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Dan Williams 1c97259740 mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags 
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.

It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that  could not be supported by all
archs Linus observed:

    I see why you *think* you want a bitmap. You think you want
    a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
    etc, so that people can do

    ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
		    | MAP_SYNC, fd, 0);

    and "know" that MAP_SYNC actually takes.

    And I'm saying that whole wish is bogus. You're fundamentally
    depending on special semantics, just make it explicit. It's already
    not portable, so don't try to make it so.

    Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
    of 0x3, and make people do

    ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
		    | MAP_SYNC, fd, 0);

    and then the kernel side is easier too (none of that random garbage
    playing games with looking at the "MAP_VALIDATE bit", but just another
    case statement in that map type thing.

    Boom. Done.

Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis.  Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.

Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-03 06:26:22 -07:00
..
kasan Merge branch 'linus' into locking/core, to pick up fixes 2017-08-10 12:20:53 +02:00
backing-dev.c mm/backing-dev.c: fix an error handling path in 'cgwb_create()' 2017-09-11 14:16:44 -06:00
balloon_compaction.c mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY 2017-09-08 18:26:46 -07:00
bootmem.c mm/bootmem.c: cosmetic improvement of code readability 2017-02-22 16:41:29 -08:00
cleancache.c fs: switch ->s_uuid to uuid_t 2017-06-05 16:59:12 +02:00
cma_debug.c mm/cma_debug.c: fix stack corruption due to sprintf usage 2017-08-18 15:32:02 -07:00
cma.c cma: fix calculation of aligned offset 2017-07-10 16:32:32 -07:00
cma.h cma: Store a name in the cma structure 2017-04-18 20:41:12 +02:00
compaction.c mm,compaction: serialize waitqueue_active() checks (for real) 2017-10-03 17:54:24 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
debug.c mm: make tlb_flush_pending global 2017-08-10 15:54:07 -07:00
dmapool.c lib/vsprintf.c: remove %Z support 2017-02-27 18:43:47 -08:00
early_ioremap.c x86/mm: Add support to access boot related data in the clear 2017-07-18 11:38:02 +02:00
fadvise.c mm: fadvise: avoid fadvise for fs without backing device 2017-09-08 18:26:47 -07:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c mm: have filemap_check_and_advance_wb_err clear AS_EIO/AS_ENOSPC 2017-10-03 17:54:24 -07:00
frame_vector.c treewide: use kv[mz]alloc* rather than opencoded variants 2017-05-08 17:15:13 -07:00
frontswap.c mm, frontswap: convert frontswap_enabled to static key 2016-07-26 16:19:19 -07:00
gup.c mm/device-public-memory: device memory cache coherent with CPU 2017-09-08 18:26:46 -07:00
highmem.c mm/highmem: make nr_free_highpages() handles all highmem zones by itself 2016-05-19 19:12:14 -07:00
hmm.c mm/hmm: avoid bloating arch that do not make use of HMM 2017-09-08 18:26:46 -07:00
huge_memory.c mm: soft-dirty: keep soft-dirty bits over thp migration 2017-09-08 18:26:45 -07:00
hugetlb_cgroup.c mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size 2016-05-20 17:58:30 -07:00
hugetlb.c powerpc updates for 4.14 2017-09-07 10:15:40 -07:00
hwpoison-inject.c mm: hwpoison: call shake_page() unconditionally 2017-05-03 15:52:12 -07:00
init-mm.c mm: Add a user_ns owner to mm_struct and fix ptrace permission checks 2016-11-22 11:49:48 -06:00
internal.h mm, oom: do not rely on TIF_MEMDIE for memory reserves access 2017-09-06 17:27:30 -07:00
interval_tree.c lib/interval_tree: fast overlap detection 2017-09-08 18:26:49 -07:00
Kconfig mm/hmm: avoid bloating arch that do not make use of HMM 2017-09-08 18:26:46 -07:00
Kconfig.debug mm: enable page poisoning early at boot 2017-05-03 15:52:10 -07:00
khugepaged.c mm: make PR_SET_THP_DISABLE immediately active 2017-07-10 16:32:31 -07:00
kmemcheck.c mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU 2017-04-18 11:42:36 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c mm: kmemleak: treat vm_struct as alternative reference to vmalloc'ed objects 2017-07-06 16:24:34 -07:00
ksm.c ksm: fix unlocked iteration over vmas in cmp_and_merge_page() 2017-10-03 17:54:23 -07:00
list_lru.c mm: memcontrol: use vmalloc fallback for large kmem memcg arrays 2017-10-03 17:54:25 -07:00
maccess.c x86: remove more uaccess_32.h complexity 2016-05-22 17:21:27 -07:00
madvise.c mm, hugetlb, soft_offline: save compound page order before page migration 2017-10-03 17:54:24 -07:00
Makefile mm/hmm: avoid bloating arch that do not make use of HMM 2017-09-08 18:26:46 -07:00
memblock.c mm/memblock.c: reversed logic in memblock_discard() 2017-08-25 16:12:46 -07:00
memcontrol.c mm/memcg: avoid page count check for zone device 2017-10-03 17:54:24 -07:00
memory_hotplug.c mm/memory_hotplug: define find_{smallest|biggest}_section_pfn as unsigned long 2017-10-03 17:54:26 -07:00
memory-failure.c x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages 2017-08-17 10:30:49 +02:00
memory.c mm/device-public-memory: fix edge case in _vm_normal_page() 2017-10-03 17:54:25 -07:00
mempolicy.c mm/mempolicy.c: remove BUG_ON() checks for VMA inside mpol_misplaced() 2017-09-08 18:26:47 -07:00
mempool.c sched/wait: Rename wait_queue_t => wait_queue_entry_t 2017-06-20 12:18:27 +02:00
memtest.c
migrate.c mm/hmm: avoid bloating arch that do not make use of HMM 2017-09-08 18:26:46 -07:00
mincore.c mm: remove shmem_mapping() shmem_zero_setup() duplicates 2017-02-24 17:46:56 -08:00
mlock.c mm/mlock.c: use page_zone() instead of page_zone_id() 2017-09-08 18:26:47 -07:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags 2017-11-03 06:26:22 -07:00
mmu_context.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
mmu_notifier.c mm/mmu_notifier: kill invalidate_page 2017-08-31 16:13:00 -07:00
mmzone.c mm/mmzone.c: swap likely to unlikely as code logic is different for next_zones_zonelist() 2017-02-22 16:41:29 -08:00
mprotect.c mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory 2017-09-08 18:26:46 -07:00
mremap.c mm: thp: check pmd migration entry in common path 2017-09-08 18:26:45 -07:00
msync.c
nobootmem.c mm: discard memblock data later 2017-08-18 15:32:01 -07:00
nommu.c Merge branch 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 18:13:32 -07:00
oom_kill.c mm, oom_reaper: skip mm structs with mmu notifiers 2017-10-03 17:54:24 -07:00
page_alloc.c mm, page_alloc: add scheduling point to memmap_init_zone 2017-10-03 17:54:25 -07:00
page_counter.c
page_ext.c mm, page_ext: periodically reschedule during page_ext_init() 2017-09-06 17:27:26 -07:00
page_idle.c mm/page_idle.c: constify attribute_group structures 2017-09-06 17:27:27 -07:00
page_io.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
page_isolation.c mm: unify new_node_page and alloc_migrate_target 2017-07-10 16:32:31 -07:00
page_owner.c mm, page_owner: skip unnecessary stack_trace entries 2017-09-13 18:53:16 -07:00
page_poison.c mm: enable page poisoning early at boot 2017-05-03 15:52:10 -07:00
page_vma_mapped.c mm/migrate: support un-addressable ZONE_DEVICE page in migration 2017-09-08 18:26:46 -07:00
page-writeback.c mm: rename global_page_state to global_zone_page_state 2017-09-06 17:27:29 -07:00
pagewalk.c mm/hugetlb: add size parameter to huge_pte_offset() 2017-07-06 16:24:34 -07:00
percpu-internal.h percpu: skip chunks if the alloc does not fit in the contig hint 2017-07-26 17:41:05 -04:00
percpu-km.c percpu: replace area map allocator with bitmap 2017-07-26 17:41:05 -04:00
percpu-stats.c percpu: fix starting offset for chunk statistics traversal 2017-09-27 14:45:57 -07:00
percpu-vm.c percpu: fix static checker warnings in pcpu_destroy_chunk 2017-06-29 11:23:38 -04:00
percpu.c percpu: fix iteration to prevent skipping over block 2017-09-28 07:39:27 -07:00
pgtable-generic.c mm: thp: enable thp migration in generic path 2017-09-08 18:26:45 -07:00
process_vm_access.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h> 2017-03-02 08:42:28 +01:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm: don't cap request size based on read-ahead setting 2016-12-12 18:55:08 -08:00
rmap.c lib/interval_tree: fast overlap detection 2017-09-08 18:26:49 -07:00
rodata_test.c mm: fix RODATA_TEST failure "rodata_test: test data was not read only" 2017-10-03 17:54:24 -07:00
shmem.c mm: treewide: remove GFP_TEMPORARY allocation flag 2017-09-13 18:53:16 -07:00
slab_common.c mm: memcontrol: use vmalloc fallback for large kmem memcg arrays 2017-10-03 17:54:25 -07:00
slab.c mm: memcontrol: account slab stats per lruvec 2017-07-06 16:24:35 -07:00
slab.h locking/lockdep: Rework FS_RECLAIM annotation 2017-08-10 12:29:03 +02:00
slob.c locking/lockdep: Rework FS_RECLAIM annotation 2017-08-10 12:29:03 +02:00
slub.c mm: treewide: remove GFP_TEMPORARY allocation flag 2017-09-13 18:53:16 -07:00
sparse-vmemmap.c mm, sparse, page_ext: drop ugly N_HIGH_MEMORY branches for allocations 2017-09-06 17:27:26 -07:00
sparse.c mm/sparse.c: fix typo in online_mem_sections 2017-09-08 18:26:47 -07:00
swap_cgroup.c mm, THP, swap: delay splitting THP during swap out 2017-07-06 16:24:31 -07:00
swap_slots.c mm/swap_slots.c: don't disable preemption while taking the per-CPU cache 2017-07-10 16:32:32 -07:00
swap_state.c mm: fix data corruption caused by lazyfree page 2017-10-03 17:54:25 -07:00
swap.c mm: avoid marking swap cached page as lazyfree 2017-10-03 17:54:24 -07:00
swapfile.c mm/swapfile.c: fix swapon frontswap_map memory leak on error 2017-09-08 18:26:47 -07:00
truncate.c mm/truncate.c: fix THP handling in invalidate_mapping_pages() 2017-07-10 16:32:32 -07:00
usercopy.c mm/usercopy: Drop extra is_vmalloc_or_module() check 2017-04-05 12:30:18 -07:00
userfaultfd.c userfaultfd: shmem: wire up shmem_mfill_zeropage_pte 2017-09-06 17:27:28 -07:00
util.c mm: rename global_page_state to global_zone_page_state 2017-09-06 17:27:29 -07:00
vmacache.c sched/headers: Prepare to move 'init_task' and 'init_thread_union' from <linux/sched.h> to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
vmalloc.c mm/vmalloc.c: don't reinvent the wheel but use existing llist API 2017-09-06 17:27:29 -07:00
vmpressure.c mm, vmpressure: pass-through notification support 2017-07-10 16:32:31 -07:00
vmscan.c mm, THP, swap: add THP swapping out fallback counting 2017-09-06 17:27:28 -07:00
vmstat.c mm: consider the number in local CPUs when reading NUMA stats 2017-09-08 18:26:47 -07:00
workingset.c mm: memcontrol: per-lruvec stats infrastructure 2017-07-06 16:24:35 -07:00
z3fold.c z3fold: fix stale list handling 2017-10-03 17:54:24 -07:00
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c
zsmalloc.c mm/zsmalloc.c: change stat type parameter to int 2017-09-08 18:26:47 -07:00
zswap.c mm/zswap.c: delete an error message for a failed memory allocation in zswap_dstmem_prepare() 2017-07-06 16:24:35 -07:00