
+	ns_subrevision(ns) = dent;
+
 	dent = securityfs_create_file(".load", 0666, dir, ns,
 				      &aa_fs_profile_load);
 	if (IS_ERR(dent))
@@ -1802,6 +1906,14 @@  static int __init aa_create_aafs(void)
 	}
 	ns_subremove(root_ns) = dent;
 
+	dent = securityfs_create_file("revision", 0444, aa_fs_entry.dentry,
+				      NULL, &ns_revision_fops);
+	if (IS_ERR(dent)) {
+		error = PTR_ERR(dent);
+		goto error;
+	}
+	ns_subrevision(root_ns) = dent;
+
 	mutex_lock(&root_ns->lock);
 	error = __aa_fs_ns_mkdir(root_ns, aa_fs_entry.dentry, "policy", NULL);
 	mutex_unlock(&root_ns->lock);
diff --git a/security/apparmor/include/apparmorfs.h b/security/apparmor/include/apparmorfs.h
index bec1cc4..b25d822 100644
--- a/security/apparmor/include/apparmorfs.h
+++ b/security/apparmor/include/apparmorfs.h
@@ -74,6 +74,7 @@  enum aafs_ns_type {
 	AAFS_NS_LOAD,
 	AAFS_NS_REPLACE,
 	AAFS_NS_REMOVE,
+	AAFS_NS_REVISION,
 	AAFS_NS_COUNT,
 	AAFS_NS_MAX_COUNT,
 	AAFS_NS_SIZE,
@@ -102,10 +103,12 @@  enum aafs_prof_type {
 #define ns_subload(X) ((X)->dents[AAFS_NS_LOAD])
 #define ns_subreplace(X) ((X)->dents[AAFS_NS_REPLACE])
 #define ns_subremove(X) ((X)->dents[AAFS_NS_REMOVE])
+#define ns_subrevision(X) ((X)->dents[AAFS_NS_REVISION])
 
 #define prof_dir(X) ((X)->dents[AAFS_PROF_DIR])
 #define prof_child_dir(X) ((X)->dents[AAFS_PROF_PROFS])
 
+void __aa_bump_ns_revision(struct aa_ns *ns);
 void __aa_fs_profile_rmdir(struct aa_profile *profile);
 void __aa_fs_profile_migrate_dents(struct aa_profile *old,
 				   struct aa_profile *new);
diff --git a/security/apparmor/include/policy_ns.h b/security/apparmor/include/policy_ns.h
index 4c16c9a..e11380b 100644
--- a/security/apparmor/include/policy_ns.h
+++ b/security/apparmor/include/policy_ns.h
@@ -68,6 +68,9 @@  struct aa_ns {
 	atomic_t uniq_null;
 	long uniq_id;
 	int level;
+	long revision;
+	wait_queue_head_t wait;
+
 	struct aa_labelset labels;
 
 	struct dentry *dents[AAFS_NS_SIZEOF];
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index f5f286a..52ccd0e 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -1004,6 +1004,7 @@  ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_label *label,
 		aa_load_ent_free(ent);
 	}
 	__aa_labelset_update_subtree(ns);
+	__aa_bump_ns_revision(ns);
 	mutex_unlock(&ns->lock);
 
 out:
@@ -1087,6 +1088,7 @@  ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_label *label,
 		/* remove namespace - can only happen if fqname[0] == ':' */
 		mutex_lock(&ns->parent->lock);
 		__aa_remove_ns(ns);
+		__aa_bump_ns_revision(ns);
 		mutex_unlock(&ns->parent->lock);
 	} else {
 		/* remove profile */
@@ -1100,6 +1102,7 @@  ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_label *label,
 		name = profile->base.hname;
 		__remove_profile(profile);
 		__aa_labelset_update_subtree(ns);
+		__aa_bump_ns_revision(ns);
 		mutex_unlock(&ns->lock);
 	}
 
diff --git a/security/apparmor/policy_ns.c b/security/apparmor/policy_ns.c
index 88043fc..e46d092 100644
--- a/security/apparmor/policy_ns.c
+++ b/security/apparmor/policy_ns.c
@@ -100,6 +100,7 @@  static struct aa_ns *alloc_ns(const char *prefix, const char *name)
 
 	INIT_LIST_HEAD(&ns->sub_ns);
 	mutex_init(&ns->lock);
+	init_waitqueue_head(&ns->wait);
 
 	/* released by free_namespace */
 	ns->unconfined = aa_alloc_profile("unconfined", NULL, GFP_KERNEL);