linux/kernel/auditfilter.c
Linus Torvalds c4cc75c332 Merge git://git.infradead.org/users/eparis/audit
Pull audit changes from Eric Paris:
 "Al used to send pull requests every couple of years but he told me to
  just start pushing them to you directly.

  Our touching outside of core audit code is pretty straight forward.  A
  couple of interface changes which hit net/.  A simple argument bug
  calling audit functions in namei.c and the removal of some assembly
  branch prediction code on ppc"

* git://git.infradead.org/users/eparis/audit: (31 commits)
  audit: fix message spacing printing auid
  Revert "audit: move kaudit thread start from auditd registration to kaudit init"
  audit: vfs: fix audit_inode call in O_CREAT case of do_last
  audit: Make testing for a valid loginuid explicit.
  audit: fix event coverage of AUDIT_ANOM_LINK
  audit: use spin_lock in audit_receive_msg to process tty logging
  audit: do not needlessly take a lock in tty_audit_exit
  audit: do not needlessly take a spinlock in copy_signal
  audit: add an option to control logging of passwords with pam_tty_audit
  audit: use spin_lock_irqsave/restore in audit tty code
  helper for some session id stuff
  audit: use a consistent audit helper to log lsm information
  audit: push loginuid and sessionid processing down
  audit: stop pushing loginid, uid, sessionid as arguments
  audit: remove the old depricated kernel interface
  audit: make validity checking generic
  audit: allow checking the type of audit message in the user filter
  audit: fix build break when AUDIT_DEBUG == 2
  audit: remove duplicate export of audit_enabled
  Audit: do not print error when LSMs disabled
  ...
2013-05-11 14:29:11 -07:00

1372 lines
33 KiB
C

/* auditfilter.c -- filtering of audit events
*
* Copyright 2003-2004 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/security.h>
#include "audit.h"
/*
* 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
* LSM 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.
*/
/* 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]),
LIST_HEAD_INIT(audit_filter_list[2]),
LIST_HEAD_INIT(audit_filter_list[3]),
LIST_HEAD_INIT(audit_filter_list[4]),
LIST_HEAD_INIT(audit_filter_list[5]),
#if AUDIT_NR_FILTERS != 6
#error Fix audit_filter_list initialiser
#endif
};
static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
LIST_HEAD_INIT(audit_rules_list[0]),
LIST_HEAD_INIT(audit_rules_list[1]),
LIST_HEAD_INIT(audit_rules_list[2]),
LIST_HEAD_INIT(audit_rules_list[3]),
LIST_HEAD_INIT(audit_rules_list[4]),
LIST_HEAD_INIT(audit_rules_list[5]),
};
DEFINE_MUTEX(audit_filter_mutex);
static inline void audit_free_rule(struct audit_entry *e)
{
int i;
struct audit_krule *erule = &e->rule;
/* some rules don't have associated watches */
if (erule->watch)
audit_put_watch(erule->watch);
if (erule->fields)
for (i = 0; i < erule->field_count; i++) {
struct audit_field *f = &erule->fields[i];
kfree(f->lsm_str);
security_audit_rule_free(f->lsm_rule);
}
kfree(erule->fields);
kfree(erule->filterkey);
kfree(e);
}
void audit_free_rule_rcu(struct rcu_head *head)
{
struct audit_entry *e = container_of(head, struct audit_entry, rcu);
audit_free_rule(e);
}
/* Initialize an audit filterlist entry. */
static inline struct audit_entry *audit_init_entry(u32 field_count)
{
struct audit_entry *entry;
struct audit_field *fields;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (unlikely(!entry))
return NULL;
fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
if (unlikely(!fields)) {
kfree(entry);
return NULL;
}
entry->rule.fields = fields;
return entry;
}
/* Unpack a filter field's string representation from user-space
* buffer. */
char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
{
char *str;
if (!*bufp || (len == 0) || (len > *remain))
return ERR_PTR(-EINVAL);
/* Of the currently implemented string fields, PATH_MAX
* defines the longest valid length.
*/
if (len > PATH_MAX)
return ERR_PTR(-ENAMETOOLONG);
str = kmalloc(len + 1, GFP_KERNEL);
if (unlikely(!str))
return ERR_PTR(-ENOMEM);
memcpy(str, *bufp, len);
str[len] = 0;
*bufp += len;
*remain -= 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 || krule->tree ||
(f->op != Audit_equal && f->op != Audit_not_equal))
return -EINVAL;
krule->inode_f = f;
return 0;
}
static __u32 *classes[AUDIT_SYSCALL_CLASSES];
int __init audit_register_class(int class, unsigned *list)
{
__u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
if (!p)
return -ENOMEM;
while (*list != ~0U) {
unsigned n = *list++;
if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
kfree(p);
return -EINVAL;
}
p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
}
if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
kfree(p);
return -EINVAL;
}
classes[class] = p;
return 0;
}
int audit_match_class(int class, unsigned syscall)
{
if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
return 0;
if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
return 0;
return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
}
#ifdef CONFIG_AUDITSYSCALL
static inline int audit_match_class_bits(int class, u32 *mask)
{
int i;
if (classes[class]) {
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
if (mask[i] & classes[class][i])
return 0;
}
return 1;
}
static int audit_match_signal(struct audit_entry *entry)
{
struct audit_field *arch = entry->rule.arch_f;
if (!arch) {
/* When arch is unspecified, we must check both masks on biarch
* as syscall number alone is ambiguous. */
return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
entry->rule.mask) &&
audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
entry->rule.mask));
}
switch(audit_classify_arch(arch->val)) {
case 0: /* native */
return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
entry->rule.mask));
case 1: /* 32bit on biarch */
return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
entry->rule.mask));
default:
return 1;
}
}
#endif
/* Common user-space to kernel rule translation. */
static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
{
unsigned listnr;
struct audit_entry *entry;
int i, err;
err = -EINVAL;
listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
switch(listnr) {
default:
goto exit_err;
#ifdef CONFIG_AUDITSYSCALL
case AUDIT_FILTER_ENTRY:
if (rule->action == AUDIT_ALWAYS)
goto exit_err;
case AUDIT_FILTER_EXIT:
case AUDIT_FILTER_TASK:
#endif
case AUDIT_FILTER_USER:
case AUDIT_FILTER_TYPE:
;
}
if (unlikely(rule->action == AUDIT_POSSIBLE)) {
printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n");
goto exit_err;
}
if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
goto exit_err;
if (rule->field_count > AUDIT_MAX_FIELDS)
goto exit_err;
err = -ENOMEM;
entry = audit_init_entry(rule->field_count);
if (!entry)
goto exit_err;
entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
entry->rule.listnr = listnr;
entry->rule.action = rule->action;
entry->rule.field_count = rule->field_count;
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
entry->rule.mask[i] = rule->mask[i];
for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
__u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
__u32 *class;
if (!(*p & AUDIT_BIT(bit)))
continue;
*p &= ~AUDIT_BIT(bit);
class = classes[i];
if (class) {
int j;
for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
entry->rule.mask[j] |= class[j];
}
}
return entry;
exit_err:
return ERR_PTR(err);
}
static u32 audit_ops[] =
{
[Audit_equal] = AUDIT_EQUAL,
[Audit_not_equal] = AUDIT_NOT_EQUAL,
[Audit_bitmask] = AUDIT_BIT_MASK,
[Audit_bittest] = AUDIT_BIT_TEST,
[Audit_lt] = AUDIT_LESS_THAN,
[Audit_gt] = AUDIT_GREATER_THAN,
[Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
[Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
};
static u32 audit_to_op(u32 op)
{
u32 n;
for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
;
return n;
}
/* check if an audit field is valid */
static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
{
switch(f->type) {
case AUDIT_MSGTYPE:
if (entry->rule.listnr != AUDIT_FILTER_TYPE &&
entry->rule.listnr != AUDIT_FILTER_USER)
return -EINVAL;
break;
};
switch(f->type) {
default:
return -EINVAL;
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_LOGINUID:
case AUDIT_OBJ_UID:
case AUDIT_GID:
case AUDIT_EGID:
case AUDIT_SGID:
case AUDIT_FSGID:
case AUDIT_OBJ_GID:
case AUDIT_PID:
case AUDIT_PERS:
case AUDIT_MSGTYPE:
case AUDIT_PPID:
case AUDIT_DEVMAJOR:
case AUDIT_DEVMINOR:
case AUDIT_EXIT:
case AUDIT_SUCCESS:
/* bit ops are only useful on syscall args */
if (f->op == Audit_bitmask || f->op == Audit_bittest)
return -EINVAL;
break;
case AUDIT_ARG0:
case AUDIT_ARG1:
case AUDIT_ARG2:
case AUDIT_ARG3:
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
case AUDIT_OBJ_USER:
case AUDIT_OBJ_ROLE:
case AUDIT_OBJ_TYPE:
case AUDIT_OBJ_LEV_LOW:
case AUDIT_OBJ_LEV_HIGH:
case AUDIT_WATCH:
case AUDIT_DIR:
case AUDIT_FILTERKEY:
break;
case AUDIT_LOGINUID_SET:
if ((f->val != 0) && (f->val != 1))
return -EINVAL;
/* FALL THROUGH */
case AUDIT_ARCH:
if (f->op != Audit_not_equal && f->op != Audit_equal)
return -EINVAL;
break;
case AUDIT_PERM:
if (f->val & ~15)
return -EINVAL;
break;
case AUDIT_FILETYPE:
if (f->val & ~S_IFMT)
return -EINVAL;
break;
case AUDIT_FIELD_COMPARE:
if (f->val > AUDIT_MAX_FIELD_COMPARE)
return -EINVAL;
break;
};
return 0;
}
/* Translate struct audit_rule_data to kernel's rule respresentation. */
static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
size_t datasz)
{
int err = 0;
struct audit_entry *entry;
void *bufp;
size_t remain = datasz - sizeof(struct audit_rule_data);
int i;
char *str;
entry = audit_to_entry_common((struct audit_rule *)data);
if (IS_ERR(entry))
goto exit_nofree;
bufp = data->buf;
entry->rule.vers_ops = 2;
for (i = 0; i < data->field_count; i++) {
struct audit_field *f = &entry->rule.fields[i];
err = -EINVAL;
f->op = audit_to_op(data->fieldflags[i]);
if (f->op == Audit_bad)
goto exit_free;
f->type = data->fields[i];
f->val = data->values[i];
f->uid = INVALID_UID;
f->gid = INVALID_GID;
f->lsm_str = NULL;
f->lsm_rule = NULL;
/* Support legacy tests for a valid loginuid */
if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) {
f->type = AUDIT_LOGINUID_SET;
f->val = 0;
}
err = audit_field_valid(entry, f);
if (err)
goto exit_free;
err = -EINVAL;
switch (f->type) {
case AUDIT_LOGINUID:
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_OBJ_UID:
f->uid = make_kuid(current_user_ns(), f->val);
if (!uid_valid(f->uid))
goto exit_free;
break;
case AUDIT_GID:
case AUDIT_EGID:
case AUDIT_SGID:
case AUDIT_FSGID:
case AUDIT_OBJ_GID:
f->gid = make_kgid(current_user_ns(), f->val);
if (!gid_valid(f->gid))
goto exit_free;
break;
case AUDIT_ARCH:
entry->rule.arch_f = f;
break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
case AUDIT_OBJ_USER:
case AUDIT_OBJ_ROLE:
case AUDIT_OBJ_TYPE:
case AUDIT_OBJ_LEV_LOW:
case AUDIT_OBJ_LEV_HIGH:
str = audit_unpack_string(&bufp, &remain, f->val);
if (IS_ERR(str))
goto exit_free;
entry->rule.buflen += f->val;
err = security_audit_rule_init(f->type, f->op, str,
(void **)&f->lsm_rule);
/* Keep currently invalid fields around in case they
* become valid after a policy reload. */
if (err == -EINVAL) {
printk(KERN_WARNING "audit rule for LSM "
"\'%s\' is invalid\n", str);
err = 0;
}
if (err) {
kfree(str);
goto exit_free;
} else
f->lsm_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_DIR:
str = audit_unpack_string(&bufp, &remain, f->val);
if (IS_ERR(str))
goto exit_free;
entry->rule.buflen += f->val;
err = audit_make_tree(&entry->rule, str, f->op);
kfree(str);
if (err)
goto exit_free;
break;
case AUDIT_INODE:
err = audit_to_inode(&entry->rule, f);
if (err)
goto exit_free;
break;
case AUDIT_FILTERKEY:
if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
goto exit_free;
str = audit_unpack_string(&bufp, &remain, f->val);
if (IS_ERR(str))
goto exit_free;
entry->rule.buflen += f->val;
entry->rule.filterkey = str;
break;
}
}
if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
entry->rule.inode_f = NULL;
exit_nofree:
return entry;
exit_free:
if (entry->rule.watch)
audit_put_watch(entry->rule.watch); /* matches initial get */
if (entry->rule.tree)
audit_put_tree(entry->rule.tree); /* that's the temporary one */
audit_free_rule(entry);
return ERR_PTR(err);
}
/* Pack a filter field's string representation into data block. */
static inline size_t audit_pack_string(void **bufp, const char *str)
{
size_t len = strlen(str);
memcpy(*bufp, str, len);
*bufp += len;
return len;
}
/* Translate kernel rule respresentation to struct audit_rule_data. */
static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
{
struct audit_rule_data *data;
void *bufp;
int i;
data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
if (unlikely(!data))
return NULL;
memset(data, 0, sizeof(*data));
data->flags = krule->flags | krule->listnr;
data->action = krule->action;
data->field_count = krule->field_count;
bufp = data->buf;
for (i = 0; i < data->field_count; i++) {
struct audit_field *f = &krule->fields[i];
data->fields[i] = f->type;
data->fieldflags[i] = audit_ops[f->op];
switch(f->type) {
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
case AUDIT_OBJ_USER:
case AUDIT_OBJ_ROLE:
case AUDIT_OBJ_TYPE:
case AUDIT_OBJ_LEV_LOW:
case AUDIT_OBJ_LEV_HIGH:
data->buflen += data->values[i] =
audit_pack_string(&bufp, f->lsm_str);
break;
case AUDIT_WATCH:
data->buflen += data->values[i] =
audit_pack_string(&bufp,
audit_watch_path(krule->watch));
break;
case AUDIT_DIR:
data->buflen += data->values[i] =
audit_pack_string(&bufp,
audit_tree_path(krule->tree));
break;
case AUDIT_FILTERKEY:
data->buflen += data->values[i] =
audit_pack_string(&bufp, krule->filterkey);
break;
default:
data->values[i] = f->val;
}
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
return data;
}
/* Compare two rules in kernel format. Considered success if rules
* don't match. */
static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
{
int i;
if (a->flags != b->flags ||
a->listnr != b->listnr ||
a->action != b->action ||
a->field_count != b->field_count)
return 1;
for (i = 0; i < a->field_count; i++) {
if (a->fields[i].type != b->fields[i].type ||
a->fields[i].op != b->fields[i].op)
return 1;
switch(a->fields[i].type) {
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
case AUDIT_OBJ_USER:
case AUDIT_OBJ_ROLE:
case AUDIT_OBJ_TYPE:
case AUDIT_OBJ_LEV_LOW:
case AUDIT_OBJ_LEV_HIGH:
if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
return 1;
break;
case AUDIT_WATCH:
if (strcmp(audit_watch_path(a->watch),
audit_watch_path(b->watch)))
return 1;
break;
case AUDIT_DIR:
if (strcmp(audit_tree_path(a->tree),
audit_tree_path(b->tree)))
return 1;
break;
case AUDIT_FILTERKEY:
/* both filterkeys exist based on above type compare */
if (strcmp(a->filterkey, b->filterkey))
return 1;
break;
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_LOGINUID:
case AUDIT_OBJ_UID:
if (!uid_eq(a->fields[i].uid, b->fields[i].uid))
return 1;
break;
case AUDIT_GID:
case AUDIT_EGID:
case AUDIT_SGID:
case AUDIT_FSGID:
case AUDIT_OBJ_GID:
if (!gid_eq(a->fields[i].gid, b->fields[i].gid))
return 1;
break;
default:
if (a->fields[i].val != b->fields[i].val)
return 1;
}
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
if (a->mask[i] != b->mask[i])
return 1;
return 0;
}
/* Duplicate LSM field information. The lsm_rule is opaque, so must be
* re-initialized. */
static inline int audit_dupe_lsm_field(struct audit_field *df,
struct audit_field *sf)
{
int ret = 0;
char *lsm_str;
/* our own copy of lsm_str */
lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
if (unlikely(!lsm_str))
return -ENOMEM;
df->lsm_str = lsm_str;
/* our own (refreshed) copy of lsm_rule */
ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
(void **)&df->lsm_rule);
/* Keep currently invalid fields around in case they
* become valid after a policy reload. */
if (ret == -EINVAL) {
printk(KERN_WARNING "audit rule for LSM \'%s\' is "
"invalid\n", df->lsm_str);
ret = 0;
}
return ret;
}
/* Duplicate an audit rule. This will be a deep copy with the exception
* of the watch - that pointer is carried over. The LSM 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.
* The rlist element is undefined; list manipulations are handled apart from
* the initial copy. */
struct audit_entry *audit_dupe_rule(struct audit_krule *old)
{
u32 fcount = old->field_count;
struct audit_entry *entry;
struct audit_krule *new;
char *fk;
int i, err = 0;
entry = audit_init_entry(fcount);
if (unlikely(!entry))
return ERR_PTR(-ENOMEM);
new = &entry->rule;
new->vers_ops = old->vers_ops;
new->flags = old->flags;
new->listnr = old->listnr;
new->action = old->action;
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
new->mask[i] = old->mask[i];
new->prio = old->prio;
new->buflen = old->buflen;
new->inode_f = old->inode_f;
new->field_count = old->field_count;
/*
* note that we are OK with not refcounting here; audit_match_tree()
* never dereferences tree and we can't get false positives there
* since we'd have to have rule gone from the list *and* removed
* before the chunks found by lookup had been allocated, i.e. before
* the beginning of list scan.
*/
new->tree = old->tree;
memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
/* deep copy this information, updating the lsm_rule fields, because
* the originals will all be freed when the old rule is freed. */
for (i = 0; i < fcount; i++) {
switch (new->fields[i].type) {
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
case AUDIT_OBJ_USER:
case AUDIT_OBJ_ROLE:
case AUDIT_OBJ_TYPE:
case AUDIT_OBJ_LEV_LOW:
case AUDIT_OBJ_LEV_HIGH:
err = audit_dupe_lsm_field(&new->fields[i],
&old->fields[i]);
break;
case AUDIT_FILTERKEY:
fk = kstrdup(old->filterkey, GFP_KERNEL);
if (unlikely(!fk))
err = -ENOMEM;
else
new->filterkey = fk;
}
if (err) {
audit_free_rule(entry);
return ERR_PTR(err);
}
}
if (old->watch) {
audit_get_watch(old->watch);
new->watch = old->watch;
}
return entry;
}
/* 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 **p)
{
struct audit_entry *e, *found = NULL;
struct list_head *list;
int h;
if (entry->rule.inode_f) {
h = audit_hash_ino(entry->rule.inode_f->val);
*p = list = &audit_inode_hash[h];
} else 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;
} else {
*p = list = &audit_filter_list[entry->rule.listnr];
}
list_for_each_entry(e, list, list)
if (!audit_compare_rule(&entry->rule, &e->rule)) {
found = e;
goto out;
}
out:
return found;
}
static u64 prio_low = ~0ULL/2;
static u64 prio_high = ~0ULL/2 - 1;
/* Add rule to given filterlist if not a duplicate. */
static inline int audit_add_rule(struct audit_entry *entry)
{
struct audit_entry *e;
struct audit_watch *watch = entry->rule.watch;
struct audit_tree *tree = entry->rule.tree;
struct list_head *list;
int err;
#ifdef CONFIG_AUDITSYSCALL
int dont_count = 0;
/* If either of these, don't count towards total */
if (entry->rule.listnr == AUDIT_FILTER_USER ||
entry->rule.listnr == AUDIT_FILTER_TYPE)
dont_count = 1;
#endif
mutex_lock(&audit_filter_mutex);
e = audit_find_rule(entry, &list);
if (e) {
mutex_unlock(&audit_filter_mutex);
err = -EEXIST;
/* normally audit_add_tree_rule() will free it on failure */
if (tree)
audit_put_tree(tree);
goto error;
}
if (watch) {
/* audit_filter_mutex is dropped and re-taken during this call */
err = audit_add_watch(&entry->rule, &list);
if (err) {
mutex_unlock(&audit_filter_mutex);
goto error;
}
}
if (tree) {
err = audit_add_tree_rule(&entry->rule);
if (err) {
mutex_unlock(&audit_filter_mutex);
goto error;
}
}
entry->rule.prio = ~0ULL;
if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
if (entry->rule.flags & AUDIT_FILTER_PREPEND)
entry->rule.prio = ++prio_high;
else
entry->rule.prio = --prio_low;
}
if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
list_add(&entry->rule.list,
&audit_rules_list[entry->rule.listnr]);
list_add_rcu(&entry->list, list);
entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
} else {
list_add_tail(&entry->rule.list,
&audit_rules_list[entry->rule.listnr]);
list_add_tail_rcu(&entry->list, list);
}
#ifdef CONFIG_AUDITSYSCALL
if (!dont_count)
audit_n_rules++;
if (!audit_match_signal(entry))
audit_signals++;
#endif
mutex_unlock(&audit_filter_mutex);
return 0;
error:
if (watch)
audit_put_watch(watch); /* tmp watch, matches initial get */
return err;
}
/* Remove an existing rule from filterlist. */
static inline int audit_del_rule(struct audit_entry *entry)
{
struct audit_entry *e;
struct audit_watch *watch = entry->rule.watch;
struct audit_tree *tree = entry->rule.tree;
struct list_head *list;
int ret = 0;
#ifdef CONFIG_AUDITSYSCALL
int dont_count = 0;
/* If either of these, don't count towards total */
if (entry->rule.listnr == AUDIT_FILTER_USER ||
entry->rule.listnr == AUDIT_FILTER_TYPE)
dont_count = 1;
#endif
mutex_lock(&audit_filter_mutex);
e = audit_find_rule(entry, &list);
if (!e) {
mutex_unlock(&audit_filter_mutex);
ret = -ENOENT;
goto out;
}
if (e->rule.watch)
audit_remove_watch_rule(&e->rule);
if (e->rule.tree)
audit_remove_tree_rule(&e->rule);
list_del_rcu(&e->list);
list_del(&e->rule.list);
call_rcu(&e->rcu, audit_free_rule_rcu);
#ifdef CONFIG_AUDITSYSCALL
if (!dont_count)
audit_n_rules--;
if (!audit_match_signal(entry))
audit_signals--;
#endif
mutex_unlock(&audit_filter_mutex);
out:
if (watch)
audit_put_watch(watch); /* match initial get */
if (tree)
audit_put_tree(tree); /* that's the temporary one */
return ret;
}
/* List rules using struct audit_rule_data. */
static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
{
struct sk_buff *skb;
struct audit_krule *r;
int i;
/* 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(r, &audit_rules_list[i], list) {
struct audit_rule_data *data;
data = audit_krule_to_data(r);
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);
}
}
skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
if (skb)
skb_queue_tail(q, skb);
}
/* Log rule additions and removals */
static void audit_log_rule_change(char *action, struct audit_krule *rule, int res)
{
struct audit_buffer *ab;
uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));
u32 sessionid = audit_get_sessionid(current);
if (!audit_enabled)
return;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
if (!ab)
return;
audit_log_format(ab, "auid=%u ses=%u" ,loginuid, sessionid);
audit_log_task_context(ab);
audit_log_format(ab, " op=");
audit_log_string(ab, action);
audit_log_key(ab, rule->filterkey);
audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
audit_log_end(ab);
}
/**
* audit_receive_filter - apply all rules to the specified message type
* @type: audit message type
* @pid: target pid for netlink audit messages
* @seq: netlink audit message sequence (serial) number
* @data: payload data
* @datasz: size of payload data
* @loginuid: loginuid of sender
* @sessionid: sessionid for netlink audit message
* @sid: SE Linux Security ID of sender
*/
int audit_receive_filter(int type, int pid, int seq, void *data, size_t datasz)
{
struct task_struct *tsk;
struct audit_netlink_list *dest;
int err = 0;
struct audit_entry *entry;
switch (type) {
case AUDIT_LIST_RULES:
/* We can't just spew out the rules here because we might fill
* the available socket buffer space and deadlock waiting for
* auditctl to read from it... which isn't ever going to
* happen if we're actually running in the context of auditctl
* trying to _send_ the stuff */
dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
if (!dest)
return -ENOMEM;
dest->pid = pid;
skb_queue_head_init(&dest->q);
mutex_lock(&audit_filter_mutex);
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)) {
skb_queue_purge(&dest->q);
kfree(dest);
err = PTR_ERR(tsk);
}
break;
case AUDIT_ADD_RULE:
entry = audit_data_to_entry(data, datasz);
if (IS_ERR(entry))
return PTR_ERR(entry);
err = audit_add_rule(entry);
audit_log_rule_change("add rule", &entry->rule, !err);
if (err)
audit_free_rule(entry);
break;
case AUDIT_DEL_RULE:
entry = audit_data_to_entry(data, datasz);
if (IS_ERR(entry))
return PTR_ERR(entry);
err = audit_del_rule(entry);
audit_log_rule_change("remove rule", &entry->rule, !err);
audit_free_rule(entry);
break;
default:
return -EINVAL;
}
return err;
}
int audit_comparator(u32 left, u32 op, u32 right)
{
switch (op) {
case Audit_equal:
return (left == right);
case Audit_not_equal:
return (left != right);
case Audit_lt:
return (left < right);
case Audit_le:
return (left <= right);
case Audit_gt:
return (left > right);
case Audit_ge:
return (left >= right);
case Audit_bitmask:
return (left & right);
case Audit_bittest:
return ((left & right) == right);
default:
BUG();
return 0;
}
}
int audit_uid_comparator(kuid_t left, u32 op, kuid_t right)
{
switch (op) {
case Audit_equal:
return uid_eq(left, right);
case Audit_not_equal:
return !uid_eq(left, right);
case Audit_lt:
return uid_lt(left, right);
case Audit_le:
return uid_lte(left, right);
case Audit_gt:
return uid_gt(left, right);
case Audit_ge:
return uid_gte(left, right);
case Audit_bitmask:
case Audit_bittest:
default:
BUG();
return 0;
}
}
int audit_gid_comparator(kgid_t left, u32 op, kgid_t right)
{
switch (op) {
case Audit_equal:
return gid_eq(left, right);
case Audit_not_equal:
return !gid_eq(left, right);
case Audit_lt:
return gid_lt(left, right);
case Audit_le:
return gid_lte(left, right);
case Audit_gt:
return gid_gt(left, right);
case Audit_ge:
return gid_gte(left, right);
case Audit_bitmask:
case Audit_bittest:
default:
BUG();
return 0;
}
}
/**
* parent_len - find the length of the parent portion of a pathname
* @path: pathname of which to determine length
*/
int parent_len(const char *path)
{
int plen;
const char *p;
plen = strlen(path);
if (plen == 0)
return plen;
/* disregard trailing slashes */
p = path + plen - 1;
while ((*p == '/') && (p > path))
p--;
/* walk backward until we find the next slash or hit beginning */
while ((*p != '/') && (p > path))
p--;
/* did we find a slash? Then increment to include it in path */
if (*p == '/')
p++;
return p - path;
}
/**
* audit_compare_dname_path - compare given dentry name with last component in
* given path. Return of 0 indicates a match.
* @dname: dentry name that we're comparing
* @path: full pathname that we're comparing
* @parentlen: length of the parent if known. Passing in AUDIT_NAME_FULL
* here indicates that we must compute this value.
*/
int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
{
int dlen, pathlen;
const char *p;
dlen = strlen(dname);
pathlen = strlen(path);
if (pathlen < dlen)
return 1;
parentlen = parentlen == AUDIT_NAME_FULL ? parent_len(path) : parentlen;
if (pathlen - parentlen != dlen)
return 1;
p = path + parentlen;
return strncmp(p, dname, dlen);
}
static int audit_filter_user_rules(struct audit_krule *rule, int type,
enum audit_state *state)
{
int i;
for (i = 0; i < rule->field_count; i++) {
struct audit_field *f = &rule->fields[i];
int result = 0;
u32 sid;
switch (f->type) {
case AUDIT_PID:
result = audit_comparator(task_pid_vnr(current), f->op, f->val);
break;
case AUDIT_UID:
result = audit_uid_comparator(current_uid(), f->op, f->uid);
break;
case AUDIT_GID:
result = audit_gid_comparator(current_gid(), f->op, f->gid);
break;
case AUDIT_LOGINUID:
result = audit_uid_comparator(audit_get_loginuid(current),
f->op, f->uid);
break;
case AUDIT_LOGINUID_SET:
result = audit_comparator(audit_loginuid_set(current),
f->op, f->val);
break;
case AUDIT_MSGTYPE:
result = audit_comparator(type, f->op, f->val);
break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
if (f->lsm_rule) {
security_task_getsecid(current, &sid);
result = security_audit_rule_match(sid,
f->type,
f->op,
f->lsm_rule,
NULL);
}
break;
}
if (!result)
return 0;
}
switch (rule->action) {
case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
}
return 1;
}
int audit_filter_user(int type)
{
enum audit_state state = AUDIT_DISABLED;
struct audit_entry *e;
int ret = 1;
rcu_read_lock();
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
if (audit_filter_user_rules(&e->rule, type, &state)) {
if (state == AUDIT_DISABLED)
ret = 0;
break;
}
}
rcu_read_unlock();
return ret; /* Audit by default */
}
int audit_filter_type(int type)
{
struct audit_entry *e;
int result = 0;
rcu_read_lock();
if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
goto unlock_and_return;
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
list) {
int i;
for (i = 0; i < e->rule.field_count; i++) {
struct audit_field *f = &e->rule.fields[i];
if (f->type == AUDIT_MSGTYPE) {
result = audit_comparator(type, f->op, f->val);
if (!result)
break;
}
}
if (result)
goto unlock_and_return;
}
unlock_and_return:
rcu_read_unlock();
return result;
}
static int update_lsm_rule(struct audit_krule *r)
{
struct audit_entry *entry = container_of(r, struct audit_entry, rule);
struct audit_entry *nentry;
int err = 0;
if (!security_audit_rule_known(r))
return 0;
nentry = audit_dupe_rule(r);
if (IS_ERR(nentry)) {
/* save the first error encountered for the
* return value */
err = PTR_ERR(nentry);
audit_panic("error updating LSM filters");
if (r->watch)
list_del(&r->rlist);
list_del_rcu(&entry->list);
list_del(&r->list);
} else {
if (r->watch || r->tree)
list_replace_init(&r->rlist, &nentry->rule.rlist);
list_replace_rcu(&entry->list, &nentry->list);
list_replace(&r->list, &nentry->rule.list);
}
call_rcu(&entry->rcu, audit_free_rule_rcu);
return err;
}
/* This function will re-initialize the lsm_rule field of all applicable rules.
* It will traverse the filter lists serarching for rules that contain LSM
* specific filter fields. When such a rule is found, it is copied, the
* LSM field is re-initialized, and the old rule is replaced with the
* updated rule. */
int audit_update_lsm_rules(void)
{
struct audit_krule *r, *n;
int i, err = 0;
/* audit_filter_mutex synchronizes the writers */
mutex_lock(&audit_filter_mutex);
for (i = 0; i < AUDIT_NR_FILTERS; i++) {
list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
int res = update_lsm_rule(r);
if (!err)
err = res;
}
}
mutex_unlock(&audit_filter_mutex);
return err;
}