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1.1.1.2 root 1: /*
2: * linux/fs/namei.c
3: *
4: * (C) 1991 Linus Torvalds
5: */
6:
1.1.1.3 root 7: /*
8: * Some corrections by tytso.
9: */
10:
1.1 root 11: #include <linux/sched.h>
12: #include <linux/kernel.h>
13: #include <asm/segment.h>
14:
1.1.1.7 ! root 15: #include <linux/string.h>
1.1 root 16: #include <fcntl.h>
17: #include <errno.h>
18: #include <const.h>
19: #include <sys/stat.h>
20:
1.1.1.5 root 21: struct inode * _namei(const char * filename, struct inode * base,
1.1.1.4 root 22: int follow_links);
23:
1.1 root 24: #define ACC_MODE(x) ("\004\002\006\377"[(x)&O_ACCMODE])
25:
26: /*
1.1.1.5 root 27: * comment out this line if you want names > MINIX_NAME_LEN chars to be
1.1 root 28: * truncated. Else they will be disallowed.
29: */
30: /* #define NO_TRUNCATE */
31:
32: /*
33: * permission()
34: *
35: * is used to check for read/write/execute permissions on a file.
36: * I don't know if we should look at just the euid or both euid and
37: * uid, but that should be easily changed.
38: */
1.1.1.5 root 39: int permission(struct inode * inode,int mask)
1.1 root 40: {
41: int mode = inode->i_mode;
42:
43: /* special case: not even root can read/write a deleted file */
1.1.1.5 root 44: if (inode->i_dev && !inode->i_nlink)
1.1 root 45: return 0;
1.1.1.5 root 46: else if (current->euid == inode->i_uid)
1.1 root 47: mode >>= 6;
1.1.1.4 root 48: else if (in_group_p(inode->i_gid))
1.1 root 49: mode >>= 3;
1.1.1.2 root 50: if (((mode & mask & 0007) == mask) || suser())
51: return 1;
52: return 0;
1.1 root 53: }
54:
55: /*
1.1.1.5 root 56: * lookup() looks up one part of a pathname, using the fs-dependent
57: * routines (currently minix_lookup) for it. It also checks for
58: * fathers (pseudo-roots, mount-points)
1.1 root 59: */
1.1.1.5 root 60: int lookup(struct inode * dir,const char * name, int len,
61: struct inode ** result)
1.1 root 62: {
1.1.1.2 root 63: struct super_block * sb;
1.1 root 64:
1.1.1.5 root 65: *result = NULL;
66: if (len==2 && get_fs_byte(name)=='.' && get_fs_byte(name+1)=='.') {
67: if (dir == current->root)
68: len = 1;
69: else if ((sb = dir->i_sb) && (dir == sb->s_mounted)) {
70: sb = dir->i_sb;
71: iput(dir);
72: if (dir = sb->s_covered)
73: dir->i_count++;
1.1.1.2 root 74: }
75: }
1.1.1.5 root 76: if (!dir)
77: return -ENOENT;
78: if (!permission(dir,MAY_EXEC)) {
79: iput(dir);
80: return -EACCES;
1.1 root 81: }
1.1.1.5 root 82: if (!len) {
83: *result = dir;
84: return 0;
85: }
86: if (!dir->i_op || !dir->i_op->lookup) {
87: iput(dir);
88: return -ENOENT;
1.1 root 89: }
1.1.1.5 root 90: return dir->i_op->lookup(dir,name,len,result);
1.1 root 91: }
92:
1.1.1.5 root 93: struct inode * follow_link(struct inode * dir, struct inode * inode)
1.1.1.4 root 94: {
1.1.1.5 root 95: if (!dir || !inode) {
1.1.1.4 root 96: iput(dir);
1.1.1.5 root 97: iput(inode);
1.1.1.4 root 98: return NULL;
99: }
1.1.1.5 root 100: if (!inode->i_op || !inode->i_op->follow_link) {
1.1.1.4 root 101: iput(dir);
102: return inode;
103: }
1.1.1.5 root 104: return inode->i_op->follow_link(dir,inode);
1.1.1.4 root 105: }
106:
1.1 root 107: /*
1.1.1.5 root 108: * dir_namei()
1.1 root 109: *
1.1.1.5 root 110: * dir_namei() returns the inode of the directory of the
111: * specified name, and the name within that directory.
1.1 root 112: */
1.1.1.5 root 113: static struct inode * dir_namei(const char * pathname,
114: int * namelen, const char ** name, struct inode * base)
1.1 root 115: {
116: char c;
117: const char * thisname;
1.1.1.5 root 118: int len,error;
119: struct inode * inode;
120:
121: if (!base) {
122: base = current->pwd;
123: base->i_count++;
1.1.1.4 root 124: }
1.1 root 125: if ((c=get_fs_byte(pathname))=='/') {
1.1.1.5 root 126: iput(base);
127: base = current->root;
1.1 root 128: pathname++;
1.1.1.5 root 129: base->i_count++;
1.1.1.4 root 130: }
1.1 root 131: while (1) {
132: thisname = pathname;
1.1.1.5 root 133: for(len=0;(c=get_fs_byte(pathname++))&&(c!='/');len++)
1.1 root 134: /* nothing */ ;
135: if (!c)
1.1.1.5 root 136: break;
137: base->i_count++;
138: error = lookup(base,thisname,len,&inode);
139: if (error) {
140: iput(base);
1.1.1.4 root 141: return NULL;
142: }
1.1.1.5 root 143: if (!(base = follow_link(base,inode)))
1.1 root 144: return NULL;
145: }
1.1.1.5 root 146: *name = thisname;
147: *namelen = len;
148: return base;
1.1 root 149: }
150:
1.1.1.5 root 151: struct inode * _namei(const char * pathname, struct inode * base,
1.1.1.4 root 152: int follow_links)
1.1 root 153: {
154: const char * basename;
1.1.1.5 root 155: int namelen,error;
156: struct inode * inode;
1.1 root 157:
1.1.1.4 root 158: if (!(base = dir_namei(pathname,&namelen,&basename,base)))
1.1 root 159: return NULL;
1.1.1.5 root 160: base->i_count++; /* lookup uses up base */
161: error = lookup(base,basename,namelen,&inode);
162: if (error) {
1.1.1.4 root 163: iput(base);
164: return NULL;
1.1 root 165: }
1.1.1.4 root 166: if (follow_links)
167: inode = follow_link(base,inode);
168: else
169: iput(base);
170: return inode;
171: }
172:
1.1.1.5 root 173: struct inode * lnamei(const char * pathname)
1.1.1.4 root 174: {
175: return _namei(pathname, NULL, 0);
176: }
177:
178: /*
179: * namei()
180: *
181: * is used by most simple commands to get the inode of a specified name.
182: * Open, link etc use their own routines, but this is enough for things
183: * like 'chmod' etc.
184: */
1.1.1.5 root 185: struct inode * namei(const char * pathname)
1.1.1.4 root 186: {
187: return _namei(pathname,NULL,1);
1.1 root 188: }
189:
190: /*
191: * open_namei()
192: *
193: * namei for open - this is in fact almost the whole open-routine.
194: */
195: int open_namei(const char * pathname, int flag, int mode,
1.1.1.5 root 196: struct inode ** res_inode)
1.1 root 197: {
198: const char * basename;
1.1.1.5 root 199: int namelen,error;
200: struct inode * dir, *inode;
1.1 root 201:
202: if ((flag & O_TRUNC) && !(flag & O_ACCMODE))
203: flag |= O_WRONLY;
204: mode &= 0777 & ~current->umask;
205: mode |= I_REGULAR;
1.1.1.4 root 206: if (!(dir = dir_namei(pathname,&namelen,&basename,NULL)))
1.1 root 207: return -ENOENT;
208: if (!namelen) { /* special case: '/usr/' etc */
209: if (!(flag & (O_ACCMODE|O_CREAT|O_TRUNC))) {
210: *res_inode=dir;
211: return 0;
212: }
213: iput(dir);
214: return -EISDIR;
215: }
1.1.1.5 root 216: dir->i_count++; /* lookup eats the dir */
217: error = lookup(dir,basename,namelen,&inode);
218: if (error) {
1.1 root 219: if (!(flag & O_CREAT)) {
220: iput(dir);
1.1.1.5 root 221: return error;
1.1 root 222: }
223: if (!permission(dir,MAY_WRITE)) {
224: iput(dir);
225: return -EACCES;
226: }
1.1.1.5 root 227: if (!dir->i_op || !dir->i_op->create) {
1.1 root 228: iput(dir);
1.1.1.5 root 229: return -EACCES;
1.1 root 230: }
1.1.1.5 root 231: return dir->i_op->create(dir,basename,namelen,mode,res_inode);
1.1 root 232: }
1.1.1.4 root 233: if (flag & O_EXCL) {
234: iput(dir);
1.1.1.5 root 235: iput(inode);
1.1 root 236: return -EEXIST;
1.1.1.4 root 237: }
1.1.1.5 root 238: if (!(inode = follow_link(dir,inode)))
239: return -ELOOP;
1.1 root 240: if ((S_ISDIR(inode->i_mode) && (flag & O_ACCMODE)) ||
1.1.1.2 root 241: !permission(inode,ACC_MODE(flag))) {
1.1 root 242: iput(inode);
243: return -EPERM;
244: }
245: inode->i_atime = CURRENT_TIME;
246: if (flag & O_TRUNC)
1.1.1.7 ! root 247: if (inode->i_op && inode->i_op->truncate) {
! 248: inode->i_size = 0;
1.1.1.6 root 249: inode->i_op->truncate(inode);
1.1.1.7 ! root 250: }
1.1 root 251: *res_inode = inode;
252: return 0;
253: }
254:
1.1.1.2 root 255: int sys_mknod(const char * filename, int mode, int dev)
256: {
257: const char * basename;
258: int namelen;
1.1.1.5 root 259: struct inode * dir;
1.1.1.2 root 260:
261: if (!suser())
262: return -EPERM;
1.1.1.4 root 263: if (!(dir = dir_namei(filename,&namelen,&basename, NULL)))
1.1.1.2 root 264: return -ENOENT;
265: if (!namelen) {
266: iput(dir);
267: return -ENOENT;
268: }
269: if (!permission(dir,MAY_WRITE)) {
270: iput(dir);
1.1.1.6 root 271: return -EACCES;
1.1.1.2 root 272: }
1.1.1.5 root 273: if (!dir->i_op || !dir->i_op->mknod) {
1.1.1.2 root 274: iput(dir);
1.1.1.5 root 275: return -EPERM;
1.1.1.2 root 276: }
1.1.1.5 root 277: return dir->i_op->mknod(dir,basename,namelen,mode,dev);
1.1.1.2 root 278: }
279:
1.1 root 280: int sys_mkdir(const char * pathname, int mode)
281: {
282: const char * basename;
283: int namelen;
1.1.1.5 root 284: struct inode * dir;
1.1 root 285:
1.1.1.4 root 286: if (!(dir = dir_namei(pathname,&namelen,&basename, NULL)))
1.1 root 287: return -ENOENT;
288: if (!namelen) {
289: iput(dir);
290: return -ENOENT;
291: }
292: if (!permission(dir,MAY_WRITE)) {
293: iput(dir);
1.1.1.6 root 294: return -EACCES;
1.1 root 295: }
1.1.1.5 root 296: if (!dir->i_op || !dir->i_op->mkdir) {
1.1 root 297: iput(dir);
1.1.1.5 root 298: return -EPERM;
1.1 root 299: }
1.1.1.5 root 300: return dir->i_op->mkdir(dir,basename,namelen,mode);
1.1 root 301: }
302:
303: int sys_rmdir(const char * name)
304: {
305: const char * basename;
306: int namelen;
1.1.1.5 root 307: struct inode * dir;
1.1 root 308:
1.1.1.4 root 309: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 310: return -ENOENT;
311: if (!namelen) {
312: iput(dir);
313: return -ENOENT;
314: }
1.1.1.3 root 315: if (!permission(dir,MAY_WRITE)) {
316: iput(dir);
1.1.1.6 root 317: return -EACCES;
1.1.1.3 root 318: }
1.1.1.5 root 319: if (!dir->i_op || !dir->i_op->rmdir) {
1.1 root 320: iput(dir);
321: return -EPERM;
322: }
1.1.1.5 root 323: return dir->i_op->rmdir(dir,basename,namelen);
1.1 root 324: }
325:
326: int sys_unlink(const char * name)
327: {
328: const char * basename;
329: int namelen;
1.1.1.5 root 330: struct inode * dir;
1.1 root 331:
1.1.1.4 root 332: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 333: return -ENOENT;
334: if (!namelen) {
335: iput(dir);
1.1.1.6 root 336: return -EPERM;
1.1 root 337: }
338: if (!permission(dir,MAY_WRITE)) {
339: iput(dir);
1.1.1.6 root 340: return -EACCES;
1.1 root 341: }
1.1.1.5 root 342: if (!dir->i_op || !dir->i_op->unlink) {
1.1.1.2 root 343: iput(dir);
344: return -EPERM;
1.1.1.3 root 345: }
1.1.1.5 root 346: return dir->i_op->unlink(dir,basename,namelen);
1.1 root 347: }
348:
1.1.1.4 root 349: int sys_symlink(const char * oldname, const char * newname)
350: {
1.1.1.5 root 351: struct inode * dir;
1.1.1.4 root 352: const char * basename;
1.1.1.5 root 353: int namelen;
1.1.1.4 root 354:
355: dir = dir_namei(newname,&namelen,&basename, NULL);
356: if (!dir)
1.1.1.6 root 357: return -ENOENT;
1.1.1.4 root 358: if (!namelen) {
359: iput(dir);
1.1.1.6 root 360: return -ENOENT;
1.1.1.4 root 361: }
362: if (!permission(dir,MAY_WRITE)) {
363: iput(dir);
1.1.1.6 root 364: return -EACCES;
1.1.1.4 root 365: }
1.1.1.5 root 366: if (!dir->i_op || !dir->i_op->symlink) {
1.1.1.4 root 367: iput(dir);
1.1.1.5 root 368: return -EPERM;
1.1.1.4 root 369: }
1.1.1.5 root 370: return dir->i_op->symlink(dir,basename,namelen,oldname);
1.1.1.4 root 371: }
372:
1.1 root 373: int sys_link(const char * oldname, const char * newname)
374: {
1.1.1.5 root 375: struct inode * oldinode, * dir;
1.1 root 376: const char * basename;
377: int namelen;
378:
1.1.1.5 root 379: oldinode = namei(oldname);
1.1 root 380: if (!oldinode)
381: return -ENOENT;
1.1.1.4 root 382: dir = dir_namei(newname,&namelen,&basename, NULL);
1.1 root 383: if (!dir) {
384: iput(oldinode);
385: return -EACCES;
386: }
387: if (!namelen) {
388: iput(oldinode);
389: iput(dir);
390: return -EPERM;
391: }
392: if (dir->i_dev != oldinode->i_dev) {
393: iput(dir);
394: iput(oldinode);
395: return -EXDEV;
396: }
397: if (!permission(dir,MAY_WRITE)) {
398: iput(dir);
399: iput(oldinode);
400: return -EACCES;
401: }
1.1.1.5 root 402: if (!dir->i_op || !dir->i_op->link) {
1.1 root 403: iput(dir);
404: iput(oldinode);
1.1.1.5 root 405: return -EPERM;
1.1 root 406: }
1.1.1.5 root 407: return dir->i_op->link(oldinode, dir, basename, namelen);
408: }
409:
410: int sys_rename(const char * oldname, const char * newname)
411: {
412: struct inode * old_dir, * new_dir;
413: const char * old_base, * new_base;
414: int old_len, new_len;
415:
416: old_dir = dir_namei(oldname,&old_len,&old_base, NULL);
417: if (!old_dir)
418: return -ENOENT;
419: if (!permission(old_dir,MAY_WRITE)) {
420: iput(old_dir);
421: return -EACCES;
1.1 root 422: }
1.1.1.5 root 423: if (!old_len || (get_fs_byte(old_base) == '.' &&
424: (old_len == 1 || (get_fs_byte(old_base+1) == '.' &&
425: old_len == 2)))) {
426: iput(old_dir);
427: return -EPERM;
428: }
429: new_dir = dir_namei(newname,&new_len,&new_base, NULL);
430: if (!new_dir) {
431: iput(old_dir);
432: return -ENOENT;
433: }
434: if (!permission(new_dir,MAY_WRITE)) {
435: iput(old_dir);
436: iput(new_dir);
437: return -EACCES;
438: }
439: if (!new_len || (get_fs_byte(new_base) == '.' &&
440: (new_len == 1 || (get_fs_byte(new_base+1) == '.' &&
441: new_len == 2)))) {
442: iput(old_dir);
443: iput(new_dir);
444: return -EPERM;
445: }
446: if (new_dir->i_dev != old_dir->i_dev) {
447: iput(old_dir);
448: iput(new_dir);
449: return -EXDEV;
450: }
451: if (!old_dir->i_op || !old_dir->i_op->rename) {
452: iput(old_dir);
453: iput(new_dir);
454: return -EPERM;
455: }
456: return old_dir->i_op->rename(old_dir, old_base, old_len,
457: new_dir, new_base, new_len);
1.1 root 458: }
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