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 #include <linux/smp_lock.h>
  12
  13 /* Taken over from the old code... */
  14
  15 /* POSIX UID/GID verification for setting inode attributes. */
  16 int inode_change_ok(struct inode *inode, struct iattr *attr)
  17 {
  18         int retval = -EPERM;
  19         unsigned int ia_valid = attr->ia_valid;
  20
  21         /* If force is set do it anyway. */
  22         if (ia_valid & ATTR_FORCE)
  23                 goto fine;
  24
  25         /* Make sure a caller can chown. */
  26         if ((ia_valid & ATTR_UID) &&
  27             (current->fsuid != inode->i_uid ||
  28              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  29                 goto error;
  30
  31         /* Make sure caller can chgrp. */
  32         if ((ia_valid & ATTR_GID) &&
  33             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid) &&
  34             !capable(CAP_CHOWN))
  35                 goto error;
  36
  37         /* Make sure a caller can chmod. */
  38         if (ia_valid & ATTR_MODE) {
  39                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
  40                         goto error;
  41                 /* Also check the setgid bit! */
  42                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
  43                                 inode->i_gid) && !capable(CAP_FSETID))
  44                         attr->ia_mode &= ~S_ISGID;
  45         }
  46
  47         /* Check for setting the inode time. */
  48         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
  49                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  50                         goto error;
  51         }
  52 fine:
  53         retval = 0;
  54 error:
  55         return retval;
  56 }
  57
  58 void inode_setattr(struct inode * inode, struct iattr * attr)
  59 {
  60         unsigned int ia_valid = attr->ia_valid;
  61
  62         if (ia_valid & ATTR_UID)
  63                 inode->i_uid = attr->ia_uid;
  64         if (ia_valid & ATTR_GID)
  65                 inode->i_gid = attr->ia_gid;
  66         if (ia_valid & ATTR_SIZE)
  67                 vmtruncate(inode, attr->ia_size);
  68         if (ia_valid & ATTR_ATIME)
  69                 inode->i_atime = attr->ia_atime;
  70         if (ia_valid & ATTR_MTIME)
  71                 inode->i_mtime = attr->ia_mtime;
  72         if (ia_valid & ATTR_CTIME)
  73                 inode->i_ctime = attr->ia_ctime;
  74         if (ia_valid & ATTR_MODE) {
  75                 inode->i_mode = attr->ia_mode;
  76                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  77                         inode->i_mode &= ~S_ISGID;
  78         }
  79         mark_inode_dirty(inode);
  80 }
  81
  82 int notify_change(struct dentry * dentry, struct iattr * attr)
  83 {
  84         struct inode *inode = dentry->d_inode;
  85         int error;
  86         time_t now = CURRENT_TIME;
  87         unsigned int ia_valid = attr->ia_valid;
  88
  89         attr->ia_ctime = now;
  90         if (!(ia_valid & ATTR_ATIME_SET))
  91                 attr->ia_atime = now;
  92         if (!(ia_valid & ATTR_MTIME_SET))
  93                 attr->ia_mtime = now;
  94
  95         lock_kernel();
  96         if (inode && inode->i_op && inode->i_op->setattr)
  97                 error = inode->i_op->setattr(dentry, attr);
  98         else {
  99                 error = inode_change_ok(inode, attr);
 100                 if (!error)
 101                         inode_setattr(inode, attr);
 102         }
 103         unlock_kernel();
 104         return error;
 105 }