// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * linux/ipc/msgutil.c

   * Copyright (C) 1999, 2004 Manfred Spraul

   */
  
  #include <linux/spinlock.h>
  #include <linux/init.h>
  #include <linux/security.h>
  #include <linux/slab.h>
  #include <linux/ipc.h>

  #include <linux/msg.h>

  #include <linux/ipc_namespace.h>

  #include <linux/utsname.h>

  #include <linux/proc_ns.h>

  #include <linux/uaccess.h>

  #include <linux/sched.h>

  
  #include "util.h"

  DEFINE_SPINLOCK(mq_lock);

  /*
   * The next 2 defines are here bc this is the only file
   * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
   * and not CONFIG_IPC_NS.
   */
  struct ipc_namespace init_ipc_ns = {

  	.ns.count = REFCOUNT_INIT(1),

  	.user_ns = &init_user_ns,

  	.ns.inum = PROC_IPC_INIT_INO,

  #ifdef CONFIG_IPC_NS
  	.ns.ops = &ipcns_operations,
  #endif

  };

  struct msg_msgseg {

  	struct msg_msgseg *next;

  	/* the next part of the message follows immediately */
  };

  #define DATALEN_MSG	((size_t)PAGE_SIZE-sizeof(struct msg_msg))
  #define DATALEN_SEG	((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))

  static struct msg_msg *alloc_msg(size_t len)

  {
  	struct msg_msg *msg;
  	struct msg_msgseg **pseg;

  	size_t alen;

  	alen = min(len, DATALEN_MSG);

  	msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);

  	if (msg == NULL)

  		return NULL;

  
  	msg->next = NULL;
  	msg->security = NULL;

  	len -= alen;
  	pseg = &msg->next;
  	while (len > 0) {
  		struct msg_msgseg *seg;

  
  		cond_resched();

  		alen = min(len, DATALEN_SEG);

  		seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);

  		if (seg == NULL)
  			goto out_err;
  		*pseg = seg;
  		seg->next = NULL;
  		pseg = &seg->next;
  		len -= alen;
  	}
  
  	return msg;
  
  out_err:
  	free_msg(msg);
  	return NULL;
  }

  struct msg_msg *load_msg(const void __user *src, size_t len)

  {
  	struct msg_msg *msg;
  	struct msg_msgseg *seg;

  	int err = -EFAULT;

  	size_t alen;

  
  	msg = alloc_msg(len);
  	if (msg == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	alen = min(len, DATALEN_MSG);

  	if (copy_from_user(msg + 1, src, alen))

  		goto out_err;

  	for (seg = msg->next; seg != NULL; seg = seg->next) {
  		len -= alen;
  		src = (char __user *)src + alen;

  		alen = min(len, DATALEN_SEG);

  		if (copy_from_user(seg + 1, src, alen))

  			goto out_err;

  	}
  
  	err = security_msg_msg_alloc(msg);
  	if (err)
  		goto out_err;
  
  	return msg;
  
  out_err:
  	free_msg(msg);
  	return ERR_PTR(err);
  }

  #ifdef CONFIG_CHECKPOINT_RESTORE
  struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
  {
  	struct msg_msgseg *dst_pseg, *src_pseg;

  	size_t len = src->m_ts;
  	size_t alen;

  	if (src->m_ts > dst->m_ts)
  		return ERR_PTR(-EINVAL);

  	alen = min(len, DATALEN_MSG);

  	memcpy(dst + 1, src + 1, alen);

  	for (dst_pseg = dst->next, src_pseg = src->next;
  	     src_pseg != NULL;
  	     dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
  
  		len -= alen;

  		alen = min(len, DATALEN_SEG);

  		memcpy(dst_pseg + 1, src_pseg + 1, alen);

  	}
  
  	dst->m_type = src->m_type;
  	dst->m_ts = src->m_ts;
  
  	return dst;
  }

  #else
  struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
  {
  	return ERR_PTR(-ENOSYS);
  }

  #endif

  int store_msg(void __user *dest, struct msg_msg *msg, size_t len)

  {

  	size_t alen;

  	struct msg_msgseg *seg;

  	alen = min(len, DATALEN_MSG);

  	if (copy_to_user(dest, msg + 1, alen))
  		return -1;

  	for (seg = msg->next; seg != NULL; seg = seg->next) {
  		len -= alen;
  		dest = (char __user *)dest + alen;

  		alen = min(len, DATALEN_SEG);

  		if (copy_to_user(dest, seg + 1, alen))
  			return -1;

  	}
  	return 0;
  }
  
  void free_msg(struct msg_msg *msg)
  {
  	struct msg_msgseg *seg;
  
  	security_msg_msg_free(msg);
  
  	seg = msg->next;
  	kfree(msg);
  	while (seg != NULL) {
  		struct msg_msgseg *tmp = seg->next;

  
  		cond_resched();

  		kfree(seg);
  		seg = tmp;
  	}
  }