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 #include <linux/dnotify.h>
  13 #include <linux/fcntl.h>
  14
  15 /* Taken over from the old code... */
  16
  17 /* POSIX UID/GID verification for setting inode attributes. */
  18 int inode_change_ok(struct inode *inode, struct iattr *attr)
  19 {
  20         int retval = -EPERM;
  21         unsigned int ia_valid = attr->ia_valid;
  22
  23         /* If force is set do it anyway. */
  24         if (ia_valid & ATTR_FORCE)
  25                 goto fine;
  26
  27         /* Make sure a caller can chown. */
  28         if ((ia_valid & ATTR_UID) &&
  29             (current->fsuid != inode->i_uid ||
  30              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  31                 goto error;
  32
  33         /* Make sure caller can chgrp. */
  34         if ((ia_valid & ATTR_GID) &&
  35             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid) &&
  36             !capable(CAP_CHOWN))
  37                 goto error;
  38
  39         /* Make sure a caller can chmod. */
  40         if (ia_valid & ATTR_MODE) {
  41                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
  42                         goto error;
  43                 /* Also check the setgid bit! */
  44                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
  45                                 inode->i_gid) && !capable(CAP_FSETID))
  46                         attr->ia_mode &= ~S_ISGID;
  47         }
  48
  49         /* Check for setting the inode time. */
  50         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
  51                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  52                         goto error;
  53         }
  54 fine:
  55         retval = 0;
  56 error:
  57         return retval;
  58 }
  59
  60 void inode_setattr(struct inode * inode, struct iattr * attr)
  61 {
  62         unsigned int ia_valid = attr->ia_valid;
  63
  64         if (ia_valid & ATTR_UID)
  65                 inode->i_uid = attr->ia_uid;
  66         if (ia_valid & ATTR_GID)
  67                 inode->i_gid = attr->ia_gid;
  68         if (ia_valid & ATTR_SIZE)
  69                 vmtruncate(inode, attr->ia_size);
  70         if (ia_valid & ATTR_ATIME)
  71                 inode->i_atime = attr->ia_atime;
  72         if (ia_valid & ATTR_MTIME)
  73                 inode->i_mtime = attr->ia_mtime;
  74         if (ia_valid & ATTR_CTIME)
  75                 inode->i_ctime = attr->ia_ctime;
  76         if (ia_valid & ATTR_MODE) {
  77                 inode->i_mode = attr->ia_mode;
  78                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  79                         inode->i_mode &= ~S_ISGID;
  80         }
  81         mark_inode_dirty(inode);
  82 }
  83
  84 static int setattr_mask(unsigned int ia_valid)
  85 {
  86         unsigned long dn_mask = 0;
  87
  88         if (ia_valid & ATTR_UID)
  89                 dn_mask |= DN_ATTRIB;
  90         if (ia_valid & ATTR_GID)
  91                 dn_mask |= DN_ATTRIB;
  92         if (ia_valid & ATTR_SIZE)
  93                 dn_mask |= DN_MODIFY;
  94         /* both times implies a utime(s) call */
  95         if ((ia_valid & (ATTR_ATIME|ATTR_MTIME)) == (ATTR_ATIME|ATTR_MTIME))
  96                 dn_mask |= DN_ATTRIB;
  97         else if (ia_valid & ATTR_ATIME)
  98                 dn_mask |= DN_ACCESS;
  99         else if (ia_valid & ATTR_MTIME)
 100                 dn_mask |= DN_MODIFY;
 101         if (ia_valid & ATTR_MODE)
 102                 dn_mask |= DN_ATTRIB;
 103         return dn_mask;
 104 }
 105
 106 int notify_change(struct dentry * dentry, struct iattr * attr)
 107 {
 108         struct inode *inode = dentry->d_inode;
 109         int error;
 110         time_t now = CURRENT_TIME;
 111         unsigned int ia_valid = attr->ia_valid;
 112
 113         if (!inode)
 114                 BUG();
 115
 116         attr->ia_ctime = now;
 117         if (!(ia_valid & ATTR_ATIME_SET))
 118                 attr->ia_atime = now;
 119         if (!(ia_valid & ATTR_MTIME_SET))
 120                 attr->ia_mtime = now;
 121
 122         lock_kernel();
 123         if (inode->i_op && inode->i_op->setattr)
 124                 error = inode->i_op->setattr(dentry, attr);
 125         else {
 126                 error = inode_change_ok(inode, attr);
 127                 if (!error)
 128                         inode_setattr(inode, attr);
 129         }
 130         unlock_kernel();
 131         if (!error) {
 132                 unsigned long dn_mask = setattr_mask(ia_valid);
 133                 if (dn_mask)
 134                         inode_dir_notify(dentry->d_parent->d_inode, dn_mask);
 135         }
 136         return error;
 137 }