On Thu, 06 Sep 2007 09:47:15 -0400
Stephen Smalley wrote:
<snip>
> >
> > @@ -431,8 +432,10 @@ static int avc_latest_notif_update(int s
> > ret = -EAGAIN;
> > }
> > } else {
> > - if (seqno > avc_cache.latest_notif)
> > + if (seqno > avc_cache.latest_notif) {
> > avc_cache.latest_notif = seqno;
> > + policy_seqno = seqno;
> > + }
>
> I would have just provided an avc interface for obtaining the seqno,
> e.g.
> u32 avc_policy_seqno(void)
> {
> return avc_cache.latest_notif;
> }
Fixed.
>
> > }
> > spin_unlock_irqrestore(¬if_lock, flag);
> >
> > diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/hooks.c linux-2.6.22/security/selinux/hooks.c
> > --- linux-2.6.22.orig/security/selinux/hooks.c 2007-07-09 08:32:17.000000000 +0900
> > +++ linux-2.6.22/security/selinux/hooks.c 2007-09-06 16:08:36.000000000 +0900
> > @@ -84,6 +84,7 @@
> > extern unsigned int policydb_loaded_version;
> > extern int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm);
> > extern int selinux_compat_net;
> > +extern u32 policy_seqno;
>
> I think that they frown upon extern declarations in .c files (versus
> in .h files), so we don't want to add more - we ultimately should clean
> up what we presently have.
Removed policy_seqno.
>
> >
> > #ifdef CONFIG_SECURITY_SELINUX_DEVELOP
> > int selinux_enforcing = 0;
> > @@ -220,6 +221,8 @@ static int file_alloc_security(struct fi
> >
> > fsec->file = file;
> > fsec->sid = tsec->sid;
> > + fsec->tsid = tsec->sid;
>
> I'm not sure why we need the separate field here, as fsec->sid already
> holds the allocating task SID and doesn't change.
I see.
removed fsec->tsid.
> > + fsec->pseqno = policy_seqno;
>
> Not sure that you want to set the seqno here versus from your new hook,
> as it could conceivably change in between.
Fixed, pseqno is set in selinux_dentry_open.
> > fsec->fown_sid = tsec->sid;
> > file->f_security = fsec;
> >
> > @@ -2458,7 +2461,7 @@ static int selinux_inode_listsecurity(st
> >
> > /* file security operations */
> >
> > -static int selinux_file_permission(struct file *file, int mask)
> > +static int do_selinux_file_permission(struct file *file, int mask)
>
> Might want to rename for clarity, e.g.
> selinux_revalidate_file_permission or
> selinux_file_permission_slow (slow path) or
> something similar.
Renamed to selinux_revalidate_file_permission.
>
> > {
> > int rc;
> > struct inode *inode = file->f_path.dentry->d_inode;
> > @@ -2480,6 +2483,43 @@ static int selinux_file_permission(struc
> > 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->tsid) {
> > + if (tsec->sid != fsec->sid) {
> > + struct vfsmount *mnt = file->f_path.mnt;
> > + struct dentry *dentry = file->f_path.dentry;
> > + struct avc_audit_data ad;
> > + int rc;
> > + AVC_AUDIT_DATA_INIT(&ad, FS);
> > + ad.u.fs.mnt = mnt;
> > + ad.u.fs.dentry = dentry;
> > + rc = avc_has_perm(tsec->sid, fsec->sid,
> > + SECCLASS_FD,
> > + FD__USE,
> > + &ad);
> > + if (rc)
> > + return rc;
> > + }
>
> Why inline the FD_USE check here given that you are falling back to the
> full function call anyway? I also don't see why you separate this from
> the rest of the comparison - I'd just make it something like:
> if (tsec->sid == fsec->sid && isec->sid == fsec->isid &&
> avc_seqno() == fsec->seqno)
> return selinux_netlbl_inode_permission(inode, mask);
> return selinux_revalidate_file_permission(file, mask);
Thanks, I missed that.
FD_USE check is called in file_permission..
Fixed like you pointed out.
> > static int selinux_file_alloc_security(struct file *file)
> > {
> > return file_alloc_security(file);
> > @@ -2715,6 +2755,16 @@ static int selinux_file_receive(struct f
> > return file_has_perm(current, file, file_to_av(file));
> > }
> >
> > +static int selinux_dentry_open(struct file *file, int flags)
> > +{
> > + struct file_security_struct *fsec;
> > + struct inode_security_struct *isec;
> > + fsec = file->f_security;
> > + isec = file->f_path.dentry->d_inode->i_security;
> > + fsec->isid = isec->sid;
>
> Set the seqno here too. Ideally, it would come straight from the AVC
> entry that was used for the open-time check, but that is a bit more
> invasive and there will always be a small window there.
Fixed, setting pseqno now.
> > diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/include/objsec.h linux-2.6.22/security/selinux/include/objsec.h
> > --- linux-2.6.22.orig/security/selinux/include/objsec.h 2007-07-09 08:32:17.000000000 +0900
> > +++ linux-2.6.22/security/selinux/include/objsec.h 2007-09-06 14:58:11.000000000 +0900
> > @@ -53,6 +53,9 @@ 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 tsid; /* SID of task at the time of file open*/
> > + u32 isid; /* SID of inode at the time of file open */
> > + u32 pseqno; /* Policy seqno at the time of file open */
>
> No need for tsid above I think.
Removed tsid.
> > diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/include/linux/security.h linux-2.6.22/include/linux/security.h
> > --- linux-2.6.22.orig/include/linux/security.h 2007-07-09 08:32:17.000000000 +0900
> > +++ linux-2.6.22/include/linux/security.h 2007-09-06 15:22:39.000000000 +0900
> > @@ -503,6 +503,11 @@ struct request_sock;
> > * @file contains the file structure being received.
> > * Return 0 if permission is granted.
> > *
> > + * Security hook for dentry
> > + *
> > + * @dentry_open
> > + * Check permission or get additional information before opening dentry.
> > + *
> > * Security hooks for task operations.
> > *
> > * @task_create:
> > @@ -1253,6 +1258,7 @@ 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 flags);
> >
> > int (*task_create) (unsigned long clone_flags);
> > int (*task_alloc_security) (struct task_struct * p);
> > @@ -1854,6 +1860,11 @@ static inline int security_file_receive
> > return security_ops->file_receive (file);
> > }
> >
> > +static inline int security_dentry_open (struct file *file, int flags)
> > +{
> > + return security_ops->dentry_open (file, flags);
> > +}
> > +
> > static inline int security_task_create (unsigned long clone_flags)
> > {
> > return security_ops->task_create (clone_flags);
>
> Need to also provide the stub definition in the #else case (SECURITY=n)
> and a stub function for the dummy security module.
Fixed.
>
> Thanks.
>
> --
> Stephen Smalley
> National Security Agency
Next is updated patch.
Signed-off-by: Yuichi Nakamura<[email protected]>
---
fs/open.c | 5 +++++
include/linux/security.h | 16 ++++++++++++++++
security/selinux/avc.c | 5 +++++
security/selinux/hooks.c | 36 +++++++++++++++++++++++++++++++++++-
security/selinux/include/avc.h | 2 ++
security/selinux/include/objsec.h | 2 ++
6 files changed, 65 insertions(+), 1 deletion(-)
diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/avc.c linux-2.6.22/security/selinux/avc.c
--- linux-2.6.22.orig/security/selinux/avc.c 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/security/selinux/avc.c 2007-09-10 09:56:22.000000000 +0900
@@ -913,3 +913,8 @@ int avc_has_perm(u32 ssid, u32 tsid, u16
avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
return rc;
}
+
+u32 avc_policy_seqno(void)
+{
+ return avc_cache.latest_notif;
+}
diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/hooks.c linux-2.6.22/security/selinux/hooks.c
--- linux-2.6.22.orig/security/selinux/hooks.c 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/security/selinux/hooks.c 2007-09-10 10:11:13.000000000 +0900
@@ -14,6 +14,8 @@
* <[email protected]>
* Copyright (C) 2006 Hewlett-Packard Development Company, L.P.
* Paul Moore, <[email protected]>
+ * Copyright (C) 2007 Hitachi Software Engineering Co., Ltd.
+ * Yuichi Nakamura <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2,
@@ -2458,7 +2460,7 @@ static int selinux_inode_listsecurity(st
/* 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;
@@ -2480,6 +2482,25 @@ static int selinux_file_permission(struc
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);
@@ -2715,6 +2736,17 @@ static int selinux_file_receive(struct f
return file_has_perm(current, file, file_to_av(file));
}
+static int selinux_dentry_open(struct file *file, int flags)
+{
+ struct file_security_struct *fsec;
+ struct inode_security_struct *isec;
+ fsec = file->f_security;
+ isec = file->f_path.dentry->d_inode->i_security;
+ fsec->isid = isec->sid;
+ fsec->pseqno = avc_policy_seqno();
+ return 0;
+}
+
/* task security operations */
static int selinux_task_create(unsigned long clone_flags)
@@ -4780,6 +4812,8 @@ static struct security_operations selinu
.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 -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/include/avc.h linux-2.6.22/security/selinux/include/avc.h
--- linux-2.6.22.orig/security/selinux/include/avc.h 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/security/selinux/include/avc.h 2007-09-10 09:56:22.000000000 +0900
@@ -110,6 +110,8 @@ 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 -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/include/objsec.h linux-2.6.22/security/selinux/include/objsec.h
--- linux-2.6.22.orig/security/selinux/include/objsec.h 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/security/selinux/include/objsec.h 2007-09-10 09:56:22.000000000 +0900
@@ -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 {
diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/fs/open.c linux-2.6.22/fs/open.c
--- linux-2.6.22.orig/fs/open.c 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/fs/open.c 2007-09-10 09:56:22.000000000 +0900
@@ -698,6 +698,11 @@ static struct file *__dentry_open(struct
if (!open && f->f_op)
open = f->f_op->open;
+
+ error = security_dentry_open(f, flags);
+ if (error)
+ goto cleanup_all;
+
if (open) {
error = open(inode, f);
if (error)
diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/include/linux/security.h linux-2.6.22/include/linux/security.h
--- linux-2.6.22.orig/include/linux/security.h 2007-07-09 08:32:17.000000000 +0900
+++ linux-2.6.22/include/linux/security.h 2007-09-10 09:56:22.000000000 +0900
@@ -503,6 +503,11 @@ struct request_sock;
* @file contains the file structure being received.
* Return 0 if permission is granted.
*
+ * Security hook for dentry
+ *
+ * @dentry_open
+ * Check permission or get additional information before opening dentry.
+ *
* Security hooks for task operations.
*
* @task_create:
@@ -1253,6 +1258,7 @@ 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 flags);
int (*task_create) (unsigned long clone_flags);
int (*task_alloc_security) (struct task_struct * p);
@@ -1854,6 +1860,11 @@ static inline int security_file_receive
return security_ops->file_receive (file);
}
+static inline int security_dentry_open (struct file *file, int flags)
+{
+ return security_ops->dentry_open (file, flags);
+}
+
static inline int security_task_create (unsigned long clone_flags)
{
return security_ops->task_create (clone_flags);
@@ -2529,6 +2540,11 @@ static inline int security_file_receive
return 0;
}
+static inline int security_dentry_open (struct file *file, int flags)
+{
+ return 0;
+}
+
static inline int security_task_create (unsigned long clone_flags)
{
return 0;
Regards,
--
Yuichi Nakamura
Hitachi Software Engineering Co., Ltd.
Japan SELinux Users Group(JSELUG): http://www.selinux.gr.jp/
SELinux Policy Editor: http://seedit.sourceforge.net/
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