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ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP

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User mode linux is the last user of the PT_DTRACE flag.  Using the flag to indicate
single stepping is a little confusing and worse changing tsk->ptrace without locking
could potentionally cause problems.

So use a thread info flag with a better name instead of flag in tsk->ptrace.

Remove the definition PT_DTRACE as uml is the last user.

Cc: stable@vger.kernel.org
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-3-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2022-04-26 16:30:17 -05:00
parent e71ba12407
commit c200e4bb44
6 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/um/include/asm/thread_info.h
View File

@ -60,6 +60,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_RESTORE_SIGMASK 7
#define TIF_NOTIFY_RESUME 8
#define TIF_SECCOMP 9 /* secure computing */
#define TIF_SINGLESTEP 10 /* single stepping userspace */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
@ -68,5 +69,6 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
#endif

2
arch/um/kernel/exec.c
View File

@ -43,7 +43,7 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
{
PT_REGS_IP(regs) = eip;
PT_REGS_SP(regs) = esp;
current->ptrace &= ~PT_DTRACE;
clear_thread_flag(TIF_SINGLESTEP);
#ifdef SUBARCH_EXECVE1
SUBARCH_EXECVE1(regs->regs);
#endif

2
arch/um/kernel/process.c
View File

@ -335,7 +335,7 @@ int singlestepping(void * t)
{
struct task_struct *task = t ? t : current;
if (!(task->ptrace & PT_DTRACE))
if (!test_thread_flag(TIF_SINGLESTEP))
return 0;
if (task->thread.singlestep_syscall)

8
arch/um/kernel/ptrace.c
View File

@ -11,7 +11,7 @@
void user_enable_single_step(struct task_struct *child)
{
child->ptrace |= PT_DTRACE;
set_tsk_thread_flag(child, TIF_SINGLESTEP);
child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING
@ -21,7 +21,7 @@ void user_enable_single_step(struct task_struct *child)
void user_disable_single_step(struct task_struct *child)
{
child->ptrace &= ~PT_DTRACE;
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING
@ -120,7 +120,7 @@ static void send_sigtrap(struct uml_pt_regs *regs, int error_code)
}
/*
* XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
* XXX Check TIF_SINGLESTEP for singlestepping check and
* PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
*/
int syscall_trace_enter(struct pt_regs *regs)
@ -144,7 +144,7 @@ void syscall_trace_leave(struct pt_regs *regs)
audit_syscall_exit(regs);
/* Fake a debug trap */
if (ptraced & PT_DTRACE)
if (test_thread_flag(TIF_SINGLESTEP))
send_sigtrap(&regs->regs, 0);
if (!test_thread_flag(TIF_SYSCALL_TRACE))

4
arch/um/kernel/signal.c
View File

@ -53,7 +53,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
unsigned long sp;
int err;
if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED))
singlestep = 1;
/* Did we come from a system call? */
@ -128,7 +128,7 @@ void do_signal(struct pt_regs *regs)
* on the host. The tracing thread will check this flag and
* PTRACE_SYSCALL if necessary.
*/
if (current->ptrace & PT_DTRACE)
if (test_thread_flag(TIF_SINGLESTEP))
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(&current->thread.regs));

1
include/linux/ptrace.h
View File

@ -30,7 +30,6 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */
#define PT_PTRACED 0x00000001
#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
#define PT_OPT_FLAG_SHIFT 3
/* PT_TRACE_* event enable flags */