mm: write_cache_pages integrity fix

[safe/jmp/linux-2.6] / fs / open.c

diff --git a/fs/open.c b/fs/open.c
index 07da935..d882fd2 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -272,6 +272,8 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)
                goto put_write_and_out;
 
        error = locks_verify_truncate(inode, NULL, length);
+       if (!error)
+               error = security_path_truncate(&path, length, 0);
        if (!error) {
                DQUOT_INIT(inode);
                error = do_truncate(path.dentry, length, 0, NULL);
@@ -329,6 +331,9 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 
        error = locks_verify_truncate(inode, file, length);
        if (!error)
+               error = security_path_truncate(&file->f_path, length,
+                                              ATTR_MTIME|ATTR_CTIME);
+       if (!error)
                error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
 out_putf:
        fput(file);
@@ -407,7 +412,7 @@ asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
        if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
                goto out_fput;
 
-       if (inode->i_op && inode->i_op->fallocate)
+       if (inode->i_op->fallocate)
                ret = inode->i_op->fallocate(inode, mode, offset, len);
        else
                ret = -EOPNOTSUPP;
@@ -425,39 +430,33 @@ out:
  */
 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 {
+       const struct cred *old_cred;
+       struct cred *override_cred;
        struct path path;
        struct inode *inode;
-       int old_fsuid, old_fsgid;
-       kernel_cap_t uninitialized_var(old_cap);  /* !SECURE_NO_SETUID_FIXUP */
        int res;
 
        if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
                return -EINVAL;
 
-       old_fsuid = current->fsuid;
-       old_fsgid = current->fsgid;
+       override_cred = prepare_creds();
+       if (!override_cred)
+               return -ENOMEM;
 
-       current->fsuid = current->uid;
-       current->fsgid = current->gid;
+       override_cred->fsuid = override_cred->uid;
+       override_cred->fsgid = override_cred->gid;
 
        if (!issecure(SECURE_NO_SETUID_FIXUP)) {
-               /*
-                * Clear the capabilities if we switch to a non-root user
-                */
-#ifndef CONFIG_SECURITY_FILE_CAPABILITIES
-               /*
-                * FIXME: There is a race here against sys_capset.  The
-                * capabilities can change yet we will restore the old
-                * value below.  We should hold task_capabilities_lock,
-                * but we cannot because user_path_at can sleep.
-                */
-#endif /* ndef CONFIG_SECURITY_FILE_CAPABILITIES */
-               if (current->uid)
-                       old_cap = cap_set_effective(__cap_empty_set);
+               /* Clear the capabilities if we switch to a non-root user */
+               if (override_cred->uid)
+                       cap_clear(override_cred->cap_effective);
                else
-                       old_cap = cap_set_effective(current->cap_permitted);
+                       override_cred->cap_effective =
+                               override_cred->cap_permitted;
        }
 
+       old_cred = override_creds(override_cred);
+
        res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
        if (res)
                goto out;
@@ -494,12 +493,8 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 out_path_release:
        path_put(&path);
 out:
-       current->fsuid = old_fsuid;
-       current->fsgid = old_fsgid;
-
-       if (!issecure(SECURE_NO_SETUID_FIXUP))
-               cap_set_effective(old_cap);
-
+       revert_creds(old_cred);
+       put_cred(override_cred);
        return res;
 }
 
@@ -792,13 +787,14 @@ static inline int __get_file_write_access(struct inode *inode,
 
 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
                                        int flags, struct file *f,
-                                       int (*open)(struct inode *, struct file *))
+                                       int (*open)(struct inode *, struct file *),
+                                       const struct cred *cred)
 {
        struct inode *inode;
        int error;
 
        f->f_flags = flags;
-       f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
+       f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
                                FMODE_PREAD | FMODE_PWRITE;
        inode = dentry->d_inode;
        if (f->f_mode & FMODE_WRITE) {
@@ -816,7 +812,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
        f->f_op = fops_get(inode->i_fop);
        file_move(f, &inode->i_sb->s_files);
 
-       error = security_dentry_open(f);
+       error = security_dentry_open(f, cred);
        if (error)
                goto cleanup_all;
 
@@ -891,6 +887,8 @@ cleanup_file:
 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
                int (*open)(struct inode *, struct file *))
 {
+       const struct cred *cred = current_cred();
+
        if (IS_ERR(nd->intent.open.file))
                goto out;
        if (IS_ERR(dentry))
@@ -898,7 +896,7 @@ struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry
        nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
                                             nd->intent.open.flags - 1,
                                             nd->intent.open.file,
-                                            open);
+                                            open, cred);
 out:
        return nd->intent.open.file;
 out_err:
@@ -917,6 +915,7 @@ EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
  */
 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
 {
+       const struct cred *cred = current_cred();
        struct file *filp;
 
        /* Pick up the filp from the open intent */
@@ -924,7 +923,7 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
        /* Has the filesystem initialised the file for us? */
        if (filp->f_path.dentry == NULL)
                filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
-                                    NULL);
+                                    NULL, cred);
        else
                path_put(&nd->path);
        return filp;
@@ -934,7 +933,8 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
  * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
  * error.
  */
-struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
+struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
+                        const struct cred *cred)
 {
        int error;
        struct file *f;
@@ -959,7 +959,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
                return ERR_PTR(error);
        }
 
-       return __dentry_open(dentry, mnt, flags, f, NULL);
+       return __dentry_open(dentry, mnt, flags, f, NULL, cred);
 }
 EXPORT_SYMBOL(dentry_open);
 
@@ -1141,8 +1141,7 @@ EXPORT_SYMBOL(sys_close);
 asmlinkage long sys_vhangup(void)
 {
        if (capable(CAP_SYS_TTY_CONFIG)) {
-               /* XXX: this needs locking */
-               tty_vhangup(current->signal->tty);
+               tty_vhangup_self();
                return 0;
        }
        return -EPERM;