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