LXR linux/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/capability.h>
  13#include <linux/fsnotify.h>
  14#include <linux/fcntl.h>
  15#include <linux/quotaops.h>
  16#include <linux/security.h>
  17
  18/* Taken over from the old code... */
  19
  20/* POSIX UID/GID verification for setting inode attributes. */
  21int inode_change_ok(struct inode *inode, struct iattr *attr)
  22{
  23        int retval = -EPERM;
  24        unsigned int ia_valid = attr->ia_valid;
  25
  26        /* If force is set do it anyway. */
  27        if (ia_valid & ATTR_FORCE)
  28                goto fine;
  29
  30        /* Make sure a caller can chown. */
  31        if ((ia_valid & ATTR_UID) &&
  32            (current->fsuid != inode->i_uid ||
  33             attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
  34                goto error;
  35
  36        /* Make sure caller can chgrp. */
  37        if ((ia_valid & ATTR_GID) &&
  38            (current->fsuid != inode->i_uid ||
  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 (!is_owner_or_cap(inode))
  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 | ATTR_TIMES_SET)) {
  55                if (!is_owner_or_cap(inode))
  56                        goto error;
  57        }
  58fine:
  59        retval = 0;
  60error:
  61        return retval;
  62}
  63
  64EXPORT_SYMBOL(inode_change_ok);
  65
  66int inode_setattr(struct inode * inode, struct iattr * attr)
  67{
  68        unsigned int ia_valid = attr->ia_valid;
  69
  70        if (ia_valid & ATTR_SIZE &&
  71            attr->ia_size != i_size_read(inode)) {
  72                int error = vmtruncate(inode, attr->ia_size);
  73                if (error)
  74                        return error;
  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 = timespec_trunc(attr->ia_atime,
  83                                                inode->i_sb->s_time_gran);
  84        if (ia_valid & ATTR_MTIME)
  85                inode->i_mtime = timespec_trunc(attr->ia_mtime,
  86                                                inode->i_sb->s_time_gran);
  87        if (ia_valid & ATTR_CTIME)
  88                inode->i_ctime = timespec_trunc(attr->ia_ctime,
  89                                                inode->i_sb->s_time_gran);
  90        if (ia_valid & ATTR_MODE) {
  91                umode_t mode = attr->ia_mode;
  92
  93                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  94                        mode &= ~S_ISGID;
  95                inode->i_mode = mode;
  96        }
  97        mark_inode_dirty(inode);
  98
  99        return 0;
 100}
 101EXPORT_SYMBOL(inode_setattr);
 102
 103int notify_change(struct dentry * dentry, struct iattr * attr)
 104{
 105        struct inode *inode = dentry->d_inode;
 106        mode_t mode = inode->i_mode;
 107        int error;
 108        struct timespec now;
 109        unsigned int ia_valid = attr->ia_valid;
 110
 111        if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
 112                if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 113                        return -EPERM;
 114        }
 115
 116        now = current_fs_time(inode->i_sb);
 117
 118        attr->ia_ctime = now;
 119        if (!(ia_valid & ATTR_ATIME_SET))
 120                attr->ia_atime = now;
 121        if (!(ia_valid & ATTR_MTIME_SET))
 122                attr->ia_mtime = now;
 123        if (ia_valid & ATTR_KILL_PRIV) {
 124                attr->ia_valid &= ~ATTR_KILL_PRIV;
 125                ia_valid &= ~ATTR_KILL_PRIV;
 126                error = security_inode_need_killpriv(dentry);
 127                if (error > 0)
 128                        error = security_inode_killpriv(dentry);
 129                if (error)
 130                        return error;
 131        }
 132
 133        /*
 134         * We now pass ATTR_KILL_S*ID to the lower level setattr function so
 135         * that the function has the ability to reinterpret a mode change
 136         * that's due to these bits. This adds an implicit restriction that
 137         * no function will ever call notify_change with both ATTR_MODE and
 138         * ATTR_KILL_S*ID set.
 139         */
 140        if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
 141            (ia_valid & ATTR_MODE))
 142                BUG();
 143
 144        if (ia_valid & ATTR_KILL_SUID) {
 145                if (mode & S_ISUID) {
 146                        ia_valid = attr->ia_valid |= ATTR_MODE;
 147                        attr->ia_mode = (inode->i_mode & ~S_ISUID);
 148                }
 149        }
 150        if (ia_valid & ATTR_KILL_SGID) {
 151                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 152                        if (!(ia_valid & ATTR_MODE)) {
 153                                ia_valid = attr->ia_valid |= ATTR_MODE;
 154                                attr->ia_mode = inode->i_mode;
 155                        }
 156                        attr->ia_mode &= ~S_ISGID;
 157                }
 158        }
 159        if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
 160                return 0;
 161
 162        if (ia_valid & ATTR_SIZE)
 163                down_write(&dentry->d_inode->i_alloc_sem);
 164
 165        if (inode->i_op && inode->i_op->setattr) {
 166                error = security_inode_setattr(dentry, attr);
 167                if (!error)
 168                        error = inode->i_op->setattr(dentry, attr);
 169        } else {
 170                error = inode_change_ok(inode, attr);
 171                if (!error)
 172                        error = security_inode_setattr(dentry, attr);
 173                if (!error) {
 174                        if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
 175                            (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
 176                                error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
 177                        if (!error)
 178                                error = inode_setattr(inode, attr);
 179                }
 180        }
 181
 182        if (ia_valid & ATTR_SIZE)
 183                up_write(&dentry->d_inode->i_alloc_sem);
 184
 185        if (!error)
 186                fsnotify_change(dentry, ia_valid);
 187
 188        return error;
 189}
 190
 191EXPORT_SYMBOL(notify_change);
 192