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e08b061ec0
pahole showed that struct audit_watch had two holes: struct audit_watch { atomic_t count; /* 0 4 */ /* XXX 4 bytes hole, try to pack */ char * path; /* 8 8 */ dev_t dev; /* 16 4 */ /* XXX 4 bytes hole, try to pack */ long unsigned int ino; /* 24 8 */ struct audit_parent * parent; /* 32 8 */ struct list_head wlist; /* 40 16 */ struct list_head rules; /* 56 16 */ /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ /* size: 72, cachelines: 2, members: 7 */ /* sum members: 64, holes: 2, sum holes: 8 */ /* last cacheline: 8 bytes */ }; /* definitions: 1 */ by moving dev after count we save 8 bytes, actually improving cacheline usage. There are typically very few of these in the kernel so it won't be a large savings, but it's a good thing no matter what. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
544 lines
14 KiB
C
544 lines
14 KiB
C
/* audit_watch.c -- watching inodes
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*
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* Copyright 2003-2009 Red Hat, Inc.
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* Copyright 2005 Hewlett-Packard Development Company, L.P.
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* Copyright 2005 IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/audit.h>
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#include <linux/kthread.h>
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#include <linux/mutex.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/netlink.h>
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#include <linux/sched.h>
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#include <linux/inotify.h>
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#include <linux/security.h>
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#include "audit.h"
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/*
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* Reference counting:
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*
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* audit_parent: lifetime is from audit_init_parent() to receipt of an IN_IGNORED
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* event. Each audit_watch holds a reference to its associated parent.
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*
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* audit_watch: if added to lists, lifetime is from audit_init_watch() to
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* audit_remove_watch(). Additionally, an audit_watch may exist
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* temporarily to assist in searching existing filter data. Each
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* audit_krule holds a reference to its associated watch.
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*/
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struct audit_watch {
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atomic_t count; /* reference count */
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dev_t dev; /* associated superblock device */
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char *path; /* insertion path */
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unsigned long ino; /* associated inode number */
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struct audit_parent *parent; /* associated parent */
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struct list_head wlist; /* entry in parent->watches list */
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struct list_head rules; /* associated rules */
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};
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struct audit_parent {
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struct list_head ilist; /* entry in inotify registration list */
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struct list_head watches; /* associated watches */
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struct inotify_watch wdata; /* inotify watch data */
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unsigned flags; /* status flags */
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};
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/* Inotify handle. */
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struct inotify_handle *audit_ih;
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/*
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* audit_parent status flags:
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*
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* AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to
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* a filesystem event to ensure we're adding audit watches to a valid parent.
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* Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot
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* receive them while we have nameidata, but must be used for IN_MOVE_SELF which
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* we can receive while holding nameidata.
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*/
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#define AUDIT_PARENT_INVALID 0x001
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/* Inotify events we care about. */
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#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF
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static void audit_free_parent(struct inotify_watch *i_watch)
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{
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struct audit_parent *parent;
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parent = container_of(i_watch, struct audit_parent, wdata);
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WARN_ON(!list_empty(&parent->watches));
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kfree(parent);
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}
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void audit_get_watch(struct audit_watch *watch)
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{
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atomic_inc(&watch->count);
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}
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void audit_put_watch(struct audit_watch *watch)
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{
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if (atomic_dec_and_test(&watch->count)) {
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WARN_ON(watch->parent);
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WARN_ON(!list_empty(&watch->rules));
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kfree(watch->path);
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kfree(watch);
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}
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}
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void audit_remove_watch(struct audit_watch *watch)
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{
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list_del(&watch->wlist);
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put_inotify_watch(&watch->parent->wdata);
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watch->parent = NULL;
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audit_put_watch(watch); /* match initial get */
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}
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char *audit_watch_path(struct audit_watch *watch)
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{
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return watch->path;
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}
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struct list_head *audit_watch_rules(struct audit_watch *watch)
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{
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return &watch->rules;
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}
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unsigned long audit_watch_inode(struct audit_watch *watch)
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{
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return watch->ino;
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}
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dev_t audit_watch_dev(struct audit_watch *watch)
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{
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return watch->dev;
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}
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/* Initialize a parent watch entry. */
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static struct audit_parent *audit_init_parent(struct nameidata *ndp)
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{
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struct audit_parent *parent;
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s32 wd;
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parent = kzalloc(sizeof(*parent), GFP_KERNEL);
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if (unlikely(!parent))
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&parent->watches);
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parent->flags = 0;
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inotify_init_watch(&parent->wdata);
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/* grab a ref so inotify watch hangs around until we take audit_filter_mutex */
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get_inotify_watch(&parent->wdata);
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wd = inotify_add_watch(audit_ih, &parent->wdata,
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ndp->path.dentry->d_inode, AUDIT_IN_WATCH);
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if (wd < 0) {
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audit_free_parent(&parent->wdata);
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return ERR_PTR(wd);
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}
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return parent;
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}
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/* Initialize a watch entry. */
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static struct audit_watch *audit_init_watch(char *path)
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{
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struct audit_watch *watch;
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watch = kzalloc(sizeof(*watch), GFP_KERNEL);
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if (unlikely(!watch))
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&watch->rules);
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atomic_set(&watch->count, 1);
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watch->path = path;
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watch->dev = (dev_t)-1;
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watch->ino = (unsigned long)-1;
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return watch;
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}
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/* Translate a watch string to kernel respresentation. */
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int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
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{
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struct audit_watch *watch;
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if (!audit_ih)
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return -EOPNOTSUPP;
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if (path[0] != '/' || path[len-1] == '/' ||
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krule->listnr != AUDIT_FILTER_EXIT ||
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op != Audit_equal ||
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krule->inode_f || krule->watch || krule->tree)
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return -EINVAL;
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watch = audit_init_watch(path);
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if (IS_ERR(watch))
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return PTR_ERR(watch);
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audit_get_watch(watch);
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krule->watch = watch;
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return 0;
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}
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/* Duplicate the given audit watch. The new watch's rules list is initialized
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* to an empty list and wlist is undefined. */
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static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
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{
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char *path;
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struct audit_watch *new;
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path = kstrdup(old->path, GFP_KERNEL);
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if (unlikely(!path))
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return ERR_PTR(-ENOMEM);
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new = audit_init_watch(path);
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if (IS_ERR(new)) {
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kfree(path);
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goto out;
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}
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new->dev = old->dev;
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new->ino = old->ino;
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get_inotify_watch(&old->parent->wdata);
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new->parent = old->parent;
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out:
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return new;
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}
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static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
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{
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if (audit_enabled) {
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struct audit_buffer *ab;
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ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
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audit_log_format(ab, "auid=%u ses=%u op=",
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audit_get_loginuid(current),
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audit_get_sessionid(current));
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audit_log_string(ab, op);
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audit_log_format(ab, " path=");
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audit_log_untrustedstring(ab, w->path);
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audit_log_key(ab, r->filterkey);
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audit_log_format(ab, " list=%d res=1", r->listnr);
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audit_log_end(ab);
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}
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}
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/* Update inode info in audit rules based on filesystem event. */
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static void audit_update_watch(struct audit_parent *parent,
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const char *dname, dev_t dev,
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unsigned long ino, unsigned invalidating)
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{
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struct audit_watch *owatch, *nwatch, *nextw;
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struct audit_krule *r, *nextr;
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struct audit_entry *oentry, *nentry;
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mutex_lock(&audit_filter_mutex);
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list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
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if (audit_compare_dname_path(dname, owatch->path, NULL))
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continue;
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/* If the update involves invalidating rules, do the inode-based
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* filtering now, so we don't omit records. */
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if (invalidating && current->audit_context)
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audit_filter_inodes(current, current->audit_context);
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nwatch = audit_dupe_watch(owatch);
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if (IS_ERR(nwatch)) {
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mutex_unlock(&audit_filter_mutex);
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audit_panic("error updating watch, skipping");
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return;
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}
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nwatch->dev = dev;
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nwatch->ino = ino;
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list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
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oentry = container_of(r, struct audit_entry, rule);
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list_del(&oentry->rule.rlist);
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list_del_rcu(&oentry->list);
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nentry = audit_dupe_rule(&oentry->rule, nwatch);
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if (IS_ERR(nentry)) {
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list_del(&oentry->rule.list);
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audit_panic("error updating watch, removing");
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} else {
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int h = audit_hash_ino((u32)ino);
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list_add(&nentry->rule.rlist, &nwatch->rules);
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list_add_rcu(&nentry->list, &audit_inode_hash[h]);
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list_replace(&oentry->rule.list,
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&nentry->rule.list);
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}
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audit_watch_log_rule_change(r, owatch, "updated rules");
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call_rcu(&oentry->rcu, audit_free_rule_rcu);
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}
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audit_remove_watch(owatch);
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goto add_watch_to_parent; /* event applies to a single watch */
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}
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mutex_unlock(&audit_filter_mutex);
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return;
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add_watch_to_parent:
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list_add(&nwatch->wlist, &parent->watches);
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mutex_unlock(&audit_filter_mutex);
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return;
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}
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/* Remove all watches & rules associated with a parent that is going away. */
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static void audit_remove_parent_watches(struct audit_parent *parent)
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{
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struct audit_watch *w, *nextw;
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struct audit_krule *r, *nextr;
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struct audit_entry *e;
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mutex_lock(&audit_filter_mutex);
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parent->flags |= AUDIT_PARENT_INVALID;
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list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
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list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
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e = container_of(r, struct audit_entry, rule);
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audit_watch_log_rule_change(r, w, "remove rule");
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list_del(&r->rlist);
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list_del(&r->list);
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list_del_rcu(&e->list);
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call_rcu(&e->rcu, audit_free_rule_rcu);
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}
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audit_remove_watch(w);
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}
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mutex_unlock(&audit_filter_mutex);
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}
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/* Unregister inotify watches for parents on in_list.
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* Generates an IN_IGNORED event. */
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void audit_inotify_unregister(struct list_head *in_list)
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{
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struct audit_parent *p, *n;
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list_for_each_entry_safe(p, n, in_list, ilist) {
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list_del(&p->ilist);
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inotify_rm_watch(audit_ih, &p->wdata);
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/* the unpin matching the pin in audit_do_del_rule() */
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unpin_inotify_watch(&p->wdata);
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}
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}
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/* Get path information necessary for adding watches. */
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static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw)
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{
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struct nameidata *ndparent, *ndwatch;
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int err;
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ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
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if (unlikely(!ndparent))
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return -ENOMEM;
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ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
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if (unlikely(!ndwatch)) {
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kfree(ndparent);
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return -ENOMEM;
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}
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err = path_lookup(path, LOOKUP_PARENT, ndparent);
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if (err) {
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kfree(ndparent);
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kfree(ndwatch);
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return err;
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}
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err = path_lookup(path, 0, ndwatch);
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if (err) {
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kfree(ndwatch);
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ndwatch = NULL;
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}
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*ndp = ndparent;
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*ndw = ndwatch;
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return 0;
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}
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/* Release resources used for watch path information. */
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static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
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{
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if (ndp) {
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path_put(&ndp->path);
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kfree(ndp);
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}
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if (ndw) {
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path_put(&ndw->path);
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kfree(ndw);
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}
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}
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/* Associate the given rule with an existing parent inotify_watch.
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* Caller must hold audit_filter_mutex. */
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static void audit_add_to_parent(struct audit_krule *krule,
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struct audit_parent *parent)
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{
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struct audit_watch *w, *watch = krule->watch;
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int watch_found = 0;
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list_for_each_entry(w, &parent->watches, wlist) {
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if (strcmp(watch->path, w->path))
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continue;
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watch_found = 1;
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/* put krule's and initial refs to temporary watch */
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audit_put_watch(watch);
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audit_put_watch(watch);
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audit_get_watch(w);
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krule->watch = watch = w;
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break;
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}
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if (!watch_found) {
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get_inotify_watch(&parent->wdata);
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watch->parent = parent;
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list_add(&watch->wlist, &parent->watches);
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}
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list_add(&krule->rlist, &watch->rules);
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}
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/* Find a matching watch entry, or add this one.
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* Caller must hold audit_filter_mutex. */
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int audit_add_watch(struct audit_krule *krule)
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{
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struct audit_watch *watch = krule->watch;
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struct inotify_watch *i_watch;
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struct audit_parent *parent;
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struct nameidata *ndp = NULL, *ndw = NULL;
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int ret = 0;
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mutex_unlock(&audit_filter_mutex);
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/* Avoid calling path_lookup under audit_filter_mutex. */
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ret = audit_get_nd(watch->path, &ndp, &ndw);
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if (ret) {
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/* caller expects mutex locked */
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mutex_lock(&audit_filter_mutex);
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goto error;
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}
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/* update watch filter fields */
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if (ndw) {
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watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
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watch->ino = ndw->path.dentry->d_inode->i_ino;
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}
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/* The audit_filter_mutex must not be held during inotify calls because
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* we hold it during inotify event callback processing. If an existing
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* inotify watch is found, inotify_find_watch() grabs a reference before
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* returning.
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*/
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if (inotify_find_watch(audit_ih, ndp->path.dentry->d_inode,
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&i_watch) < 0) {
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parent = audit_init_parent(ndp);
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if (IS_ERR(parent)) {
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/* caller expects mutex locked */
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mutex_lock(&audit_filter_mutex);
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ret = PTR_ERR(parent);
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goto error;
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}
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} else
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parent = container_of(i_watch, struct audit_parent, wdata);
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mutex_lock(&audit_filter_mutex);
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/* parent was moved before we took audit_filter_mutex */
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if (parent->flags & AUDIT_PARENT_INVALID)
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ret = -ENOENT;
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else
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audit_add_to_parent(krule, parent);
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/* match get in audit_init_parent or inotify_find_watch */
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put_inotify_watch(&parent->wdata);
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error:
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audit_put_nd(ndp, ndw); /* NULL args OK */
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return ret;
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}
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void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list)
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{
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struct audit_watch *watch = krule->watch;
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struct audit_parent *parent = watch->parent;
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list_del(&krule->rlist);
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if (list_empty(&watch->rules)) {
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audit_remove_watch(watch);
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if (list_empty(&parent->watches)) {
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/* Put parent on the inotify un-registration
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* list. Grab a reference before releasing
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* audit_filter_mutex, to be released in
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* audit_inotify_unregister().
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* If filesystem is going away, just leave
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* the sucker alone, eviction will take
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* care of it. */
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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);
|