Commit 93315ed6 authored by Amy Griffis's avatar Amy Griffis Committed by Al Viro

[PATCH] audit string fields interface + consumer

Updated patch to dynamically allocate audit rule fields in kernel's
internal representation.  Added unlikely() calls for testing memory
allocation result.

Amy Griffis wrote:     [Wed Jan 11 2006, 02:02:31PM EST]
> Modify audit's kernel-userspace interface to allow the specification
> of string fields in audit rules.
>
> Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
(cherry picked from 5ffc4a863f92351b720fe3e9c5cd647accff9e03 commit)
parent af601e46
......@@ -50,15 +50,18 @@
*/
#define AUDIT_GET 1000 /* Get status */
#define AUDIT_SET 1001 /* Set status (enable/disable/auditd) */
#define AUDIT_LIST 1002 /* List syscall filtering rules */
#define AUDIT_ADD 1003 /* Add syscall filtering rule */
#define AUDIT_DEL 1004 /* Delete syscall filtering rule */
#define AUDIT_LIST 1002 /* List syscall rules -- deprecated */
#define AUDIT_ADD 1003 /* Add syscall rule -- deprecated */
#define AUDIT_DEL 1004 /* Delete syscall rule -- deprecated */
#define AUDIT_USER 1005 /* Message from userspace -- deprecated */
#define AUDIT_LOGIN 1006 /* Define the login id and information */
#define AUDIT_WATCH_INS 1007 /* Insert file/dir watch entry */
#define AUDIT_WATCH_REM 1008 /* Remove file/dir watch entry */
#define AUDIT_WATCH_LIST 1009 /* List all file/dir watches */
#define AUDIT_SIGNAL_INFO 1010 /* Get info about sender of signal to auditd */
#define AUDIT_ADD_RULE 1011 /* Add syscall filtering rule */
#define AUDIT_DEL_RULE 1012 /* Delete syscall filtering rule */
#define AUDIT_LIST_RULES 1013 /* List syscall filtering rules */
#define AUDIT_FIRST_USER_MSG 1100 /* Userspace messages mostly uninteresting to kernel */
#define AUDIT_USER_AVC 1107 /* We filter this differently */
......@@ -229,6 +232,26 @@ struct audit_status {
__u32 backlog; /* messages waiting in queue */
};
/* audit_rule_data supports filter rules with both integer and string
* fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and
* AUDIT_LIST_RULES requests.
*/
struct audit_rule_data {
__u32 flags; /* AUDIT_PER_{TASK,CALL}, AUDIT_PREPEND */
__u32 action; /* AUDIT_NEVER, AUDIT_POSSIBLE, AUDIT_ALWAYS */
__u32 field_count;
__u32 mask[AUDIT_BITMASK_SIZE];
__u32 fields[AUDIT_MAX_FIELDS];
__u32 values[AUDIT_MAX_FIELDS];
__u32 fieldflags[AUDIT_MAX_FIELDS];
__u32 buflen; /* total length of string fields */
char buf[0]; /* string fields buffer */
};
/* audit_rule is supported to maintain backward compatibility with
* userspace. It supports integer fields only and corresponds to
* AUDIT_ADD, AUDIT_DEL and AUDIT_LIST requests.
*/
struct audit_rule { /* for AUDIT_LIST, AUDIT_ADD, and AUDIT_DEL */
__u32 flags; /* AUDIT_PER_{TASK,CALL}, AUDIT_PREPEND */
__u32 action; /* AUDIT_NEVER, AUDIT_POSSIBLE, AUDIT_ALWAYS */
......@@ -338,7 +361,7 @@ extern void audit_log_d_path(struct audit_buffer *ab,
extern int audit_filter_user(struct netlink_skb_parms *cb, int type);
extern int audit_filter_type(int type);
extern int audit_receive_filter(int type, int pid, int uid, int seq,
void *data, uid_t loginuid);
void *data, size_t datasz, uid_t loginuid);
#else
#define audit_log(c,g,t,f,...) do { ; } while (0)
#define audit_log_start(c,g,t) ({ NULL; })
......
......@@ -52,6 +52,7 @@
#include <linux/audit.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
......@@ -361,9 +362,12 @@ static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type)
switch (msg_type) {
case AUDIT_GET:
case AUDIT_LIST:
case AUDIT_LIST_RULES:
case AUDIT_SET:
case AUDIT_ADD:
case AUDIT_ADD_RULE:
case AUDIT_DEL:
case AUDIT_DEL_RULE:
case AUDIT_SIGNAL_INFO:
if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL))
err = -EPERM;
......@@ -470,12 +474,23 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
break;
case AUDIT_ADD:
case AUDIT_DEL:
if (nlh->nlmsg_len < sizeof(struct audit_rule))
if (nlmsg_len(nlh) < sizeof(struct audit_rule))
return -EINVAL;
/* fallthrough */
case AUDIT_LIST:
err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
uid, seq, data, loginuid);
uid, seq, data, nlmsg_len(nlh),
loginuid);
break;
case AUDIT_ADD_RULE:
case AUDIT_DEL_RULE:
if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
return -EINVAL;
/* fallthrough */
case AUDIT_LIST_RULES:
err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
uid, seq, data, nlmsg_len(nlh),
loginuid);
break;
case AUDIT_SIGNAL_INFO:
sig_data.uid = audit_sig_uid;
......
......@@ -52,10 +52,27 @@ enum audit_state {
};
/* Rule lists */
struct audit_field {
u32 type;
u32 val;
u32 op;
};
struct audit_krule {
int vers_ops;
u32 flags;
u32 listnr;
u32 action;
u32 mask[AUDIT_BITMASK_SIZE];
u32 buflen; /* for data alloc on list rules */
u32 field_count;
struct audit_field *fields;
};
struct audit_entry {
struct list_head list;
struct rcu_head rcu;
struct audit_rule rule;
struct list_head list;
struct rcu_head rcu;
struct audit_krule rule;
};
......
......@@ -40,52 +40,279 @@ struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
#endif
};
/* Copy rule from user-space to kernel-space. Called from
* audit_add_rule during AUDIT_ADD. */
static inline int audit_copy_rule(struct audit_rule *d, struct audit_rule *s)
static inline void audit_free_rule(struct audit_entry *e)
{
kfree(e->rule.fields);
kfree(e);
}
static inline void audit_free_rule_rcu(struct rcu_head *head)
{
struct audit_entry *e = container_of(head, struct audit_entry, rcu);
audit_free_rule(e);
}
/* Unpack a filter field's string representation from user-space
* buffer. */
static __attribute__((unused)) 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;
}
/* 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;
struct audit_field *fields;
int i, err;
err = -EINVAL;
listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
switch(listnr) {
default:
goto exit_err;
case AUDIT_FILTER_USER:
case AUDIT_FILTER_TYPE:
#ifdef CONFIG_AUDITSYSCALL
case AUDIT_FILTER_ENTRY:
case AUDIT_FILTER_EXIT:
case AUDIT_FILTER_TASK:
#endif
;
}
if (rule->action != AUDIT_NEVER && rule->action != AUDIT_POSSIBLE &&
rule->action != AUDIT_ALWAYS)
goto exit_err;
if (rule->field_count > AUDIT_MAX_FIELDS)
goto exit_err;
err = -ENOMEM;
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (unlikely(!entry))
goto exit_err;
fields = kmalloc(sizeof(*fields) * rule->field_count, GFP_KERNEL);
if (unlikely(!fields)) {
kfree(entry);
goto exit_err;
}
memset(&entry->rule, 0, sizeof(struct audit_krule));
memset(fields, 0, sizeof(struct audit_field));
entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
entry->rule.listnr = listnr;
entry->rule.action = rule->action;
entry->rule.field_count = rule->field_count;
entry->rule.fields = fields;
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
entry->rule.mask[i] = rule->mask[i];
return entry;
exit_err:
return ERR_PTR(err);
}
/* 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;
if (s->action != AUDIT_NEVER
&& s->action != AUDIT_POSSIBLE
&& s->action != AUDIT_ALWAYS)
return -1;
if (s->field_count < 0 || s->field_count > AUDIT_MAX_FIELDS)
return -1;
if ((s->flags & ~AUDIT_FILTER_PREPEND) >= AUDIT_NR_FILTERS)
return -1;
d->flags = s->flags;
d->action = s->action;
d->field_count = s->field_count;
for (i = 0; i < d->field_count; i++) {
d->fields[i] = s->fields[i];
d->values[i] = s->values[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];
if (rule->fields[i] & AUDIT_UNUSED_BITS) {
err = -EINVAL;
goto exit_free;
}
f->op = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
f->val = rule->values[i];
entry->rule.vers_ops = (f->op & AUDIT_OPERATORS) ? 2 : 1;
if (f->op & AUDIT_NEGATE)
f->op |= AUDIT_NOT_EQUAL;
else if (!(f->op & AUDIT_OPERATORS))
f->op |= AUDIT_EQUAL;
f->op &= ~AUDIT_NEGATE;
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i];
return 0;
exit_nofree:
return entry;
exit_free:
audit_free_rule(entry);
return ERR_PTR(err);
}
/* Check to see if two rules are identical. It is called from
* audit_add_rule during AUDIT_ADD and
* audit_del_rule during AUDIT_DEL. */
static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)
/* 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;
if (a->flags != b->flags)
return 1;
entry = audit_to_entry_common((struct audit_rule *)data);
if (IS_ERR(entry))
goto exit_nofree;
if (a->action != b->action)
return 1;
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;
if (!(data->fieldflags[i] & AUDIT_OPERATORS) ||
data->fieldflags[i] & ~AUDIT_OPERATORS)
goto exit_free;
f->op = data->fieldflags[i] & AUDIT_OPERATORS;
f->type = data->fields[i];
switch(f->type) {
/* call type-specific conversion routines here */
default:
f->val = data->values[i];
}
}
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, 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 = kmalloc(sizeof(*rule), GFP_KERNEL);
if (unlikely(!rule))
return ERR_PTR(-ENOMEM);
memset(rule, 0, sizeof(*rule));
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] |= krule->fields[i].op;
}
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];
return rule;
}
if (a->field_count != b->field_count)
/* 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 ERR_PTR(-ENOMEM);
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] = f->op;
switch(f->type) {
/* call type-specific conversion routines here */
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] != b->fields[i]
|| a->values[i] != b->values[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) {
/* call type-specific comparison routines here */
default:
if (a->fields[i].val != b->fields[i].val)
return 1;
}
}
for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
......@@ -95,41 +322,21 @@ static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)
return 0;
}
/* Note that audit_add_rule and audit_del_rule are called via
* audit_receive() in audit.c, and are protected by
/* Add rule to given filterlist if not a duplicate. Protected by
* audit_netlink_sem. */
static inline int audit_add_rule(struct audit_rule *rule,
static inline int audit_add_rule(struct audit_entry *entry,
struct list_head *list)
{
struct audit_entry *entry;
int i;
struct audit_entry *e;
/* Do not use the _rcu iterator here, since this is the only
* addition routine. */
list_for_each_entry(entry, list, list) {
if (!audit_compare_rule(rule, &entry->rule))
list_for_each_entry(e, list, list) {
if (!audit_compare_rule(&entry->rule, &e->rule))
return -EEXIST;
}
for (i = 0; i < rule->field_count; i++) {
if (rule->fields[i] & AUDIT_UNUSED_BITS)
return -EINVAL;
if ( rule->fields[i] & AUDIT_NEGATE)
rule->fields[i] |= AUDIT_NOT_EQUAL;
else if ( (rule->fields[i] & AUDIT_OPERATORS) == 0 )
rule->fields[i] |= AUDIT_EQUAL;
rule->fields[i] &= ~AUDIT_NEGATE;
}
if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL)))
return -ENOMEM;
if (audit_copy_rule(&entry->rule, rule)) {
kfree(entry);
return -EINVAL;
}
if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
list_add_rcu(&entry->list, list);
} else {
list_add_tail_rcu(&entry->list, list);
......@@ -138,16 +345,9 @@ static inline int audit_add_rule(struct audit_rule *rule,
return 0;
}
static inline void audit_free_rule(struct rcu_head *head)
{
struct audit_entry *e = container_of(head, struct audit_entry, rcu);
kfree(e);
}
/* Note that audit_add_rule and audit_del_rule are called via
* audit_receive() in audit.c, and are protected by
/* Remove an existing rule from filterlist. Protected by
* audit_netlink_sem. */
static inline int audit_del_rule(struct audit_rule *rule,
static inline int audit_del_rule(struct audit_entry *entry,
struct list_head *list)
{
struct audit_entry *e;
......@@ -155,16 +355,18 @@ static inline int audit_del_rule(struct audit_rule *rule,
/* 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(rule, &e->rule)) {
if (!audit_compare_rule(&entry->rule, &e->rule)) {
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule);
call_rcu(&e->rcu, audit_free_rule_rcu);
return 0;
}
}
return -ENOENT; /* No matching rule */
}
static int audit_list_rules(void *_dest)
/* List rules using struct audit_rule. Exists for backward
* compatibility with userspace. */
static int audit_list(void *_dest)
{
int pid, seq;
int *dest = _dest;
......@@ -180,9 +382,16 @@ static int audit_list_rules(void *_dest)
/* The *_rcu iterators not needed here because we are
always called with audit_netlink_sem held. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
list_for_each_entry(entry, &audit_filter_list[i], list)
list_for_each_entry(entry, &audit_filter_list[i], list) {
struct audit_rule *rule;
rule = audit_krule_to_rule(&entry->rule);
if (unlikely(!rule))
break;
audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
&entry->rule, sizeof(entry->rule));
rule, sizeof(*rule));
kfree(rule);
}
}
audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
......@@ -190,6 +399,40 @@ static int audit_list_rules(void *_dest)
return 0;
}
/* List rules using struct audit_rule_data. */
static int audit_list_rules(void *_dest)
{
int pid, seq;
int *dest = _dest;
struct audit_entry *e;
int i;
pid = dest[0];
seq = dest[1];
kfree(dest);
down(&audit_netlink_sem);
/* The *_rcu iterators not needed here because we are
always called with audit_netlink_sem held. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
list_for_each_entry(e, &audit_filter_list[i], list) {
struct audit_rule_data *data;
data = audit_krule_to_data(&e->rule);
if (unlikely(!data))
break;
audit_send_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
data, sizeof(*data));
kfree(data);
}
}
audit_send_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
up(&audit_netlink_sem);
return 0;
}
/**
* audit_receive_filter - apply all rules to the specified message type
* @type: audit message type
......@@ -197,18 +440,20 @@ static int audit_list_rules(void *_dest)
* @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
*/
int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
uid_t loginuid)
size_t datasz, uid_t loginuid)
{
struct task_struct *tsk;
int *dest;
int err = 0;
unsigned listnr;
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
......@@ -221,41 +466,48 @@ int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
dest[0] = pid;
dest[1] = seq;
tsk = kthread_run(audit_list_rules, dest, "audit_list_rules");
if (type == AUDIT_LIST)
tsk = kthread_run(audit_list, dest, "audit_list");
else
tsk = kthread_run(audit_list_rules, dest,
"audit_list_rules");
if (IS_ERR(tsk)) {
kfree(dest);
err = PTR_ERR(tsk);
}
break;
case AUDIT_ADD:
listnr = ((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND;
switch(listnr) {
default:
return -EINVAL;
case AUDIT_FILTER_USER:
case AUDIT_FILTER_TYPE:
#ifdef CONFIG_AUDITSYSCALL
case AUDIT_FILTER_ENTRY:
case AUDIT_FILTER_EXIT:
case AUDIT_FILTER_TASK:
#endif
;