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 #include <linux/time.h>
  18
  19 /* Taken over from the old code... */
  20
  21 /* POSIX UID/GID verification for setting inode attributes. */
  22 int inode_change_ok(struct inode *inode, struct iattr *attr)
  23 {
  24         int retval = -EPERM;
  25         unsigned int ia_valid = attr->ia_valid;
  26
  27         /* If force is set do it anyway. */
  28         if (ia_valid & ATTR_FORCE)
  29                 goto fine;
  30
  31         /* Make sure a caller can chown. */
  32         if ((ia_valid & ATTR_UID) &&
  33             (current->fsuid != inode->i_uid ||
  34              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  35                 goto error;
  36
  37         /* Make sure caller can chgrp. */
  38         if ((ia_valid & ATTR_GID) &&
  39             (current->fsuid != inode->i_uid ||
  40             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
  41             !capable(CAP_CHOWN))
  42                 goto error;
  43
  44         /* Make sure a caller can chmod. */
  45         if (ia_valid & ATTR_MODE) {
  46                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
  47                         goto error;
  48                 /* Also check the setgid bit! */
  49                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
  50                                 inode->i_gid) && !capable(CAP_FSETID))
  51                         attr->ia_mode &= ~S_ISGID;
  52         }
  53
  54         /* Check for setting the inode time. */
  55         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
  56                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  57                         goto error;
  58         }
  59 fine:
  60         retval = 0;
  61 error:
  62         return retval;
  63 }
  64
  65 EXPORT_SYMBOL(inode_change_ok);
  66
  67 int inode_setattr(struct inode * inode, struct iattr * attr)
  68 {
  69         unsigned int ia_valid = attr->ia_valid;
  70         int error = 0;
  71
  72         if (ia_valid & ATTR_SIZE) {
  73                 if (attr->ia_size != i_size_read(inode)) {
  74                         error = vmtruncate(inode, attr->ia_size);
  75                         if (error || (ia_valid == ATTR_SIZE))
  76                                 goto out;
  77                 } else {
  78                         /*
  79                          * We skipped the truncate but must still update
  80                          * timestamps
  81                          */
  82                         ia_valid |= ATTR_MTIME|ATTR_CTIME;
  83                 }
  84         }
  85
  86         if (ia_valid & ATTR_UID)
  87                 inode->i_uid = attr->ia_uid;
  88         if (ia_valid & ATTR_GID)
  89                 inode->i_gid = attr->ia_gid;
  90         if (ia_valid & ATTR_ATIME)
  91                 inode->i_atime = timespec_trunc(attr->ia_atime,
  92                                                 inode->i_sb->s_time_gran);
  93         if (ia_valid & ATTR_MTIME)
  94                 inode->i_mtime = timespec_trunc(attr->ia_mtime,
  95                                                 inode->i_sb->s_time_gran);
  96         if (ia_valid & ATTR_CTIME)
  97                 inode->i_ctime = timespec_trunc(attr->ia_ctime,
  98                                                 inode->i_sb->s_time_gran);
  99         if (ia_valid & ATTR_MODE) {
 100                 umode_t mode = attr->ia_mode;
 101
 102                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 103                         mode &= ~S_ISGID;
 104                 inode->i_mode = mode;
 105         }
 106         mark_inode_dirty(inode);
 107 out:
 108         return error;
 109 }
 110
 111 EXPORT_SYMBOL(inode_setattr);
 112
 113 int setattr_mask(unsigned int ia_valid)
 114 {
 115         unsigned long dn_mask = 0;
 116
 117         if (ia_valid & ATTR_UID)
 118                 dn_mask |= DN_ATTRIB;
 119         if (ia_valid & ATTR_GID)
 120                 dn_mask |= DN_ATTRIB;
 121         if (ia_valid & ATTR_SIZE)
 122                 dn_mask |= DN_MODIFY;
 123         /* both times implies a utime(s) call */
 124         if ((ia_valid & (ATTR_ATIME|ATTR_MTIME)) == (ATTR_ATIME|ATTR_MTIME))
 125                 dn_mask |= DN_ATTRIB;
 126         else if (ia_valid & ATTR_ATIME)
 127                 dn_mask |= DN_ACCESS;
 128         else if (ia_valid & ATTR_MTIME)
 129                 dn_mask |= DN_MODIFY;
 130         if (ia_valid & ATTR_MODE)
 131                 dn_mask |= DN_ATTRIB;
 132         return dn_mask;
 133 }
 134
 135 int notify_change(struct dentry * dentry, struct iattr * attr)
 136 {
 137         struct inode *inode = dentry->d_inode;
 138         mode_t mode;
 139         int error;
 140         struct timespec now;
 141         unsigned int ia_valid = attr->ia_valid;
 142
 143         if (!inode)
 144                 BUG();
 145
 146         mode = inode->i_mode;
 147         now = current_fs_time(inode->i_sb);
 148
 149         attr->ia_ctime = now;
 150         if (!(ia_valid & ATTR_ATIME_SET))
 151                 attr->ia_atime = now;
 152         if (!(ia_valid & ATTR_MTIME_SET))
 153                 attr->ia_mtime = now;
 154         if (ia_valid & ATTR_KILL_SUID) {
 155                 attr->ia_valid &= ~ATTR_KILL_SUID;
 156                 if (mode & S_ISUID) {
 157                         if (!(ia_valid & ATTR_MODE)) {
 158                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 159                                 attr->ia_mode = inode->i_mode;
 160                         }
 161                         attr->ia_mode &= ~S_ISUID;
 162                 }
 163         }
 164         if (ia_valid & ATTR_KILL_SGID) {
 165                 attr->ia_valid &= ~ ATTR_KILL_SGID;
 166                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 167                         if (!(ia_valid & ATTR_MODE)) {
 168                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 169                                 attr->ia_mode = inode->i_mode;
 170                         }
 171                         attr->ia_mode &= ~S_ISGID;
 172                 }
 173         }
 174         if (!attr->ia_valid)
 175                 return 0;
 176
 177         if (ia_valid & ATTR_SIZE)
 178                 down_write(&dentry->d_inode->i_alloc_sem);
 179
 180         if (inode->i_op && inode->i_op->setattr) {
 181                 error = security_inode_setattr(dentry, attr);
 182                 if (!error)
 183                         error = inode->i_op->setattr(dentry, attr);
 184         } else {
 185                 error = inode_change_ok(inode, attr);
 186                 if (!error)
 187                         error = security_inode_setattr(dentry, attr);
 188                 if (!error) {
 189                         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 190                             (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 191                                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 192                         if (!error)
 193                                 error = inode_setattr(inode, attr);
 194                 }
 195         }
 196
 197         if (ia_valid & ATTR_SIZE)
 198                 up_write(&dentry->d_inode->i_alloc_sem);
 199
 200         if (!error) {
 201                 unsigned long dn_mask = setattr_mask(ia_valid);
 202                 if (dn_mask)
 203                         dnotify_parent(dentry, dn_mask);
 204         }
 205         return error;
 206 }
 207
 208 EXPORT_SYMBOL(notify_change);