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/* 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;
}


/* Translate struct audit_rule to kernel's rule respresentation.
* Exists for backward compatibility with userspace. */
static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
{
struct audit_entry *entry;
int err = 0;
int i;

entry = audit_to_entry_common(rule);
if (IS_ERR(entry))
goto exit_nofree;

for (i = 0; i < rule->field_count; i++) {
struct audit_field *f = &entry->rule.fields[i];
u32 n;

n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);

/* Support for legacy operators where
* AUDIT_NEGATE bit signifies != and otherwise assumes == */
if (n & AUDIT_NEGATE)
f->op = Audit_not_equal;
else if (!n)
f->op = Audit_equal;
else
f->op = audit_to_op(n);

entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1;

f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
f->val = rule->values[i];

err = -EINVAL;
if (f->op == Audit_bad)
goto exit_free;

switch(f->type) {
default:
goto exit_free;
case AUDIT_PID:
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_GID:
case AUDIT_EGID:
case AUDIT_SGID:
case AUDIT_FSGID:
case AUDIT_LOGINUID:
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)
goto exit_free;
break;
case AUDIT_ARG0:
case AUDIT_ARG1:
case AUDIT_ARG2:
case AUDIT_ARG3:
break;
/* arch is only allowed to be = or != */
case AUDIT_ARCH:
if (f->op != Audit_not_equal && f->op != Audit_equal)
goto exit_free;
entry->rule.arch_f = f;
break;
case AUDIT_PERM:
if (f->val & ~15)
goto exit_free;
break;
case AUDIT_FILETYPE:
if (f->val & ~S_IFMT)
goto exit_free;
break;
case AUDIT_INODE:
err = audit_to_inode(&entry->rule, f);
if (err)
goto exit_free;
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:
audit_free_rule(entry);
return ERR_PTR(err);
}

/* 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->lsm_str = NULL;
f->lsm_rule = NULL;
switch(f->type) {
case AUDIT_PID:
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_GID:
case AUDIT_EGID:
case AUDIT_SGID:
case AUDIT_FSGID:
case AUDIT_LOGINUID:
case AUDIT_PERS:
case AUDIT_MSGTYPE:
case AUDIT_PPID:
case AUDIT_DEVMAJOR:
case AUDIT_DEVMINOR:
case AUDIT_EXIT:
case AUDIT_SUCCESS:
case AUDIT_ARG0:
case AUDIT_ARG1:
case AUDIT_ARG2:
case AUDIT_ARG3:
case AUDIT_OBJ_UID:
case AUDIT_OBJ_GID:
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;
case AUDIT_PERM:
if (f->val & ~15)
goto exit_free;
break;
case AUDIT_FILETYPE:
if (f->val & ~S_IFMT)
goto exit_free;
break;
case AUDIT_FIELD_COMPARE:
if (f->val > AUDIT_MAX_FIELD_COMPARE)
goto exit_free;
break;
default:
goto exit_free;
}
}

if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
entry->rule.inode_f = NULL;

exit_nofree:
return entry;

exit_free:
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.
* Exists for backward compatibility with userspace. */
static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
{
struct audit_rule *rule;
int i;

rule = kzalloc(sizeof(*rule), GFP_KERNEL);
if (unlikely(!rule))
return NULL;

rule->flags = krule->flags | krule->listnr;
rule->action = krule->action;
rule->field_count = krule->field_count;
for (i = 0; i < rule->field_count; i++) {
rule->values[i] = krule->fields[i].val;
rule->fields[i] = krule->fields[i].type;

if (krule->vers_ops == 1) {
if (krule->fields[i].op == Audit_not_equal)
rule->fields[i] |= AUDIT_NEGATE;
} else {
rule->fields[i] |= audit_ops[krule->fields[i].op];
}
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];

return rule;
}

/* 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;
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. Exists for backward
* compatibility with userspace. */
static void audit_list(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 *rule;

rule = audit_krule_to_rule(r);
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);
}

/* 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(uid_t loginuid, u32 sessionid, u32 sid,
char *action, struct audit_krule *rule,
int res)
{
struct audit_buffer *ab;

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);
if (sid) {
char *ctx = NULL;
u32 len;
if (security_secid_to_secctx(sid, &ctx, &len))
audit_log_format(ab, " ssid=%u", sid);
else {
audit_log_format(ab, " subj=%s", ctx);
security_release_secctx(ctx, len);
}
}
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
* @uid: target uid 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 uid, int seq, void *data,
size_t datasz, uid_t loginuid, u32 sessionid, u32 sid)
{
struct task_struct *tsk;
struct audit_netlink_list *dest;
int err = 0;
struct audit_entry *entry;

switch (type) {
case AUDIT_LIST:
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);
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)) {
skb_queue_purge(&dest->q);
kfree(dest);
err = PTR_ERR(tsk);
}
break;
case AUDIT_ADD:
case AUDIT_ADD_RULE:
if (type == AUDIT_ADD)
entry = audit_rule_to_entry(data);
else
entry = audit_data_to_entry(data, datasz);
if (IS_ERR(entry))
return PTR_ERR(entry);

err = audit_add_rule(entry);
audit_log_rule_change(loginuid, sessionid, sid, "add rule",
&entry->rule, !err);

if (err)
audit_free_rule(entry);
break;
case AUDIT_DEL:
case AUDIT_DEL_RULE:
if (type == AUDIT_DEL)
entry = audit_rule_to_entry(data);
else
entry = audit_data_to_entry(data, datasz);
if (IS_ERR(entry))
return PTR_ERR(entry);

err = audit_del_rule(entry);
audit_log_rule_change(loginuid, sessionid, sid, "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;
}
}

/* 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 *dirlen)
{
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 length of path's directory component */
if (dirlen)
*dirlen = p - path;
return strncmp(p, dname, dlen);
}

static int audit_filter_user_rules(struct netlink_skb_parms *cb,
struct audit_krule *rule,
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(cb->creds.pid, f->op, f->val);
break;
case AUDIT_UID:
result = audit_comparator(cb->creds.uid, f->op, f->val);
break;
case AUDIT_GID:
result = audit_comparator(cb->creds.gid, f->op, f->val);
break;
case AUDIT_LOGINUID:
result = audit_comparator(audit_get_loginuid(current),
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(struct netlink_skb_parms *cb)
{
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(cb, &e->rule, &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;
}
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