Commit f7ee1964 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

rseq: Replace the original debug implementation 



Just utilize the new infrastructure and put the original one to rest.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084307.212510692@linutronix.de
parent abc850e7

kernel/rseq.c

+12 −69
Original line number Diff line number Diff line
@@ -474,85 +474,28 @@ void __rseq_handle_notify_resume(struct ksignal *ksig, struct pt_regs *regs) 
}



#ifdef CONFIG_DEBUG_RSEQ

/*

 * Unsigned comparison will be true when ip >= start_ip, and when

 * ip < start_ip + post_commit_offset.

 */

static bool in_rseq_cs(unsigned long ip, struct rseq_cs *rseq_cs)

{

	return ip - rseq_cs->start_ip < rseq_cs->post_commit_offset;

}



/*

 * If the rseq_cs field of 'struct rseq' contains a valid pointer to

 * user-space, copy 'struct rseq_cs' from user-space and validate its fields.

 */

static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)

{

	struct rseq __user *urseq = t->rseq.usrptr;

	struct rseq_cs __user *urseq_cs;

	u32 __user *usig;

	u64 ptr;

	u32 sig;

	int ret;



	if (get_user(ptr, &rseq->rseq_cs))

		return -EFAULT;



	/* If the rseq_cs pointer is NULL, return a cleared struct rseq_cs. */

	if (!ptr) {

		memset(rseq_cs, 0, sizeof(*rseq_cs));

		return 0;

	}

	/* Check that the pointer value fits in the user-space process space. */

	if (ptr >= TASK_SIZE)

		return -EINVAL;

	urseq_cs = (struct rseq_cs __user *)(unsigned long)ptr;

	if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)))

		return -EFAULT;



	if (rseq_cs->start_ip >= TASK_SIZE ||

	    rseq_cs->start_ip + rseq_cs->post_commit_offset >= TASK_SIZE ||

	    rseq_cs->abort_ip >= TASK_SIZE ||

	    rseq_cs->version > 0)

		return -EINVAL;

	/* Check for overflow. */

	if (rseq_cs->start_ip + rseq_cs->post_commit_offset < rseq_cs->start_ip)

		return -EINVAL;

	/* Ensure that abort_ip is not in the critical section. */

	if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset)

		return -EINVAL;



	usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32));

	ret = get_user(sig, usig);

	if (ret)

		return ret;



	if (current->rseq.sig != sig) {

		printk_ratelimited(KERN_WARNING

			"Possible attack attempt. Unexpected rseq signature 0x%x, expecting 0x%x (pid=%d, addr=%p).\n",

			sig, current->rseq.sig, current->pid, usig);

		return -EINVAL;

	}

	return 0;

}



/*

 * Terminate the process if a syscall is issued within a restartable

 * sequence.

 */

void rseq_syscall(struct pt_regs *regs)

{

	unsigned long ip = instruction_pointer(regs);

	struct task_struct *t = current;

	struct rseq_cs rseq_cs;

	u64 csaddr;



	if (!t->rseq.usrptr)

	if (!t->rseq.event.has_rseq)

		return;

	if (rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))

	if (get_user(csaddr, &t->rseq.usrptr->rseq_cs))

		goto fail;

	if (likely(!csaddr))

		return;

	if (unlikely(csaddr >= TASK_SIZE))

		goto fail;

	if (rseq_debug_update_user_cs(t, regs, csaddr))

		return;

fail:

	force_sig(SIGSEGV);

}



#endif



/*