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