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2021-04-26iov_iter: Four fixes for ITER_XARRAYDavid Howells
Fix four things[1] in the patch that adds ITER_XARRAY[2]: (1) Remove the address_space struct predeclaration. This is a holdover from when it was ITER_MAPPING. (2) Fix _copy_mc_to_iter() so that the xarray segment updates count and iov_offset in the iterator before returning. (3) Fix iov_iter_alignment() to not loop in the xarray case. Because the middle pages are all whole pages, only the end pages need be considered - and this can be reduced to just looking at the start position in the xarray and the iteration size. (4) Fix iov_iter_advance() to limit the size of the advance to no more than the remaining iteration size. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Jeff Layton <jlayton@redhat.com> Tested-by: Dave Wysochanski <dwysocha@redhat.com> Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1] Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2]
2021-04-23iov_iter: Add ITER_XARRAYDavid Howells
Add an iterator, ITER_XARRAY, that walks through a set of pages attached to an xarray, starting at a given page and offset and walking for the specified amount of bytes. The iterator supports transparent huge pages. The iterate_xarray() macro calls the helper function with rcu_access() helped. I think that this is only a problem for iov_iter_for_each_range() - and that returns an error for ITER_XARRAY (also, this function does not appear to be called). The caller must guarantee that the pages are all present and they must be locked using PG_locked, PG_writeback or PG_fscache to prevent them from going away or being migrated whilst they're being accessed. This is useful for copying data from socket buffers to inodes in network filesystems and for transferring data between those inodes and the cache using direct I/O. Whilst it is true that ITER_BVEC could be used instead, that would require a bio_vec array to be allocated to refer to all the pages - which should be redundant if inode->i_pages also points to all these pages. Note that older versions of this patch implemented an ITER_MAPPING instead, which was almost the same. Changes: v7: - Rename iter_xarray_copy_pages() to iter_xarray_populate_pages()[1]. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org> Tested-by: Dave Wysochanski <dwysocha@redhat.com> Tested-By: Marc Dionne <marc.dionne@auristor.com> cc: Alexander Viro <viro@zeniv.linux.org.uk> cc: Matthew Wilcox (Oracle) <willy@infradead.org> cc: Christoph Hellwig <hch@lst.de> cc: linux-mm@kvack.org cc: linux-cachefs@redhat.com cc: linux-afs@lists.infradead.org cc: linux-nfs@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: ceph-devel@vger.kernel.org cc: v9fs-developer@lists.sourceforge.net cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/3577430.1579705075@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/158861205740.340223.16592990225607814022.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/159465785214.1376674.6062549291411362531.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/160588477334.3465195.3608963255682568730.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/161118129703.1232039.17141248432017826976.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/161161026313.2537118.14676007075365418649.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/161340386671.1303470.10752208972482479840.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/161539527815.286939.14607323792547049341.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/161653786033.2770958.14154191921867463240.stgit@warthog.procyon.org.uk/ # v5 Link: https://lore.kernel.org/r/161789064740.6155.11932541175173658065.stgit@warthog.procyon.org.uk/ # v6 Link: https://lore.kernel.org/r/27c369a8f42bb8a617672b2dc0126a5c6df5a050.camel@kernel.org [1]
2021-02-04udp: fix skb_copy_and_csum_datagram with odd segment sizesWillem de Bruijn
When iteratively computing a checksum with csum_block_add, track the offset "pos" to correctly rotate in csum_block_add when offset is odd. The open coded implementation of skb_copy_and_csum_datagram did this. With the switch to __skb_datagram_iter calling csum_and_copy_to_iter, pos was reinitialized to 0 on each call. Bring back the pos by passing it along with the csum to the callback. Changes v1->v2 - pass csum value, instead of csump pointer (Alexander Duyck) Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/ Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers") Reported-by: Oliver Graute <oliver.graute@gmail.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2020-10-12Merge branch 'work.iov_iter' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull compat iovec cleanups from Al Viro: "Christoph's series around import_iovec() and compat variant thereof" * 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: security/keys: remove compat_keyctl_instantiate_key_iov mm: remove compat_process_vm_{readv,writev} fs: remove compat_sys_vmsplice fs: remove the compat readv/writev syscalls fs: remove various compat readv/writev helpers iov_iter: transparently handle compat iovecs in import_iovec iov_iter: refactor rw_copy_check_uvector and import_iovec iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c compat.h: fix a spelling error in <linux/compat.h>
2020-10-06x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()Dan Williams
In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: <stable@vger.kernel.org> Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
2020-10-03iov_iter: transparently handle compat iovecs in import_iovecChristoph Hellwig
Use in compat_syscall to import either native or the compat iovecs, and remove the now superflous compat_import_iovec. This removes the need for special compat logic in most callers, and the remaining ones can still be simplified by using __import_iovec with a bool compat parameter. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-10-03iov_iter: refactor rw_copy_check_uvector and import_iovecChristoph Hellwig
Split rw_copy_check_uvector into two new helpers with more sensible calling conventions: - iovec_from_user copies a iovec from userspace either into the provided stack buffer if it fits, or allocates a new buffer for it. Returns the actually used iovec. It also verifies that iov_len does fit a signed type, and handles compat iovecs if the compat flag is set. - __import_iovec consolidates the native and compat versions of import_iovec. It calls iovec_from_user, then validates each iovec actually points to user addresses, and ensures the total length doesn't overflow. This has two major implications: - the access_process_vm case loses the total lenght checking, which wasn't required anyway, given that each call receives two iovecs for the local and remote side of the operation, and it verifies the total length on the local side already. - instead of a single loop there now are two loops over the iovecs. Given that the iovecs are cache hot this doesn't make a major difference Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-06-30iov_iter: Move unnecessary inclusion of crypto/hash.hHerbert Xu
The header file linux/uio.h includes crypto/hash.h which pulls in most of the Crypto API. Since linux/uio.h is used throughout the kernel this means that every tiny bit of change to the Crypto API causes the entire kernel to get rebuilt. This patch fixes this by moving it into lib/iov_iter.c instead where it is actually used. This patch also fixes the ifdef to use CRYPTO_HASH instead of just CRYPTO which does not guarantee the existence of ahash. Unfortunately a number of drivers were relying on linux/uio.h to provide access to linux/slab.h. This patch adds inclusions of linux/slab.h as detected by build failures. Also skbuff.h was relying on this to provide a declaration for ahash_request. This patch adds a forward declaration instead. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-10-31pipe: Use head and tail pointers for the ring, not cursor and lengthDavid Howells
Convert pipes to use head and tail pointers for the buffer ring rather than pointer and length as the latter requires two atomic ops to update (or a combined op) whereas the former only requires one. (1) The head pointer is the point at which production occurs and points to the slot in which the next buffer will be placed. This is equivalent to pipe->curbuf + pipe->nrbufs. The head pointer belongs to the write-side. (2) The tail pointer is the point at which consumption occurs. It points to the next slot to be consumed. This is equivalent to pipe->curbuf. The tail pointer belongs to the read-side. (3) head and tail are allowed to run to UINT_MAX and wrap naturally. They are only masked off when the array is being accessed, e.g.: pipe->bufs[head & mask] This means that it is not necessary to have a dead slot in the ring as head == tail isn't ambiguous. (4) The ring is empty if "head == tail". A helper, pipe_empty(), is provided for this. (5) The occupancy of the ring is "head - tail". A helper, pipe_occupancy(), is provided for this. (6) The number of free slots in the ring is "pipe->ring_size - occupancy". A helper, pipe_space_for_user() is provided to indicate how many slots userspace may use. (7) The ring is full if "head - tail >= pipe->ring_size". A helper, pipe_full(), is provided for this. Signed-off-by: David Howells <dhowells@redhat.com>
2019-07-13Merge tag 'for-5.3/io_uring-20190711' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull io_uring updates from Jens Axboe: "This contains: - Support for recvmsg/sendmsg as first class opcodes. I don't envision going much further down this path, as there are plans in progress to support potentially any system call in an async fashion through io_uring. But I think it does make sense to have certain core ops available directly, especially those that can support a "try this non-blocking" flag/mode. (me) - Handle generic short reads automatically. This can happen fairly easily if parts of the buffered read is cached. Since the application needs to issue another request for the remainder, just do this internally and save kernel/user roundtrip while providing a nicer more robust API. (me) - Support for linked SQEs. This allows SQEs to depend on each other, enabling an application to eg queue a read-from-this-file,write-to-that-file pair. (me) - Fix race in stopping SQ thread (Jackie)" * tag 'for-5.3/io_uring-20190711' of git://git.kernel.dk/linux-block: io_uring: fix io_sq_thread_stop running in front of io_sq_thread io_uring: add support for recvmsg() io_uring: add support for sendmsg() io_uring: add support for sqe links io_uring: punt short reads to async context uio: make import_iovec()/compat_import_iovec() return bytes on success
2019-06-29block: never take page references for ITER_BVECChristoph Hellwig
If we pass pages through an iov_iter we always already have a reference in the caller. Thus remove the ITER_BVEC_FLAG_NO_REF and don't take reference to pages by default for bvec backed iov_iters. Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-05-31uio: make import_iovec()/compat_import_iovec() return bytes on successJens Axboe
Currently these functions return < 0 on error, and 0 for success. Change that so that we return < 0 on error, but number of bytes for success. Some callers already treat the return value that way, others need a slight tweak. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152Thomas Gleixner
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-01iov_iter: fix iov_iter_typeMing Lei
Commit 875f1d0769cd ("iov_iter: add ITER_BVEC_FLAG_NO_REF flag") introduces one extra flag of ITER_BVEC_FLAG_NO_REF, and this flag is stored into iter->type. However, iov_iter_type() doesn't consider the new added flag, fix it by masking this flag in iov_iter_type(). Fixes: 875f1d0769cd ("iov_iter: add ITER_BVEC_FLAG_NO_REF flag") Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-03-23Merge tag 'io_uring-20190323' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull io_uring fixes and improvements from Jens Axboe: "The first five in this series are heavily inspired by the work Al did on the aio side to fix the races there. The last two re-introduce a feature that was in io_uring before it got merged, but which I pulled since we didn't have a good way to have BVEC iters that already have a stable reference. These aren't necessarily related to block, it's just how io_uring pins fixed buffers" * tag 'io_uring-20190323' of git://git.kernel.dk/linux-block: block: add BIO_NO_PAGE_REF flag iov_iter: add ITER_BVEC_FLAG_NO_REF flag io_uring: mark me as the maintainer io_uring: retry bulk slab allocs as single allocs io_uring: fix poll races io_uring: fix fget/fput handling io_uring: add prepped flag io_uring: make io_read/write return an integer io_uring: use regular request ref counts
2019-03-18iov_iter: add ITER_BVEC_FLAG_NO_REF flagJens Axboe
For ITER_BVEC, if we're holding on to kernel pages, the caller doesn't need to grab a reference to the bvec pages, and drop that same reference on IO completion. This is essentially safe for any ITER_BVEC, but some use cases end up reusing pages and uncondtionally dropping a page reference on completion. And example of that is sendfile(2), that ends up being a splice_in + splice_out on the pipe pages. Add a flag that tells us it's fine to not grab a page reference to the bvec pages, since that caller knows not to drop a reference when it's done with the pages. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-04uio: remove the unused iov_for_each macroChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-12-13iov_iter: introduce hash_and_copy_to_iter helperSagi Grimberg
Allow consumers that want to use iov iterator helpers and also update a predefined hash calculation online when copying data. This is useful when copying incoming network buffers to a local iterator and calculate a digest on the incoming stream. nvme-tcp host driver that will be introduced in following patches is the first consumer via skb_copy_and_hash_datagram_iter. Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sagi Grimberg <sagi@lightbitslabs.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-12-13iov_iter: pass void csum pointer to csum_and_copy_to_iterSagi Grimberg
The single caller to csum_and_copy_to_iter is skb_copy_and_csum_datagram and we are trying to unite its logic with skb_copy_datagram_iter by passing a callback to the copy function that we want to apply. Thus, we need to make the checksum pointer private to the function. Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sagi Grimberg <sagi@lightbitslabs.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-10-24iov_iter: Add I/O discard iteratorDavid Howells
Add a new iterator, ITER_DISCARD, that can only be used in READ mode and just discards any data copied to it. This is useful in a network filesystem for discarding any unwanted data sent by a server. Signed-off-by: David Howells <dhowells@redhat.com>
2018-10-24iov_iter: Separate type from direction and use accessor functionsDavid Howells
In the iov_iter struct, separate the iterator type from the iterator direction and use accessor functions to access them in most places. Convert a bunch of places to use switch-statements to access them rather then chains of bitwise-AND statements. This makes it easier to add further iterator types. Also, this can be more efficient as to implement a switch of small contiguous integers, the compiler can use ~50% fewer compare instructions than it has to use bitwise-and instructions. Further, cease passing the iterator type into the iterator setup function. The iterator function can set that itself. Only the direction is required. Signed-off-by: David Howells <dhowells@redhat.com>
2018-10-24iov_iter: Use accessor functionDavid Howells
Use accessor functions to access an iterator's type and direction. This allows for the possibility of using some other method of determining the type of iterator than if-chains with bitwise-AND conditions. Signed-off-by: David Howells <dhowells@redhat.com>
2018-09-12uaccess: Fix is_source param for check_copy_size() in copy_to_iter_mcsafe()Dave Jiang
copy_to_iter_mcsafe() is passing in the is_source parameter as "false" to check_copy_size(). This is different than what copy_to_iter() does. Also, the addr parameter passed to check_copy_size() is the source so therefore we should be passing in "true" instead. Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()") Cc: <stable@vger.kernel.org> Reported-by: Fan Du <fan.du@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> Reported-by: Wenwei Tao <wenwei.tww@alibaba-inc.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-05-22uio, lib: Fix CONFIG_ARCH_HAS_UACCESS_MCSAFE compilationDan Williams
Add a common Kconfig CONFIG_ARCH_HAS_UACCESS_MCSAFE that archs can optionally select, and fixup the declaration of _copy_to_iter_mcsafe(). Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()") Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-05-15x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()Dan Williams
Use the updated memcpy_mcsafe() implementation to define copy_user_mcsafe() and copy_to_iter_mcsafe(). The most significant difference from typical copy_to_iter() is that the ITER_KVEC and ITER_BVEC iterator types can fail to complete a full transfer. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: hch@lst.de Cc: linux-fsdevel@vger.kernel.org Cc: linux-nvdimm@lists.01.org Link: http://lkml.kernel.org/r/152539239150.31796.9189779163576449784.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-11new primitive: iov_iter_for_each_range()Al Viro
For kvec and bvec: feeds segments to given callback as long as it returns 0. For iovec and pipe: fails. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-10-11kill iov_shorten()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-07-10fix brown paperbag bug in inlined copy_..._iter()Al Viro
"copied nothing" == "return 0", not "return full size". Fixes: aa28de275a24 "iov_iter/hardening: move object size checks to inlined part" Spotted-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-07-07Merge branch 'uaccess-work.iov_iter' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull iov_iter hardening from Al Viro: "This is the iov_iter/uaccess/hardening pile. For one thing, it trims the inline part of copy_to_user/copy_from_user to the minimum that *does* need to be inlined - object size checks, basically. For another, it sanitizes the checks for iov_iter primitives. There are 4 groups of checks: access_ok(), might_fault(), object size and KASAN. - access_ok() had been verified by whoever had set the iov_iter up. However, that has happened in a function far away, so proving that there's no path to actual copying bypassing those checks is hard and proving that iov_iter has not been buggered in the meanwhile is also not pleasant. So we want those redone in actual copyin/copyout. - might_fault() is better off consolidated - we know whether it needs to be checked as soon as we enter iov_iter primitive and observe the iov_iter flavour. No need to wait until the copyin/copyout. The call chains are short enough to make sure we won't miss anything - in fact, it's more robust that way, since there are cases where we do e.g. forced fault-in before getting to copyin/copyout. It's not quite what we need to check (in particular, combination of iovec-backed and set_fs(KERNEL_DS) is almost certainly a bug, not a cause to skip checks), but that's for later series. For now let's keep might_fault(). - KASAN checks belong in copyin/copyout - at the same level where other iov_iter flavours would've hit them in memcpy(). - object size checks should apply to *all* iov_iter flavours, not just iovec-backed ones. There are two groups of primitives - one gets the kernel object described as pointer + size (copy_to_iter(), etc.) while another gets it as page + offset + size (copy_page_to_iter(), etc.) For the first group the checks are best done where we actually have a chance to find the object size. In other words, those belong in inline wrappers in uio.h, before calling into iov_iter.c. Same kind as we have for inlined part of copy_to_user(). For the second group there is no object to look at - offset in page is just a number, it bears no type information. So we do them in the common helper called by iov_iter.c primitives of that kind. All it currently does is checking that we are not trying to access outside of the compound page; eventually we might want to add some sanity checks on the page involved. So the things we need in copyin/copyout part of iov_iter.c do not quite match anything in uaccess.h (we want no zeroing, we *do* want access_ok() and KASAN and we want no might_fault() or object size checks done on that level). OTOH, these needs are simple enough to provide a couple of helpers (static in iov_iter.c) doing just what we need..." * 'uaccess-work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: iov_iter: saner checks on copyin/copyout iov_iter: sanity checks for copy to/from page primitives iov_iter/hardening: move object size checks to inlined part copy_{to,from}_user(): consolidate object size checks copy_{from,to}_user(): move kasan checks and might_fault() out-of-line
2017-06-29iov_iter/hardening: move object size checks to inlined partAl Viro
There we actually have useful information about object sizes. Note: this patch has them done for all iov_iter flavours. Right now we do them twice in iovec case, but that'll change very shortly. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-06-09x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass ↵Dan Williams
operations The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-02[iov_iter] new privimitive: iov_iter_revert()Al Viro
opposite to iov_iter_advance(); the caller is responsible for never using it to move back past the initial position. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-16Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: - more ->d_init() stuff (work.dcache) - pathname resolution cleanups (work.namei) - a few missing iov_iter primitives - copy_from_iter_full() and friends. Either copy the full requested amount, advance the iterator and return true, or fail, return false and do _not_ advance the iterator. Quite a few open-coded callers converted (and became more readable and harder to fuck up that way) (work.iov_iter) - several assorted patches, the big one being logfs removal * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: logfs: remove from tree vfs: fix put_compat_statfs64() does not handle errors namei: fold should_follow_link() with the step into not-followed link namei: pass both WALK_GET and WALK_MORE to should_follow_link() namei: invert WALK_PUT logics namei: shift interpretation of LOOKUP_FOLLOW inside should_follow_link() namei: saner calling conventions for mountpoint_last() namei.c: get rid of user_path_parent() switch getfrag callbacks to ..._full() primitives make skb_add_data,{_nocache}() and skb_copy_to_page_nocache() advance only on success [iov_iter] new primitives - copy_from_iter_full() and friends don't open-code file_inode() ceph: switch to use of ->d_init() ceph: unify dentry_operations instances lustre: switch to use of ->d_init()
2016-12-05[iov_iter] new primitives - copy_from_iter_full() and friendsAl Viro
copy_from_iter_full(), copy_from_iter_full_nocache() and csum_and_copy_from_iter_full() - counterparts of copy_from_iter() et.al., advancing iterator only in case of successful full copy and returning whether it had been successful or not. Convert some obvious users. *NOTE* - do not blindly assume that something is a good candidate for those unless you are sure that not advancing iov_iter in failure case is the right thing in this case. Anything that does short read/short write kind of stuff (or is in a loop, etc.) is unlikely to be a good one. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-11-01fs: decouple READ and WRITE from the block layer opsChristoph Hellwig
Move READ and WRITE to kernel.h and don't define them in terms of block layer ops; they are our generic data direction indicators these days and have no more resemblance with the block layer ops. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-10-10Merge branch 'work.splice_read' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull splice fixups from Al Viro: "A couple of fixups for interaction of pipe-backed iov_iter with O_DIRECT reads + constification of a couple of primitives in uio.h missed by previous rounds. Kudos to davej - his fuzzing has caught those bugs" * 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: [btrfs] fix check_direct_IO() for non-iovec iterators constify iov_iter_count() and iter_is_iovec() fix ITER_PIPE interaction with direct_IO
2016-10-10Merge branch 'work.misc' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs updates from Al Viro: "Assorted misc bits and pieces. There are several single-topic branches left after this (rename2 series from Miklos, current_time series from Deepa Dinamani, xattr series from Andreas, uaccess stuff from from me) and I'd prefer to send those separately" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (39 commits) proc: switch auxv to use of __mem_open() hpfs: support FIEMAP cifs: get rid of unused arguments of CIFSSMBWrite() posix_acl: uapi header split posix_acl: xattr representation cleanups fs/aio.c: eliminate redundant loads in put_aio_ring_file fs/internal.h: add const to ns_dentry_operations declaration compat: remove compat_printk() fs/buffer.c: make __getblk_slow() static proc: unsigned file descriptors fs/file: more unsigned file descriptors fs: compat: remove redundant check of nr_segs cachefiles: Fix attempt to read i_blocks after deleting file [ver #2] cifs: don't use memcpy() to copy struct iov_iter get rid of separate multipage fault-in primitives fs: Avoid premature clearing of capabilities fs: Give dentry to inode_change_ok() instead of inode fuse: Propagate dentry down to inode_change_ok() ceph: Propagate dentry down to inode_change_ok() xfs: Propagate dentry down to inode_change_ok() ...
2016-10-10constify iov_iter_count() and iter_is_iovec()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-10-05new iov_iter flavour: pipe-backedAl Viro
iov_iter variant for passing data into pipe. copy_to_iter() copies data into page(s) it has allocated and stuffs them into the pipe; copy_page_to_iter() stuffs there a reference to the page given to it. Both will try to coalesce if possible. iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages() and friends will do as copy_to_iter() would have and return the pages where the data would've been copied. iov_iter_advance() will truncate everything past the spot it has advanced to. New primitive: iov_iter_pipe(), used for initializing those. pipe should be locked all along. Running out of space acts as fault would for iovec-backed ones; in other words, giving it to ->read_iter() may result in short read if the pipe overflows, or -EFAULT if it happens with nothing copied there. In other words, ->read_iter() on those acts pretty much like ->splice_read(). Moreover, all generic_file_splice_read() users, as well as many other ->splice_read() instances can be switched to that scheme - that'll happen in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-27get rid of separate multipage fault-in primitivesAl Viro
* the only remaining callers of "short" fault-ins are just as happy with generic variants (both in lib/iov_iter.c); switch them to multipage variants, kill the "short" ones * rename the multipage variants to now available plain ones. * get rid of compat macro defining iov_iter_fault_in_multipage_readable by expanding it in its only user. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-17fix iov_iter_fault_in_readable()Al Viro
... by turning it into what used to be multipages counterpart Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-08fix the copy vs. map logics in blk_rq_map_user_iov()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06iov_iter: constify {csum_and_,}copy_to_iter()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11new helper: iov_iter_rw()Omar Sandoval
Get either READ or WRITE out of iter->type. Signed-off-by: Omar Sandoval <osandov@osandov.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11Merge branch 'iov_iter' into for-nextAl Viro
2015-04-11VFS: Add iov_iter_fault_in_multipages_readable()Anton Altaparmakov
simillar to iov_iter_fault_in_readable() but differs in that it is not limited to faulting in the first iovec and instead faults in "bytes" bytes iterating over the iovecs as necessary. Also, instead of only faulting in the first and last page of the range, all pages are faulted in. This function is needed by NTFS when it does multi page file writes. Signed-off-by: Anton Altaparmakov <anton@tuxera.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-30saner iov_iter initialization primitivesAl Viro
iovec-backed iov_iter instances are assumed to satisfy several properties: * no more than UIO_MAXIOV elements in iovec array * total size of all ranges is no more than MAX_RW_COUNT * all ranges pass access_ok(). The problem is, invariants of data structures should be established in the primitives creating those data structures, not in the code using those primitives. And iov_iter_init() violates that principle. For a while we managed to get away with that, but once the use of iov_iter started to spread, it didn't take long for shit to hit the fan - missed check in sys_sendto() had introduced a roothole. We _do_ have primitives for importing and validating iovecs (both native and compat ones) and those primitives are almost always followed by shoving the resulting iovec into iov_iter. Life would be considerably simpler (and safer) if we combined those primitives with initializing iov_iter. That gives us two new primitives - import_iovec() and compat_import_iovec(). Calling conventions: iovec = iov_array; err = import_iovec(direction, uvec, nr_segs, ARRAY_SIZE(iov_array), &iovec, &iter); imports user vector into kernel space (into iov_array if it fits, allocated if it doesn't fit or if iovec was NULL), validates it and sets iter up to refer to it. On success 0 is returned and allocated kernel copy (or NULL if the array had fit into caller-supplied one) is returned via iovec. On failure all allocations are undone and -E... is returned. If the total size of ranges exceeds MAX_RW_COUNT, the excess is silently truncated. compat_import_iovec() expects uvec to be a pointer to user array of compat_iovec; otherwise it's identical to import_iovec(). Finally, import_single_range() sets iov_iter backed by single-element iovec covering a user-supplied range - err = import_single_range(direction, address, size, iovec, &iter); does validation and sets iter up. Again, size in excess of MAX_RW_COUNT gets silently truncated. Next commits will be switching the things up to use of those and reducing the amount of iov_iter_init() instances. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-17new helper: dup_iter()Al Viro
Copy iter and kmemdup the underlying array for the copy. Returns a pointer to result of kmemdup() to be kfree()'d later. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-17Merge branch 'iov_iter' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull iov_iter updates from Al Viro: "More iov_iter work - missing counterpart of iov_iter_init() for bvec-backed ones and vfs_read_iter()/vfs_write_iter() - wrappers for sync calls of ->read_iter()/->write_iter()" * 'iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: add vfs_iter_{read,write} helpers new helper: iov_iter_bvec()
2015-02-04vhost: vhost_scsi_handle_vq() should just use copy_from_user()Al Viro
it has just verified that it asks no more than the length of the first segment of iovec. And with that the last user of stuff in lib/iovec.c is gone. RIP. Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: kvm@vger.kernel.org Cc: virtualization@lists.linux-foundation.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>