---

yaml
---
r: 157338
b: refs/heads/master
c: e0e8173
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ed6d76e4c32de0c2ad5f1d572b948ef49e465176
+refs/heads/master: e0e817392b9acf2c98d3be80c233dddb1b52003d

trunk/fs/nfsd/auth.c

@@ -34,6 +34,8 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
 	int flags = nfsexp_flags(rqstp, exp);
 	int ret;
 
+	validate_process_creds();
+
 	/* discard any old override before preparing the new set */
 	revert_creds(get_cred(current->real_cred));
 	new = prepare_creds();
@@ -86,8 +88,10 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
 	else
 		new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
 							new->cap_permitted);
+	validate_process_creds();
 	put_cred(override_creds(new));
 	put_cred(new);
+	validate_process_creds();
 	return 0;
 
 oom:

trunk/fs/nfsd/nfssvc.c

@@ -496,7 +496,9 @@ nfsd(void *vrqstp)
 		/* Lock the export hash tables for reading. */
 		exp_readlock();
 
+		validate_process_creds();
 		svc_process(rqstp);
+		validate_process_creds();
 
 		/* Unlock export hash tables */
 		exp_readunlock();

trunk/fs/nfsd/vfs.c

@@ -684,6 +684,8 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 	__be32		err;
 	int		host_err;
 
+	validate_process_creds();
+
 	/*
 	 * If we get here, then the client has already done an "open",
 	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
@@ -740,6 +742,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 out_nfserr:
 	err = nfserrno(host_err);
 out:
+	validate_process_creds();
 	return err;
 }
 

trunk/fs/open.c

@@ -959,6 +959,8 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 	int error;
 	struct file *f;
 
+	validate_creds(cred);
+
 	/*
 	 * We must always pass in a valid mount pointer.   Historically
 	 * callers got away with not passing it, but we must enforce this at

trunk/include/linux/cred.h

@@ -114,6 +114,13 @@ struct thread_group_cred {
  */
 struct cred {
 	atomic_t	usage;
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	atomic_t	subscribers;	/* number of processes subscribed */
+	void		*put_addr;
+	unsigned	magic;
+#define CRED_MAGIC	0x43736564
+#define CRED_MAGIC_DEAD	0x44656144
+#endif
 	uid_t		uid;		/* real UID of the task */
 	gid_t		gid;		/* real GID of the task */
 	uid_t		suid;		/* saved UID of the task */
@@ -143,6 +150,7 @@ struct cred {
 };
 
 extern void __put_cred(struct cred *);
+extern void exit_creds(struct task_struct *);
 extern int copy_creds(struct task_struct *, unsigned long);
 extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
@@ -158,6 +166,60 @@ extern int set_security_override_from_ctx(struct cred *, const char *);
 extern int set_create_files_as(struct cred *, struct inode *);
 extern void __init cred_init(void);
 
+/*
+ * check for validity of credentials
+ */
+#ifdef CONFIG_DEBUG_CREDENTIALS
+extern void __invalid_creds(const struct cred *, const char *, unsigned);
+extern void __validate_process_creds(struct task_struct *,
+				     const char *, unsigned);
+
+static inline bool creds_are_invalid(const struct cred *cred)
+{
+	if (cred->magic != CRED_MAGIC)
+		return true;
+	if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers))
+		return true;
+#ifdef CONFIG_SECURITY_SELINUX
+	if ((unsigned long) cred->security < PAGE_SIZE)
+		return true;
+	if ((*(u32*)cred->security & 0xffffff00) ==
+	    (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
+		return true;
+#endif
+	return false;
+}
+
+static inline void __validate_creds(const struct cred *cred,
+				    const char *file, unsigned line)
+{
+	if (unlikely(creds_are_invalid(cred)))
+		__invalid_creds(cred, file, line);
+}
+
+#define validate_creds(cred)				\
+do {							\
+	__validate_creds((cred), __FILE__, __LINE__);	\
+} while(0)
+
+#define validate_process_creds()				\
+do {								\
+	__validate_process_creds(current, __FILE__, __LINE__);	\
+} while(0)
+
+extern void validate_creds_for_do_exit(struct task_struct *);
+#else
+static inline void validate_creds(const struct cred *cred)
+{
+}
+static inline void validate_creds_for_do_exit(struct task_struct *tsk)
+{
+}
+static inline void validate_process_creds(void)
+{
+}
+#endif
+
 /**
  * get_new_cred - Get a reference on a new set of credentials
  * @cred: The new credentials to reference
@@ -187,6 +249,7 @@ static inline struct cred *get_new_cred(struct cred *cred)
 static inline const struct cred *get_cred(const struct cred *cred)
 {
 	struct cred *nonconst_cred = (struct cred *) cred;
+	validate_creds(cred);
 	return get_new_cred(nonconst_cred);
 }
 
@@ -205,7 +268,7 @@ static inline void put_cred(const struct cred *_cred)
 {
 	struct cred *cred = (struct cred *) _cred;
 
-	BUG_ON(atomic_read(&(cred)->usage) <= 0);
+	validate_creds(cred);
 	if (atomic_dec_and_test(&(cred)->usage))
 		__put_cred(cred);
 }