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/fsnotify.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 EXPORT_SYMBOL(inode_setattr);
 111
 112 int notify_change(struct dentry * dentry, struct iattr * attr)
 113 {
 114         struct inode *inode = dentry->d_inode;
 115         mode_t mode;
 116         int error;
 117         struct timespec now;
 118         unsigned int ia_valid = attr->ia_valid;
 119
 120         mode = inode->i_mode;
 121         now = current_fs_time(inode->i_sb);
 122
 123         attr->ia_ctime = now;
 124         if (!(ia_valid & ATTR_ATIME_SET))
 125                 attr->ia_atime = now;
 126         if (!(ia_valid & ATTR_MTIME_SET))
 127                 attr->ia_mtime = now;
 128         if (ia_valid & ATTR_KILL_SUID) {
 129                 attr->ia_valid &= ~ATTR_KILL_SUID;
 130                 if (mode & S_ISUID) {
 131                         if (!(ia_valid & ATTR_MODE)) {
 132                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 133                                 attr->ia_mode = inode->i_mode;
 134                         }
 135                         attr->ia_mode &= ~S_ISUID;
 136                 }
 137         }
 138         if (ia_valid & ATTR_KILL_SGID) {
 139                 attr->ia_valid &= ~ ATTR_KILL_SGID;
 140                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 141                         if (!(ia_valid & ATTR_MODE)) {
 142                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 143                                 attr->ia_mode = inode->i_mode;
 144                         }
 145                         attr->ia_mode &= ~S_ISGID;
 146                 }
 147         }
 148         if (!attr->ia_valid)
 149                 return 0;
 150
 151         if (ia_valid & ATTR_SIZE)
 152                 down_write(&dentry->d_inode->i_alloc_sem);
 153
 154         if (inode->i_op && inode->i_op->setattr) {
 155                 error = security_inode_setattr(dentry, attr);
 156                 if (!error)
 157                         error = inode->i_op->setattr(dentry, attr);
 158         } else {
 159                 error = inode_change_ok(inode, attr);
 160                 if (!error)
 161                         error = security_inode_setattr(dentry, attr);
 162                 if (!error) {
 163                         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 164                             (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 165                                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 166                         if (!error)
 167                                 error = inode_setattr(inode, attr);
 168                 }
 169         }
 170
 171         if (ia_valid & ATTR_SIZE)
 172                 up_write(&dentry->d_inode->i_alloc_sem);
 173
 174         if (!error)
 175                 fsnotify_change(dentry, ia_valid);
 176
 177         return error;
 178 }
 179
 180 EXPORT_SYMBOL(notify_change);