fs/attr.c

   1 /*
   2  *  linux/fs/attr.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  changes by Thomas Schoebel-Theuer
   6  */
   7
   8 #include <linux/sched.h>
   9 #include <linux/mm.h>
  10 #include <linux/string.h>
  11
  12 /* Taken over from the old code... */
  13
  14 /* POSIX UID/GID verification for setting inode attributes. */
  15 int inode_change_ok(struct inode *inode, struct iattr *attr)
  16 {
  17         int retval = -EPERM;
  18         unsigned int ia_valid = attr->ia_valid;
  19
  20         /* If force is set do it anyway. */
  21         if (ia_valid & ATTR_FORCE)
  22                 goto fine;
  23
  24         /* Make sure a caller can chown. */
  25         if ((ia_valid & ATTR_UID) &&
  26             (current->fsuid != inode->i_uid ||
  27              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  28                 goto error;
  29
  30         /* Make sure caller can chgrp. */
  31         if ((ia_valid & ATTR_GID) &&
  32             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid) &&
  33             !capable(CAP_CHOWN))
  34                 goto error;
  35
  36         /* Make sure a caller can chmod. */
  37         if (ia_valid & ATTR_MODE) {
  38                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
  39                         goto error;
  40                 /* Also check the setgid bit! */
  41                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
  42                                 inode->i_gid) && !capable(CAP_FSETID))
  43                         attr->ia_mode &= ~S_ISGID;
  44         }
  45
  46         /* Check for setting the inode time. */
  47         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
  48                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  49                         goto error;
  50         }
  51 fine:
  52         retval = 0;
  53 error:
  54         return retval;
  55 }
  56
  57 void inode_setattr(struct inode * inode, struct iattr * attr)
  58 {
  59         unsigned int ia_valid = attr->ia_valid;
  60
  61         if (ia_valid & ATTR_UID)
  62                 inode->i_uid = attr->ia_uid;
  63         if (ia_valid & ATTR_GID)
  64                 inode->i_gid = attr->ia_gid;
  65         if (ia_valid & ATTR_SIZE)
  66                 inode->i_size = attr->ia_size;
  67         if (ia_valid & ATTR_ATIME)
  68                 inode->i_atime = attr->ia_atime;
  69         if (ia_valid & ATTR_MTIME)
  70                 inode->i_mtime = attr->ia_mtime;
  71         if (ia_valid & ATTR_CTIME)
  72                 inode->i_ctime = attr->ia_ctime;
  73         if (ia_valid & ATTR_MODE) {
  74                 inode->i_mode = attr->ia_mode;
  75                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  76                         inode->i_mode &= ~S_ISGID;
  77         }
  78         mark_inode_dirty(inode);
  79 }
  80
  81 int notify_change(struct dentry * dentry, struct iattr * attr)
  82 {
  83         struct inode *inode = dentry->d_inode;
  84         int error;
  85         time_t now = CURRENT_TIME;
  86         unsigned int ia_valid = attr->ia_valid;
  87
  88         attr->ia_ctime = now;
  89         if (!(ia_valid & ATTR_ATIME_SET))
  90                 attr->ia_atime = now;
  91         if (!(ia_valid & ATTR_MTIME_SET))
  92                 attr->ia_mtime = now;
  93
  94         if (inode->i_sb && inode->i_sb->s_op &&
  95             inode->i_sb->s_op->notify_change)
  96                 error = inode->i_sb->s_op->notify_change(dentry, attr);
  97         else {
  98                 error = inode_change_ok(inode, attr);
  99                 if (!error)
 100                         inode_setattr(inode, attr);
 101         }
 102         return error;
 103 }