LXR linux-bk/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. */
  20int inode_change_ok(struct inode *inode, struct iattr *attr)
  21{
  22        int retval = -EPERM;
  23        unsigned int ia_valid = attr->ia_valid;
  24
  25        lock_kernel();
  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            (!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        }
  58fine:
  59        retval = 0;
  60error:
  61        unlock_kernel();
  62        return retval;
  63}
  64
  65int inode_setattr(struct inode * inode, struct iattr * attr)
  66{
  67        unsigned int ia_valid = attr->ia_valid;
  68        int error = 0;
  69        
  70        lock_kernel();
  71        if (ia_valid & ATTR_SIZE) {
  72                error = vmtruncate(inode, attr->ia_size);
  73                if (error)
  74                        goto out;
  75        }
  76
  77        if (ia_valid & ATTR_UID)
  78                inode->i_uid = attr->ia_uid;
  79        if (ia_valid & ATTR_GID)
  80                inode->i_gid = attr->ia_gid;
  81        if (ia_valid & ATTR_ATIME)
  82                inode->i_atime = attr->ia_atime;
  83        if (ia_valid & ATTR_MTIME)
  84                inode->i_mtime = attr->ia_mtime;
  85        if (ia_valid & ATTR_CTIME)
  86                inode->i_ctime = attr->ia_ctime;
  87        if (ia_valid & ATTR_MODE) {
  88                inode->i_mode = attr->ia_mode;
  89                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  90                        inode->i_mode &= ~S_ISGID;
  91        }
  92        mark_inode_dirty(inode);
  93out:
  94        unlock_kernel();
  95        return error;
  96}
  97
  98static int setattr_mask(unsigned int ia_valid)
  99{
 100        unsigned long dn_mask = 0;
 101
 102        if (ia_valid & ATTR_UID)
 103                dn_mask |= DN_ATTRIB;
 104        if (ia_valid & ATTR_GID)
 105                dn_mask |= DN_ATTRIB;
 106        if (ia_valid & ATTR_SIZE)
 107                dn_mask |= DN_MODIFY;
 108        /* both times implies a utime(s) call */
 109        if ((ia_valid & (ATTR_ATIME|ATTR_MTIME)) == (ATTR_ATIME|ATTR_MTIME))
 110                dn_mask |= DN_ATTRIB;
 111        else if (ia_valid & ATTR_ATIME)
 112                dn_mask |= DN_ACCESS;
 113        else if (ia_valid & ATTR_MTIME)
 114                dn_mask |= DN_MODIFY;
 115        if (ia_valid & ATTR_MODE)
 116                dn_mask |= DN_ATTRIB;
 117        return dn_mask;
 118}
 119
 120int notify_change(struct dentry * dentry, struct iattr * attr)
 121{
 122        struct inode *inode = dentry->d_inode;
 123        mode_t mode = inode->i_mode;
 124        int error;
 125        time_t now = CURRENT_TIME;
 126        unsigned int ia_valid = attr->ia_valid;
 127
 128        if (!inode)
 129                BUG();
 130
 131        attr->ia_ctime = now;
 132        if (!(ia_valid & ATTR_ATIME_SET))
 133                attr->ia_atime = now;
 134        if (!(ia_valid & ATTR_MTIME_SET))
 135                attr->ia_mtime = now;
 136        if (ia_valid & ATTR_KILL_SUID) {
 137                if (mode & S_ISUID) {
 138                        if (!(ia_valid & ATTR_MODE)) {
 139                                ia_valid = attr->ia_valid |= ATTR_MODE;
 140                                attr->ia_mode = inode->i_mode;
 141                        }
 142                        attr->ia_mode &= ~S_ISUID;
 143                }
 144        }
 145        if (ia_valid & ATTR_KILL_SGID) {
 146                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 147                        if (!(ia_valid & ATTR_MODE)) {
 148                                ia_valid = attr->ia_valid |= ATTR_MODE;
 149                                attr->ia_mode = inode->i_mode;
 150                        }
 151                        attr->ia_mode &= ~S_ISGID;
 152                }
 153        }
 154
 155        if (inode->i_op && inode->i_op->setattr) {
 156                error = security_ops->inode_setattr(dentry, attr);
 157                if (!error)
 158                        error = inode->i_op->setattr(dentry, attr);
 159        } else {
 160                error = inode_change_ok(inode, attr);
 161                if (!error)
 162                        error = security_ops->inode_setattr(dentry, attr);
 163                if (!error) {
 164                        if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 165                            (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 166                                error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 167                        if (!error)
 168                                error = inode_setattr(inode, attr);
 169                }
 170        }
 171        if (!error) {
 172                unsigned long dn_mask = setattr_mask(ia_valid);
 173                if (dn_mask)
 174                        dnotify_parent(dentry, dn_mask);
 175        }
 176        return error;
 177}
 178