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audit: dynamically allocate audit_names when not enough space is in the names array

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This patch does 2 things.  First it reduces the number of audit_names
allocated in every audit context from 20 to 5.  5 should be enough for all
'normal' syscalls (rename being the worst).  Some syscalls can still touch
more the 5 inodes such as mount.  When rpc filesystem is mounted it will
create inodes and those can exceed 5.  To handle that problem this patch will
dynamically allocate audit_names if it needs more than 5.  This should
decrease the typicall memory usage while still supporting all the possible
kernel operations.

Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris 2012-01-03 14:23:05 -05:00 committed by Al Viro
parent 5ef30ee53b
commit 5195d8e217
1 changed files with 215 additions and 188 deletions
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403
kernel/auditsc.c
View file

@ -71,8 +71,9 @@
#include "audit.h"
/* AUDIT_NAMES is the number of slots we reserve in the audit_context
* for saving names from getname(). */
#define AUDIT_NAMES 20
* for saving names from getname(). If we get more names we will allocate
* a name dynamically and also add those to the list anchored by names_list. */
#define AUDIT_NAMES 5
/* Indicates that audit should log the full pathname. */
#define AUDIT_NAME_FULL -1
@ -101,9 +102,8 @@ struct audit_cap_data {
*
* Further, in fs/namei.c:path_lookup() we store the inode and device. */
struct audit_names {
struct list_head list; /* audit_context->names_list */
const char *name;
int name_len; /* number of name's characters to log */
unsigned name_put; /* call __putname() for this name */
unsigned long ino;
dev_t dev;
umode_t mode;
@ -113,6 +113,14 @@ struct audit_names {
u32 osid;
struct audit_cap_data fcap;
unsigned int fcap_ver;
int name_len; /* number of name's characters to log */
bool name_put; /* call __putname() for this name */
/*
* This was an allocated audit_names and not from the array of
* names allocated in the task audit context. Thus this name
* should be freed on syscall exit
*/
bool should_free;
};
struct audit_aux_data {
@ -174,8 +182,17 @@ struct audit_context {
long return_code;/* syscall return code */
u64 prio;
int return_valid; /* return code is valid */
int name_count;
struct audit_names names[AUDIT_NAMES];
/*
* The names_list is the list of all audit_names collected during this
* syscall. The first AUDIT_NAMES entries in the names_list will
* actually be from the preallocated_names array for performance
* reasons. Except during allocation they should never be referenced
* through the preallocated_names array and should only be found/used
* by running the names_list.
*/
struct audit_names preallocated_names[AUDIT_NAMES];
int name_count; /* total records in names_list */
struct list_head names_list; /* anchor for struct audit_names->list */
char * filterkey; /* key for rule that triggered record */
struct path pwd;
struct audit_context *previous; /* For nested syscalls */
@ -307,17 +324,18 @@ static int audit_match_perm(struct audit_context *ctx, int mask)
static int audit_match_filetype(struct audit_context *ctx, int val)
{
int index;
struct audit_names *n;
umode_t mode = (umode_t)val;
if (unlikely(!ctx))
return 0;
for (index = 0; index < ctx->name_count; index++) {
if ((ctx->names[index].ino != -1) &&
((ctx->names[index].mode & S_IFMT) == mode))
list_for_each_entry(n, &ctx->names_list, list) {
if ((n->ino != -1) &&
((n->mode & S_IFMT) == mode))
return 1;
}
return 0;
}
@ -456,13 +474,14 @@ static int audit_filter_rules(struct task_struct *tsk,
bool task_creation)
{
const struct cred *cred;
int i, j, need_sid = 1;
int i, need_sid = 1;
u32 sid;
cred = rcu_dereference_check(tsk->cred, tsk == current || task_creation);
for (i = 0; i < rule->field_count; i++) {
struct audit_field *f = &rule->fields[i];
struct audit_names *n;
int result = 0;
switch (f->type) {
@ -525,8 +544,8 @@ static int audit_filter_rules(struct task_struct *tsk,
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)) {
list_for_each_entry(n, &ctx->names_list, list) {
if (audit_comparator(MAJOR(n->dev), f->op, f->val)) {
++result;
break;
}
@ -538,8 +557,8 @@ static int audit_filter_rules(struct task_struct *tsk,
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)) {
list_for_each_entry(n, &ctx->names_list, list) {
if (audit_comparator(MINOR(n->dev), f->op, f->val)) {
++result;
break;
}
@ -550,8 +569,8 @@ static int audit_filter_rules(struct task_struct *tsk,
if (name)
result = (name->ino == f->val);
else if (ctx) {
for (j = 0; j < ctx->name_count; j++) {
if (audit_comparator(ctx->names[j].ino, f->op, f->val)) {
list_for_each_entry(n, &ctx->names_list, list) {
if (audit_comparator(n->ino, f->op, f->val)) {
++result;
break;
}
@ -606,11 +625,10 @@ static int audit_filter_rules(struct task_struct *tsk,
name->osid, f->type, f->op,
f->lsm_rule, ctx);
} else if (ctx) {
for (j = 0; j < ctx->name_count; j++) {
if (security_audit_rule_match(
ctx->names[j].osid,
f->type, f->op,
f->lsm_rule, ctx)) {
list_for_each_entry(n, &ctx->names_list, list) {
if (security_audit_rule_match(n->osid, f->type,
f->op, f->lsm_rule,
ctx)) {
++result;
break;
}
@ -721,40 +739,53 @@ 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
/*
* Given an audit_name check the inode hash table to see if they match.
* Called holding the rcu read lock to protect the use of audit_inode_hash
*/
static int audit_filter_inode_name(struct task_struct *tsk,
struct audit_names *n,
struct audit_context *ctx) {
int word, bit;
int h = audit_hash_ino((u32)n->ino);
struct list_head *list = &audit_inode_hash[h];
struct audit_entry *e;
enum audit_state state;
word = AUDIT_WORD(ctx->major);
bit = AUDIT_BIT(ctx->major);
if (list_empty(list))
return 0;
list_for_each_entry_rcu(e, list, list) {
if ((e->rule.mask[word] & bit) == bit &&
audit_filter_rules(tsk, &e->rule, ctx, n, &state, false)) {
ctx->current_state = state;
return 1;
}
}
return 0;
}
/* 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[].
* buckets applicable to the inode numbers in audit_names.
* Regarding audit_state, same rules apply as for audit_filter_syscall().
*/
void audit_filter_inodes(struct task_struct *tsk, struct audit_context *ctx)
{
int i;
struct audit_entry *e;
enum audit_state state;
struct audit_names *n;
if (audit_pid && tsk->tgid == audit_pid)
return;
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, false)) {
rcu_read_unlock();
ctx->current_state = state;
return;
}
}
list_for_each_entry(n, &ctx->names_list, list) {
if (audit_filter_inode_name(tsk, n, ctx))
break;
}
rcu_read_unlock();
}
@ -798,7 +829,7 @@ static inline struct audit_context *audit_get_context(struct task_struct *tsk,
static inline void audit_free_names(struct audit_context *context)
{
int i;
struct audit_names *n, *next;
#if AUDIT_DEBUG == 2
if (context->put_count + context->ino_count != context->name_count) {
@ -809,10 +840,9 @@ static inline void audit_free_names(struct audit_context *context)
context->serial, context->major, context->in_syscall,
context->name_count, context->put_count,
context->ino_count);
for (i = 0; i < context->name_count; i++) {
list_for_each_entry(n, &context->names_list, list) {
printk(KERN_ERR "names[%d] = %p = %s\n", i,
context->names[i].name,
context->names[i].name ?: "(null)");
n->name, n->name ?: "(null)");
}
dump_stack();
return;
@ -823,9 +853,12 @@ static inline void audit_free_names(struct audit_context *context)
context->ino_count = 0;
#endif
for (i = 0; i < context->name_count; i++) {
if (context->names[i].name && context->names[i].name_put)
__putname(context->names[i].name);
list_for_each_entry_safe(n, next, &context->names_list, list) {
list_del(&n->list);
if (n->name && n->name_put)
__putname(n->name);
if (n->should_free)
kfree(n);
}
context->name_count = 0;
path_put(&context->pwd);
@ -863,6 +896,7 @@ static inline struct audit_context *audit_alloc_context(enum audit_state state)
return NULL;
audit_zero_context(context, state);
INIT_LIST_HEAD(&context->killed_trees);
INIT_LIST_HEAD(&context->names_list);
return context;
}
@ -1323,6 +1357,68 @@ static void show_special(struct audit_context *context, int *call_panic)
audit_log_end(ab);
}
static void audit_log_name(struct audit_context *context, struct audit_names *n,
int record_num, int *call_panic)
{
struct audit_buffer *ab;
ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
if (!ab)
return; /* audit_panic has been called */
audit_log_format(ab, "item=%d", record_num);
if (n->name) {
switch (n->name_len) {
case AUDIT_NAME_FULL:
/* log the full path */
audit_log_format(ab, " name=");
audit_log_untrustedstring(ab, n->name);
break;
case 0:
/* name was specified as a relative path and the
* directory component is the cwd */
audit_log_d_path(ab, "name=", &context->pwd);
break;
default:
/* log the name's directory component */
audit_log_format(ab, " name=");
audit_log_n_untrustedstring(ab, n->name,
n->name_len);
}
} else
audit_log_format(ab, " name=(null)");
if (n->ino != (unsigned long)-1) {
audit_log_format(ab, " inode=%lu"
" dev=%02x:%02x mode=%#ho"
" ouid=%u ogid=%u rdev=%02x:%02x",
n->ino,
MAJOR(n->dev),
MINOR(n->dev),
n->mode,
n->uid,
n->gid,
MAJOR(n->rdev),
MINOR(n->rdev));
}
if (n->osid != 0) {
char *ctx = NULL;
u32 len;
if (security_secid_to_secctx(
n->osid, &ctx, &len)) {
audit_log_format(ab, " osid=%u", n->osid);
*call_panic = 2;
} else {
audit_log_format(ab, " obj=%s", ctx);
security_release_secctx(ctx, len);
}
}
audit_log_fcaps(ab, n);
audit_log_end(ab);
}
static void audit_log_exit(struct audit_context *context, struct task_struct *tsk)
{
const struct cred *cred;
@ -1330,6 +1426,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
struct audit_buffer *ab;
struct audit_aux_data *aux;
const char *tty;
struct audit_names *n;
/* tsk == current */
context->pid = tsk->pid;
@ -1469,66 +1566,10 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
audit_log_end(ab);
}
}
for (i = 0; i < context->name_count; i++) {
struct audit_names *n = &context->names[i];
ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
if (!ab)
continue; /* audit_panic has been called */
audit_log_format(ab, "item=%d", i);
if (n->name) {
switch(n->name_len) {
case AUDIT_NAME_FULL:
/* log the full path */
audit_log_format(ab, " name=");
audit_log_untrustedstring(ab, n->name);
break;
case 0:
/* name was specified as a relative path and the
* directory component is the cwd */
audit_log_d_path(ab, "name=", &context->pwd);
break;
default:
/* log the name's directory component */
audit_log_format(ab, " name=");
audit_log_n_untrustedstring(ab, n->name,
n->name_len);
}
} else
audit_log_format(ab, " name=(null)");
if (n->ino != (unsigned long)-1) {
audit_log_format(ab, " inode=%lu"
" dev=%02x:%02x mode=%#ho"
" ouid=%u ogid=%u rdev=%02x:%02x",
n->ino,
MAJOR(n->dev),
MINOR(n->dev),
n->mode,
n->uid,
n->gid,
MAJOR(n->rdev),
MINOR(n->rdev));
}
if (n->osid != 0) {
char *ctx = NULL;
u32 len;
if (security_secid_to_secctx(
n->osid, &ctx, &len)) {
audit_log_format(ab, " osid=%u", n->osid);
call_panic = 2;
} else {
audit_log_format(ab, " obj=%s", ctx);
security_release_secctx(ctx, len);
}
}
audit_log_fcaps(ab, n);
audit_log_end(ab);
}
i = 0;
list_for_each_entry(n, &context->names_list, list)
audit_log_name(context, n, i++, &call_panic);
/* Send end of event record to help user space know we are finished */
ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE);
@ -1820,6 +1861,30 @@ static void handle_path(const struct dentry *dentry)
#endif
}
static struct audit_names *audit_alloc_name(struct audit_context *context)
{
struct audit_names *aname;
if (context->name_count < AUDIT_NAMES) {
aname = &context->preallocated_names[context->name_count];
memset(aname, 0, sizeof(*aname));
} else {
aname = kzalloc(sizeof(*aname), GFP_NOFS);
if (!aname)
return NULL;
aname->should_free = true;
}
aname->ino = (unsigned long)-1;
list_add_tail(&aname->list, &context->names_list);
context->name_count++;
#if AUDIT_DEBUG
context->ino_count++;
#endif
return aname;
}
/**
* audit_getname - add a name to the list
* @name: name to add
@ -1830,6 +1895,7 @@ static void handle_path(const struct dentry *dentry)
void __audit_getname(const char *name)
{
struct audit_context *context = current->audit_context;
struct audit_names *n;
if (IS_ERR(name) || !name)
return;
@ -1842,13 +1908,15 @@ void __audit_getname(const char *name)
#endif
return;
}
BUG_ON(context->name_count >= AUDIT_NAMES);
context->names[context->name_count].name = name;
context->names[context->name_count].name_len = AUDIT_NAME_FULL;
context->names[context->name_count].name_put = 1;
context->names[context->name_count].ino = (unsigned long)-1;
context->names[context->name_count].osid = 0;
++context->name_count;
n = audit_alloc_name(context);
if (!n)
return;
n->name = name;
n->name_len = AUDIT_NAME_FULL;
n->name_put = true;
if (!context->pwd.dentry)
get_fs_pwd(current->fs, &context->pwd);
}
@ -1870,12 +1938,13 @@ void audit_putname(const char *name)
printk(KERN_ERR "%s:%d(:%d): __putname(%p)\n",
__FILE__, __LINE__, context->serial, name);
if (context->name_count) {
struct audit_names *n;
int i;
for (i = 0; i < context->name_count; i++)
list_for_each_entry(n, &context->names_list, list)
printk(KERN_ERR "name[%d] = %p = %s\n", i,
context->names[i].name,
context->names[i].name ?: "(null)");
}
n->name, n->name ?: "(null)");
}
#endif
__putname(name);
}
@ -1896,39 +1965,11 @@ void audit_putname(const char *name)
#endif
}
static int audit_inc_name_count(struct audit_context *context,
const struct inode *inode)
{
if (context->name_count >= AUDIT_NAMES) {
if (inode)
printk(KERN_DEBUG "audit: name_count maxed, losing inode data: "
"dev=%02x:%02x, inode=%lu\n",
MAJOR(inode->i_sb->s_dev),
MINOR(inode->i_sb->s_dev),
inode->i_ino);
else
printk(KERN_DEBUG "name_count maxed, losing inode data\n");
return 1;
}
context->name_count++;
#if AUDIT_DEBUG
context->ino_count++;
#endif
return 0;
}
static inline int audit_copy_fcaps(struct audit_names *name, const struct dentry *dentry)
{
struct cpu_vfs_cap_data caps;
int rc;
memset(&name->fcap.permitted, 0, sizeof(kernel_cap_t));
memset(&name->fcap.inheritable, 0, sizeof(kernel_cap_t));
name->fcap.fE = 0;
name->fcap_ver = 0;
if (!dentry)
return 0;
@ -1968,30 +2009,25 @@ static void audit_copy_inode(struct audit_names *name, const struct dentry *dent
*/
void __audit_inode(const char *name, const struct dentry *dentry)
{
int idx;
struct audit_context *context = current->audit_context;
const struct inode *inode = dentry->d_inode;
struct audit_names *n;
if (!context->in_syscall)
return;
if (context->name_count
&& context->names[context->name_count-1].name
&& context->names[context->name_count-1].name == name)
idx = context->name_count - 1;
else if (context->name_count > 1
&& context->names[context->name_count-2].name
&& context->names[context->name_count-2].name == name)
idx = context->name_count - 2;
else {
/* FIXME: how much do we care about inodes that have no
* associated name? */
if (audit_inc_name_count(context, inode))
return;
idx = context->name_count - 1;
context->names[idx].name = NULL;
list_for_each_entry_reverse(n, &context->names_list, list) {
if (n->name && (n->name == name))
goto out;
}
/* unable to find the name from a previous getname() */
n = audit_alloc_name(context);
if (!n)
return;
out:
handle_path(dentry);
audit_copy_inode(&context->names[idx], dentry, inode);
audit_copy_inode(n, dentry, inode);
}
/**
@ -2010,11 +2046,11 @@ void __audit_inode(const char *name, const struct dentry *dentry)
void __audit_inode_child(const struct dentry *dentry,
const struct inode *parent)
{
int idx;
struct audit_context *context = current->audit_context;
const char *found_parent = NULL, *found_child = NULL;
const struct inode *inode = dentry->d_inode;
const char *dname = dentry->d_name.name;
struct audit_names *n;
int dirlen = 0;
if (!context->in_syscall)
@ -2024,9 +2060,7 @@ void __audit_inode_child(const struct dentry *dentry,
handle_one(inode);
/* parent is more likely, look for it first */
for (idx = 0; idx < context->name_count; idx++) {
struct audit_names *n = &context->names[idx];
list_for_each_entry(n, &context->names_list, list) {
if (!n->name)
continue;
@ -2039,9 +2073,7 @@ void __audit_inode_child(const struct dentry *dentry,
}
/* no matching parent, look for matching child */
for (idx = 0; idx < context->name_count; idx++) {
struct audit_names *n = &context->names[idx];
list_for_each_entry(n, &context->names_list, list) {
if (!n->name)
continue;
@ -2059,34 +2091,29 @@ void __audit_inode_child(const struct dentry *dentry,
add_names:
if (!found_parent) {
if (audit_inc_name_count(context, parent))
n = audit_alloc_name(context);
if (!n)
return;
idx = context->name_count - 1;
context->names[idx].name = NULL;
audit_copy_inode(&context->names[idx], NULL, parent);
audit_copy_inode(n, NULL, parent);
}
if (!found_child) {
if (audit_inc_name_count(context, inode))
n = audit_alloc_name(context);
if (!n)
return;
idx = context->name_count - 1;
/* Re-use the name belonging to the slot for a matching parent
* directory. All names for this context are relinquished in
* audit_free_names() */
if (found_parent) {
context->names[idx].name = found_parent;
context->names[idx].name_len = AUDIT_NAME_FULL;
n->name = found_parent;
n->name_len = AUDIT_NAME_FULL;
/* don't call __putname() */
context->names[idx].name_put = 0;
} else {
context->names[idx].name = NULL;
n->name_put = false;
}
if (inode)
audit_copy_inode(&context->names[idx], NULL, inode);
else
context->names[idx].ino = (unsigned long)-1;
audit_copy_inode(n, NULL, inode);
}
}
EXPORT_SYMBOL_GPL(__audit_inode_child);