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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:
1.1.1.9 ! root 11: #include <errno.h>
! 12: #include <const.h>
! 13:
1.1 root 14: #include <asm/segment.h>
15:
1.1.1.9 ! root 16: #include <linux/sched.h>
! 17: #include <linux/kernel.h>
1.1.1.7 root 18: #include <linux/string.h>
1.1.1.9 ! root 19: #include <linux/fcntl.h>
1.1.1.8 root 20: #include <linux/stat.h>
1.1 root 21:
1.1.1.5 root 22: struct inode * _namei(const char * filename, struct inode * base,
1.1.1.4 root 23: int follow_links);
24:
1.1 root 25: #define ACC_MODE(x) ("\004\002\006\377"[(x)&O_ACCMODE])
26:
27: /*
1.1.1.5 root 28: * comment out this line if you want names > MINIX_NAME_LEN chars to be
1.1 root 29: * truncated. Else they will be disallowed.
30: */
31: /* #define NO_TRUNCATE */
32:
33: /*
34: * permission()
35: *
36: * is used to check for read/write/execute permissions on a file.
37: * I don't know if we should look at just the euid or both euid and
38: * uid, but that should be easily changed.
39: */
1.1.1.5 root 40: int permission(struct inode * inode,int mask)
1.1 root 41: {
42: int mode = inode->i_mode;
43:
44: /* special case: not even root can read/write a deleted file */
1.1.1.5 root 45: if (inode->i_dev && !inode->i_nlink)
1.1 root 46: return 0;
1.1.1.5 root 47: else if (current->euid == inode->i_uid)
1.1 root 48: mode >>= 6;
1.1.1.4 root 49: else if (in_group_p(inode->i_gid))
1.1 root 50: mode >>= 3;
1.1.1.2 root 51: if (((mode & mask & 0007) == mask) || suser())
52: return 1;
53: return 0;
1.1 root 54: }
55:
56: /*
1.1.1.5 root 57: * lookup() looks up one part of a pathname, using the fs-dependent
58: * routines (currently minix_lookup) for it. It also checks for
59: * fathers (pseudo-roots, mount-points)
1.1 root 60: */
1.1.1.5 root 61: int lookup(struct inode * dir,const char * name, int len,
62: struct inode ** result)
1.1 root 63: {
1.1.1.2 root 64: struct super_block * sb;
1.1 root 65:
1.1.1.5 root 66: *result = NULL;
67: if (len==2 && get_fs_byte(name)=='.' && get_fs_byte(name+1)=='.') {
68: if (dir == current->root)
69: len = 1;
70: else if ((sb = dir->i_sb) && (dir == sb->s_mounted)) {
71: sb = dir->i_sb;
72: iput(dir);
73: if (dir = sb->s_covered)
74: dir->i_count++;
1.1.1.2 root 75: }
76: }
1.1.1.5 root 77: if (!dir)
78: return -ENOENT;
79: if (!permission(dir,MAY_EXEC)) {
80: iput(dir);
81: return -EACCES;
1.1 root 82: }
1.1.1.5 root 83: if (!len) {
84: *result = dir;
85: return 0;
86: }
87: if (!dir->i_op || !dir->i_op->lookup) {
88: iput(dir);
89: return -ENOENT;
1.1 root 90: }
1.1.1.5 root 91: return dir->i_op->lookup(dir,name,len,result);
1.1 root 92: }
93:
1.1.1.5 root 94: struct inode * follow_link(struct inode * dir, struct inode * inode)
1.1.1.4 root 95: {
1.1.1.5 root 96: if (!dir || !inode) {
1.1.1.4 root 97: iput(dir);
1.1.1.5 root 98: iput(inode);
1.1.1.4 root 99: return NULL;
100: }
1.1.1.5 root 101: if (!inode->i_op || !inode->i_op->follow_link) {
1.1.1.4 root 102: iput(dir);
103: return inode;
104: }
1.1.1.5 root 105: return inode->i_op->follow_link(dir,inode);
1.1.1.4 root 106: }
107:
1.1 root 108: /*
1.1.1.5 root 109: * dir_namei()
1.1 root 110: *
1.1.1.5 root 111: * dir_namei() returns the inode of the directory of the
112: * specified name, and the name within that directory.
1.1 root 113: */
1.1.1.5 root 114: static struct inode * dir_namei(const char * pathname,
115: int * namelen, const char ** name, struct inode * base)
1.1 root 116: {
117: char c;
118: const char * thisname;
1.1.1.5 root 119: int len,error;
120: struct inode * inode;
121:
122: if (!base) {
123: base = current->pwd;
124: base->i_count++;
1.1.1.4 root 125: }
1.1 root 126: if ((c=get_fs_byte(pathname))=='/') {
1.1.1.5 root 127: iput(base);
128: base = current->root;
1.1 root 129: pathname++;
1.1.1.5 root 130: base->i_count++;
1.1.1.4 root 131: }
1.1 root 132: while (1) {
133: thisname = pathname;
1.1.1.5 root 134: for(len=0;(c=get_fs_byte(pathname++))&&(c!='/');len++)
1.1 root 135: /* nothing */ ;
136: if (!c)
1.1.1.5 root 137: break;
138: base->i_count++;
139: error = lookup(base,thisname,len,&inode);
140: if (error) {
141: iput(base);
1.1.1.4 root 142: return NULL;
143: }
1.1.1.5 root 144: if (!(base = follow_link(base,inode)))
1.1 root 145: return NULL;
146: }
1.1.1.5 root 147: *name = thisname;
148: *namelen = len;
149: return base;
1.1 root 150: }
151:
1.1.1.5 root 152: struct inode * _namei(const char * pathname, struct inode * base,
1.1.1.4 root 153: int follow_links)
1.1 root 154: {
155: const char * basename;
1.1.1.5 root 156: int namelen,error;
157: struct inode * inode;
1.1 root 158:
1.1.1.4 root 159: if (!(base = dir_namei(pathname,&namelen,&basename,base)))
1.1 root 160: return NULL;
1.1.1.5 root 161: base->i_count++; /* lookup uses up base */
162: error = lookup(base,basename,namelen,&inode);
163: if (error) {
1.1.1.4 root 164: iput(base);
165: return NULL;
1.1 root 166: }
1.1.1.4 root 167: if (follow_links)
168: inode = follow_link(base,inode);
169: else
170: iput(base);
171: return inode;
172: }
173:
1.1.1.5 root 174: struct inode * lnamei(const char * pathname)
1.1.1.4 root 175: {
176: return _namei(pathname, NULL, 0);
177: }
178:
179: /*
180: * namei()
181: *
182: * is used by most simple commands to get the inode of a specified name.
183: * Open, link etc use their own routines, but this is enough for things
184: * like 'chmod' etc.
185: */
1.1.1.5 root 186: struct inode * namei(const char * pathname)
1.1.1.4 root 187: {
188: return _namei(pathname,NULL,1);
1.1 root 189: }
190:
191: /*
192: * open_namei()
193: *
194: * namei for open - this is in fact almost the whole open-routine.
195: */
196: int open_namei(const char * pathname, int flag, int mode,
1.1.1.5 root 197: struct inode ** res_inode)
1.1 root 198: {
199: const char * basename;
1.1.1.5 root 200: int namelen,error;
201: struct inode * dir, *inode;
1.1 root 202:
203: if ((flag & O_TRUNC) && !(flag & O_ACCMODE))
204: flag |= O_WRONLY;
1.1.1.8 root 205: mode &= 07777 & ~current->umask;
1.1 root 206: mode |= I_REGULAR;
1.1.1.4 root 207: if (!(dir = dir_namei(pathname,&namelen,&basename,NULL)))
1.1 root 208: return -ENOENT;
209: if (!namelen) { /* special case: '/usr/' etc */
210: if (!(flag & (O_ACCMODE|O_CREAT|O_TRUNC))) {
211: *res_inode=dir;
212: return 0;
213: }
214: iput(dir);
215: return -EISDIR;
216: }
1.1.1.5 root 217: dir->i_count++; /* lookup eats the dir */
218: error = lookup(dir,basename,namelen,&inode);
219: if (error) {
1.1 root 220: if (!(flag & O_CREAT)) {
221: iput(dir);
1.1.1.5 root 222: return error;
1.1 root 223: }
224: if (!permission(dir,MAY_WRITE)) {
225: iput(dir);
226: return -EACCES;
227: }
1.1.1.5 root 228: if (!dir->i_op || !dir->i_op->create) {
1.1 root 229: iput(dir);
1.1.1.5 root 230: return -EACCES;
1.1 root 231: }
1.1.1.5 root 232: return dir->i_op->create(dir,basename,namelen,mode,res_inode);
1.1 root 233: }
1.1.1.4 root 234: if (flag & O_EXCL) {
235: iput(dir);
1.1.1.5 root 236: iput(inode);
1.1 root 237: return -EEXIST;
1.1.1.4 root 238: }
1.1.1.5 root 239: if (!(inode = follow_link(dir,inode)))
240: return -ELOOP;
1.1 root 241: if ((S_ISDIR(inode->i_mode) && (flag & O_ACCMODE)) ||
1.1.1.2 root 242: !permission(inode,ACC_MODE(flag))) {
1.1 root 243: iput(inode);
244: return -EPERM;
245: }
246: inode->i_atime = CURRENT_TIME;
247: if (flag & O_TRUNC)
1.1.1.7 root 248: if (inode->i_op && inode->i_op->truncate) {
249: inode->i_size = 0;
1.1.1.6 root 250: inode->i_op->truncate(inode);
1.1.1.7 root 251: }
1.1 root 252: *res_inode = inode;
253: return 0;
254: }
255:
1.1.1.8 root 256: int do_mknod(const char * filename, int mode, int dev)
1.1.1.2 root 257: {
258: const char * basename;
259: int namelen;
1.1.1.5 root 260: struct inode * dir;
1.1.1.2 root 261:
1.1.1.4 root 262: if (!(dir = dir_namei(filename,&namelen,&basename, NULL)))
1.1.1.2 root 263: return -ENOENT;
264: if (!namelen) {
265: iput(dir);
266: return -ENOENT;
267: }
268: if (!permission(dir,MAY_WRITE)) {
269: iput(dir);
1.1.1.6 root 270: return -EACCES;
1.1.1.2 root 271: }
1.1.1.5 root 272: if (!dir->i_op || !dir->i_op->mknod) {
1.1.1.2 root 273: iput(dir);
1.1.1.5 root 274: return -EPERM;
1.1.1.2 root 275: }
1.1.1.5 root 276: return dir->i_op->mknod(dir,basename,namelen,mode,dev);
1.1.1.2 root 277: }
278:
1.1.1.8 root 279: int sys_mknod(const char * filename, int mode, int dev)
280: {
1.1.1.9 ! root 281: if (S_ISFIFO(mode) || suser())
1.1.1.8 root 282: return do_mknod(filename,mode,dev);
283: return -EPERM;
284: }
285:
1.1 root 286: int sys_mkdir(const char * pathname, int mode)
287: {
288: const char * basename;
289: int namelen;
1.1.1.5 root 290: struct inode * dir;
1.1 root 291:
1.1.1.4 root 292: if (!(dir = dir_namei(pathname,&namelen,&basename, NULL)))
1.1 root 293: return -ENOENT;
294: if (!namelen) {
295: iput(dir);
296: return -ENOENT;
297: }
298: if (!permission(dir,MAY_WRITE)) {
299: iput(dir);
1.1.1.6 root 300: return -EACCES;
1.1 root 301: }
1.1.1.5 root 302: if (!dir->i_op || !dir->i_op->mkdir) {
1.1 root 303: iput(dir);
1.1.1.5 root 304: return -EPERM;
1.1 root 305: }
1.1.1.5 root 306: return dir->i_op->mkdir(dir,basename,namelen,mode);
1.1 root 307: }
308:
309: int sys_rmdir(const char * name)
310: {
311: const char * basename;
312: int namelen;
1.1.1.5 root 313: struct inode * dir;
1.1 root 314:
1.1.1.4 root 315: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 316: return -ENOENT;
317: if (!namelen) {
318: iput(dir);
319: return -ENOENT;
320: }
1.1.1.3 root 321: if (!permission(dir,MAY_WRITE)) {
322: iput(dir);
1.1.1.6 root 323: return -EACCES;
1.1.1.3 root 324: }
1.1.1.5 root 325: if (!dir->i_op || !dir->i_op->rmdir) {
1.1 root 326: iput(dir);
327: return -EPERM;
328: }
1.1.1.5 root 329: return dir->i_op->rmdir(dir,basename,namelen);
1.1 root 330: }
331:
332: int sys_unlink(const char * name)
333: {
334: const char * basename;
335: int namelen;
1.1.1.5 root 336: struct inode * dir;
1.1 root 337:
1.1.1.4 root 338: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 339: return -ENOENT;
340: if (!namelen) {
341: iput(dir);
1.1.1.6 root 342: return -EPERM;
1.1 root 343: }
344: if (!permission(dir,MAY_WRITE)) {
345: iput(dir);
1.1.1.6 root 346: return -EACCES;
1.1 root 347: }
1.1.1.5 root 348: if (!dir->i_op || !dir->i_op->unlink) {
1.1.1.2 root 349: iput(dir);
350: return -EPERM;
1.1.1.3 root 351: }
1.1.1.5 root 352: return dir->i_op->unlink(dir,basename,namelen);
1.1 root 353: }
354:
1.1.1.4 root 355: int sys_symlink(const char * oldname, const char * newname)
356: {
1.1.1.5 root 357: struct inode * dir;
1.1.1.4 root 358: const char * basename;
1.1.1.5 root 359: int namelen;
1.1.1.4 root 360:
361: dir = dir_namei(newname,&namelen,&basename, NULL);
362: if (!dir)
1.1.1.6 root 363: return -ENOENT;
1.1.1.4 root 364: if (!namelen) {
365: iput(dir);
1.1.1.6 root 366: return -ENOENT;
1.1.1.4 root 367: }
368: if (!permission(dir,MAY_WRITE)) {
369: iput(dir);
1.1.1.6 root 370: return -EACCES;
1.1.1.4 root 371: }
1.1.1.5 root 372: if (!dir->i_op || !dir->i_op->symlink) {
1.1.1.4 root 373: iput(dir);
1.1.1.5 root 374: return -EPERM;
1.1.1.4 root 375: }
1.1.1.5 root 376: return dir->i_op->symlink(dir,basename,namelen,oldname);
1.1.1.4 root 377: }
378:
1.1 root 379: int sys_link(const char * oldname, const char * newname)
380: {
1.1.1.5 root 381: struct inode * oldinode, * dir;
1.1 root 382: const char * basename;
383: int namelen;
384:
1.1.1.5 root 385: oldinode = namei(oldname);
1.1 root 386: if (!oldinode)
387: return -ENOENT;
1.1.1.4 root 388: dir = dir_namei(newname,&namelen,&basename, NULL);
1.1 root 389: if (!dir) {
390: iput(oldinode);
391: return -EACCES;
392: }
393: if (!namelen) {
394: iput(oldinode);
395: iput(dir);
396: return -EPERM;
397: }
398: if (dir->i_dev != oldinode->i_dev) {
399: iput(dir);
400: iput(oldinode);
401: return -EXDEV;
402: }
403: if (!permission(dir,MAY_WRITE)) {
404: iput(dir);
405: iput(oldinode);
406: return -EACCES;
407: }
1.1.1.5 root 408: if (!dir->i_op || !dir->i_op->link) {
1.1 root 409: iput(dir);
410: iput(oldinode);
1.1.1.5 root 411: return -EPERM;
1.1 root 412: }
1.1.1.5 root 413: return dir->i_op->link(oldinode, dir, basename, namelen);
414: }
415:
416: int sys_rename(const char * oldname, const char * newname)
417: {
418: struct inode * old_dir, * new_dir;
419: const char * old_base, * new_base;
420: int old_len, new_len;
421:
422: old_dir = dir_namei(oldname,&old_len,&old_base, NULL);
423: if (!old_dir)
424: return -ENOENT;
425: if (!permission(old_dir,MAY_WRITE)) {
426: iput(old_dir);
427: return -EACCES;
1.1 root 428: }
1.1.1.5 root 429: if (!old_len || (get_fs_byte(old_base) == '.' &&
430: (old_len == 1 || (get_fs_byte(old_base+1) == '.' &&
431: old_len == 2)))) {
432: iput(old_dir);
433: return -EPERM;
434: }
435: new_dir = dir_namei(newname,&new_len,&new_base, NULL);
436: if (!new_dir) {
437: iput(old_dir);
438: return -ENOENT;
439: }
440: if (!permission(new_dir,MAY_WRITE)) {
441: iput(old_dir);
442: iput(new_dir);
443: return -EACCES;
444: }
445: if (!new_len || (get_fs_byte(new_base) == '.' &&
446: (new_len == 1 || (get_fs_byte(new_base+1) == '.' &&
447: new_len == 2)))) {
448: iput(old_dir);
449: iput(new_dir);
450: return -EPERM;
451: }
452: if (new_dir->i_dev != old_dir->i_dev) {
453: iput(old_dir);
454: iput(new_dir);
455: return -EXDEV;
456: }
457: if (!old_dir->i_op || !old_dir->i_op->rename) {
458: iput(old_dir);
459: iput(new_dir);
460: return -EPERM;
461: }
462: return old_dir->i_op->rename(old_dir, old_base, old_len,
463: new_dir, new_base, new_len);
1.1 root 464: }
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