| /* 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/slab.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 */ |
| dev_t dev; /* associated superblock device */ |
| char *path; /* insertion path */ |
| 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); |