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-rw-r--r--include/linux/cred.h65
1 files changed, 64 insertions, 1 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h
index b3c76e8..85439ab 100644
--- a/include/linux/cred.h
+++ b/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);
}
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