namei.c 5.7 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * linux/fs/sysv/namei.c
  4. *
  5. * minix/namei.c
  6. * Copyright (C) 1991, 1992 Linus Torvalds
  7. *
  8. * coh/namei.c
  9. * Copyright (C) 1993 Pascal Haible, Bruno Haible
  10. *
  11. * sysv/namei.c
  12. * Copyright (C) 1993 Bruno Haible
  13. * Copyright (C) 1997, 1998 Krzysztof G. Baranowski
  14. */
  15. #include <linux/pagemap.h>
  16. #include "sysv.h"
  17. static int add_nondir(struct dentry *dentry, struct inode *inode)
  18. {
  19. int err = sysv_add_link(dentry, inode);
  20. if (!err) {
  21. d_instantiate(dentry, inode);
  22. return 0;
  23. }
  24. inode_dec_link_count(inode);
  25. iput(inode);
  26. return err;
  27. }
  28. static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
  29. {
  30. struct inode * inode = NULL;
  31. ino_t ino;
  32. if (dentry->d_name.len > SYSV_NAMELEN)
  33. return ERR_PTR(-ENAMETOOLONG);
  34. ino = sysv_inode_by_name(dentry);
  35. if (ino)
  36. inode = sysv_iget(dir->i_sb, ino);
  37. return d_splice_alias(inode, dentry);
  38. }
  39. static int sysv_mknod(struct user_namespace *mnt_userns, struct inode *dir,
  40. struct dentry *dentry, umode_t mode, dev_t rdev)
  41. {
  42. struct inode * inode;
  43. int err;
  44. if (!old_valid_dev(rdev))
  45. return -EINVAL;
  46. inode = sysv_new_inode(dir, mode);
  47. err = PTR_ERR(inode);
  48. if (!IS_ERR(inode)) {
  49. sysv_set_inode(inode, rdev);
  50. mark_inode_dirty(inode);
  51. err = add_nondir(dentry, inode);
  52. }
  53. return err;
  54. }
  55. static int sysv_create(struct user_namespace *mnt_userns, struct inode *dir,
  56. struct dentry *dentry, umode_t mode, bool excl)
  57. {
  58. return sysv_mknod(&init_user_ns, dir, dentry, mode, 0);
  59. }
  60. static int sysv_symlink(struct user_namespace *mnt_userns, struct inode *dir,
  61. struct dentry *dentry, const char *symname)
  62. {
  63. int err = -ENAMETOOLONG;
  64. int l = strlen(symname)+1;
  65. struct inode * inode;
  66. if (l > dir->i_sb->s_blocksize)
  67. goto out;
  68. inode = sysv_new_inode(dir, S_IFLNK|0777);
  69. err = PTR_ERR(inode);
  70. if (IS_ERR(inode))
  71. goto out;
  72. sysv_set_inode(inode, 0);
  73. err = page_symlink(inode, symname, l);
  74. if (err)
  75. goto out_fail;
  76. mark_inode_dirty(inode);
  77. err = add_nondir(dentry, inode);
  78. out:
  79. return err;
  80. out_fail:
  81. inode_dec_link_count(inode);
  82. iput(inode);
  83. goto out;
  84. }
  85. static int sysv_link(struct dentry * old_dentry, struct inode * dir,
  86. struct dentry * dentry)
  87. {
  88. struct inode *inode = d_inode(old_dentry);
  89. inode->i_ctime = current_time(inode);
  90. inode_inc_link_count(inode);
  91. ihold(inode);
  92. return add_nondir(dentry, inode);
  93. }
  94. static int sysv_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
  95. struct dentry *dentry, umode_t mode)
  96. {
  97. struct inode * inode;
  98. int err;
  99. inode_inc_link_count(dir);
  100. inode = sysv_new_inode(dir, S_IFDIR|mode);
  101. err = PTR_ERR(inode);
  102. if (IS_ERR(inode))
  103. goto out_dir;
  104. sysv_set_inode(inode, 0);
  105. inode_inc_link_count(inode);
  106. err = sysv_make_empty(inode, dir);
  107. if (err)
  108. goto out_fail;
  109. err = sysv_add_link(dentry, inode);
  110. if (err)
  111. goto out_fail;
  112. d_instantiate(dentry, inode);
  113. out:
  114. return err;
  115. out_fail:
  116. inode_dec_link_count(inode);
  117. inode_dec_link_count(inode);
  118. iput(inode);
  119. out_dir:
  120. inode_dec_link_count(dir);
  121. goto out;
  122. }
  123. static int sysv_unlink(struct inode * dir, struct dentry * dentry)
  124. {
  125. struct inode * inode = d_inode(dentry);
  126. struct page * page;
  127. struct sysv_dir_entry * de;
  128. int err = -ENOENT;
  129. de = sysv_find_entry(dentry, &page);
  130. if (!de)
  131. goto out;
  132. err = sysv_delete_entry (de, page);
  133. if (err)
  134. goto out;
  135. inode->i_ctime = dir->i_ctime;
  136. inode_dec_link_count(inode);
  137. out:
  138. return err;
  139. }
  140. static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
  141. {
  142. struct inode *inode = d_inode(dentry);
  143. int err = -ENOTEMPTY;
  144. if (sysv_empty_dir(inode)) {
  145. err = sysv_unlink(dir, dentry);
  146. if (!err) {
  147. inode->i_size = 0;
  148. inode_dec_link_count(inode);
  149. inode_dec_link_count(dir);
  150. }
  151. }
  152. return err;
  153. }
  154. /*
  155. * Anybody can rename anything with this: the permission checks are left to the
  156. * higher-level routines.
  157. */
  158. static int sysv_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
  159. struct dentry *old_dentry, struct inode *new_dir,
  160. struct dentry *new_dentry, unsigned int flags)
  161. {
  162. struct inode * old_inode = d_inode(old_dentry);
  163. struct inode * new_inode = d_inode(new_dentry);
  164. struct page * dir_page = NULL;
  165. struct sysv_dir_entry * dir_de = NULL;
  166. struct page * old_page;
  167. struct sysv_dir_entry * old_de;
  168. int err = -ENOENT;
  169. if (flags & ~RENAME_NOREPLACE)
  170. return -EINVAL;
  171. old_de = sysv_find_entry(old_dentry, &old_page);
  172. if (!old_de)
  173. goto out;
  174. if (S_ISDIR(old_inode->i_mode)) {
  175. err = -EIO;
  176. dir_de = sysv_dotdot(old_inode, &dir_page);
  177. if (!dir_de)
  178. goto out_old;
  179. }
  180. if (new_inode) {
  181. struct page * new_page;
  182. struct sysv_dir_entry * new_de;
  183. err = -ENOTEMPTY;
  184. if (dir_de && !sysv_empty_dir(new_inode))
  185. goto out_dir;
  186. err = -ENOENT;
  187. new_de = sysv_find_entry(new_dentry, &new_page);
  188. if (!new_de)
  189. goto out_dir;
  190. sysv_set_link(new_de, new_page, old_inode);
  191. new_inode->i_ctime = current_time(new_inode);
  192. if (dir_de)
  193. drop_nlink(new_inode);
  194. inode_dec_link_count(new_inode);
  195. } else {
  196. err = sysv_add_link(new_dentry, old_inode);
  197. if (err)
  198. goto out_dir;
  199. if (dir_de)
  200. inode_inc_link_count(new_dir);
  201. }
  202. sysv_delete_entry(old_de, old_page);
  203. mark_inode_dirty(old_inode);
  204. if (dir_de) {
  205. sysv_set_link(dir_de, dir_page, new_dir);
  206. inode_dec_link_count(old_dir);
  207. }
  208. return 0;
  209. out_dir:
  210. if (dir_de) {
  211. kunmap(dir_page);
  212. put_page(dir_page);
  213. }
  214. out_old:
  215. kunmap(old_page);
  216. put_page(old_page);
  217. out:
  218. return err;
  219. }
  220. /*
  221. * directories can handle most operations...
  222. */
  223. const struct inode_operations sysv_dir_inode_operations = {
  224. .create = sysv_create,
  225. .lookup = sysv_lookup,
  226. .link = sysv_link,
  227. .unlink = sysv_unlink,
  228. .symlink = sysv_symlink,
  229. .mkdir = sysv_mkdir,
  230. .rmdir = sysv_rmdir,
  231. .mknod = sysv_mknod,
  232. .rename = sysv_rename,
  233. .getattr = sysv_getattr,
  234. };