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/module.h>
   9 #include <linux/time.h>
  10 #include <linux/mm.h>
  11 #include <linux/string.h>
  12 #include <linux/smp_lock.h>
  13 #include <linux/dnotify.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/quotaops.h>
  16 #include <linux/security.h>
  17
  18 /* Taken over from the old code... */
  19
  20 /* POSIX UID/GID verification for setting inode attributes. */
  21 int inode_change_ok(struct inode *inode, struct iattr *attr)
  22 {
  23         int retval = -EPERM;
  24         unsigned int ia_valid = attr->ia_valid;
  25
  26         /* If force is set do it anyway. */
  27         if (ia_valid & ATTR_FORCE)
  28                 goto fine;
  29
  30         /* Make sure a caller can chown. */
  31         if ((ia_valid & ATTR_UID) &&
  32             (current->fsuid != inode->i_uid ||
  33              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  34                 goto error;
  35
  36         /* Make sure caller can chgrp. */
  37         if ((ia_valid & ATTR_GID) &&
  38             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid) &&
  39             !capable(CAP_CHOWN))
  40                 goto error;
  41
  42         /* Make sure a caller can chmod. */
  43         if (ia_valid & ATTR_MODE) {
  44                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
  45                         goto error;
  46                 /* Also check the setgid bit! */
  47                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
  48                                 inode->i_gid) && !capable(CAP_FSETID))
  49                         attr->ia_mode &= ~S_ISGID;
  50         }
  51
  52         /* Check for setting the inode time. */
  53         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
  54                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  55                         goto error;
  56         }
  57 fine:
  58         retval = 0;
  59 error:
  60         return retval;
  61 }
  62
  63 EXPORT_SYMBOL(inode_change_ok);
  64
  65 int inode_setattr(struct inode * inode, struct iattr * attr)
  66 {
  67         unsigned int ia_valid = attr->ia_valid;
  68         int error = 0;
  69
  70         if (ia_valid & ATTR_SIZE) {
  71                 if (attr->ia_size != i_size_read(inode)) {
  72                         error = vmtruncate(inode, attr->ia_size);
  73                         if (error || (ia_valid == ATTR_SIZE))
  74                                 goto out;
  75                 } else {
  76                         /*
  77                          * We skipped the truncate but must still update
  78                          * timestamps
  79                          */
  80                         ia_valid |= ATTR_MTIME|ATTR_CTIME;
  81                 }
  82         }
  83
  84         if (ia_valid & ATTR_UID)
  85                 inode->i_uid = attr->ia_uid;
  86         if (ia_valid & ATTR_GID)
  87                 inode->i_gid = attr->ia_gid;
  88         if (ia_valid & ATTR_ATIME)
  89                 inode->i_atime = attr->ia_atime;
  90         if (ia_valid & ATTR_MTIME)
  91                 inode->i_mtime = attr->ia_mtime;
  92         if (ia_valid & ATTR_CTIME)
  93                 inode->i_ctime = attr->ia_ctime;
  94         if (ia_valid & ATTR_MODE) {
  95                 umode_t mode = attr->ia_mode;
  96
  97                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  98                         mode &= ~S_ISGID;
  99                 inode->i_mode = mode;
 100         }
 101         mark_inode_dirty(inode);
 102 out:
 103         return error;
 104 }
 105
 106 EXPORT_SYMBOL(inode_setattr);
 107
 108 int setattr_mask(unsigned int ia_valid)
 109 {
 110         unsigned long dn_mask = 0;
 111
 112         if (ia_valid & ATTR_UID)
 113                 dn_mask |= DN_ATTRIB;
 114         if (ia_valid & ATTR_GID)
 115                 dn_mask |= DN_ATTRIB;
 116         if (ia_valid & ATTR_SIZE)
 117                 dn_mask |= DN_MODIFY;
 118         /* both times implies a utime(s) call */
 119         if ((ia_valid & (ATTR_ATIME|ATTR_MTIME)) == (ATTR_ATIME|ATTR_MTIME))
 120                 dn_mask |= DN_ATTRIB;
 121         else if (ia_valid & ATTR_ATIME)
 122                 dn_mask |= DN_ACCESS;
 123         else if (ia_valid & ATTR_MTIME)
 124                 dn_mask |= DN_MODIFY;
 125         if (ia_valid & ATTR_MODE)
 126                 dn_mask |= DN_ATTRIB;
 127         return dn_mask;
 128 }
 129
 130 int notify_change(struct dentry * dentry, struct iattr * attr)
 131 {
 132         struct inode *inode = dentry->d_inode;
 133         mode_t mode = inode->i_mode;
 134         int error;
 135         struct timespec now = CURRENT_TIME;
 136         unsigned int ia_valid = attr->ia_valid;
 137
 138         if (!inode)
 139                 BUG();
 140
 141         attr->ia_ctime = now;
 142         if (!(ia_valid & ATTR_ATIME_SET))
 143                 attr->ia_atime = now;
 144         if (!(ia_valid & ATTR_MTIME_SET))
 145                 attr->ia_mtime = now;
 146         if (ia_valid & ATTR_KILL_SUID) {
 147                 attr->ia_valid &= ~ATTR_KILL_SUID;
 148                 if (mode & S_ISUID) {
 149                         if (!(ia_valid & ATTR_MODE)) {
 150                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 151                                 attr->ia_mode = inode->i_mode;
 152                         }
 153                         attr->ia_mode &= ~S_ISUID;
 154                 }
 155         }
 156         if (ia_valid & ATTR_KILL_SGID) {
 157                 attr->ia_valid &= ~ ATTR_KILL_SGID;
 158                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 159                         if (!(ia_valid & ATTR_MODE)) {
 160                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 161                                 attr->ia_mode = inode->i_mode;
 162                         }
 163                         attr->ia_mode &= ~S_ISGID;
 164                 }
 165         }
 166         if (!attr->ia_valid)
 167                 return 0;
 168
 169         if (inode->i_op && inode->i_op->setattr) {
 170                 error = security_inode_setattr(dentry, attr);
 171                 if (!error)
 172                         error = inode->i_op->setattr(dentry, attr);
 173         } else {
 174                 error = inode_change_ok(inode, attr);
 175                 if (!error)
 176                         error = security_inode_setattr(dentry, attr);
 177                 if (!error) {
 178                         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 179                             (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 180                                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 181                         if (!error)
 182                                 error = inode_setattr(inode, attr);
 183                 }
 184         }
 185         if (!error) {
 186                 unsigned long dn_mask = setattr_mask(ia_valid);
 187                 if (dn_mask)
 188                         dnotify_parent(dentry, dn_mask);
 189         }
 190         return error;
 191 }
 192
 193 EXPORT_SYMBOL(notify_change);