1 files changed, 543 insertions, 0 deletions

diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
new file mode 100644
index 000000000000..0e96dbc60ea9
--- /dev/null
+++ b/kernel/audit_watch.c
@@ -0,0 +1,543 @@
+/* audit_watch.c -- watching inodes
+ *
+ * Copyright 2003-2009 Red Hat, Inc.
+ * Copyright 2005 Hewlett-Packard Development Company, L.P.
+ * Copyright 2005 IBM Corporation
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/audit.h>
+#include <linux/kthread.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/netlink.h>
+#include <linux/sched.h>
+#include <linux/inotify.h>
+#include <linux/security.h>
+#include "audit.h"
+
+/*
+ * Reference counting:
+ *
+ * audit_parent: lifetime is from audit_init_parent() to receipt of an IN_IGNORED
+ *      event.  Each audit_watch holds a reference to its associated parent.
+ *
+ * audit_watch: if added to lists, lifetime is from audit_init_watch() to
+ *      audit_remove_watch().  Additionally, an audit_watch may exist
+ *      temporarily to assist in searching existing filter data.  Each
+ *      audit_krule holds a reference to its associated watch.
+ */
+
+struct audit_watch {
+        atomic_t                count;  /* reference count */
+        char                    *path;  /* insertion path */
+        dev_t                   dev;    /* associated superblock device */
+        unsigned long           ino;    /* associated inode number */
+        struct audit_parent     *parent; /* associated parent */
+        struct list_head        wlist;  /* entry in parent->watches list */
+        struct list_head        rules;  /* associated rules */
+};
+
+struct audit_parent {
+        struct list_head        ilist;  /* entry in inotify registration list */
+        struct list_head        watches; /* associated watches */
+        struct inotify_watch    wdata;  /* inotify watch data */
+        unsigned                flags;  /* status flags */
+};
+
+/* Inotify handle. */
+struct inotify_handle *audit_ih;
+
+/*
+ * audit_parent status flags:
+ *
+ * AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to
+ * a filesystem event to ensure we're adding audit watches to a valid parent.
+ * Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot
+ * receive them while we have nameidata, but must be used for IN_MOVE_SELF which
+ * we can receive while holding nameidata.
+ */
+#define AUDIT_PARENT_INVALID    0x001
+
+/* Inotify events we care about. */
+#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF
+
+static void audit_free_parent(struct inotify_watch *i_watch)
+{
+        struct audit_parent *parent;
+
+        parent = container_of(i_watch, struct audit_parent, wdata);
+        WARN_ON(!list_empty(&parent->watches));
+        kfree(parent);
+}
+
+void audit_get_watch(struct audit_watch *watch)
+{
+        atomic_inc(&watch->count);
+}
+
+void audit_put_watch(struct audit_watch *watch)
+{
+        if (atomic_dec_and_test(&watch->count)) {
+                WARN_ON(watch->parent);
+                WARN_ON(!list_empty(&watch->rules));
+                kfree(watch->path);
+                kfree(watch);
+        }
+}
+
+void audit_remove_watch(struct audit_watch *watch)
+{
+        list_del(&watch->wlist);
+        put_inotify_watch(&watch->parent->wdata);
+        watch->parent = NULL;
+        audit_put_watch(watch); /* match initial get */
+}
+
+char *audit_watch_path(struct audit_watch *watch)
+{
+        return watch->path;
+}
+
+struct list_head *audit_watch_rules(struct audit_watch *watch)
+{
+        return &watch->rules;
+}
+
+unsigned long audit_watch_inode(struct audit_watch *watch)
+{
+        return watch->ino;
+}
+
+dev_t audit_watch_dev(struct audit_watch *watch)
+{
+        return watch->dev;
+}
+
+/* Initialize a parent watch entry. */
+static struct audit_parent *audit_init_parent(struct nameidata *ndp)
+{
+        struct audit_parent *parent;
+        s32 wd;
+
+        parent = kzalloc(sizeof(*parent), GFP_KERNEL);
+        if (unlikely(!parent))
+                return ERR_PTR(-ENOMEM);
+
+        INIT_LIST_HEAD(&parent->watches);
+        parent->flags = 0;
+
+        inotify_init_watch(&parent->wdata);
+        /* grab a ref so inotify watch hangs around until we take audit_filter_mutex */
+        get_inotify_watch(&parent->wdata);
+        wd = inotify_add_watch(audit_ih, &parent->wdata,
+                               ndp->path.dentry->d_inode, AUDIT_IN_WATCH);
+        if (wd < 0) {
+                audit_free_parent(&parent->wdata);
+                return ERR_PTR(wd);
+        }
+
+        return parent;
+}
+
+/* Initialize a watch entry. */
+static struct audit_watch *audit_init_watch(char *path)
+{
+        struct audit_watch *watch;
+
+        watch = kzalloc(sizeof(*watch), GFP_KERNEL);
+        if (unlikely(!watch))
+                return ERR_PTR(-ENOMEM);
+
+        INIT_LIST_HEAD(&watch->rules);
+        atomic_set(&watch->count, 1);
+        watch->path = path;
+        watch->dev = (dev_t)-1;
+        watch->ino = (unsigned long)-1;
+
+        return watch;
+}
+
+/* Translate a watch string to kernel respresentation. */
+int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
+{
+        struct audit_watch *watch;
+
+        if (!audit_ih)
+                return -EOPNOTSUPP;
+
+        if (path[0] != '/' || path[len-1] == '/' ||
+            krule->listnr != AUDIT_FILTER_EXIT ||
+            op != Audit_equal ||
+            krule->inode_f || krule->watch || krule->tree)
+                return -EINVAL;
+
+        watch = audit_init_watch(path);
+        if (IS_ERR(watch))
+                return PTR_ERR(watch);
+
+        audit_get_watch(watch);
+        krule->watch = watch;
+
+        return 0;
+}
+
+/* Duplicate the given audit watch.  The new watch's rules list is initialized
+ * to an empty list and wlist is undefined. */
+static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
+{
+        char *path;
+        struct audit_watch *new;
+
+        path = kstrdup(old->path, GFP_KERNEL);
+        if (unlikely(!path))
+                return ERR_PTR(-ENOMEM);
+
+        new = audit_init_watch(path);
+        if (IS_ERR(new)) {
+                kfree(path);
+                goto out;
+        }
+
+        new->dev = old->dev;
+        new->ino = old->ino;
+        get_inotify_watch(&old->parent->wdata);
+        new->parent = old->parent;
+
+out:
+        return new;
+}
+
+static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
+{
+        if (audit_enabled) {
+                struct audit_buffer *ab;
+                ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
+                audit_log_format(ab, "auid=%u ses=%u op=",
+                                 audit_get_loginuid(current),
+                                 audit_get_sessionid(current));
+                audit_log_string(ab, op);
+                audit_log_format(ab, " path=");
+                audit_log_untrustedstring(ab, w->path);
+                audit_log_key(ab, r->filterkey);
+                audit_log_format(ab, " list=%d res=1", r->listnr);
+                audit_log_end(ab);
+        }
+}
+
+/* Update inode info in audit rules based on filesystem event. */
+static void audit_update_watch(struct audit_parent *parent,
+                               const char *dname, dev_t dev,
+                               unsigned long ino, unsigned invalidating)
+{
+        struct audit_watch *owatch, *nwatch, *nextw;
+        struct audit_krule *r, *nextr;
+        struct audit_entry *oentry, *nentry;
+
+        mutex_lock(&audit_filter_mutex);
+        list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
+                if (audit_compare_dname_path(dname, owatch->path, NULL))
+                        continue;
+
+                /* If the update involves invalidating rules, do the inode-based
+                 * filtering now, so we don't omit records. */
+                if (invalidating && current->audit_context)
+                        audit_filter_inodes(current, current->audit_context);
+
+                nwatch = audit_dupe_watch(owatch);
+                if (IS_ERR(nwatch)) {
+                        mutex_unlock(&audit_filter_mutex);
+                        audit_panic("error updating watch, skipping");
+                        return;
+                }
+                nwatch->dev = dev;
+                nwatch->ino = ino;
+
+                list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
+
+                        oentry = container_of(r, struct audit_entry, rule);
+                        list_del(&oentry->rule.rlist);
+                        list_del_rcu(&oentry->list);
+
+                        nentry = audit_dupe_rule(&oentry->rule, nwatch);
+                        if (IS_ERR(nentry)) {
+                                list_del(&oentry->rule.list);
+                                audit_panic("error updating watch, removing");
+                        } else {
+                                int h = audit_hash_ino((u32)ino);
+                                list_add(&nentry->rule.rlist, &nwatch->rules);
+                                list_add_rcu(&nentry->list, &audit_inode_hash[h]);
+                                list_replace(&oentry->rule.list,
+                                             &nentry->rule.list);
+                        }
+
+                        audit_watch_log_rule_change(r, owatch, "updated rules");
+
+                        call_rcu(&oentry->rcu, audit_free_rule_rcu);
+                }
+
+                audit_remove_watch(owatch);
+                goto add_watch_to_parent; /* event applies to a single watch */
+        }
+        mutex_unlock(&audit_filter_mutex);
+        return;
+
+add_watch_to_parent:
+        list_add(&nwatch->wlist, &parent->watches);
+        mutex_unlock(&audit_filter_mutex);
+        return;
+}
+
+/* Remove all watches & rules associated with a parent that is going away. */
+static void audit_remove_parent_watches(struct audit_parent *parent)
+{
+        struct audit_watch *w, *nextw;
+        struct audit_krule *r, *nextr;
+        struct audit_entry *e;
+
+        mutex_lock(&audit_filter_mutex);
+        parent->flags |= AUDIT_PARENT_INVALID;
+        list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
+                list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
+                        e = container_of(r, struct audit_entry, rule);
+                        audit_watch_log_rule_change(r, w, "remove rule");
+                        list_del(&r->rlist);
+                        list_del(&r->list);
+                        list_del_rcu(&e->list);
+                        call_rcu(&e->rcu, audit_free_rule_rcu);
+                }
+                audit_remove_watch(w);
+        }
+        mutex_unlock(&audit_filter_mutex);
+}
+
+/* Unregister inotify watches for parents on in_list.
+ * Generates an IN_IGNORED event. */
+void audit_inotify_unregister(struct list_head *in_list)
+{
+        struct audit_parent *p, *n;
+
+        list_for_each_entry_safe(p, n, in_list, ilist) {
+                list_del(&p->ilist);
+                inotify_rm_watch(audit_ih, &p->wdata);
+                /* the unpin matching the pin in audit_do_del_rule() */
+                unpin_inotify_watch(&p->wdata);
+        }
+}
+
+/* Get path information necessary for adding watches. */
+static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw)
+{
+        struct nameidata *ndparent, *ndwatch;
+        int err;
+
+        ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
+        if (unlikely(!ndparent))
+                return -ENOMEM;
+
+        ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
+        if (unlikely(!ndwatch)) {
+                kfree(ndparent);
+                return -ENOMEM;
+        }
+
+        err = path_lookup(path, LOOKUP_PARENT, ndparent);
+        if (err) {
+                kfree(ndparent);
+                kfree(ndwatch);
+                return err;
+        }
+
+        err = path_lookup(path, 0, ndwatch);
+        if (err) {
+                kfree(ndwatch);
+                ndwatch = NULL;
+        }
+
+        *ndp = ndparent;
+        *ndw = ndwatch;
+
+        return 0;
+}
+
+/* Release resources used for watch path information. */
+static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
+{
+        if (ndp) {
+                path_put(&ndp->path);
+                kfree(ndp);
+        }
+        if (ndw) {
+                path_put(&ndw->path);
+                kfree(ndw);
+        }
+}
+
+/* Associate the given rule with an existing parent inotify_watch.
+ * Caller must hold audit_filter_mutex. */
+static void audit_add_to_parent(struct audit_krule *krule,
+                                struct audit_parent *parent)
+{
+        struct audit_watch *w, *watch = krule->watch;
+        int watch_found = 0;
+
+        list_for_each_entry(w, &parent->watches, wlist) {
+                if (strcmp(watch->path, w->path))
+                        continue;
+
+                watch_found = 1;
+
+                /* put krule's and initial refs to temporary watch */
+                audit_put_watch(watch);
+                audit_put_watch(watch);
+
+                audit_get_watch(w);
+                krule->watch = watch = w;
+                break;
+        }
+
+        if (!watch_found) {
+                get_inotify_watch(&parent->wdata);
+                watch->parent = parent;
+
+                list_add(&watch->wlist, &parent->watches);
+        }
+        list_add(&krule->rlist, &watch->rules);
+}
+
+/* Find a matching watch entry, or add this one.
+ * Caller must hold audit_filter_mutex. */
+int audit_add_watch(struct audit_krule *krule)
+{
+        struct audit_watch *watch = krule->watch;
+        struct inotify_watch *i_watch;
+        struct audit_parent *parent;
+        struct nameidata *ndp = NULL, *ndw = NULL;
+        int ret = 0;
+
+        mutex_unlock(&audit_filter_mutex);
+
+        /* Avoid calling path_lookup under audit_filter_mutex. */
+        ret = audit_get_nd(watch->path, &ndp, &ndw);
+        if (ret) {
+                /* caller expects mutex locked */
+                mutex_lock(&audit_filter_mutex);
+                goto error;
+        }
+
+        /* update watch filter fields */
+        if (ndw) {
+                watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
+                watch->ino = ndw->path.dentry->d_inode->i_ino;
+        }
+
+        /* The audit_filter_mutex must not be held during inotify calls because
+         * we hold it during inotify event callback processing.  If an existing
+         * inotify watch is found, inotify_find_watch() grabs a reference before
+         * returning.
+         */
+        if (inotify_find_watch(audit_ih, ndp->path.dentry->d_inode,
+                               &i_watch) < 0) {
+                parent = audit_init_parent(ndp);
+                if (IS_ERR(parent)) {
+                        /* caller expects mutex locked */
+                        mutex_lock(&audit_filter_mutex);
+                        ret = PTR_ERR(parent);
+                        goto error;
+                }
+        } else
+                parent = container_of(i_watch, struct audit_parent, wdata);
+
+        mutex_lock(&audit_filter_mutex);
+
+        /* parent was moved before we took audit_filter_mutex */
+        if (parent->flags & AUDIT_PARENT_INVALID)
+                ret = -ENOENT;
+        else
+                audit_add_to_parent(krule, parent);
+
+        /* match get in audit_init_parent or inotify_find_watch */
+        put_inotify_watch(&parent->wdata);
+
+error:
+        audit_put_nd(ndp, ndw);         /* NULL args OK */
+        return ret;
+
+}
+
+void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list)
+{
+        struct audit_watch *watch = krule->watch;
+        struct audit_parent *parent = watch->parent;
+
+        list_del(&krule->rlist);
+
+        if (list_empty(&watch->rules)) {
+                audit_remove_watch(watch);
+
+                if (list_empty(&parent->watches)) {
+                        /* Put parent on the inotify un-registration
+                         * list.  Grab a reference before releasing
+                         * audit_filter_mutex, to be released in
+                         * audit_inotify_unregister().
+                         * If filesystem is going away, just leave
+                         * the sucker alone, eviction will take
+                         * care of it. */
+                        if (pin_inotify_watch(&parent->wdata))
+                                list_add(&parent->ilist, list);
+                }
+        }
+}
+
+/* Update watch data in audit rules based on inotify events. */
+static void audit_handle_ievent(struct inotify_watch *i_watch, u32 wd, u32 mask,
+                         u32 cookie, const char *dname, struct inode *inode)
+{
+        struct audit_parent *parent;
+
+        parent = container_of(i_watch, struct audit_parent, wdata);
+
+        if (mask & (IN_CREATE|IN_MOVED_TO) && inode)
+                audit_update_watch(parent, dname, inode->i_sb->s_dev,
+                                   inode->i_ino, 0);
+        else if (mask & (IN_DELETE|IN_MOVED_FROM))
+                audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
+        /* inotify automatically removes the watch and sends IN_IGNORED */
+        else if (mask & (IN_DELETE_SELF|IN_UNMOUNT))
+                audit_remove_parent_watches(parent);
+        /* inotify does not remove the watch, so remove it manually */
+        else if(mask & IN_MOVE_SELF) {
+                audit_remove_parent_watches(parent);
+                inotify_remove_watch_locked(audit_ih, i_watch);
+        } else if (mask & IN_IGNORED)
+                put_inotify_watch(i_watch);
+}
+
+static const struct inotify_operations audit_inotify_ops = {
+        .handle_event   = audit_handle_ievent,
+        .destroy_watch  = audit_free_parent,
+};
+
+static int __init audit_watch_init(void)
+{
+        audit_ih = inotify_init(&audit_inotify_ops);
+        if (IS_ERR(audit_ih))
+                audit_panic("cannot initialize inotify handle");
+        return 0;
+}
+subsys_initcall(audit_watch_init);