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[PATCH] audit: path-based rules

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In this implementation, audit registers inotify watches on the parent
directories of paths specified in audit rules.  When audit's inotify
event handler is called, it updates any affected rules based on the
filesystem event.  If the parent directory is renamed, removed, or its
filesystem is unmounted, audit removes all rules referencing that
inotify watch.

To keep things simple, this implementation limits location-based
auditing to the directory entries in an existing directory.  Given
a path-based rule for /foo/bar/passwd, the following table applies:

    passwd modified -- audit event logged
    passwd replaced -- audit event logged, rules list updated
    bar renamed     -- rule removed
    foo renamed     -- untracked, meaning that the rule now applies to
		       the new location

Audit users typically want to have many rules referencing filesystem
objects, which can significantly impact filtering performance.  This
patch also adds an inode-number-based rule hash to mitigate this
situation.

The patch is relative to the audit git tree:
http://kernel.org/git/?p=linux/kernel/git/viro/audit-current.git;a=summary
and uses the inotify kernel API:
http://lkml.org/lkml/2006/6/1/145

Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Amy Griffis 2006-04-07 16:55:56 -04:00 committed by Al Viro
parent 20ca73bc79
commit f368c07d72
6 changed files with 903 additions and 89 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/audit.h
View file

@ -165,6 +165,7 @@
#define AUDIT_INODE 102
#define AUDIT_EXIT 103
#define AUDIT_SUCCESS 104 /* exit >= 0; value ignored */
#define AUDIT_WATCH 105
#define AUDIT_ARG0 200
#define AUDIT_ARG1 (AUDIT_ARG0+1)

3
init/Kconfig
View file

@ -182,7 +182,8 @@ config AUDITSYSCALL
help
Enable low-overhead system-call auditing infrastructure that
can be used independently or with another kernel subsystem,
such as SELinux.
such as SELinux. To use audit's filesystem watch feature, please
ensure that INOTIFY is configured.
config IKCONFIG
bool "Kernel .config support"

41
kernel/audit.c
View file

@ -56,6 +56,7 @@
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/selinux.h>
#include <linux/inotify.h>
#include "audit.h"
@ -103,6 +104,12 @@ static atomic_t audit_lost = ATOMIC_INIT(0);
/* The netlink socket. */
static struct sock *audit_sock;
/* Inotify handle. */
struct inotify_handle *audit_ih;
/* Hash for inode-based rules */
struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
/* The audit_freelist is a list of pre-allocated audit buffers (if more
* than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
* being placed on the freelist). */
@ -115,10 +122,8 @@ static struct task_struct *kauditd_task;
static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
/* The netlink socket is only to be read by 1 CPU, which lets us assume
* that list additions and deletions never happen simultaneously in
* auditsc.c */
DEFINE_MUTEX(audit_netlink_mutex);
/* Serialize requests from userspace. */
static DEFINE_MUTEX(audit_cmd_mutex);
/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
* audit records. Since printk uses a 1024 byte buffer, this buffer
@ -373,8 +378,8 @@ int audit_send_list(void *_dest)
struct sk_buff *skb;
/* wait for parent to finish and send an ACK */
mutex_lock(&audit_netlink_mutex);
mutex_unlock(&audit_netlink_mutex);
mutex_lock(&audit_cmd_mutex);
mutex_unlock(&audit_cmd_mutex);
while ((skb = __skb_dequeue(&dest->q)) != NULL)
netlink_unicast(audit_sock, skb, pid, 0);
@ -665,20 +670,30 @@ static void audit_receive(struct sock *sk, int length)
struct sk_buff *skb;
unsigned int qlen;
mutex_lock(&audit_netlink_mutex);
mutex_lock(&audit_cmd_mutex);
for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
skb = skb_dequeue(&sk->sk_receive_queue);
audit_receive_skb(skb);
kfree_skb(skb);
}
mutex_unlock(&audit_netlink_mutex);
mutex_unlock(&audit_cmd_mutex);
}
#ifdef CONFIG_AUDITSYSCALL
static const struct inotify_operations audit_inotify_ops = {
.handle_event = audit_handle_ievent,
.destroy_watch = audit_free_parent,
};
#endif
/* Initialize audit support at boot time. */
static int __init audit_init(void)
{
#ifdef CONFIG_AUDITSYSCALL
int i;
#endif
printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
audit_default ? "enabled" : "disabled");
audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive,
@ -697,6 +712,16 @@ static int __init audit_init(void)
selinux_audit_set_callback(&selinux_audit_rule_update);
audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
#ifdef CONFIG_AUDITSYSCALL
audit_ih = inotify_init(&audit_inotify_ops);
if (IS_ERR(audit_ih))
audit_panic("cannot initialize inotify handle");
for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
INIT_LIST_HEAD(&audit_inode_hash[i]);
#endif
return 0;
}
__initcall(audit_init);

38
kernel/audit.h
View file

@ -19,7 +19,6 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/audit.h>
#include <linux/skbuff.h>
@ -54,6 +53,18 @@ enum audit_state {
};
/* Rule lists */
struct audit_parent;
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_field {
u32 type;
u32 val;
@ -71,6 +82,9 @@ struct audit_krule {
u32 buflen; /* for data alloc on list rules */
u32 field_count;
struct audit_field *fields;
struct audit_field *inode_f; /* quick access to an inode field */
struct audit_watch *watch; /* associated watch */
struct list_head rlist; /* entry in audit_watch.rules list */
};
struct audit_entry {
@ -79,10 +93,18 @@ struct audit_entry {
struct audit_krule rule;
};
extern int audit_pid;
extern int audit_comparator(const u32 left, const u32 op, const u32 right);
#define AUDIT_INODE_BUCKETS 32
extern struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
static inline int audit_hash_ino(u32 ino)
{
return (ino & (AUDIT_INODE_BUCKETS-1));
}
extern int audit_comparator(const u32 left, const u32 op, const u32 right);
extern int audit_compare_dname_path(const char *dname, const char *path);
extern struct sk_buff * audit_make_reply(int pid, int seq, int type,
int done, int multi,
void *payload, int size);
@ -91,7 +113,6 @@ extern void audit_send_reply(int pid, int seq, int type,
void *payload, int size);
extern void audit_log_lost(const char *message);
extern void audit_panic(const char *message);
extern struct mutex audit_netlink_mutex;
struct audit_netlink_list {
int pid;
@ -100,6 +121,10 @@ struct audit_netlink_list {
int audit_send_list(void *);
struct inotify_watch;
extern void audit_free_parent(struct inotify_watch *);
extern void audit_handle_ievent(struct inotify_watch *, u32, u32, u32,
const char *, struct inode *);
extern int selinux_audit_rule_update(void);
#ifdef CONFIG_AUDITSYSCALL
@ -109,6 +134,11 @@ static inline void audit_signal_info(int sig, struct task_struct *t)
if (unlikely(audit_pid && t->tgid == audit_pid))
__audit_signal_info(sig, t);
}
extern enum audit_state audit_filter_inodes(struct task_struct *,
struct audit_context *);
extern void audit_set_auditable(struct audit_context *);
#else
#define audit_signal_info(s,t)
#define audit_filter_inodes(t,c) AUDIT_DISABLED
#define audit_set_auditable(c)
#endif

787
kernel/auditfilter.c
View file

@ -22,13 +22,59 @@
#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/selinux.h>
#include "audit.h"
/* There are three lists of rules -- one to search at task creation
* time, one to search at syscall entry time, and another to search at
* syscall exit time. */
/*
* Locking model:
*
* audit_filter_mutex:
* Synchronizes writes and blocking reads of audit's filterlist
* data. Rcu is used to traverse the filterlist and access
* contents of structs audit_entry, audit_watch and opaque
* selinux rules during filtering. If modified, these structures
* must be copied and replace their counterparts in the filterlist.
* An audit_parent struct is not accessed during filtering, so may
* be written directly provided audit_filter_mutex is held.
*/
/*
* 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_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 */
};
/*
* 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
/* Audit filter lists, defined in <linux/audit.h> */
struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
LIST_HEAD_INIT(audit_filter_list[0]),
LIST_HEAD_INIT(audit_filter_list[1]),
@ -41,9 +87,53 @@ struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
#endif
};
static DEFINE_MUTEX(audit_filter_mutex);
/* Inotify handle */
extern struct inotify_handle *audit_ih;
/* Inotify events we care about. */
#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF
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);
}
static inline void audit_get_watch(struct audit_watch *watch)
{
atomic_inc(&watch->count);
}
static 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);
}
}
static 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 */
}
static inline void audit_free_rule(struct audit_entry *e)
{
int i;
/* some rules don't have associated watches */
if (e->rule.watch)
audit_put_watch(e->rule.watch);
if (e->rule.fields)
for (i = 0; i < e->rule.field_count; i++) {
struct audit_field *f = &e->rule.fields[i];
@ -60,6 +150,50 @@ static inline void audit_free_rule_rcu(struct rcu_head *head)
audit_free_rule(e);
}
/* 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->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;
}
/* Initialize an audit filterlist entry. */
static inline struct audit_entry *audit_init_entry(u32 field_count)
{
@ -107,6 +241,43 @@ static char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
return str;
}
/* Translate an inode field to kernel respresentation. */
static inline int audit_to_inode(struct audit_krule *krule,
struct audit_field *f)
{
if (krule->listnr != AUDIT_FILTER_EXIT ||
krule->watch || krule->inode_f)
return -EINVAL;
krule->inode_f = f;
return 0;
}
/* Translate a watch string to kernel respresentation. */
static 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) /* 1 inode # per rule, for hash */
return -EINVAL;
watch = audit_init_watch(path);
if (unlikely(IS_ERR(watch)))
return PTR_ERR(watch);
audit_get_watch(watch);
krule->watch = watch;
return 0;
}
/* Common user-space to kernel rule translation. */
static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
{
@ -161,6 +332,7 @@ static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
{
struct audit_entry *entry;
struct audit_field *f;
int err = 0;
int i;
@ -175,14 +347,23 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
f->val = rule->values[i];
if (f->type & AUDIT_UNUSED_BITS ||
f->type == AUDIT_SE_USER ||
f->type == AUDIT_SE_ROLE ||
f->type == AUDIT_SE_TYPE ||
f->type == AUDIT_SE_SEN ||
f->type == AUDIT_SE_CLR) {
err = -EINVAL;
err = -EINVAL;
if (f->type & AUDIT_UNUSED_BITS)
goto exit_free;
switch(f->type) {
case AUDIT_SE_USER:
case AUDIT_SE_ROLE:
case AUDIT_SE_TYPE:
case AUDIT_SE_SEN:
case AUDIT_SE_CLR:
case AUDIT_WATCH:
goto exit_free;
case AUDIT_INODE:
err = audit_to_inode(&entry->rule, f);
if (err)
goto exit_free;
break;
}
entry->rule.vers_ops = (f->op & AUDIT_OPERATORS) ? 2 : 1;
@ -199,6 +380,18 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
}
}
f = entry->rule.inode_f;
if (f) {
switch(f->op) {
case AUDIT_NOT_EQUAL:
entry->rule.inode_f = NULL;
case AUDIT_EQUAL:
break;
default:
goto exit_free;
}
}
exit_nofree:
return entry;
@ -213,6 +406,7 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
{
int err = 0;
struct audit_entry *entry;
struct audit_field *f;
void *bufp;
size_t remain = datasz - sizeof(struct audit_rule_data);
int i;
@ -263,6 +457,35 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
} else
f->se_str = str;
break;
case AUDIT_WATCH:
str = audit_unpack_string(&bufp, &remain, f->val);
if (IS_ERR(str))
goto exit_free;
entry->rule.buflen += f->val;
err = audit_to_watch(&entry->rule, str, f->val, f->op);
if (err) {
kfree(str);
goto exit_free;
}
break;
case AUDIT_INODE:
err = audit_to_inode(&entry->rule, f);
if (err)
goto exit_free;
break;
}
}
f = entry->rule.inode_f;
if (f) {
switch(f->op) {
case AUDIT_NOT_EQUAL:
entry->rule.inode_f = NULL;
case AUDIT_EQUAL:
break;
default:
goto exit_free;
}
}
@ -346,6 +569,10 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
data->buflen += data->values[i] =
audit_pack_string(&bufp, f->se_str);
break;
case AUDIT_WATCH:
data->buflen += data->values[i] =
audit_pack_string(&bufp, krule->watch->path);
break;
default:
data->values[i] = f->val;
}
@ -381,6 +608,10 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
if (strcmp(a->fields[i].se_str, b->fields[i].se_str))
return 1;
break;
case AUDIT_WATCH:
if (strcmp(a->watch->path, b->watch->path))
return 1;
break;
default:
if (a->fields[i].val != b->fields[i].val)
return 1;
@ -394,6 +625,32 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
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 (unlikely(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;
}
/* Duplicate selinux field information. The se_rule is opaque, so must be
* re-initialized. */
static inline int audit_dupe_selinux_field(struct audit_field *df,
@ -425,8 +682,11 @@ static inline int audit_dupe_selinux_field(struct audit_field *df,
/* Duplicate an audit rule. This will be a deep copy with the exception
* of the watch - that pointer is carried over. The selinux specific fields
* will be updated in the copy. The point is to be able to replace the old
* rule with the new rule in the filterlist, then free the old rule. */
static struct audit_entry *audit_dupe_rule(struct audit_krule *old)
* rule with the new rule in the filterlist, then free the old rule.
* The rlist element is undefined; list manipulations are handled apart from
* the initial copy. */
static struct audit_entry *audit_dupe_rule(struct audit_krule *old,
struct audit_watch *watch)
{
u32 fcount = old->field_count;
struct audit_entry *entry;
@ -445,6 +705,8 @@ static struct audit_entry *audit_dupe_rule(struct audit_krule *old)
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
new->mask[i] = old->mask[i];
new->buflen = old->buflen;
new->inode_f = old->inode_f;
new->watch = NULL;
new->field_count = old->field_count;
memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
@ -466,21 +728,318 @@ static struct audit_entry *audit_dupe_rule(struct audit_krule *old)
}
}
if (watch) {
audit_get_watch(watch);
new->watch = watch;
}
return entry;
}
/* Add rule to given filterlist if not a duplicate. Protected by
* audit_netlink_mutex. */
static inline int audit_add_rule(struct audit_entry *entry,
struct list_head *list)
/* 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;
struct audit_buffer *ab;
mutex_lock(&audit_filter_mutex);
list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
if (audit_compare_dname_path(dname, owatch->path))
continue;
/* If the update involves invalidating rules, do the inode-based
* filtering now, so we don't omit records. */
if (invalidating &&
audit_filter_inodes(current, current->audit_context) == AUDIT_RECORD_CONTEXT)
audit_set_auditable(current->audit_context);
nwatch = audit_dupe_watch(owatch);
if (unlikely(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 (unlikely(IS_ERR(nentry)))
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]);
}
call_rcu(&oentry->rcu, audit_free_rule_rcu);
}
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, "audit updated rules specifying watch=");
audit_log_untrustedstring(ab, owatch->path);
audit_log_format(ab, " with dev=%u ino=%lu\n", dev, ino);
audit_log_end(ab);
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;
/* Do not use the _rcu iterator here, since this is the only
* addition routine. */
list_for_each_entry(e, list, list) {
if (!audit_compare_rule(&entry->rule, &e->rule))
return -EEXIST;
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);
list_del(&r->rlist);
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule_rcu);
audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit implicitly removed rule from list=%d\n",
AUDIT_FILTER_EXIT);
}
audit_remove_watch(w);
}
mutex_unlock(&audit_filter_mutex);
}
/* Unregister inotify watches for parents on in_list.
* Generates an IN_IGNORED event. */
static 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 put matching the get in audit_do_del_rule() */
put_inotify_watch(&p->wdata);
}
}
/* Find an existing audit rule.
* Caller must hold audit_filter_mutex to prevent stale rule data. */
static struct audit_entry *audit_find_rule(struct audit_entry *entry,
struct list_head *list)
{
struct audit_entry *e, *found = NULL;
int h;
if (entry->rule.watch) {
/* we don't know the inode number, so must walk entire hash */
for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
list = &audit_inode_hash[h];
list_for_each_entry(e, list, list)
if (!audit_compare_rule(&entry->rule, &e->rule)) {
found = e;
goto out;
}
}
goto out;
}
list_for_each_entry(e, list, list)
if (!audit_compare_rule(&entry->rule, &e->rule)) {
found = e;
goto out;
}
out:
return found;
}
/* 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_release(ndp);
kfree(ndp);
}
if (ndw) {
path_release(ndw);
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. */
static int audit_add_watch(struct audit_krule *krule, struct nameidata *ndp,
struct nameidata *ndw)
{
struct audit_watch *watch = krule->watch;
struct inotify_watch *i_watch;
struct audit_parent *parent;
int ret = 0;
/* update watch filter fields */
if (ndw) {
watch->dev = ndw->dentry->d_inode->i_sb->s_dev;
watch->ino = ndw->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.
*/
mutex_unlock(&audit_filter_mutex);
if (inotify_find_watch(audit_ih, ndp->dentry->d_inode, &i_watch) < 0) {
parent = audit_init_parent(ndp);
if (IS_ERR(parent)) {
/* caller expects mutex locked */
mutex_lock(&audit_filter_mutex);
return PTR_ERR(parent);
}
} 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);
return ret;
}
/* Add rule to given filterlist if not a duplicate. */
static inline int audit_add_rule(struct audit_entry *entry,
struct list_head *list)
{
struct audit_entry *e;
struct audit_field *inode_f = entry->rule.inode_f;
struct audit_watch *watch = entry->rule.watch;
struct nameidata *ndp, *ndw;
int h, err, putnd_needed = 0;
if (inode_f) {
h = audit_hash_ino(inode_f->val);
list = &audit_inode_hash[h];
}
mutex_lock(&audit_filter_mutex);
e = audit_find_rule(entry, list);
mutex_unlock(&audit_filter_mutex);
if (e) {
err = -EEXIST;
goto error;
}
/* Avoid calling path_lookup under audit_filter_mutex. */
if (watch) {
err = audit_get_nd(watch->path, &ndp, &ndw);
if (err)
goto error;
putnd_needed = 1;
}
mutex_lock(&audit_filter_mutex);
if (watch) {
/* audit_filter_mutex is dropped and re-taken during this call */
err = audit_add_watch(&entry->rule, ndp, ndw);
if (err) {
mutex_unlock(&audit_filter_mutex);
goto error;
}
h = audit_hash_ino((u32)watch->ino);
list = &audit_inode_hash[h];
}
if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
@ -488,27 +1047,77 @@ static inline int audit_add_rule(struct audit_entry *entry,
} else {
list_add_tail_rcu(&entry->list, list);
}
mutex_unlock(&audit_filter_mutex);
return 0;
if (putnd_needed)
audit_put_nd(ndp, ndw);
return 0;
error:
if (putnd_needed)
audit_put_nd(ndp, ndw);
if (watch)
audit_put_watch(watch); /* tmp watch, matches initial get */
return err;
}
/* Remove an existing rule from filterlist. Protected by
* audit_netlink_mutex. */
/* Remove an existing rule from filterlist. */
static inline int audit_del_rule(struct audit_entry *entry,
struct list_head *list)
{
struct audit_entry *e;
struct audit_field *inode_f = entry->rule.inode_f;
struct audit_watch *watch, *tmp_watch = entry->rule.watch;
LIST_HEAD(inotify_list);
int h, ret = 0;
/* Do not use the _rcu iterator here, since this is the only
* deletion routine. */
list_for_each_entry(e, list, list) {
if (!audit_compare_rule(&entry->rule, &e->rule)) {
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule_rcu);
return 0;
if (inode_f) {
h = audit_hash_ino(inode_f->val);
list = &audit_inode_hash[h];
}
mutex_lock(&audit_filter_mutex);
e = audit_find_rule(entry, list);
if (!e) {
mutex_unlock(&audit_filter_mutex);
ret = -ENOENT;
goto out;
}
watch = e->rule.watch;
if (watch) {
struct audit_parent *parent = watch->parent;
list_del(&e->rule.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(). */
list_add(&parent->ilist, &inotify_list);
get_inotify_watch(&parent->wdata);
}
}
}
return -ENOENT; /* No matching rule */
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule_rcu);
mutex_unlock(&audit_filter_mutex);
if (!list_empty(&inotify_list))
audit_inotify_unregister(&inotify_list);
out:
if (tmp_watch)
audit_put_watch(tmp_watch); /* match initial get */
return ret;
}
/* List rules using struct audit_rule. Exists for backward
@ -519,8 +1128,8 @@ static void audit_list(int pid, int seq, struct sk_buff_head *q)
struct audit_entry *entry;
int i;
/* The *_rcu iterators not needed here because we are
always called with audit_netlink_mutex held. */
/* This is a blocking read, so use audit_filter_mutex instead of rcu
* iterator to sync with list writers. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
list_for_each_entry(entry, &audit_filter_list[i], list) {
struct audit_rule *rule;
@ -535,6 +1144,20 @@ static void audit_list(int pid, int seq, struct sk_buff_head *q)
kfree(rule);
}
}
for (i = 0; i < AUDIT_INODE_BUCKETS; i++) {
list_for_each_entry(entry, &audit_inode_hash[i], list) {
struct audit_rule *rule;
rule = audit_krule_to_rule(&entry->rule);
if (unlikely(!rule))
break;
skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
rule, sizeof(*rule));
if (skb)
skb_queue_tail(q, skb);
kfree(rule);
}
}
skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
if (skb)
skb_queue_tail(q, skb);
@ -547,8 +1170,8 @@ static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
struct audit_entry *e;
int i;
/* The *_rcu iterators not needed here because we are
always called with audit_netlink_mutex held. */
/* This is a blocking read, so use audit_filter_mutex instead of rcu
* iterator to sync with list writers. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
list_for_each_entry(e, &audit_filter_list[i], list) {
struct audit_rule_data *data;
@ -557,7 +1180,21 @@ static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
if (unlikely(!data))
break;
skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
data, sizeof(*data));
data, sizeof(*data) + data->buflen);
if (skb)
skb_queue_tail(q, skb);
kfree(data);
}
}
for (i=0; i< AUDIT_INODE_BUCKETS; i++) {
list_for_each_entry(e, &audit_inode_hash[i], list) {
struct audit_rule_data *data;
data = audit_krule_to_data(&e->rule);
if (unlikely(!data))
break;
skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
data, sizeof(*data) + data->buflen);
if (skb)
skb_queue_tail(q, skb);
kfree(data);
@ -602,10 +1239,12 @@ int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
dest->pid = pid;
skb_queue_head_init(&dest->q);
mutex_lock(&audit_filter_mutex);
if (type == AUDIT_LIST)
audit_list(pid, seq, &dest->q);
else
audit_list_rules(pid, seq, &dest->q);
mutex_unlock(&audit_filter_mutex);
tsk = kthread_run(audit_send_list, dest, "audit_send_list");
if (IS_ERR(tsk)) {
@ -625,6 +1264,7 @@ int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
err = audit_add_rule(entry,
&audit_filter_list[entry->rule.listnr]);
if (sid) {
char *ctx = NULL;
u32 len;
@ -705,7 +1345,39 @@ int audit_comparator(const u32 left, const u32 op, const u32 right)
return 0;
}
/* Compare given dentry name with last component in given path,
* return of 0 indicates a match. */
int audit_compare_dname_path(const char *dname, const char *path)
{
int dlen, plen;
const char *p;
if (!dname || !path)
return 1;
dlen = strlen(dname);
plen = strlen(path);
if (plen < dlen)
return 1;
/* disregard trailing slashes */
p = path + plen - 1;
while ((*p == '/') && (p > path))
p--;
/* find last path component */
p = p - dlen + 1;
if (p < path)
return 1;
else if (p > path) {
if (*--p != '/')
return 1;
else
p++;
}
return strncmp(p, dname, dlen);
}
static int audit_filter_user_rules(struct netlink_skb_parms *cb,
struct audit_krule *rule,
@ -818,32 +1490,65 @@ static inline int audit_rule_has_selinux(struct audit_krule *rule)
int selinux_audit_rule_update(void)
{
struct audit_entry *entry, *n, *nentry;
struct audit_watch *watch;
int i, err = 0;
/* audit_netlink_mutex synchronizes the writers */
mutex_lock(&audit_netlink_mutex);
/* audit_filter_mutex synchronizes the writers */
mutex_lock(&audit_filter_mutex);
for (i = 0; i < AUDIT_NR_FILTERS; i++) {
list_for_each_entry_safe(entry, n, &audit_filter_list[i], list) {
if (!audit_rule_has_selinux(&entry->rule))
continue;
nentry = audit_dupe_rule(&entry->rule);
watch = entry->rule.watch;
nentry = audit_dupe_rule(&entry->rule, watch);
if (unlikely(IS_ERR(nentry))) {
/* save the first error encountered for the
* return value */
if (!err)
err = PTR_ERR(nentry);
audit_panic("error updating selinux filters");
if (watch)
list_del(&entry->rule.rlist);
list_del_rcu(&entry->list);
} else {
if (watch) {
list_add(&nentry->rule.rlist,
&watch->rules);
list_del(&entry->rule.rlist);
}
list_replace_rcu(&entry->list, &nentry->list);
}
call_rcu(&entry->rcu, audit_free_rule_rcu);
}
}
mutex_unlock(&audit_netlink_mutex);
mutex_unlock(&audit_filter_mutex);
return err;
}
/* Update watch data in audit rules based on inotify events. */
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);
}

122
kernel/auditsc.c
View file

@ -200,12 +200,13 @@ struct audit_context {
#endif
};
/* Determine if any context name data matches a rule's watch data */
/* Compare a task_struct with an audit_rule. Return 1 on match, 0
* otherwise. */
static int audit_filter_rules(struct task_struct *tsk,
struct audit_krule *rule,
struct audit_context *ctx,
struct audit_names *name,
enum audit_state *state)
{
int i, j, need_sid = 1;
@ -268,7 +269,10 @@ static int audit_filter_rules(struct task_struct *tsk,
}
break;
case AUDIT_DEVMAJOR:
if (ctx) {
if (name)
result = audit_comparator(MAJOR(name->dev),
f->op, f->val);
else if (ctx) {
for (j = 0; j < ctx->name_count; j++) {
if (audit_comparator(MAJOR(ctx->names[j].dev), f->op, f->val)) {
++result;
@ -278,7 +282,10 @@ static int audit_filter_rules(struct task_struct *tsk,
}
break;
case AUDIT_DEVMINOR:
if (ctx) {
if (name)
result = audit_comparator(MINOR(name->dev),
f->op, f->val);
else if (ctx) {
for (j = 0; j < ctx->name_count; j++) {
if (audit_comparator(MINOR(ctx->names[j].dev), f->op, f->val)) {
++result;
@ -288,7 +295,10 @@ static int audit_filter_rules(struct task_struct *tsk,
}
break;
case AUDIT_INODE:
if (ctx) {
if (name)
result = (name->ino == f->val ||
name->pino == f->val);
else if (ctx) {
for (j = 0; j < ctx->name_count; j++) {
if (audit_comparator(ctx->names[j].ino, f->op, f->val) ||
audit_comparator(ctx->names[j].pino, f->op, f->val)) {
@ -298,6 +308,12 @@ static int audit_filter_rules(struct task_struct *tsk,
}
}
break;
case AUDIT_WATCH:
if (name && rule->watch->ino != (unsigned long)-1)
result = (name->dev == rule->watch->dev &&
(name->ino == rule->watch->ino ||
name->pino == rule->watch->ino));
break;
case AUDIT_LOGINUID:
result = 0;
if (ctx)
@ -354,7 +370,7 @@ static enum audit_state audit_filter_task(struct task_struct *tsk)
rcu_read_lock();
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TASK], list) {
if (audit_filter_rules(tsk, &e->rule, NULL, &state)) {
if (audit_filter_rules(tsk, &e->rule, NULL, NULL, &state)) {
rcu_read_unlock();
return state;
}
@ -384,8 +400,9 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
int bit = AUDIT_BIT(ctx->major);
list_for_each_entry_rcu(e, list, list) {
if ((e->rule.mask[word] & bit) == bit
&& audit_filter_rules(tsk, &e->rule, ctx, &state)) {
if ((e->rule.mask[word] & bit) == bit &&
audit_filter_rules(tsk, &e->rule, ctx, NULL,
&state)) {
rcu_read_unlock();
return state;
}
@ -395,6 +412,49 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
return AUDIT_BUILD_CONTEXT;
}
/* At syscall exit time, this filter is called if any audit_names[] have been
* collected during syscall processing. We only check rules in sublists at hash
* buckets applicable to the inode numbers in audit_names[].
* Regarding audit_state, same rules apply as for audit_filter_syscall().
*/
enum audit_state audit_filter_inodes(struct task_struct *tsk,
struct audit_context *ctx)
{
int i;
struct audit_entry *e;
enum audit_state state;
if (audit_pid && tsk->tgid == audit_pid)
return AUDIT_DISABLED;
rcu_read_lock();
for (i = 0; i < ctx->name_count; i++) {
int word = AUDIT_WORD(ctx->major);
int bit = AUDIT_BIT(ctx->major);
struct audit_names *n = &ctx->names[i];
int h = audit_hash_ino((u32)n->ino);
struct list_head *list = &audit_inode_hash[h];
if (list_empty(list))
continue;
list_for_each_entry_rcu(e, list, list) {
if ((e->rule.mask[word] & bit) == bit &&
audit_filter_rules(tsk, &e->rule, ctx, n, &state)) {
rcu_read_unlock();
return state;
}
}
}
rcu_read_unlock();
return AUDIT_BUILD_CONTEXT;
}
void audit_set_auditable(struct audit_context *ctx)
{
ctx->auditable = 1;
}
static inline struct audit_context *audit_get_context(struct task_struct *tsk,
int return_valid,
int return_code)
@ -408,11 +468,20 @@ static inline struct audit_context *audit_get_context(struct task_struct *tsk,
if (context->in_syscall && !context->auditable) {
enum audit_state state;
state = audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_EXIT]);
if (state == AUDIT_RECORD_CONTEXT) {
context->auditable = 1;
goto get_context;
}
state = audit_filter_inodes(tsk, context);
if (state == AUDIT_RECORD_CONTEXT)
context->auditable = 1;
}
get_context:
context->pid = tsk->pid;
context->ppid = sys_getppid(); /* sic. tsk == current in all cases */
context->uid = tsk->uid;
@ -1142,37 +1211,20 @@ void __audit_inode_child(const char *dname, const struct inode *inode,
return;
/* determine matching parent */
if (dname)
for (idx = 0; idx < context->name_count; idx++)
if (context->names[idx].pino == pino) {
const char *n;
const char *name = context->names[idx].name;
int dlen = strlen(dname);
int nlen = name ? strlen(name) : 0;
if (!dname)
goto no_match;
for (idx = 0; idx < context->name_count; idx++)
if (context->names[idx].pino == pino) {
const char *name = context->names[idx].name;
if (nlen < dlen)
continue;
/* disregard trailing slashes */
n = name + nlen - 1;
while ((*n == '/') && (n > name))
n--;
if (!name)
continue;
/* find last path component */
n = n - dlen + 1;
if (n < name)
continue;
else if (n > name) {
if (*--n != '/')
continue;
else
n++;
}
if (strncmp(n, dname, dlen) == 0)
goto update_context;
}
if (audit_compare_dname_path(dname, name) == 0)
goto update_context;
}
no_match:
/* catch-all in case match not found */
idx = context->name_count++;
context->names[idx].name = NULL;