ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS

The IBPB control code in x86 removed the usage. Remove the functionality
which was introduced for this.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Casey Schaufler <[email protected]>
Cc: Asit Mallick <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Jon Masters <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Dave Stewart <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

Author: KAGA-KOKO

include/linux/ptrace.h

@@ -64,15 +64,12 @@ extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
 #define PTRACE_MODE_NOAUDIT	0x04
 #define PTRACE_MODE_FSCREDS	0x08
 #define PTRACE_MODE_REALCREDS	0x10
-#define PTRACE_MODE_SCHED	0x20
-#define PTRACE_MODE_IBPB	0x40
 
 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
-#define PTRACE_MODE_SPEC_IBPB (PTRACE_MODE_ATTACH_REALCREDS | PTRACE_MODE_IBPB)
 
 /**
  * ptrace_may_access - check whether the caller is permitted to access
@@ -90,20 +87,6 @@ extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  */
 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
 
-/**
- * ptrace_may_access - check whether the caller is permitted to access
- * a target task.
- * @task: target task
- * @mode: selects type of access and caller credentials
- *
- * Returns true on success, false on denial.
- *
- * Similar to ptrace_may_access(). Only to be called from context switch
- * code. Does not call into audit and the regular LSM hooks due to locking
- * constraints.
- */
-extern bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode);
-
 static inline int ptrace_reparented(struct task_struct *child)
 {
 	return !same_thread_group(child->real_parent, child->parent);

kernel/ptrace.c

@@ -261,9 +261,6 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 
 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 {
-	if (mode & PTRACE_MODE_SCHED)
-		return false;
-
 	if (mode & PTRACE_MODE_NOAUDIT)
 		return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 	else
@@ -331,16 +328,9 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	     !ptrace_has_cap(mm->user_ns, mode)))
 	    return -EPERM;
 
-	if (mode & PTRACE_MODE_SCHED)
-		return 0;
 	return security_ptrace_access_check(task, mode);
 }
 
-bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode)
-{
-	return __ptrace_may_access(task, mode | PTRACE_MODE_SCHED);
-}
-
 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	int err;