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authorYuichi Nakamura <ynakam@hitachisoft.jp>2007-09-14 09:27:07 +0900
committerJames Morris <jmorris@namei.org>2007-10-17 08:59:31 +1000
commit788e7dd4c22e6f41b3a118fd8c291f831f6fddbb (patch)
treecbe2d2a360aaf7dc243bef432e1c50507ae6db7b /security/selinux
parent3232c110b56bd01c5f0fdfd16b4d695f2e05b0a9 (diff)
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: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/avc.c5
-rw-r--r--security/selinux/hooks.c53
-rw-r--r--security/selinux/include/avc.h2
-rw-r--r--security/selinux/include/objsec.h2
4 files changed, 61 insertions, 1 deletions
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 0e69adf63bdb..81b3dff3cbf0 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -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;
+}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index cf76150e623e..97b7e2738097 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -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,
diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h
index e145f6e13b0b..553607a19e92 100644
--- a/security/selinux/include/avc.h
+++ b/security/selinux/include/avc.h
@@ -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
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 91b88f0ba20c..642a9fd319ad 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -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 {