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Integrity: IMA file free imbalance

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The number of calls to ima_path_check()/ima_file_free()
should be balanced.  An extra call to fput(), indicates
the file could have been accessed without first being
measured.

Although f_count is incremented/decremented in places other
than fget/fput, like fget_light/fput_light and get_file, the
current task must already hold a file refcnt.  The call to
__fput() is delayed until the refcnt becomes 0, resulting
in ima_file_free() flagging any changes.

- add hook to increment opencount for IPC shared memory(SYSV),
  shmat files, and /dev/zero
- moved NULL iint test in opencount_get()

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Mimi Zohar
2009-02-04 09:07:02 -05:00
committed by James Morris
parent f4bd857bc8
commit 1df9f0a731
6 changed files with 72 additions and 0 deletions
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42
security/integrity/ima/ima_main.c
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@@ -66,6 +66,19 @@ void ima_file_free(struct file *file)
return;
mutex_lock(&iint->mutex);
if (iint->opencount <= 0) {
printk(KERN_INFO
"%s: %s open/free imbalance (r:%ld w:%ld o:%ld f:%ld)\n",
__FUNCTION__, file->f_dentry->d_name.name,
iint->readcount, iint->writecount,
iint->opencount, atomic_long_read(&file->f_count));
if (!(iint->flags & IMA_IINT_DUMP_STACK)) {
dump_stack();
iint->flags |= IMA_IINT_DUMP_STACK;
}
}
iint->opencount--;
if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
iint->readcount--;
@@ -119,6 +132,7 @@ static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
pr_info("%s dentry_open failed\n", filename);
return rc;
}
iint->opencount++;
iint->readcount++;
rc = ima_collect_measurement(iint, file);
@@ -159,6 +173,7 @@ int ima_path_check(struct path *path, int mask)
return 0;
mutex_lock(&iint->mutex);
iint->opencount++;
if ((mask & MAY_WRITE) || (mask == 0))
iint->writecount++;
else if (mask & (MAY_READ | MAY_EXEC))
@@ -219,6 +234,21 @@ out:
return rc;
}
static void opencount_get(struct file *file)
{
struct inode *inode = file->f_dentry->d_inode;
struct ima_iint_cache *iint;
if (!ima_initialized || !S_ISREG(inode->i_mode))
return;
iint = ima_iint_find_insert_get(inode);
if (!iint)
return;
mutex_lock(&iint->mutex);
iint->opencount++;
mutex_unlock(&iint->mutex);
}
/**
* ima_file_mmap - based on policy, collect/store measurement.
* @file: pointer to the file to be measured (May be NULL)
@@ -242,6 +272,18 @@ int ima_file_mmap(struct file *file, unsigned long prot)
return 0;
}
/*
* ima_shm_check - IPC shm and shmat create/fput a file
*
* Maintain the opencount for these files to prevent unnecessary
* imbalance messages.
*/
void ima_shm_check(struct file *file)
{
opencount_get(file);
return;
}
/**
* ima_bprm_check - based on policy, collect/store measurement.
* @bprm: contains the linux_binprm structure