Commit 788e7dd4 authored by Yuichi Nakamura's avatar Yuichi Nakamura Committed by James Morris

SELinux: Improve read/write performance

It reduces the selinux overhead on read/write by only revalidating
permissions in selinux_file_permission if the task or inode labels have
changed or the policy has changed since the open-time check.  A new LSM
hook, security_dentry_open, is added to capture the necessary state at open
time to allow this optimization.

(see http://marc.info/?l=selinux&m=118972995207740&w=2)

Signed-off-by: Yuichi Nakamura<ynakam@hitachisoft.jp>
Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 3232c110
......@@ -757,6 +757,10 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_op = fops_get(inode->i_fop);
file_move(f, &inode->i_sb->s_files);
error = security_dentry_open(f);
if (error)
goto cleanup_all;
if (!open && f->f_op)
open = f->f_op->open;
if (open) {
......
......@@ -504,6 +504,13 @@ struct request_sock;
* @file contains the file structure being received.
* Return 0 if permission is granted.
*
* Security hook for dentry
*
* @dentry_open
* Save open-time permission checking state for later use upon
* file_permission, and recheck access if anything has changed
* since inode_permission.
*
* Security hooks for task operations.
*
* @task_create:
......@@ -1256,6 +1263,7 @@ struct security_operations {
int (*file_send_sigiotask) (struct task_struct * tsk,
struct fown_struct * fown, int sig);
int (*file_receive) (struct file * file);
int (*dentry_open) (struct file *file);
int (*task_create) (unsigned long clone_flags);
int (*task_alloc_security) (struct task_struct * p);
......@@ -1864,6 +1872,11 @@ static inline int security_file_receive (struct file *file)
return security_ops->file_receive (file);
}
static inline int security_dentry_open (struct file *file)
{
return security_ops->dentry_open (file);
}
static inline int security_task_create (unsigned long clone_flags)
{
return security_ops->task_create (clone_flags);
......@@ -2546,6 +2559,11 @@ static inline int security_file_receive (struct file *file)
return 0;
}
static inline int security_dentry_open (struct file *file)
{
return 0;
}
static inline int security_task_create (unsigned long clone_flags)
{
return 0;
......
......@@ -463,6 +463,11 @@ static int dummy_file_receive (struct file *file)
return 0;
}
static int dummy_dentry_open (struct file *file)
{
return 0;
}
static int dummy_task_create (unsigned long clone_flags)
{
return 0;
......@@ -1033,6 +1038,7 @@ void security_fixup_ops (struct security_operations *ops)
set_to_dummy_if_null(ops, file_set_fowner);
set_to_dummy_if_null(ops, file_send_sigiotask);
set_to_dummy_if_null(ops, file_receive);
set_to_dummy_if_null(ops, dentry_open);
set_to_dummy_if_null(ops, task_create);
set_to_dummy_if_null(ops, task_alloc_security);
set_to_dummy_if_null(ops, task_free_security);
......
......@@ -916,3 +916,8 @@ int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
return rc;
}
u32 avc_policy_seqno(void)
{
return avc_cache.latest_notif;
}
......@@ -14,6 +14,8 @@
* <dgoeddel@trustedcs.com>
* Copyright (C) 2006 Hewlett-Packard Development Company, L.P.
* Paul Moore, <paul.moore@hp.com>
* Copyright (C) 2007 Hitachi Software Engineering Co., Ltd.
* Yuichi Nakamura <ynakam@hitachisoft.jp>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2,
......@@ -2464,7 +2466,7 @@ static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t
/* file security operations */
static int selinux_file_permission(struct file *file, int mask)
static int selinux_revalidate_file_permission(struct file *file, int mask)
{
int rc;
struct inode *inode = file->f_path.dentry->d_inode;
......@@ -2486,6 +2488,25 @@ static int selinux_file_permission(struct file *file, int mask)
return selinux_netlbl_inode_permission(inode, mask);
}
static int selinux_file_permission(struct file *file, int mask)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct task_security_struct *tsec = current->security;
struct file_security_struct *fsec = file->f_security;
struct inode_security_struct *isec = inode->i_security;
if (!mask) {
/* No permission to check. Existence test. */
return 0;
}
if (tsec->sid == fsec->sid && fsec->isid == isec->sid
&& fsec->pseqno == avc_policy_seqno())
return selinux_netlbl_inode_permission(inode, mask);
return selinux_revalidate_file_permission(file, mask);
}
static int selinux_file_alloc_security(struct file *file)
{
return file_alloc_security(file);
......@@ -2725,6 +2746,34 @@ static int selinux_file_receive(struct file *file)
return file_has_perm(current, file, file_to_av(file));
}
static int selinux_dentry_open(struct file *file)
{
struct file_security_struct *fsec;
struct inode *inode;
struct inode_security_struct *isec;
inode = file->f_path.dentry->d_inode;
fsec = file->f_security;
isec = inode->i_security;
/*
* Save inode label and policy sequence number
* at open-time so that selinux_file_permission
* can determine whether revalidation is necessary.
* Task label is already saved in the file security
* struct as its SID.
*/
fsec->isid = isec->sid;
fsec->pseqno = avc_policy_seqno();
/*
* Since the inode label or policy seqno may have changed
* between the selinux_inode_permission check and the saving
* of state above, recheck that access is still permitted.
* Otherwise, access might never be revalidated against the
* new inode label or new policy.
* This check is not redundant - do not remove.
*/
return inode_has_perm(current, inode, file_to_av(file), NULL);
}
/* task security operations */
static int selinux_task_create(unsigned long clone_flags)
......@@ -4794,6 +4843,8 @@ static struct security_operations selinux_ops = {
.file_send_sigiotask = selinux_file_send_sigiotask,
.file_receive = selinux_file_receive,
.dentry_open = selinux_dentry_open,
.task_create = selinux_task_create,
.task_alloc_security = selinux_task_alloc_security,
.task_free_security = selinux_task_free_security,
......
......@@ -112,6 +112,8 @@ int avc_has_perm(u32 ssid, u32 tsid,
u16 tclass, u32 requested,
struct avc_audit_data *auditdata);
u32 avc_policy_seqno(void);
#define AVC_CALLBACK_GRANT 1
#define AVC_CALLBACK_TRY_REVOKE 2
#define AVC_CALLBACK_REVOKE 4
......
......@@ -53,6 +53,8 @@ struct file_security_struct {
struct file *file; /* back pointer to file object */
u32 sid; /* SID of open file description */
u32 fown_sid; /* SID of file owner (for SIGIO) */
u32 isid; /* SID of inode at the time of file open */
u32 pseqno; /* Policy seqno at the time of file open */
};
struct superblock_security_struct {
......
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