oss-sec mailing list archives
Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access
From: Haggai Eran <haggaie () mellanox com>
Date: Thu, 2 Apr 2015 18:12:58 +0000
On Thursday, April 2, 2015 7:44 PM, Shachar Raindel wrote:
-----Original Message----- From: Yann Droneaud [mailto:ydroneaud () opteya com] Sent: Thursday, April 02, 2015 7:35 PM To: Haggai Eran Cc: Shachar Raindel; Sagi Grimberg; oss-security () lists openwall com; <linux-rdma () vger kernel org> (linux-rdma () vger kernel org); linux- kernel () vger kernel org; stable () vger kernel org Subject: Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Hi Haggai, Le jeudi 02 avril 2015 à 18:18 +0300, Haggai Eran a écrit :On 02/04/2015 16:30, Yann Droneaud wrote:Hi, Le jeudi 02 avril 2015 à 10:52 +0000, Shachar Raindel a écrit :-----Original Message----- From: Yann Droneaud [mailto:ydroneaud () opteya com] Sent: Thursday, April 02, 2015 1:05 PM Le mercredi 18 mars 2015 à 17:39 +0000, Shachar Raindel a écrit :+ /* + * If the combination of the addr and size requested for thismemory+ * region causes an integer overflow, return error. + */ + if ((PAGE_ALIGN(addr + size) <= size) || + (PAGE_ALIGN(addr + size) <= addr)) + return ERR_PTR(-EINVAL); +Can access_ok() be used here ? if (!access_ok(writable ? VERIFY_WRITE : VERIFY_READ, addr, size)) return ERR_PTR(-EINVAL);No, this will break the current ODP semantics. ODP allows the user to register memory that is not accessible yet. This is a critical design feature, as it allows avoiding holding a registration cache. Adding this check will break the behavior, forcing memory to be all accessible when registering an ODP MR.Where's the check for the range being in userspace memory space, especially for the ODP case ? For non ODP case (eg. plain old behavior), does get_user_pages() ensure the requested pages fit in userspace region on all architectures ? I think so.Yes, get_user_pages will return a smaller amount of pages thanrequestedif it encounters an unmapped region (or a region without write permissions for write requests). If this happens, the loop in ib_umem_get calls get_user_pages again with the next set of pages, and this time if it the first page still cannot be mapped an error isreturned.In ODP case, I'm not sure such check is ever done ?In ODP, we also call get_user_pages, but only when a page fault occurs (see ib_umem_odp_map_dma_pages()). This allows the user to pre-registera memory region that contains unmapped virtual space, and then mmap different files into that area without needing to re-register.OK, thanks for the description. ... Another related question: as the large memory range could be registered by user space with ibv_reg_mr(pd, base, size, IB_ACCESS_ON_DEMAND), what's prevent the kernel to map a file as the result of mmap(0, ...) in this region, making it available remotely through IBV_WR_RDMA_READ / IBV_WR_RDMA_WRITE ?This is not a bug. This is a feature. Exposing a file through RDMA, using ODP, can be done exactly like this. Given that the application explicitly requested this behavior, I don't see why it is a problem. Actually, some of our tests use such flows. The mmu notifiers mechanism allow us to do this safely. When the page is written back to disk, it is removed from the ODP mapping. When it is accessed by the HCA, it is brought back to RAM.
I want to add that we would like to see users registering a very large memory region (perhaps the entire process address space) for local access, and then enabling remote access only to specific regions using memory windows. However, this isn't supported yet by our driver. Still, there are valid cases where you would still want the results of an mmap(0,...) call to be remotely accessible, in cases where there is enough trust between the local process and the remote process. It may help a middleware communication library register a large portion of the address space in advance, and still work with random pointers given to it by another application module. Regards, Haggai
Current thread:
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access, (continued)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Roland Dreier (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Roland Dreier (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Haggai Eran (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Haggai Eran (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Solar Designer (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 02)
- RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Shachar Raindel (Apr 02)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 08)
- Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access Yann Droneaud (Apr 08)