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Merge branch 'ima-memory-use-fixes'

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* ima-memory-use-fixes:
  IMA: fix the ToMToU logic
  IMA: explicit IMA i_flag to remove global lock on inode_delete
  IMA: drop refcnt from ima_iint_cache since it isn't needed
  IMA: only allocate iint when needed
  IMA: move read counter into struct inode
  IMA: use i_writecount rather than a private counter
  IMA: use inode->i_lock to protect read and write counters
  IMA: convert internal flags from long to char
  IMA: use unsigned int instead of long for counters
  IMA: drop the inode opencount since it isn't needed for operation
  IMA: use rbtree instead of radix tree for inode information cache
This commit is contained in:
Linus Torvalds 2010-10-26 11:37:48 -07:00
commit f9ba5375a8
7 changed files with 205 additions and 180 deletions
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1
fs/inode.c
View File

@ -24,6 +24,7 @@
#include <linux/mount.h>
#include <linux/async.h>
#include <linux/posix_acl.h>
#include <linux/ima.h>
/*
* This is needed for the following functions:

6
include/linux/fs.h
View File

@ -231,6 +231,7 @@ struct inodes_stat_t {
#define S_NOCMTIME 128 /* Do not update file c/mtime */
#define S_SWAPFILE 256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE 512 /* Inode is fs-internal */
#define S_IMA 1024 /* Inode has an associated IMA struct */
/*
* Note that nosuid etc flags are inode-specific: setting some file-system
@ -265,6 +266,7 @@ struct inodes_stat_t {
#define IS_NOCMTIME(inode) ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode) ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode) ((inode)->i_flags & S_PRIVATE)
#define IS_IMA(inode) ((inode)->i_flags & S_IMA)
/* the read-only stuff doesn't really belong here, but any other place is
probably as bad and I don't want to create yet another include file. */
@ -772,6 +774,10 @@ struct inode {
unsigned int i_flags;
#ifdef CONFIG_IMA
/* protected by i_lock */
unsigned int i_readcount; /* struct files open RO */
#endif
atomic_t i_writecount;
#ifdef CONFIG_SECURITY
void *i_security;

18
security/integrity/ima/ima.h
View File

@ -70,6 +70,7 @@ int ima_init(void);
void ima_cleanup(void);
int ima_fs_init(void);
void ima_fs_cleanup(void);
int ima_inode_alloc(struct inode *inode);
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode);
int ima_calc_hash(struct file *file, char *digest);
@ -96,19 +97,16 @@ static inline unsigned long ima_hash_key(u8 *digest)
}
/* iint cache flags */
#define IMA_MEASURED 1
#define IMA_MEASURED 0x01
/* integrity data associated with an inode */
struct ima_iint_cache {
struct rb_node rb_node; /* rooted in ima_iint_tree */
struct inode *inode; /* back pointer to inode in question */
u64 version; /* track inode changes */
unsigned long flags;
unsigned char flags;
u8 digest[IMA_DIGEST_SIZE];
struct mutex mutex; /* protects: version, flags, digest */
long readcount; /* measured files readcount */
long writecount; /* measured files writecount */
long opencount; /* opens reference count */
struct kref refcount; /* ima_iint_cache reference count */
struct rcu_head rcu;
};
/* LIM API function definitions */
@ -122,13 +120,11 @@ int ima_store_template(struct ima_template_entry *entry, int violation,
void ima_template_show(struct seq_file *m, void *e,
enum ima_show_type show);
/* radix tree calls to lookup, insert, delete
/* rbtree tree calls to lookup, insert, delete
* integrity data associated with an inode.
*/
struct ima_iint_cache *ima_iint_insert(struct inode *inode);
struct ima_iint_cache *ima_iint_find_get(struct inode *inode);
void iint_free(struct kref *kref);
void iint_rcu_free(struct rcu_head *rcu);
struct ima_iint_cache *ima_iint_find(struct inode *inode);
/* IMA policy related functions */
enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK };

2
security/integrity/ima/ima_api.c
View File

@ -116,7 +116,7 @@ int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
{
int must_measure;
if (iint->flags & IMA_MEASURED)
if (iint && iint->flags & IMA_MEASURED)
return 1;
must_measure = ima_match_policy(inode, function, mask);

162
security/integrity/ima/ima_iint.c
View File

@ -12,100 +12,121 @@
* File: ima_iint.c
* - implements the IMA hooks: ima_inode_alloc, ima_inode_free
* - cache integrity information associated with an inode
* using a radix tree.
* using a rbtree tree.
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/radix-tree.h>
#include <linux/rbtree.h>
#include "ima.h"
RADIX_TREE(ima_iint_store, GFP_ATOMIC);
DEFINE_SPINLOCK(ima_iint_lock);
static struct rb_root ima_iint_tree = RB_ROOT;
static DEFINE_SPINLOCK(ima_iint_lock);
static struct kmem_cache *iint_cache __read_mostly;
int iint_initialized = 0;
/* ima_iint_find_get - return the iint associated with an inode
*
* ima_iint_find_get gets a reference to the iint. Caller must
* remember to put the iint reference.
/*
* __ima_iint_find - return the iint associated with an inode
*/
struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
{
struct ima_iint_cache *iint;
struct rb_node *n = ima_iint_tree.rb_node;
assert_spin_locked(&ima_iint_lock);
while (n) {
iint = rb_entry(n, struct ima_iint_cache, rb_node);
if (inode < iint->inode)
n = n->rb_left;
else if (inode > iint->inode)
n = n->rb_right;
else
break;
}
if (!n)
return NULL;
return iint;
}
/*
* ima_iint_find - return the iint associated with an inode
*/
struct ima_iint_cache *ima_iint_find(struct inode *inode)
{
struct ima_iint_cache *iint;
rcu_read_lock();
iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
if (!iint)
goto out;
kref_get(&iint->refcount);
out:
rcu_read_unlock();
if (!IS_IMA(inode))
return NULL;
spin_lock(&ima_iint_lock);
iint = __ima_iint_find(inode);
spin_unlock(&ima_iint_lock);
return iint;
}
static void iint_free(struct ima_iint_cache *iint)
{
iint->version = 0;
iint->flags = 0UL;
kmem_cache_free(iint_cache, iint);
}
/**
* ima_inode_alloc - allocate an iint associated with an inode
* @inode: pointer to the inode
*/
int ima_inode_alloc(struct inode *inode)
{
struct ima_iint_cache *iint = NULL;
int rc = 0;
struct rb_node **p;
struct rb_node *new_node, *parent = NULL;
struct ima_iint_cache *new_iint, *test_iint;
int rc;
iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
if (!iint)
new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
if (!new_iint)
return -ENOMEM;
rc = radix_tree_preload(GFP_NOFS);
if (rc < 0)
goto out;
new_iint->inode = inode;
new_node = &new_iint->rb_node;
mutex_lock(&inode->i_mutex); /* i_flags */
spin_lock(&ima_iint_lock);
rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
p = &ima_iint_tree.rb_node;
while (*p) {
parent = *p;
test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);
rc = -EEXIST;
if (inode < test_iint->inode)
p = &(*p)->rb_left;
else if (inode > test_iint->inode)
p = &(*p)->rb_right;
else
goto out_err;
}
inode->i_flags |= S_IMA;
rb_link_node(new_node, parent, p);
rb_insert_color(new_node, &ima_iint_tree);
spin_unlock(&ima_iint_lock);
radix_tree_preload_end();
out:
if (rc < 0)
kmem_cache_free(iint_cache, iint);
mutex_unlock(&inode->i_mutex); /* i_flags */
return 0;
out_err:
spin_unlock(&ima_iint_lock);
mutex_unlock(&inode->i_mutex); /* i_flags */
iint_free(new_iint);
return rc;
}
/* iint_free - called when the iint refcount goes to zero */
void iint_free(struct kref *kref)
{
struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
refcount);
iint->version = 0;
iint->flags = 0UL;
if (iint->readcount != 0) {
printk(KERN_INFO "%s: readcount: %ld\n", __func__,
iint->readcount);
iint->readcount = 0;
}
if (iint->writecount != 0) {
printk(KERN_INFO "%s: writecount: %ld\n", __func__,
iint->writecount);
iint->writecount = 0;
}
if (iint->opencount != 0) {
printk(KERN_INFO "%s: opencount: %ld\n", __func__,
iint->opencount);
iint->opencount = 0;
}
kref_init(&iint->refcount);
kmem_cache_free(iint_cache, iint);
}
void iint_rcu_free(struct rcu_head *rcu_head)
{
struct ima_iint_cache *iint = container_of(rcu_head,
struct ima_iint_cache, rcu);
kref_put(&iint->refcount, iint_free);
}
/**
* ima_inode_free - called on security_inode_free
* @inode: pointer to the inode
@ -116,11 +137,20 @@ void ima_inode_free(struct inode *inode)
{
struct ima_iint_cache *iint;
if (inode->i_readcount)
printk(KERN_INFO "%s: readcount: %u\n", __func__, inode->i_readcount);
inode->i_readcount = 0;
if (!IS_IMA(inode))
return;
spin_lock(&ima_iint_lock);
iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
iint = __ima_iint_find(inode);
rb_erase(&iint->rb_node, &ima_iint_tree);
spin_unlock(&ima_iint_lock);
if (iint)
call_rcu(&iint->rcu, iint_rcu_free);
iint_free(iint);
}
static void init_once(void *foo)
@ -131,10 +161,6 @@ static void init_once(void *foo)
iint->version = 0;
iint->flags = 0UL;
mutex_init(&iint->mutex);
iint->readcount = 0;
iint->writecount = 0;
iint->opencount = 0;
kref_init(&iint->refcount);
}
static int __init ima_iintcache_init(void)

186
security/integrity/ima/ima_main.c
View File

@ -85,50 +85,6 @@ out:
return found;
}
/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
*
* When opening a file for read, if the file is already open for write,
* the file could change, resulting in a file measurement error.
*
* Opening a file for write, if the file is already open for read, results
* in a time of measure, time of use (ToMToU) error.
*
* In either case invalidate the PCR.
*/
enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
static void ima_read_write_check(enum iint_pcr_error error,
struct ima_iint_cache *iint,
struct inode *inode,
const unsigned char *filename)
{
switch (error) {
case TOMTOU:
if (iint->readcount > 0)
ima_add_violation(inode, filename, "invalid_pcr",
"ToMToU");
break;
case OPEN_WRITERS:
if (iint->writecount > 0)
ima_add_violation(inode, filename, "invalid_pcr",
"open_writers");
break;
}
}
/*
* Update the counts given an fmode_t
*/
static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
{
BUG_ON(!mutex_is_locked(&iint->mutex));
iint->opencount++;
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
iint->readcount++;
if (mode & FMODE_WRITE)
iint->writecount++;
}
/*
* ima_counts_get - increment file counts
*
@ -145,62 +101,101 @@ void ima_counts_get(struct file *file)
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
fmode_t mode = file->f_mode;
struct ima_iint_cache *iint;
int rc;
bool send_tomtou = false, send_writers = false;
if (!iint_initialized || !S_ISREG(inode->i_mode))
if (!S_ISREG(inode->i_mode))
return;
iint = ima_iint_find_get(inode);
if (!iint)
return;
mutex_lock(&iint->mutex);
spin_lock(&inode->i_lock);
if (!ima_initialized)
goto out;
rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
if (rc < 0)
goto out;
if (mode & FMODE_WRITE) {
ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
if (inode->i_readcount && IS_IMA(inode))
send_tomtou = true;
goto out;
}
ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
out:
ima_inc_counts(iint, file->f_mode);
mutex_unlock(&iint->mutex);
kref_put(&iint->refcount, iint_free);
rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
if (rc < 0)
goto out;
if (atomic_read(&inode->i_writecount) > 0)
send_writers = true;
out:
/* remember the vfs deals with i_writecount */
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
inode->i_readcount++;
spin_unlock(&inode->i_lock);
if (send_tomtou)
ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
"ToMToU");
if (send_writers)
ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
"open_writers");
}
/*
* Decrement ima counts
*/
static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
struct file *file)
static void ima_dec_counts(struct inode *inode, struct file *file)
{
mode_t mode = file->f_mode;
BUG_ON(!mutex_is_locked(&iint->mutex));
iint->opencount--;
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
iint->readcount--;
if (mode & FMODE_WRITE) {
iint->writecount--;
if (iint->writecount == 0) {
if (iint->version != inode->i_version)
iint->flags &= ~IMA_MEASURED;
assert_spin_locked(&inode->i_lock);
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
if (unlikely(inode->i_readcount == 0)) {
if (!ima_limit_imbalance(file)) {
printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
__func__, inode->i_readcount);
dump_stack();
}
return;
}
inode->i_readcount--;
}
}
if (((iint->opencount < 0) ||
(iint->readcount < 0) ||
(iint->writecount < 0)) &&
!ima_limit_imbalance(file)) {
printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
__func__, iint->readcount, iint->writecount,
iint->opencount);
dump_stack();
}
static void ima_check_last_writer(struct ima_iint_cache *iint,
struct inode *inode,
struct file *file)
{
mode_t mode = file->f_mode;
BUG_ON(!mutex_is_locked(&iint->mutex));
assert_spin_locked(&inode->i_lock);
if (mode & FMODE_WRITE &&
atomic_read(&inode->i_writecount) == 1 &&
iint->version != inode->i_version)
iint->flags &= ~IMA_MEASURED;
}
static void ima_file_free_iint(struct ima_iint_cache *iint, struct inode *inode,
struct file *file)
{
mutex_lock(&iint->mutex);
spin_lock(&inode->i_lock);
ima_dec_counts(inode, file);
ima_check_last_writer(iint, inode, file);
spin_unlock(&inode->i_lock);
mutex_unlock(&iint->mutex);
}
static void ima_file_free_noiint(struct inode *inode, struct file *file)
{
spin_lock(&inode->i_lock);
ima_dec_counts(inode, file);
spin_unlock(&inode->i_lock);
}
/**
@ -208,7 +203,7 @@ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
* @file: pointer to file structure being freed
*
* Flag files that changed, based on i_version;
* and decrement the iint readcount/writecount.
* and decrement the i_readcount.
*/
void ima_file_free(struct file *file)
{
@ -217,14 +212,14 @@ void ima_file_free(struct file *file)
if (!iint_initialized || !S_ISREG(inode->i_mode))
return;
iint = ima_iint_find_get(inode);
if (!iint)
return;
mutex_lock(&iint->mutex);
ima_dec_counts(iint, inode, file);
mutex_unlock(&iint->mutex);
kref_put(&iint->refcount, iint_free);
iint = ima_iint_find(inode);
if (iint)
ima_file_free_iint(iint, inode, file);
else
ima_file_free_noiint(inode, file);
}
static int process_measurement(struct file *file, const unsigned char *filename,
@ -236,11 +231,21 @@ static int process_measurement(struct file *file, const unsigned char *filename,
if (!ima_initialized || !S_ISREG(inode->i_mode))
return 0;
iint = ima_iint_find_get(inode);
if (!iint)
return -ENOMEM;
rc = ima_must_measure(NULL, inode, mask, function);
if (rc != 0)
return rc;
retry:
iint = ima_iint_find(inode);
if (!iint) {
rc = ima_inode_alloc(inode);
if (!rc || rc == -EEXIST)
goto retry;
return rc;
}
mutex_lock(&iint->mutex);
rc = ima_must_measure(iint, inode, mask, function);
if (rc != 0)
goto out;
@ -250,7 +255,6 @@ static int process_measurement(struct file *file, const unsigned char *filename,
ima_store_measurement(iint, file, filename);
out:
mutex_unlock(&iint->mutex);
kref_put(&iint->refcount, iint_free);
return rc;
}

10
security/security.c
View File

@ -325,16 +325,8 @@ EXPORT_SYMBOL(security_sb_parse_opts_str);
int security_inode_alloc(struct inode *inode)
{
int ret;
inode->i_security = NULL;
ret = security_ops->inode_alloc_security(inode);
if (ret)
return ret;
ret = ima_inode_alloc(inode);
if (ret)
security_inode_free(inode);
return ret;
return security_ops->inode_alloc_security(inode);
}
void security_inode_free(struct inode *inode)