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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:
15: #include <string.h>
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);
1.1.1.5 root 170: if (inode) {
171: inode->i_atime=CURRENT_TIME;
172: inode->i_dirt=1;
173: }
1.1.1.4 root 174: return inode;
175: }
176:
1.1.1.5 root 177: struct inode * lnamei(const char * pathname)
1.1.1.4 root 178: {
179: return _namei(pathname, NULL, 0);
180: }
181:
182: /*
183: * namei()
184: *
185: * is used by most simple commands to get the inode of a specified name.
186: * Open, link etc use their own routines, but this is enough for things
187: * like 'chmod' etc.
188: */
1.1.1.5 root 189: struct inode * namei(const char * pathname)
1.1.1.4 root 190: {
191: return _namei(pathname,NULL,1);
1.1 root 192: }
193:
194: /*
195: * open_namei()
196: *
197: * namei for open - this is in fact almost the whole open-routine.
198: */
199: int open_namei(const char * pathname, int flag, int mode,
1.1.1.5 root 200: struct inode ** res_inode)
1.1 root 201: {
202: const char * basename;
1.1.1.5 root 203: int namelen,error;
204: struct inode * dir, *inode;
1.1 root 205:
206: if ((flag & O_TRUNC) && !(flag & O_ACCMODE))
207: flag |= O_WRONLY;
208: mode &= 0777 & ~current->umask;
209: mode |= I_REGULAR;
1.1.1.4 root 210: if (!(dir = dir_namei(pathname,&namelen,&basename,NULL)))
1.1 root 211: return -ENOENT;
212: if (!namelen) { /* special case: '/usr/' etc */
213: if (!(flag & (O_ACCMODE|O_CREAT|O_TRUNC))) {
214: *res_inode=dir;
215: return 0;
216: }
217: iput(dir);
218: return -EISDIR;
219: }
1.1.1.5 root 220: dir->i_count++; /* lookup eats the dir */
221: error = lookup(dir,basename,namelen,&inode);
222: if (error) {
1.1 root 223: if (!(flag & O_CREAT)) {
224: iput(dir);
1.1.1.5 root 225: return error;
1.1 root 226: }
227: if (!permission(dir,MAY_WRITE)) {
228: iput(dir);
229: return -EACCES;
230: }
1.1.1.5 root 231: if (!dir->i_op || !dir->i_op->create) {
1.1 root 232: iput(dir);
1.1.1.5 root 233: return -EACCES;
1.1 root 234: }
1.1.1.5 root 235: return dir->i_op->create(dir,basename,namelen,mode,res_inode);
1.1 root 236: }
1.1.1.4 root 237: if (flag & O_EXCL) {
238: iput(dir);
1.1.1.5 root 239: iput(inode);
1.1 root 240: return -EEXIST;
1.1.1.4 root 241: }
1.1.1.5 root 242: if (!(inode = follow_link(dir,inode)))
243: return -ELOOP;
1.1 root 244: if ((S_ISDIR(inode->i_mode) && (flag & O_ACCMODE)) ||
1.1.1.2 root 245: !permission(inode,ACC_MODE(flag))) {
1.1 root 246: iput(inode);
247: return -EPERM;
248: }
249: inode->i_atime = CURRENT_TIME;
250: if (flag & O_TRUNC)
1.1.1.6 ! root 251: if (inode->i_op && inode->i_op->truncate)
! 252: inode->i_op->truncate(inode);
1.1 root 253: *res_inode = inode;
254: return 0;
255: }
256:
1.1.1.2 root 257: int sys_mknod(const char * filename, int mode, int dev)
258: {
259: const char * basename;
260: int namelen;
1.1.1.5 root 261: struct inode * dir;
1.1.1.2 root 262:
263: if (!suser())
264: return -EPERM;
1.1.1.4 root 265: if (!(dir = dir_namei(filename,&namelen,&basename, NULL)))
1.1.1.2 root 266: return -ENOENT;
267: if (!namelen) {
268: iput(dir);
269: return -ENOENT;
270: }
271: if (!permission(dir,MAY_WRITE)) {
272: iput(dir);
1.1.1.6 ! root 273: return -EACCES;
1.1.1.2 root 274: }
1.1.1.5 root 275: if (!dir->i_op || !dir->i_op->mknod) {
1.1.1.2 root 276: iput(dir);
1.1.1.5 root 277: return -EPERM;
1.1.1.2 root 278: }
1.1.1.5 root 279: return dir->i_op->mknod(dir,basename,namelen,mode,dev);
1.1.1.2 root 280: }
281:
1.1 root 282: int sys_mkdir(const char * pathname, int mode)
283: {
284: const char * basename;
285: int namelen;
1.1.1.5 root 286: struct inode * dir;
1.1 root 287:
1.1.1.4 root 288: if (!(dir = dir_namei(pathname,&namelen,&basename, NULL)))
1.1 root 289: return -ENOENT;
290: if (!namelen) {
291: iput(dir);
292: return -ENOENT;
293: }
294: if (!permission(dir,MAY_WRITE)) {
295: iput(dir);
1.1.1.6 ! root 296: return -EACCES;
1.1 root 297: }
1.1.1.5 root 298: if (!dir->i_op || !dir->i_op->mkdir) {
1.1 root 299: iput(dir);
1.1.1.5 root 300: return -EPERM;
1.1 root 301: }
1.1.1.5 root 302: return dir->i_op->mkdir(dir,basename,namelen,mode);
1.1 root 303: }
304:
305: int sys_rmdir(const char * name)
306: {
307: const char * basename;
308: int namelen;
1.1.1.5 root 309: struct inode * dir;
1.1 root 310:
1.1.1.4 root 311: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 312: return -ENOENT;
313: if (!namelen) {
314: iput(dir);
315: return -ENOENT;
316: }
1.1.1.3 root 317: if (!permission(dir,MAY_WRITE)) {
318: iput(dir);
1.1.1.6 ! root 319: return -EACCES;
1.1.1.3 root 320: }
1.1.1.5 root 321: if (!dir->i_op || !dir->i_op->rmdir) {
1.1 root 322: iput(dir);
323: return -EPERM;
324: }
1.1.1.5 root 325: return dir->i_op->rmdir(dir,basename,namelen);
1.1 root 326: }
327:
328: int sys_unlink(const char * name)
329: {
330: const char * basename;
331: int namelen;
1.1.1.5 root 332: struct inode * dir;
1.1 root 333:
1.1.1.4 root 334: if (!(dir = dir_namei(name,&namelen,&basename, NULL)))
1.1 root 335: return -ENOENT;
336: if (!namelen) {
337: iput(dir);
1.1.1.6 ! root 338: return -EPERM;
1.1 root 339: }
340: if (!permission(dir,MAY_WRITE)) {
341: iput(dir);
1.1.1.6 ! root 342: return -EACCES;
1.1 root 343: }
1.1.1.5 root 344: if (!dir->i_op || !dir->i_op->unlink) {
1.1.1.2 root 345: iput(dir);
346: return -EPERM;
1.1.1.3 root 347: }
1.1.1.5 root 348: return dir->i_op->unlink(dir,basename,namelen);
1.1 root 349: }
350:
1.1.1.4 root 351: int sys_symlink(const char * oldname, const char * newname)
352: {
1.1.1.5 root 353: struct inode * dir;
1.1.1.4 root 354: const char * basename;
1.1.1.5 root 355: int namelen;
1.1.1.4 root 356:
357: dir = dir_namei(newname,&namelen,&basename, NULL);
358: if (!dir)
1.1.1.6 ! root 359: return -ENOENT;
1.1.1.4 root 360: if (!namelen) {
361: iput(dir);
1.1.1.6 ! root 362: return -ENOENT;
1.1.1.4 root 363: }
364: if (!permission(dir,MAY_WRITE)) {
365: iput(dir);
1.1.1.6 ! root 366: return -EACCES;
1.1.1.4 root 367: }
1.1.1.5 root 368: if (!dir->i_op || !dir->i_op->symlink) {
1.1.1.4 root 369: iput(dir);
1.1.1.5 root 370: return -EPERM;
1.1.1.4 root 371: }
1.1.1.5 root 372: return dir->i_op->symlink(dir,basename,namelen,oldname);
1.1.1.4 root 373: }
374:
1.1 root 375: int sys_link(const char * oldname, const char * newname)
376: {
1.1.1.5 root 377: struct inode * oldinode, * dir;
1.1 root 378: const char * basename;
379: int namelen;
380:
1.1.1.5 root 381: oldinode = namei(oldname);
1.1 root 382: if (!oldinode)
383: return -ENOENT;
1.1.1.4 root 384: dir = dir_namei(newname,&namelen,&basename, NULL);
1.1 root 385: if (!dir) {
386: iput(oldinode);
387: return -EACCES;
388: }
389: if (!namelen) {
390: iput(oldinode);
391: iput(dir);
392: return -EPERM;
393: }
394: if (dir->i_dev != oldinode->i_dev) {
395: iput(dir);
396: iput(oldinode);
397: return -EXDEV;
398: }
399: if (!permission(dir,MAY_WRITE)) {
400: iput(dir);
401: iput(oldinode);
402: return -EACCES;
403: }
1.1.1.5 root 404: if (!dir->i_op || !dir->i_op->link) {
1.1 root 405: iput(dir);
406: iput(oldinode);
1.1.1.5 root 407: return -EPERM;
1.1 root 408: }
1.1.1.5 root 409: return dir->i_op->link(oldinode, dir, basename, namelen);
410: }
411:
412: int sys_rename(const char * oldname, const char * newname)
413: {
414: struct inode * old_dir, * new_dir;
415: const char * old_base, * new_base;
416: int old_len, new_len;
417:
418: old_dir = dir_namei(oldname,&old_len,&old_base, NULL);
419: if (!old_dir)
420: return -ENOENT;
421: if (!permission(old_dir,MAY_WRITE)) {
422: iput(old_dir);
423: return -EACCES;
1.1 root 424: }
1.1.1.5 root 425: if (!old_len || (get_fs_byte(old_base) == '.' &&
426: (old_len == 1 || (get_fs_byte(old_base+1) == '.' &&
427: old_len == 2)))) {
428: iput(old_dir);
429: return -EPERM;
430: }
431: new_dir = dir_namei(newname,&new_len,&new_base, NULL);
432: if (!new_dir) {
433: iput(old_dir);
434: return -ENOENT;
435: }
436: if (!permission(new_dir,MAY_WRITE)) {
437: iput(old_dir);
438: iput(new_dir);
439: return -EACCES;
440: }
441: if (!new_len || (get_fs_byte(new_base) == '.' &&
442: (new_len == 1 || (get_fs_byte(new_base+1) == '.' &&
443: new_len == 2)))) {
444: iput(old_dir);
445: iput(new_dir);
446: return -EPERM;
447: }
448: if (new_dir->i_dev != old_dir->i_dev) {
449: iput(old_dir);
450: iput(new_dir);
451: return -EXDEV;
452: }
453: if (!old_dir->i_op || !old_dir->i_op->rename) {
454: iput(old_dir);
455: iput(new_dir);
456: return -EPERM;
457: }
458: return old_dir->i_op->rename(old_dir, old_base, old_len,
459: new_dir, new_base, new_len);
1.1 root 460: }
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