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/capability.h>
  14 #include <linux/fsnotify.h>
  15 #include <linux/fcntl.h>
  16 #include <linux/quotaops.h>
  17 #include <linux/security.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
  71         if (ia_valid & ATTR_SIZE &&
  72             attr->ia_size != i_size_read(inode)) {
  73                 int error = vmtruncate(inode, attr->ia_size);
  74                 if (error)
  75                         return error;
  76         }
  77
  78         if (ia_valid & ATTR_UID)
  79                 inode->i_uid = attr->ia_uid;
  80         if (ia_valid & ATTR_GID)
  81                 inode->i_gid = attr->ia_gid;
  82         if (ia_valid & ATTR_ATIME)
  83                 inode->i_atime = timespec_trunc(attr->ia_atime,
  84                                                 inode->i_sb->s_time_gran);
  85         if (ia_valid & ATTR_MTIME)
  86                 inode->i_mtime = timespec_trunc(attr->ia_mtime,
  87                                                 inode->i_sb->s_time_gran);
  88         if (ia_valid & ATTR_CTIME)
  89                 inode->i_ctime = timespec_trunc(attr->ia_ctime,
  90                                                 inode->i_sb->s_time_gran);
  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
 100         return 0;
 101 }
 102 EXPORT_SYMBOL(inode_setattr);
 103
 104 int notify_change(struct dentry * dentry, struct iattr * attr)
 105 {
 106         struct inode *inode = dentry->d_inode;
 107         mode_t mode;
 108         int error;
 109         struct timespec now;
 110         unsigned int ia_valid = attr->ia_valid;
 111
 112         mode = inode->i_mode;
 113         now = current_fs_time(inode->i_sb);
 114
 115         attr->ia_ctime = now;
 116         if (!(ia_valid & ATTR_ATIME_SET))
 117                 attr->ia_atime = now;
 118         if (!(ia_valid & ATTR_MTIME_SET))
 119                 attr->ia_mtime = now;
 120         if (ia_valid & ATTR_KILL_SUID) {
 121                 attr->ia_valid &= ~ATTR_KILL_SUID;
 122                 if (mode & S_ISUID) {
 123                         if (!(ia_valid & ATTR_MODE)) {
 124                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 125                                 attr->ia_mode = inode->i_mode;
 126                         }
 127                         attr->ia_mode &= ~S_ISUID;
 128                 }
 129         }
 130         if (ia_valid & ATTR_KILL_SGID) {
 131                 attr->ia_valid &= ~ ATTR_KILL_SGID;
 132                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 133                         if (!(ia_valid & ATTR_MODE)) {
 134                                 ia_valid = attr->ia_valid |= ATTR_MODE;
 135                                 attr->ia_mode = inode->i_mode;
 136                         }
 137                         attr->ia_mode &= ~S_ISGID;
 138                 }
 139         }
 140         if (!attr->ia_valid)
 141                 return 0;
 142
 143         if (ia_valid & ATTR_SIZE)
 144                 down_write(&dentry->d_inode->i_alloc_sem);
 145
 146         if (inode->i_op && inode->i_op->setattr) {
 147                 error = security_inode_setattr(dentry, attr);
 148                 if (!error)
 149                         error = inode->i_op->setattr(dentry, attr);
 150         } else {
 151                 error = inode_change_ok(inode, attr);
 152                 if (!error)
 153                         error = security_inode_setattr(dentry, attr);
 154                 if (!error) {
 155                         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 156                             (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 157                                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 158                         if (!error)
 159                                 error = inode_setattr(inode, attr);
 160                 }
 161         }
 162
 163         if (ia_valid & ATTR_SIZE)
 164                 up_write(&dentry->d_inode->i_alloc_sem);
 165
 166         if (!error)
 167                 fsnotify_change(dentry, ia_valid);
 168
 169         return error;
 170 }
 171
 172 EXPORT_SYMBOL(notify_change);