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Two earlier bug fixes have created a security problem in the hfi1 driver. One fix aimed to solve an issue where current->mm was not valid when closing the hfi1 cdev. It attempted to do this by saving a cached value of the current->mm pointer at file open time. This is a problem if another process with access to the FD calls in via write() or ioctl() to pin pages via the hfi driver. The other fix tried to solve a use after free by taking a reference on the mm. To fix this correctly we use the existing cached value of the mm in the mmu notifier. Now we can check in the insert, evict, etc. routines that current->mm matched what the notifier was registered for. If not, then don't allow access. The register of the mmu notifier will save the mm pointer. Since in do_exit() the exit_mm() is called before exit_files(), which would call our close routine a reference is needed on the mm. We rely on the mmgrab done by the registration of the notifier, whereas before it was explicit. The mmu notifier deregistration happens when the user context is torn down, the creation of which triggered the registration. Also of note is we do not do any explicit work to protect the interval tree notifier. It doesn't seem that this is going to be needed since we aren't actually doing anything with current->mm. The interval tree notifier stuff still has a FIXME noted from a previous commit that will be addressed in a follow on patch. Cc: <stable@vger.kernel.org> Fixes:e0cf75deab("IB/hfi1: Fix mm_struct use after free") Fixes:3faa3d9a30("IB/hfi1: Make use of mm consistent") Link: https://lore.kernel.org/r/20201125210112.104301.51331.stgit@awfm-01.aw.intel.com Suggested-by: Jann Horn <jannh@google.com> Reported-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
103 lines
3.8 KiB
C
103 lines
3.8 KiB
C
/*
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* Copyright(c) 2020 Cornelis Networks, Inc.
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* Copyright(c) 2016 Intel Corporation.
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*
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* This file is provided under a dual BSD/GPLv2 license. When using or
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* redistributing this file, you may do so under either license.
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*
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* GPL LICENSE SUMMARY
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* BSD LICENSE
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of Intel Corporation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifndef _HFI1_MMU_RB_H
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#define _HFI1_MMU_RB_H
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#include "hfi.h"
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struct mmu_rb_node {
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unsigned long addr;
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unsigned long len;
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unsigned long __last;
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struct rb_node node;
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struct mmu_rb_handler *handler;
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struct list_head list;
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};
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/*
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* NOTE: filter, insert, invalidate, and evict must not sleep. Only remove is
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* allowed to sleep.
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*/
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struct mmu_rb_ops {
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bool (*filter)(struct mmu_rb_node *node, unsigned long addr,
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unsigned long len);
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int (*insert)(void *ops_arg, struct mmu_rb_node *mnode);
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void (*remove)(void *ops_arg, struct mmu_rb_node *mnode);
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int (*invalidate)(void *ops_arg, struct mmu_rb_node *node);
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int (*evict)(void *ops_arg, struct mmu_rb_node *mnode,
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void *evict_arg, bool *stop);
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};
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struct mmu_rb_handler {
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struct mmu_notifier mn;
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struct rb_root_cached root;
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void *ops_arg;
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spinlock_t lock; /* protect the RB tree */
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struct mmu_rb_ops *ops;
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struct list_head lru_list;
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struct work_struct del_work;
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struct list_head del_list;
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struct workqueue_struct *wq;
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};
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int hfi1_mmu_rb_register(void *ops_arg,
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struct mmu_rb_ops *ops,
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struct workqueue_struct *wq,
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struct mmu_rb_handler **handler);
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void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler);
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int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
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struct mmu_rb_node *mnode);
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void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg);
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void hfi1_mmu_rb_remove(struct mmu_rb_handler *handler,
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struct mmu_rb_node *mnode);
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bool hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler *handler,
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unsigned long addr, unsigned long len,
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struct mmu_rb_node **rb_node);
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#endif /* _HFI1_MMU_RB_H */
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