msgutil.c 2.3 KB

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  1. /*
  2. * linux/ipc/msgutil.c
  3. * Copyright (C) 1999, 2004 Manfred Spraul
  4. *
  5. * This file is released under GNU General Public Licence version 2 or
  6. * (at your option) any later version.
  7. *
  8. * See the file COPYING for more details.
  9. */
  10. #include <linux/spinlock.h>
  11. #include <linux/init.h>
  12. #include <linux/security.h>
  13. #include <linux/slab.h>
  14. #include <linux/ipc.h>
  15. #include <asm/uaccess.h>
  16. #include "util.h"
  17. struct msg_msgseg {
  18. struct msg_msgseg* next;
  19. /* the next part of the message follows immediately */
  20. };
  21. #define DATALEN_MSG (PAGE_SIZE-sizeof(struct msg_msg))
  22. #define DATALEN_SEG (PAGE_SIZE-sizeof(struct msg_msgseg))
  23. struct msg_msg *load_msg(const void __user *src, int len)
  24. {
  25. struct msg_msg *msg;
  26. struct msg_msgseg **pseg;
  27. int err;
  28. int alen;
  29. alen = len;
  30. if (alen > DATALEN_MSG)
  31. alen = DATALEN_MSG;
  32. msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  33. if (msg == NULL)
  34. return ERR_PTR(-ENOMEM);
  35. msg->next = NULL;
  36. msg->security = NULL;
  37. if (copy_from_user(msg + 1, src, alen)) {
  38. err = -EFAULT;
  39. goto out_err;
  40. }
  41. len -= alen;
  42. src = ((char __user *)src) + alen;
  43. pseg = &msg->next;
  44. while (len > 0) {
  45. struct msg_msgseg *seg;
  46. alen = len;
  47. if (alen > DATALEN_SEG)
  48. alen = DATALEN_SEG;
  49. seg = kmalloc(sizeof(*seg) + alen,
  50. GFP_KERNEL);
  51. if (seg == NULL) {
  52. err = -ENOMEM;
  53. goto out_err;
  54. }
  55. *pseg = seg;
  56. seg->next = NULL;
  57. if (copy_from_user(seg + 1, src, alen)) {
  58. err = -EFAULT;
  59. goto out_err;
  60. }
  61. pseg = &seg->next;
  62. len -= alen;
  63. src = ((char __user *)src) + alen;
  64. }
  65. err = security_msg_msg_alloc(msg);
  66. if (err)
  67. goto out_err;
  68. return msg;
  69. out_err:
  70. free_msg(msg);
  71. return ERR_PTR(err);
  72. }
  73. int store_msg(void __user *dest, struct msg_msg *msg, int len)
  74. {
  75. int alen;
  76. struct msg_msgseg *seg;
  77. alen = len;
  78. if (alen > DATALEN_MSG)
  79. alen = DATALEN_MSG;
  80. if (copy_to_user(dest, msg + 1, alen))
  81. return -1;
  82. len -= alen;
  83. dest = ((char __user *)dest) + alen;
  84. seg = msg->next;
  85. while (len > 0) {
  86. alen = len;
  87. if (alen > DATALEN_SEG)
  88. alen = DATALEN_SEG;
  89. if (copy_to_user(dest, seg + 1, alen))
  90. return -1;
  91. len -= alen;
  92. dest = ((char __user *)dest) + alen;
  93. seg = seg->next;
  94. }
  95. return 0;
  96. }
  97. void free_msg(struct msg_msg *msg)
  98. {
  99. struct msg_msgseg *seg;
  100. security_msg_msg_free(msg);
  101. seg = msg->next;
  102. kfree(msg);
  103. while (seg != NULL) {
  104. struct msg_msgseg *tmp = seg->next;
  105. kfree(seg);
  106. seg = tmp;
  107. }
  108. }