Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1049 insertions, 0 deletions

diff --git a/io_uring/register.c b/io_uring/register.c
new file mode 100644
index 000000000..02bc103bc
--- /dev/null
+++ b/io_uring/register.c
@@ -0,0 +1,1049 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Code related to the io_uring_register() syscall
+ *
+ * Copyright (C) 2023 Jens Axboe
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/syscalls.h>
+#include <linux/refcount.h>
+#include <linux/bits.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+#include <linux/compat.h>
+#include <linux/io_uring.h>
+#include <linux/io_uring_types.h>
+
+#include "filetable.h"
+#include "io_uring.h"
+#include "opdef.h"
+#include "tctx.h"
+#include "rsrc.h"
+#include "sqpoll.h"
+#include "register.h"
+#include "cancel.h"
+#include "kbuf.h"
+#include "napi.h"
+#include "eventfd.h"
+#include "msg_ring.h"
+#include "memmap.h"
+#include "zcrx.h"
+#include "query.h"
+#include "bpf_filter.h"
+
+#define IORING_MAX_RESTRICTIONS	(IORING_RESTRICTION_LAST + \
+				 IORING_REGISTER_LAST + IORING_OP_LAST)
+
+static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg,
+			   unsigned nr_args)
+{
+	struct io_uring_probe *p;
+	size_t size;
+	int i, ret;
+
+	if (nr_args > IORING_OP_LAST)
+		nr_args = IORING_OP_LAST;
+
+	size = struct_size(p, ops, nr_args);
+	p = memdup_user(arg, size);
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+	ret = -EINVAL;
+	if (memchr_inv(p, 0, size))
+		goto out;
+
+	p->last_op = IORING_OP_LAST - 1;
+
+	for (i = 0; i < nr_args; i++) {
+		p->ops[i].op = i;
+		if (io_uring_op_supported(i))
+			p->ops[i].flags = IO_URING_OP_SUPPORTED;
+	}
+	p->ops_len = i;
+
+	ret = 0;
+	if (copy_to_user(arg, p, size))
+		ret = -EFAULT;
+out:
+	kfree(p);
+	return ret;
+}
+
+int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
+{
+	const struct cred *creds;
+
+	creds = xa_erase(&ctx->personalities, id);
+	if (creds) {
+		put_cred(creds);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+
+static int io_register_personality(struct io_ring_ctx *ctx)
+{
+	const struct cred *creds;
+	u32 id;
+	int ret;
+
+	creds = get_current_cred();
+
+	ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
+			XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
+	if (ret < 0) {
+		put_cred(creds);
+		return ret;
+	}
+	return id;
+}
+
+/*
+ * Returns number of restrictions parsed and added on success, or < 0 for
+ * an error.
+ */
+static __cold int io_parse_restrictions(void __user *arg, unsigned int nr_args,
+					struct io_restriction *restrictions)
+{
+	struct io_uring_restriction *res;
+	size_t size;
+	int i, ret;
+
+	if (!arg || nr_args > IORING_MAX_RESTRICTIONS)
+		return -EINVAL;
+
+	size = array_size(nr_args, sizeof(*res));
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+
+	res = memdup_user(arg, size);
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+
+	ret = -EINVAL;
+
+	for (i = 0; i < nr_args; i++) {
+		switch (res[i].opcode) {
+		case IORING_RESTRICTION_REGISTER_OP:
+			if (res[i].register_op >= IORING_REGISTER_LAST)
+				goto err;
+			__set_bit(res[i].register_op, restrictions->register_op);
+			restrictions->reg_registered = true;
+			break;
+		case IORING_RESTRICTION_SQE_OP:
+			if (res[i].sqe_op >= IORING_OP_LAST)
+				goto err;
+			__set_bit(res[i].sqe_op, restrictions->sqe_op);
+			restrictions->op_registered = true;
+			break;
+		case IORING_RESTRICTION_SQE_FLAGS_ALLOWED:
+			restrictions->sqe_flags_allowed = res[i].sqe_flags;
+			restrictions->op_registered = true;
+			break;
+		case IORING_RESTRICTION_SQE_FLAGS_REQUIRED:
+			restrictions->sqe_flags_required = res[i].sqe_flags;
+			restrictions->op_registered = true;
+			break;
+		default:
+			goto err;
+		}
+	}
+	ret = nr_args;
+	if (!nr_args) {
+		restrictions->op_registered = true;
+		restrictions->reg_registered = true;
+	}
+err:
+	kfree(res);
+	return ret;
+}
+
+static __cold int io_register_restrictions(struct io_ring_ctx *ctx,
+					   void __user *arg, unsigned int nr_args)
+{
+	int ret;
+
+	/* Restrictions allowed only if rings started disabled */
+	if (!(ctx->flags & IORING_SETUP_R_DISABLED))
+		return -EBADFD;
+
+	/* We allow only a single restrictions registration */
+	if (ctx->restrictions.op_registered || ctx->restrictions.reg_registered)
+		return -EBUSY;
+
+	ret = io_parse_restrictions(arg, nr_args, &ctx->restrictions);
+	/*
+	 * Reset all restrictions if an error happened, but retain any COW'ed
+	 * settings.
+	 */
+	if (ret < 0) {
+		struct io_bpf_filters *bpf = ctx->restrictions.bpf_filters;
+		bool cowed = ctx->restrictions.bpf_filters_cow;
+
+		memset(&ctx->restrictions, 0, sizeof(ctx->restrictions));
+		ctx->restrictions.bpf_filters = bpf;
+		ctx->restrictions.bpf_filters_cow = cowed;
+		return ret;
+	}
+	if (ctx->restrictions.op_registered)
+		ctx->int_flags |= IO_RING_F_OP_RESTRICTED;
+	if (ctx->restrictions.reg_registered)
+		ctx->int_flags |= IO_RING_F_REG_RESTRICTED;
+	return 0;
+}
+
+static int io_register_restrictions_task(void __user *arg, unsigned int nr_args)
+{
+	struct io_uring_task_restriction __user *ures = arg;
+	struct io_uring_task_restriction tres;
+	struct io_restriction *res;
+	int ret;
+
+	/* Disallow if task already has registered restrictions */
+	if (current->io_uring_restrict)
+		return -EPERM;
+	/*
+	 * Similar to seccomp, disallow setting a filter if task_no_new_privs
+	 * is false and we're not CAP_SYS_ADMIN.
+	 */
+	if (!task_no_new_privs(current) &&
+	    !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
+		return -EACCES;
+	if (nr_args != 1)
+		return -EINVAL;
+
+	if (copy_from_user(&tres, arg, sizeof(tres)))
+		return -EFAULT;
+
+	if (tres.flags)
+		return -EINVAL;
+	if (!mem_is_zero(tres.resv, sizeof(tres.resv)))
+		return -EINVAL;
+
+	res = kzalloc_obj(*res, GFP_KERNEL_ACCOUNT);
+	if (!res)
+		return -ENOMEM;
+
+	ret = io_parse_restrictions(ures->restrictions, tres.nr_res, res);
+	if (ret < 0) {
+		kfree(res);
+		return ret;
+	}
+	current->io_uring_restrict = res;
+	return 0;
+}
+
+static int io_register_bpf_filter_task(void __user *arg, unsigned int nr_args)
+{
+	struct io_restriction *res;
+	int ret;
+
+	/*
+	 * Similar to seccomp, disallow setting a filter if task_no_new_privs
+	 * is false and we're not CAP_SYS_ADMIN.
+	 */
+	if (!task_no_new_privs(current) &&
+	    !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (nr_args != 1)
+		return -EINVAL;
+
+	/* If no task restrictions exist, setup a new set */
+	res = current->io_uring_restrict;
+	if (!res) {
+		res = kzalloc_obj(*res, GFP_KERNEL_ACCOUNT);
+		if (!res)
+			return -ENOMEM;
+	}
+
+	ret = io_register_bpf_filter(res, arg);
+	if (ret) {
+		if (res != current->io_uring_restrict)
+			kfree(res);
+		return ret;
+	}
+	if (!current->io_uring_restrict)
+		current->io_uring_restrict = res;
+	return 0;
+}
+
+static int io_register_enable_rings(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_R_DISABLED))
+		return -EBADFD;
+
+	if (ctx->flags & IORING_SETUP_SINGLE_ISSUER) {
+		ctx->submitter_task = get_task_struct(current);
+		/*
+		 * Lazy activation attempts would fail if it was polled before
+		 * submitter_task is set.
+		 */
+		if (wq_has_sleeper(&ctx->poll_wq))
+			io_activate_pollwq(ctx);
+	}
+
+	/* Keep submitter_task store before clearing IORING_SETUP_R_DISABLED */
+	smp_store_release(&ctx->flags, ctx->flags & ~IORING_SETUP_R_DISABLED);
+	if (ctx->sq_data && wq_has_sleeper(&ctx->sq_data->wait))
+		wake_up(&ctx->sq_data->wait);
+	return 0;
+}
+
+static __cold int __io_register_iowq_aff(struct io_ring_ctx *ctx,
+					 cpumask_var_t new_mask)
+{
+	int ret;
+
+	if (!(ctx->flags & IORING_SETUP_SQPOLL)) {
+		ret = io_wq_cpu_affinity(current->io_uring, new_mask);
+	} else {
+		mutex_unlock(&ctx->uring_lock);
+		ret = io_sqpoll_wq_cpu_affinity(ctx, new_mask);
+		mutex_lock(&ctx->uring_lock);
+	}
+
+	return ret;
+}
+
+static __cold int io_register_iowq_aff(struct io_ring_ctx *ctx,
+				       void __user *arg, unsigned len)
+{
+	cpumask_var_t new_mask;
+	int ret;
+
+	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_clear(new_mask);
+	if (len > cpumask_size())
+		len = cpumask_size();
+
+#ifdef CONFIG_COMPAT
+	if (in_compat_syscall())
+		ret = compat_get_bitmap(cpumask_bits(new_mask),
+					(const compat_ulong_t __user *)arg,
+					len * 8 /* CHAR_BIT */);
+	else
+#endif
+		ret = copy_from_user(new_mask, arg, len);
+
+	if (ret) {
+		free_cpumask_var(new_mask);
+		return -EFAULT;
+	}
+
+	ret = __io_register_iowq_aff(ctx, new_mask);
+	free_cpumask_var(new_mask);
+	return ret;
+}
+
+static __cold int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
+{
+	return __io_register_iowq_aff(ctx, NULL);
+}
+
+static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
+					       void __user *arg)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_tctx_node *node;
+	struct io_uring_task *tctx = NULL;
+	struct io_sq_data *sqd = NULL;
+	__u32 new_count[2];
+	int i, ret;
+
+	if (copy_from_user(new_count, arg, sizeof(new_count)))
+		return -EFAULT;
+	for (i = 0; i < ARRAY_SIZE(new_count); i++)
+		if (new_count[i] > INT_MAX)
+			return -EINVAL;
+
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		sqd = ctx->sq_data;
+		if (sqd) {
+			struct task_struct *tsk;
+
+			/*
+			 * Observe the correct sqd->lock -> ctx->uring_lock
+			 * ordering. Fine to drop uring_lock here, we hold
+			 * a ref to the ctx.
+			 */
+			refcount_inc(&sqd->refs);
+			mutex_unlock(&ctx->uring_lock);
+			mutex_lock(&sqd->lock);
+			mutex_lock(&ctx->uring_lock);
+			tsk = sqpoll_task_locked(sqd);
+			if (tsk)
+				tctx = tsk->io_uring;
+		}
+	} else {
+		tctx = current->io_uring;
+	}
+
+	BUILD_BUG_ON(sizeof(new_count) != sizeof(ctx->iowq_limits));
+
+	for (i = 0; i < ARRAY_SIZE(new_count); i++)
+		if (new_count[i])
+			ctx->iowq_limits[i] = new_count[i];
+	ctx->int_flags |= IO_RING_F_IOWQ_LIMITS_SET;
+
+	if (tctx && tctx->io_wq) {
+		ret = io_wq_max_workers(tctx->io_wq, new_count);
+		if (ret)
+			goto err;
+	} else {
+		memset(new_count, 0, sizeof(new_count));
+	}
+
+	if (sqd) {
+		mutex_unlock(&ctx->uring_lock);
+		mutex_unlock(&sqd->lock);
+		io_put_sq_data(sqd);
+		mutex_lock(&ctx->uring_lock);
+	}
+
+	if (copy_to_user(arg, new_count, sizeof(new_count)))
+		return -EFAULT;
+
+	/* that's it for SQPOLL, only the SQPOLL task creates requests */
+	if (sqd)
+		return 0;
+
+	/* now propagate the restriction to all registered users */
+	mutex_lock(&ctx->tctx_lock);
+	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
+		tctx = node->task->io_uring;
+		if (WARN_ON_ONCE(!tctx->io_wq))
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(new_count); i++)
+			new_count[i] = ctx->iowq_limits[i];
+		/* ignore errors, it always returns zero anyway */
+		(void)io_wq_max_workers(tctx->io_wq, new_count);
+	}
+	mutex_unlock(&ctx->tctx_lock);
+	return 0;
+err:
+	if (sqd) {
+		mutex_unlock(&ctx->uring_lock);
+		mutex_unlock(&sqd->lock);
+		io_put_sq_data(sqd);
+		mutex_lock(&ctx->uring_lock);
+	}
+	return ret;
+}
+
+static int io_register_clock(struct io_ring_ctx *ctx,
+			     struct io_uring_clock_register __user *arg)
+{
+	struct io_uring_clock_register reg;
+
+	if (copy_from_user(&reg, arg, sizeof(reg)))
+		return -EFAULT;
+	if (memchr_inv(&reg.__resv, 0, sizeof(reg.__resv)))
+		return -EINVAL;
+
+	switch (reg.clockid) {
+	case CLOCK_MONOTONIC:
+		ctx->clock_offset = 0;
+		break;
+	case CLOCK_BOOTTIME:
+		ctx->clock_offset = TK_OFFS_BOOT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ctx->clockid = reg.clockid;
+	return 0;
+}
+
+/*
+ * State to maintain until we can swap. Both new and old state, used for
+ * either mapping or freeing.
+ */
+struct io_ring_ctx_rings {
+	struct io_rings *rings;
+	struct io_uring_sqe *sq_sqes;
+
+	struct io_mapped_region sq_region;
+	struct io_mapped_region ring_region;
+};
+
+static void io_register_free_rings(struct io_ring_ctx *ctx,
+				   struct io_ring_ctx_rings *r)
+{
+	io_free_region(ctx->user, &r->sq_region);
+	io_free_region(ctx->user, &r->ring_region);
+}
+
+#define swap_old(ctx, o, n, field)		\
+	do {					\
+		(o).field = (ctx)->field;	\
+		(ctx)->field = (n).field;	\
+	} while (0)
+
+#define RESIZE_FLAGS	(IORING_SETUP_CQSIZE | IORING_SETUP_CLAMP)
+#define COPY_FLAGS	(IORING_SETUP_NO_SQARRAY | IORING_SETUP_SQE128 | \
+			 IORING_SETUP_CQE32 | IORING_SETUP_NO_MMAP | \
+			 IORING_SETUP_CQE_MIXED | IORING_SETUP_SQE_MIXED)
+
+static int io_register_resize_rings(struct io_ring_ctx *ctx, void __user *arg)
+{
+	struct io_ctx_config config;
+	struct io_uring_region_desc rd;
+	struct io_ring_ctx_rings o = { }, n = { }, *to_free = NULL;
+	unsigned i, tail, old_head;
+	struct io_uring_params *p = &config.p;
+	struct io_rings_layout *rl = &config.layout;
+	u32 *o_sq_array, *n_sq_array = NULL;
+	int ret;
+
+	memset(&config, 0, sizeof(config));
+
+	/* limited to DEFER_TASKRUN for now */
+	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
+		return -EINVAL;
+	if (copy_from_user(p, arg, sizeof(*p)))
+		return -EFAULT;
+	if (p->flags & ~RESIZE_FLAGS)
+		return -EINVAL;
+
+	/* properties that are always inherited */
+	p->flags |= (ctx->flags & COPY_FLAGS);
+
+	ret = io_prepare_config(&config);
+	if (unlikely(ret))
+		return ret;
+
+	memset(&rd, 0, sizeof(rd));
+	rd.size = PAGE_ALIGN(rl->rings_size);
+	if (p->flags & IORING_SETUP_NO_MMAP) {
+		rd.user_addr = p->cq_off.user_addr;
+		rd.flags |= IORING_MEM_REGION_TYPE_USER;
+	}
+	ret = io_create_region(ctx, &n.ring_region, &rd, IORING_OFF_CQ_RING);
+	if (ret)
+		return ret;
+
+	n.rings = io_region_get_ptr(&n.ring_region);
+
+	/*
+	 * At this point n.rings is shared with userspace, just like o.rings
+	 * is as well. While we don't expect userspace to modify it while
+	 * a resize is in progress, and it's most likely that userspace will
+	 * shoot itself in the foot if it does, we can't always assume good
+	 * intent... Use read/write once helpers from here on to indicate the
+	 * shared nature of it.
+	 */
+	WRITE_ONCE(n.rings->sq_ring_mask, p->sq_entries - 1);
+	WRITE_ONCE(n.rings->cq_ring_mask, p->cq_entries - 1);
+	WRITE_ONCE(n.rings->sq_ring_entries, p->sq_entries);
+	WRITE_ONCE(n.rings->cq_ring_entries, p->cq_entries);
+
+	if (copy_to_user(arg, p, sizeof(*p))) {
+		io_register_free_rings(ctx, &n);
+		return -EFAULT;
+	}
+
+	memset(&rd, 0, sizeof(rd));
+	rd.size = PAGE_ALIGN(rl->sq_size);
+	if (p->flags & IORING_SETUP_NO_MMAP) {
+		rd.user_addr = p->sq_off.user_addr;
+		rd.flags |= IORING_MEM_REGION_TYPE_USER;
+	}
+	ret = io_create_region(ctx, &n.sq_region, &rd, IORING_OFF_SQES);
+	if (ret) {
+		io_register_free_rings(ctx, &n);
+		return ret;
+	}
+	n.sq_sqes = io_region_get_ptr(&n.sq_region);
+
+	/*
+	 * If using SQPOLL, park the thread
+	 */
+	if (ctx->sq_data) {
+		mutex_unlock(&ctx->uring_lock);
+		io_sq_thread_park(ctx->sq_data);
+		mutex_lock(&ctx->uring_lock);
+	}
+
+	/*
+	 * We'll do the swap. Grab the ctx->mmap_lock, which will exclude
+	 * any new mmap's on the ring fd. Clear out existing mappings to prevent
+	 * mmap from seeing them, as we'll unmap them. Any attempt to mmap
+	 * existing rings beyond this point will fail. Not that it could proceed
+	 * at this point anyway, as the io_uring mmap side needs go grab the
+	 * ctx->mmap_lock as well. Likewise, hold the completion lock over the
+	 * duration of the actual swap.
+	 */
+	mutex_lock(&ctx->mmap_lock);
+	spin_lock(&ctx->completion_lock);
+	o.rings = ctx->rings;
+	ctx->rings = NULL;
+	o.sq_sqes = ctx->sq_sqes;
+	ctx->sq_sqes = NULL;
+	o_sq_array = ctx->sq_array;
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
+		n_sq_array = (u32 *)((char *)n.rings + rl->sq_array_offset);
+
+	/*
+	 * Now copy SQ and CQ entries, if any. If either of the destination
+	 * rings can't hold what is already there, then fail the operation.
+	 */
+	tail = READ_ONCE(o.rings->sq.tail);
+	old_head = READ_ONCE(o.rings->sq.head);
+	if (tail - old_head > p->sq_entries)
+		goto overflow;
+	for (i = old_head; i < tail; i++) {
+		unsigned int dst, src;
+		size_t sq_size;
+
+		dst = i & (p->sq_entries - 1);
+		src = i & (ctx->sq_entries - 1);
+		if (n_sq_array) {
+			src = READ_ONCE(o_sq_array[src]);
+			if (unlikely(src >= ctx->sq_entries)) {
+				WRITE_ONCE(n_sq_array[dst], UINT_MAX);
+				continue;
+			}
+			WRITE_ONCE(n_sq_array[dst], dst);
+		}
+
+		sq_size = sizeof(struct io_uring_sqe);
+		if (ctx->flags & IORING_SETUP_SQE128) {
+			dst <<= 1;
+			src <<= 1;
+			sq_size <<= 1;
+		}
+		memcpy(&n.sq_sqes[dst], &o.sq_sqes[src], sq_size);
+	}
+	WRITE_ONCE(n.rings->sq.head, old_head);
+	WRITE_ONCE(n.rings->sq.tail, tail);
+
+	tail = READ_ONCE(o.rings->cq.tail);
+	old_head = READ_ONCE(o.rings->cq.head);
+	if (tail - old_head > p->cq_entries) {
+overflow:
+		/* restore old rings, and return -EOVERFLOW via cleanup path */
+		ctx->rings = o.rings;
+		ctx->sq_sqes = o.sq_sqes;
+		to_free = &n;
+		ret = -EOVERFLOW;
+		goto out;
+	}
+	for (i = old_head; i < tail; i++) {
+		unsigned index, dst_mask, src_mask;
+		size_t cq_size;
+
+		index = i;
+		cq_size = sizeof(struct io_uring_cqe);
+		src_mask = ctx->cq_entries - 1;
+		dst_mask = p->cq_entries - 1;
+		if (ctx->flags & IORING_SETUP_CQE32) {
+			index <<= 1;
+			cq_size <<= 1;
+			src_mask = (ctx->cq_entries << 1) - 1;
+			dst_mask = (p->cq_entries << 1) - 1;
+		}
+		memcpy(&n.rings->cqes[index & dst_mask], &o.rings->cqes[index & src_mask], cq_size);
+	}
+	WRITE_ONCE(n.rings->cq.head, old_head);
+	WRITE_ONCE(n.rings->cq.tail, tail);
+	/* invalidate cached cqe refill */
+	ctx->cqe_cached = ctx->cqe_sentinel = NULL;
+
+	WRITE_ONCE(n.rings->sq_dropped, READ_ONCE(o.rings->sq_dropped));
+	atomic_set(&n.rings->sq_flags, atomic_read(&o.rings->sq_flags));
+	WRITE_ONCE(n.rings->cq_flags, READ_ONCE(o.rings->cq_flags));
+	WRITE_ONCE(n.rings->cq_overflow, READ_ONCE(o.rings->cq_overflow));
+
+	/* all done, store old pointers and assign new ones */
+	if (n_sq_array)
+		ctx->sq_array = n_sq_array;
+
+	ctx->sq_entries = p->sq_entries;
+	ctx->cq_entries = p->cq_entries;
+
+	/*
+	 * Just mark any flag we may have missed and that the application
+	 * should act on unconditionally. Worst case it'll be an extra
+	 * syscall.
+	 */
+	atomic_or(IORING_SQ_TASKRUN | IORING_SQ_NEED_WAKEUP, &n.rings->sq_flags);
+	ctx->rings = n.rings;
+	rcu_assign_pointer(ctx->rings_rcu, n.rings);
+
+	ctx->sq_sqes = n.sq_sqes;
+	swap_old(ctx, o, n, ring_region);
+	swap_old(ctx, o, n, sq_region);
+	to_free = &o;
+	ret = 0;
+out:
+	spin_unlock(&ctx->completion_lock);
+	mutex_unlock(&ctx->mmap_lock);
+	/* Wait for concurrent io_ctx_mark_taskrun() */
+	if (to_free == &o)
+		synchronize_rcu_expedited();
+	io_register_free_rings(ctx, to_free);
+
+	if (ctx->sq_data)
+		io_sq_thread_unpark(ctx->sq_data);
+
+	return ret;
+}
+
+static int io_register_mem_region(struct io_ring_ctx *ctx, void __user *uarg)
+{
+	struct io_uring_mem_region_reg __user *reg_uptr = uarg;
+	struct io_uring_mem_region_reg reg;
+	struct io_uring_region_desc __user *rd_uptr;
+	struct io_uring_region_desc rd;
+	struct io_mapped_region region = {};
+	int ret;
+
+	if (io_region_is_set(&ctx->param_region))
+		return -EBUSY;
+	if (copy_from_user(&reg, reg_uptr, sizeof(reg)))
+		return -EFAULT;
+	rd_uptr = u64_to_user_ptr(reg.region_uptr);
+	if (copy_from_user(&rd, rd_uptr, sizeof(rd)))
+		return -EFAULT;
+	if (memchr_inv(&reg.__resv, 0, sizeof(reg.__resv)))
+		return -EINVAL;
+	if (reg.flags & ~IORING_MEM_REGION_REG_WAIT_ARG)
+		return -EINVAL;
+
+	/*
+	 * This ensures there are no waiters. Waiters are unlocked and it's
+	 * hard to synchronise with them, especially if we need to initialise
+	 * the region.
+	 */
+	if ((reg.flags & IORING_MEM_REGION_REG_WAIT_ARG) &&
+	    !(ctx->flags & IORING_SETUP_R_DISABLED))
+		return -EINVAL;
+
+	ret = io_create_region(ctx, &region, &rd, IORING_MAP_OFF_PARAM_REGION);
+	if (ret)
+		return ret;
+	if (copy_to_user(rd_uptr, &rd, sizeof(rd))) {
+		io_free_region(ctx->user, &region);
+		return -EFAULT;
+	}
+
+	if (reg.flags & IORING_MEM_REGION_REG_WAIT_ARG) {
+		ctx->cq_wait_arg = io_region_get_ptr(&region);
+		ctx->cq_wait_size = rd.size;
+	}
+
+	io_region_publish(ctx, &region, &ctx->param_region);
+	return 0;
+}
+
+static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
+			       void __user *arg, unsigned nr_args)
+	__releases(ctx->uring_lock)
+	__acquires(ctx->uring_lock)
+{
+	int ret;
+
+	/*
+	 * We don't quiesce the refs for register anymore and so it can't be
+	 * dying as we're holding a file ref here.
+	 */
+	if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
+		return -ENXIO;
+
+	if (ctx->submitter_task && ctx->submitter_task != current)
+		return -EEXIST;
+
+	if ((ctx->int_flags & IO_RING_F_REG_RESTRICTED) && !(ctx->flags & IORING_SETUP_R_DISABLED)) {
+		opcode = array_index_nospec(opcode, IORING_REGISTER_LAST);
+		if (!test_bit(opcode, ctx->restrictions.register_op))
+			return -EACCES;
+	}
+
+	switch (opcode) {
+	case IORING_REGISTER_BUFFERS:
+		ret = -EFAULT;
+		if (!arg)
+			break;
+		ret = io_sqe_buffers_register(ctx, arg, nr_args, NULL);
+		break;
+	case IORING_UNREGISTER_BUFFERS:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_buffers_unregister(ctx);
+		break;
+	case IORING_REGISTER_FILES:
+		ret = -EFAULT;
+		if (!arg)
+			break;
+		ret = io_sqe_files_register(ctx, arg, nr_args, NULL);
+		break;
+	case IORING_UNREGISTER_FILES:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_files_unregister(ctx);
+		break;
+	case IORING_REGISTER_FILES_UPDATE:
+		ret = io_register_files_update(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_EVENTFD:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_eventfd_register(ctx, arg, 0);
+		break;
+	case IORING_REGISTER_EVENTFD_ASYNC:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_eventfd_register(ctx, arg, 1);
+		break;
+	case IORING_UNREGISTER_EVENTFD:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_eventfd_unregister(ctx);
+		break;
+	case IORING_REGISTER_PROBE:
+		ret = -EINVAL;
+		if (!arg || nr_args > 256)
+			break;
+		ret = io_probe(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_PERSONALITY:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_register_personality(ctx);
+		break;
+	case IORING_UNREGISTER_PERSONALITY:
+		ret = -EINVAL;
+		if (arg)
+			break;
+		ret = io_unregister_personality(ctx, nr_args);
+		break;
+	case IORING_REGISTER_ENABLE_RINGS:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_register_enable_rings(ctx);
+		break;
+	case IORING_REGISTER_RESTRICTIONS:
+		ret = io_register_restrictions(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_FILES2:
+		ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_FILE);
+		break;
+	case IORING_REGISTER_FILES_UPDATE2:
+		ret = io_register_rsrc_update(ctx, arg, nr_args,
+					      IORING_RSRC_FILE);
+		break;
+	case IORING_REGISTER_BUFFERS2:
+		ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_BUFFER);
+		break;
+	case IORING_REGISTER_BUFFERS_UPDATE:
+		ret = io_register_rsrc_update(ctx, arg, nr_args,
+					      IORING_RSRC_BUFFER);
+		break;
+	case IORING_REGISTER_IOWQ_AFF:
+		ret = -EINVAL;
+		if (!arg || !nr_args)
+			break;
+		ret = io_register_iowq_aff(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_IOWQ_AFF:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_unregister_iowq_aff(ctx);
+		break;
+	case IORING_REGISTER_IOWQ_MAX_WORKERS:
+		ret = -EINVAL;
+		if (!arg || nr_args != 2)
+			break;
+		ret = io_register_iowq_max_workers(ctx, arg);
+		break;
+	case IORING_REGISTER_RING_FDS:
+		ret = io_ringfd_register(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_RING_FDS:
+		ret = io_ringfd_unregister(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_PBUF_RING:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_pbuf_ring(ctx, arg);
+		break;
+	case IORING_UNREGISTER_PBUF_RING:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_unregister_pbuf_ring(ctx, arg);
+		break;
+	case IORING_REGISTER_SYNC_CANCEL:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_sync_cancel(ctx, arg);
+		break;
+	case IORING_REGISTER_FILE_ALLOC_RANGE:
+		ret = -EINVAL;
+		if (!arg || nr_args)
+			break;
+		ret = io_register_file_alloc_range(ctx, arg);
+		break;
+	case IORING_REGISTER_PBUF_STATUS:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_pbuf_status(ctx, arg);
+		break;
+	case IORING_REGISTER_NAPI:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_napi(ctx, arg);
+		break;
+	case IORING_UNREGISTER_NAPI:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_unregister_napi(ctx, arg);
+		break;
+	case IORING_REGISTER_CLOCK:
+		ret = -EINVAL;
+		if (!arg || nr_args)
+			break;
+		ret = io_register_clock(ctx, arg);
+		break;
+	case IORING_REGISTER_CLONE_BUFFERS:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_clone_buffers(ctx, arg);
+		break;
+	case IORING_REGISTER_ZCRX_IFQ:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_zcrx(ctx, arg);
+		break;
+	case IORING_REGISTER_RESIZE_RINGS:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_resize_rings(ctx, arg);
+		break;
+	case IORING_REGISTER_MEM_REGION:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_mem_region(ctx, arg);
+		break;
+	case IORING_REGISTER_QUERY:
+		ret = io_query(arg, nr_args);
+		break;
+	case IORING_REGISTER_ZCRX_CTRL:
+		ret = io_zcrx_ctrl(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_BPF_FILTER:
+		ret = -EINVAL;
+
+		if (nr_args != 1)
+			break;
+		ret = io_register_bpf_filter(&ctx->restrictions, arg);
+		if (!ret)
+			WRITE_ONCE(ctx->bpf_filters,
+				   ctx->restrictions.bpf_filters->filters);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int io_uring_register_send_msg_ring(void __user *arg, unsigned int nr_args)
+{
+	struct io_uring_sqe sqe;
+
+	if (!arg || nr_args != 1)
+		return -EINVAL;
+	if (copy_from_user(&sqe, arg, sizeof(sqe)))
+		return -EFAULT;
+	/* no flags supported */
+	if (sqe.flags)
+		return -EINVAL;
+	if (sqe.opcode != IORING_OP_MSG_RING)
+		return -EINVAL;
+
+	return io_uring_sync_msg_ring(&sqe);
+}
+
+/*
+ * "blind" registration opcodes are ones where there's no ring given, and
+ * hence the source fd must be -1.
+ */
+static int io_uring_register_blind(unsigned int opcode, void __user *arg,
+				   unsigned int nr_args)
+{
+	switch (opcode) {
+	case IORING_REGISTER_SEND_MSG_RING:
+		return io_uring_register_send_msg_ring(arg, nr_args);
+	case IORING_REGISTER_QUERY:
+		return io_query(arg, nr_args);
+	case IORING_REGISTER_RESTRICTIONS:
+		return io_register_restrictions_task(arg, nr_args);
+	case IORING_REGISTER_BPF_FILTER:
+		return io_register_bpf_filter_task(arg, nr_args);
+	}
+	return -EINVAL;
+}
+
+SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
+		void __user *, arg, unsigned int, nr_args)
+{
+	struct io_ring_ctx *ctx;
+	long ret = -EBADF;
+	struct file *file;
+	bool use_registered_ring;
+
+	use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);
+	opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
+
+	if (opcode >= IORING_REGISTER_LAST)
+		return -EINVAL;
+
+	if (fd == -1)
+		return io_uring_register_blind(opcode, arg, nr_args);
+
+	file = io_uring_ctx_get_file(fd, use_registered_ring);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+	ctx = file->private_data;
+
+	mutex_lock(&ctx->uring_lock);
+	ret = __io_uring_register(ctx, opcode, arg, nr_args);
+
+	trace_io_uring_register(ctx, opcode, ctx->file_table.data.nr,
+				ctx->buf_table.nr, ret);
+	mutex_unlock(&ctx->uring_lock);
+
+	if (!use_registered_ring)
+		fput(file);
+	return ret;
+}