This patch adds pretty print support to the basic arraymap.
Support for other bpf maps can be added later.

This patch adds new attrs to the BPF_MAP_CREATE command to allow
specifying the btf_fd, btf_key_id and btf_value_id.  The
BPF_MAP_CREATE can then associate the btf to the map if
the creating map supports BTF.

A BTF supported map needs to implement two new map ops,
map_seq_show_elem() and map_check_btf().  This patch has
implemented these new map ops for the basic arraymap.

It also adds file_operations, bpffs_map_fops, to the pinned
map such that the pinned map can be opened and read.
After that, the user has an intuitive way to do
"cat bpffs/pathto/a-pinned-map" instead of getting
an error.

bpffs_map_fops should not be extended further to support
other operations.  Other operations (e.g. write/key-lookup...)
should be realized by the userspace tools (e.g. bpftool) through
the BPF_OBJ_GET_INFO_BY_FD, map's lookup/update interface...etc.
Follow up patches will allow the userspace to obtain
the BTF from a map-fd.

Here is a sample output when reading a pinned arraymap
with the following map's value:

struct map_value {
	int count_a;
	int count_b;
};

cat /sys/fs/bpf/pinned_array_map:

0: {1,2}
1: {3,4}
2: {5,6}
...
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds BPF_OBJ_GET_INFO_BY_FD support to BTF fd.
The original BTF data, which was used to create the BTF fd during
the earlier BPF_BTF_LOAD call, will be returned.

The userspace is expected to allocate buffer
to info.info and the buffer size is set to info.info_len before
calling BPF_OBJ_GET_INFO_BY_FD.

The original BTF data is copied to the userspace buffer (info.info).
Only upto the user's specified info.info_len will be copied.

The original BTF data size is set to info.info_len.  The userspace
needs to check if it is bigger than its allocated buffer size.
If it is, the userspace should realloc with the kernel-returned
info.info_len and call the BPF_OBJ_GET_INFO_BY_FD again.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds a BPF_BTF_LOAD command which
1) loads and verifies the BTF (implemented in earlier patches)
2) returns a BTF fd to userspace.  In the next patch, the
   BTF fd can be specified during BPF_MAP_CREATE.

It currently limits to CAP_SYS_ADMIN.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds pretty print capability for data with BTF type info.
The current usage is to allow pretty print for a BPF map.

The next few patches will allow a read() on a pinned map with BTF
type info for its key and value.

This patch uses the seq_printf() infra.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

After collecting all btf_type in the first pass in an earlier patch,
the second pass (in this patch) can validate the reference types
(e.g. the referring type does exist and it does not refer to itself).

While checking the reference type, it also gathers other information (e.g.
the size of an array).  This info will be useful in checking the
struct's members in a later patch.  They will also be useful in doing
pretty print later.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch introduces BPF type Format (BTF).

BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map.  Hence, it basically focus
on the C programming language which the modern BPF is primary
using.  The first use case is to provide a generic pretty print
capability for a BPF map.

BTF has its root from CTF (Compact C-Type format).  To simplify
the handling of BTF data, BTF removes the differences between
small and big type/struct-member.  Hence, BTF consistently uses u32
instead of supporting both "one u16" and "two u32 (+padding)" in
describing type and struct-member.

It also raises the number of types (and functions) limit
from 0x7fff to 0x7fffffff.

Due to the above changes,  the format is not compatible to CTF.
Hence, BTF starts with a new BTF_MAGIC and version number.

This patch does the first verification pass to the BTF.  The first
pass checks:
1. meta-data size (e.g. It does not go beyond the total btf's size)
2. name_offset is valid
3. Each BTF_KIND (e.g. int, enum, struct....) does its
   own check of its meta-data.

Some other checks, like checking a struct's member is referring
to a valid type, can only be done in the second pass.  The second
verification pass will be implemented in the next patch.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Adding new bpf helper which would allow us to manipulate
xdp's data_end pointer, and allow us to reduce packet's size
indended use case: to generate ICMP messages from XDP context,
where such message would contain truncated original packet.
Signed-off-by: NNikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Like tos inherit, ttl inherit should also means inherit the inner protocol's
ttl values, which actually not implemented in vxlan yet.

But we could not treat ttl == 0 as "use the inner TTL", because that would be
used also when the "ttl" option is not specified and that would be a behavior
change, and breaking real use cases.

So add a different attribute IFLA_VXLAN_TTL_INHERIT when "ttl inherit" is
specified with ip cmd.
Reported-by: NJianlin Shi <jishi@redhat.com>
Suggested-by: NJiri Benc <jbenc@redhat.com>
Signed-off-by: NHangbin Liu <liuhangbin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The statistics such as InHdrErrors should be counted on the ingress
netdev rather than on the dev from the dst, which is the egress.
Signed-off-by: NStephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

BPF core gets access to __inet6_bind via ipv6_bpf_stub_impl, so it is
not invoked directly outside of af_inet6.c. Make it static and move
inet6_bind after to avoid forward declaration.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Changing API ndo_xdp_xmit to take a struct xdp_frame instead of struct
xdp_buff.  This brings xdp_return_frame and ndp_xdp_xmit in sync.

This builds towards changing the API further to become a bulk API,
because xdp_buff is not a queue-able object while xdp_frame is.

V4: Adjust for commit 59655a5b ("tuntap: XDP_TX can use native XDP")
V7: Adjust for commit d9314c47 ("i40e: add support for XDP_REDIRECT")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Changing API xdp_return_frame() to take struct xdp_frame as argument,
seems like a natural choice. But there are some subtle performance
details here that needs extra care, which is a deliberate choice.

When de-referencing xdp_frame on a remote CPU during DMA-TX
completion, result in the cache-line is change to "Shared"
state. Later when the page is reused for RX, then this xdp_frame
cache-line is written, which change the state to "Modified".

This situation already happens (naturally) for, virtio_net, tun and
cpumap as the xdp_frame pointer is the queued object.  In tun and
cpumap, the ptr_ring is used for efficiently transferring cache-lines
(with pointers) between CPUs. Thus, the only option is to
de-referencing xdp_frame.

It is only the ixgbe driver that had an optimization, in which it can
avoid doing the de-reference of xdp_frame.  The driver already have
TX-ring queue, which (in case of remote DMA-TX completion) have to be
transferred between CPUs anyhow.  In this data area, we stored a
struct xdp_mem_info and a data pointer, which allowed us to avoid
de-referencing xdp_frame.

To compensate for this, a prefetchw is used for telling the cache
coherency protocol about our access pattern.  My benchmarks show that
this prefetchw is enough to compensate the ixgbe driver.

V7: Adjust for commit d9314c47 ("i40e: add support for XDP_REDIRECT")
V8: Adjust for commit bd658dda ("net/mlx5e: Separate dma base address
and offset in dma_sync call")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

New allocator type MEM_TYPE_PAGE_POOL for page_pool usage.

The registered allocator page_pool pointer is not available directly
from xdp_rxq_info, but it could be (if needed).  For now, the driver
should keep separate track of the page_pool pointer, which it should
use for RX-ring page allocation.

As suggested by Saeed, to maintain a symmetric API it is the drivers
responsibility to allocate/create and free/destroy the page_pool.
Thus, after the driver have called xdp_rxq_info_unreg(), it is drivers
responsibility to free the page_pool, but with a RCU free call.  This
is done easily via the page_pool helper page_pool_destroy() (which
avoids touching any driver code during the RCU callback, which could
happen after the driver have been unloaded).

V8: address issues found by kbuild test robot
 - Address sparse should be static warnings
 - Allow xdp.o to be compiled without page_pool.o

V9: Remove inline from .c file, compiler knows best
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Need a fast page recycle mechanism for ndo_xdp_xmit API for returning
pages on DMA-TX completion time, which have good cross CPU
performance, given DMA-TX completion time can happen on a remote CPU.

Refurbish my page_pool code, that was presented[1] at MM-summit 2016.
Adapted page_pool code to not depend the page allocator and
integration into struct page.  The DMA mapping feature is kept,
even-though it will not be activated/used in this patchset.

[1] http://people.netfilter.org/hawk/presentations/MM-summit2016/generic_page_pool_mm_summit2016.pdf

V2: Adjustments requested by Tariq
 - Changed page_pool_create return codes, don't return NULL, only
   ERR_PTR, as this simplifies err handling in drivers.

V4: many small improvements and cleanups
- Add DOC comment section, that can be used by kernel-doc
- Improve fallback mode, to work better with refcnt based recycling
  e.g. remove a WARN as pointed out by Tariq
  e.g. quicker fallback if ptr_ring is empty.

V5: Fixed SPDX license as pointed out by Alexei

V6: Adjustments requested by Eric Dumazet
 - Adjust ____cacheline_aligned_in_smp usage/placement
 - Move rcu_head in struct page_pool
 - Free pages quicker on destroy, minimize resources delayed an RCU period
 - Remove code for forward/backward compat ABI interface

V8: Issues found by kbuild test robot
 - Address sparse should be static warnings
 - Only compile+link when a driver use/select page_pool,
   mlx5 selects CONFIG_PAGE_POOL, although its first used in two patches
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the IDA infrastructure for getting a cyclic increasing ID number,
that is used for keeping track of each registered allocator per
RX-queue xdp_rxq_info.  Instead of using the IDR infrastructure, which
uses a radix tree, use a dynamic rhashtable, for creating ID to
pointer lookup table, because this is faster.

The problem that is being solved here is that, the xdp_rxq_info
pointer (stored in xdp_buff) cannot be used directly, as the
guaranteed lifetime is too short.  The info is needed on a
(potentially) remote CPU during DMA-TX completion time . In an
xdp_frame the xdp_mem_info is stored, when it got converted from an
xdp_buff, which is sufficient for the simple page refcnt based recycle
schemes.

For more advanced allocators there is a need to store a pointer to the
registered allocator.  Thus, there is a need to guard the lifetime or
validity of the allocator pointer, which is done through this
rhashtable ID map to pointer. The removal and validity of of the
allocator and helper struct xdp_mem_allocator is guarded by RCU.  The
allocator will be created by the driver, and registered with
xdp_rxq_info_reg_mem_model().

It is up-to debate who is responsible for freeing the allocator
pointer or invoking the allocator destructor function.  In any case,
this must happen via RCU freeing.

Use the IDA infrastructure for getting a cyclic increasing ID number,
that is used for keeping track of each registered allocator per
RX-queue xdp_rxq_info.

V4: Per req of Jason Wang
- Use xdp_rxq_info_reg_mem_model() in all drivers implementing
  XDP_REDIRECT, even-though it's not strictly necessary when
  allocator==NULL for type MEM_TYPE_PAGE_SHARED (given it's zero).

V6: Per req of Alex Duyck
- Introduce rhashtable_lookup() call in later patch

V8: Address sparse should be static warnings (from kbuild test robot)
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The generic xdp_frame format, was inspired by the cpumap own internal
xdp_pkt format.  It is now time to convert it over to the generic
xdp_frame format.  The cpumap needs one extra field dev_rx.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The tuntap driver invented it's own driver specific way of queuing
XDP packets, by storing the xdp_buff information in the top of
the XDP frame data.

Convert it over to use the more generic xdp_frame structure.  The
main problem with the in-driver method is that the xdp_rxq_info pointer
cannot be trused/used when dequeueing the frame.

V3: Remove check based on feedback from Jason
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is needed to convert drivers tuntap and virtio_net.

This is a generalization of what is done inside cpumap, which will be
converted later.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is done to prepare for the next patch, and it is also
nice to move this XDP related struct out of filter.h.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce an xdp_return_frame API, and convert over cpumap as
the first user, given it have queued XDP frame structure to leverage.

V3: Cleanup and remove C99 style comments, pointed out by Alex Duyck.
V6: Remove comment that id will be added later (Req by Alex Duyck)
V8: Rename enum mem_type to xdp_mem_type (found by kbuild test robot)
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This tracepoint was replaced by inet_sock_set_state in 563e0bb0 and not
used anywhere in the kernel anymore. Remove it.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds missing values for the max read request size.
E.g. network driver r8169 uses a value of 4K.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some networks can make sure TCP payload can exactly fit 4KB pages,
with well chosen MSS/MTU and architectures.

Implement mmap() system call so that applications can avoid
copying data without complex splice() games.

Note that a successful mmap( X bytes) on TCP socket is consuming
bytes, as if recvmsg() has been done. (tp->copied += X)

Only PROT_READ mappings are accepted, as skb page frags
are fundamentally shared and read only.

If tcp_mmap() finds data that is not a full page, or a patch of
urgent data, -EINVAL is returned, no bytes are consumed.

Application must fallback to recvmsg() to read the problematic sequence.

mmap() wont block,  regardless of socket being in blocking or
non-blocking mode. If not enough bytes are in receive queue,
mmap() would return -EAGAIN, or -EIO if socket is in a state
where no other bytes can be added into receive queue.

An application might use SO_RCVLOWAT, poll() and/or ioctl( FIONREAD)
to efficiently use mmap()

On the sender side, MSG_EOR might help to clearly separate unaligned
headers and 4K-aligned chunks if necessary.

Tested:

mlx4 (cx-3) 40Gbit NIC, with tcp_mmap program provided in following patch.
MTU set to 4168  (4096 TCP payload, 40 bytes IPv6 header, 32 bytes TCP header)

Without mmap() (tcp_mmap -s)

received 32768 MB (0 % mmap'ed) in 8.13342 s, 33.7961 Gbit,
  cpu usage user:0.034 sys:3.778, 116.333 usec per MB, 63062 c-switches
received 32768 MB (0 % mmap'ed) in 8.14501 s, 33.748 Gbit,
  cpu usage user:0.029 sys:3.997, 122.864 usec per MB, 61903 c-switches
received 32768 MB (0 % mmap'ed) in 8.11723 s, 33.8635 Gbit,
  cpu usage user:0.048 sys:3.964, 122.437 usec per MB, 62983 c-switches
received 32768 MB (0 % mmap'ed) in 8.39189 s, 32.7552 Gbit,
  cpu usage user:0.038 sys:4.181, 128.754 usec per MB, 55834 c-switches

With mmap() on receiver (tcp_mmap -s -z)

received 32768 MB (100 % mmap'ed) in 8.03083 s, 34.2278 Gbit,
  cpu usage user:0.024 sys:1.466, 45.4712 usec per MB, 65479 c-switches
received 32768 MB (100 % mmap'ed) in 7.98805 s, 34.4111 Gbit,
  cpu usage user:0.026 sys:1.401, 43.5486 usec per MB, 65447 c-switches
received 32768 MB (100 % mmap'ed) in 7.98377 s, 34.4296 Gbit,
  cpu usage user:0.028 sys:1.452, 45.166 usec per MB, 65496 c-switches
received 32768 MB (99.9969 % mmap'ed) in 8.01838 s, 34.281 Gbit,
  cpu usage user:0.02 sys:1.446, 44.7388 usec per MB, 65505 c-switches
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SO_RCVLOWAT is properly handled in tcp_poll(), so that POLLIN is only
generated when enough bytes are available in receive queue, after
David change (commit c7004482 "tcp: Respect SO_RCVLOWAT in tcp_poll().")

But TCP still calls sk->sk_data_ready() for each chunk added in receive
queue, meaning thread is awaken, and goes back to sleep shortly after.

Tested:

tcp_mmap test program, receiving 32768 MB of data with SO_RCVLOWAT set to 512KB

-> Should get ~2 wakeups (c-switches) per MB, regardless of how many
(tiny or big) packets were received.

High speed (mostly full size GRO packets)

received 32768 MB (100 % mmap'ed) in 8.03112 s, 34.2266 Gbit,
  cpu usage user:0.037 sys:1.404, 43.9758 usec per MB, 65497 c-switches

received 32768 MB (99.9954 % mmap'ed) in 7.98453 s, 34.4263 Gbit,
  cpu usage user:0.03 sys:1.422, 44.3115 usec per MB, 65485 c-switches

Low speed (sender is ratelimited and sends 1-MSS at a time, so GRO is not helping)

received 22474.5 MB (100 % mmap'ed) in 6015.35 s, 0.0313414 Gbit,
  cpu usage user:0.05 sys:1.586, 72.7952 usec per MB, 44950 c-switches
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Applications might use SO_RCVLOWAT on TCP socket hoping to receive
one [E]POLLIN event only when a given amount of bytes are ready in socket
receive queue.

Problem is that receive autotuning is not aware of this constraint,
meaning sk_rcvbuf might be too small to allow all bytes to be stored.

Add a new (struct proto_ops)->set_rcvlowat method so that a protocol
can override the default setsockopt(SO_RCVLOWAT) behavior.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root.  Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.

[willy@infradead.org: fix nds32, fs/dax.c]
  Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NJeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This results in no change in structure size on 64-bit machines as it
fits in the padding between the gfp_t and the void *.  32-bit machines
will grow the structure from 8 to 12 bytes.  Almost all radix trees are
protected with (at least) a spinlock, so as they are converted from
radix trees to xarrays, the data structures will shrink again.

Initialising the spinlock requires a name for the benefit of lockdep, so
RADIX_TREE_INIT() now needs to know the name of the radix tree it's
initialising, and so do IDR_INIT() and IDA_INIT().

Also add the xa_lock() and xa_unlock() family of wrappers to make it
easier to use the lock.  If we could rely on -fplan9-extensions in the
compiler, we could avoid all of this syntactic sugar, but that wasn't
added until gcc 4.6.

Link: http://lkml.kernel.org/r/20180313132639.17387-8-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NJeff Layton <jlayton@kernel.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

XFS currently contains a copy-and-paste of __set_page_dirty().  Export
it from buffer.c instead.

Link: http://lkml.kernel.org/r/20180313132639.17387-6-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NJeff Layton <jlayton@kernel.org>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "XArray", v9.  (First part thereof).

This patchset is, I believe, appropriate for merging for 4.17.  It
contains the XArray implementation, to eventually replace the radix
tree, and converts the page cache to use it.

This conversion keeps the radix tree and XArray data structures in sync
at all times.  That allows us to convert the page cache one function at
a time and should allow for easier bisection.  Other than renaming some
elements of the structures, the data structures are fundamentally
unchanged; a radix tree walk and an XArray walk will touch the same
number of cachelines.  I have changes planned to the XArray data
structure, but those will happen in future patches.

Improvements the XArray has over the radix tree:

 - The radix tree provides operations like other trees do; 'insert' and
   'delete'. But what most users really want is an automatically
   resizing array, and so it makes more sense to give users an API that
   is like an array -- 'load' and 'store'. We still have an 'insert'
   operation for users that really want that semantic.

 - The XArray considers locking as part of its API. This simplifies a
   lot of users who formerly had to manage their own locking just for
   the radix tree. It also improves code generation as we can now tell
   RCU that we're holding a lock and it doesn't need to generate as much
   fencing code. The other advantage is that tree nodes can be moved
   (not yet implemented).

 - GFP flags are now parameters to calls which may need to allocate
   memory. The radix tree forced users to decide what the allocation
   flags would be at creation time. It's much clearer to specify them at
   allocation time.

 - Memory is not preloaded; we don't tie up dozens of pages on the off
   chance that the slab allocator fails. Instead, we drop the lock,
   allocate a new node and retry the operation. We have to convert all
   the radix tree, IDA and IDR preload users before we can realise this
   benefit, but I have not yet found a user which cannot be converted.

 - The XArray provides a cmpxchg operation. The radix tree forces users
   to roll their own (and at least four have).

 - Iterators take a 'max' parameter. That simplifies many users and will
   reduce the amount of iteration done.

 - Iteration can proceed backwards. We only have one user for this, but
   since it's called as part of the pagefault readahead algorithm, that
   seemed worth mentioning.

 - RCU-protected pointers are not exposed as part of the API. There are
   some fun bugs where the page cache forgets to use rcu_dereference()
   in the current codebase.

 - Value entries gain an extra bit compared to radix tree exceptional
   entries. That gives us the extra bit we need to put huge page swap
   entries in the page cache.

 - Some iterators now take a 'filter' argument instead of having
   separate iterators for tagged/untagged iterations.

The page cache is improved by this:

 - Shorter, easier to read code

 - More efficient iterations

 - Reduction in size of struct address_space

 - Fewer walks from the top of the data structure; the XArray API
   encourages staying at the leaf node and conducting operations there.

This patch (of 8):

None of these bits may be used for slab allocations, so we can use them
as radix tree flags as long as we mask them off before passing them to
the slab allocator. Move the IDR flag from the high bits to the
GFP_ZONEMASK bits.

Link: http://lkml.kernel.org/r/20180313132639.17387-3-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NJeff Layton <jlayton@kernel.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Minor cleanups available by _UL and _ULL.

Link: http://lkml.kernel.org/r/1519301715-31798-5-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ARM, ARM64 and UniCore32 duplicate the definition of UL():

  #define UL(x) _AC(x, UL)

This is not actually arch-specific, so it will be useful to move it to a
common header.  Currently, we only have the uapi variant for
linux/const.h, so I am creating include/linux/const.h.

I also added _UL(), _ULL() and ULL() because _AC() is mostly used in
the form either _AC(..., UL) or _AC(..., ULL).  I expect they will be
replaced in follow-up cleanups.  The underscore-prefixed ones should
be used for exported headers.

Link: http://lkml.kernel.org/r/1519301715-31798-4-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NGuan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NRussell King <rmk+kernel@armlinux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "linux/const.h: cleanups of macros such as UL(), _BITUL(),
BIT() etc", v3.

ARM, ARM64, UniCore32 define UL() as a shorthand of _AC(..., UL).  More
architectures may introduce it in the future.

UL() is arch-agnostic, and useful. So let's move it to
include/linux/const.h

Currently, <asm/memory.h> must be included to use UL().  It pulls in more
bloats just for defining some bit macros.

I posted V2 one year ago.

The previous posts are:
https://patchwork.kernel.org/patch/9498273/
https://patchwork.kernel.org/patch/9498275/
https://patchwork.kernel.org/patch/9498269/
https://patchwork.kernel.org/patch/9498271/

At that time, what blocked this series was a comment from
David Howells:
  You need to be very careful doing this.  Some userspace stuff
  depends on the guard macro names on the kernel header files.

(https://patchwork.kernel.org/patch/9498275/)

Looking at the code closer, I noticed this is not a problem.

See the following line.
https://github.com/torvalds/linux/blob/v4.16-rc2/scripts/headers_install.sh#L40

scripts/headers_install.sh rips off _UAPI prefix from guard macro names.

I ran "make headers_install" and confirmed the result is what I expect.

So, we can prefix the include guard of include/uapi/linux/const.h,
and add a new include/linux/const.h.

This patch (of 4):

I am going to add include/linux/const.h for the kernel space.

Add _UAPI to the include guard of include/uapi/linux/const.h to
prepare for that.

Please notice the guard name of the exported one will be kept as-is.
So, this commit has no impact to the userspace even if some userspace
stuff depends on the guard macro names.

scripts/headers_install.sh processes exported headers by SED, and
rips off "_UAPI" from guard macro names.

  #ifndef _UAPI_LINUX_CONST_H
  #define _UAPI_LINUX_CONST_H

will be turned into

  #ifndef _LINUX_CONST_H
  #define _LINUX_CONST_H

Link: http://lkml.kernel.org/r/1519301715-31798-2-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Both load_elf_interp and load_elf_binary rely on elf_map to map segments
on a controlled address and they use MAP_FIXED to enforce that.  This is
however dangerous thing prone to silent data corruption which can be
even exploitable.

Let's take CVE-2017-1000253 as an example.  At the time (before commit
eab09532: "binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
ELF_ET_DYN_BASE was at TASK_SIZE / 3 * 2 which is not that far away from
the stack top on 32b (legacy) memory layout (only 1GB away).  Therefore
we could end up mapping over the existing stack with some luck.

The issue has been fixed since then (a87938b2: "fs/binfmt_elf.c: fix
bug in loading of PIE binaries"), ELF_ET_DYN_BASE moved moved much
further from the stack (eab09532 and later by c715b72c: "mm:
revert x86_64 and arm64 ELF_ET_DYN_BASE base changes") and excessive
stack consumption early during execve fully stopped by da029c11
("exec: Limit arg stack to at most 75% of _STK_LIM").  So we should be
safe and any attack should be impractical.  On the other hand this is
just too subtle assumption so it can break quite easily and hard to
spot.

I believe that the MAP_FIXED usage in load_elf_binary (et. al) is still
fundamentally dangerous.  Moreover it shouldn't be even needed.  We are
at the early process stage and so there shouldn't be unrelated mappings
(except for stack and loader) existing so mmap for a given address should
succeed even without MAP_FIXED.  Something is terribly wrong if this is
not the case and we should rather fail than silently corrupt the
underlying mapping.

Address this issue by changing MAP_FIXED to the newly added
MAP_FIXED_NOREPLACE.  This will mean that mmap will fail if there is an
existing mapping clashing with the requested one without clobbering it.

[mhocko@suse.com: fix build]
[akpm@linux-foundation.org: coding-style fixes]
[avagin@openvz.org: don't use the same value for MAP_FIXED_NOREPLACE and MAP_SYNC]
  Link: http://lkml.kernel.org/r/20171218184916.24445-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/20171213092550.2774-3-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrei Vagin <avagin@openvz.org>
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NKhalid Aziz <khalid.aziz@oracle.com>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "mm: introduce MAP_FIXED_NOREPLACE", v2.

This has started as a follow up discussion [3][4] resulting in the
runtime failure caused by hardening patch [5] which removes MAP_FIXED
from the elf loader because MAP_FIXED is inherently dangerous as it
might silently clobber an existing underlying mapping (e.g.  stack).
The reason for the failure is that some architectures enforce an
alignment for the given address hint without MAP_FIXED used (e.g.  for
shared or file backed mappings).

One way around this would be excluding those archs which do alignment
tricks from the hardening [6].  The patch is really trivial but it has
been objected, rightfully so, that this screams for a more generic
solution.  We basically want a non-destructive MAP_FIXED.

The first patch introduced MAP_FIXED_NOREPLACE which enforces the given
address but unlike MAP_FIXED it fails with EEXIST if the given range
conflicts with an existing one.  The flag is introduced as a completely
new one rather than a MAP_FIXED extension because of the backward
compatibility.  We really want a never-clobber semantic even on older
kernels which do not recognize the flag.  Unfortunately mmap sucks
wrt flags evaluation because we do not EINVAL on unknown flags.  On
those kernels we would simply use the traditional hint based semantic so
the caller can still get a different address (which sucks) but at least
not silently corrupt an existing mapping.  I do not see a good way
around that.  Except we won't export expose the new semantic to the
userspace at all.

It seems there are users who would like to have something like that.
Jemalloc has been mentioned by Michael Ellerman [7]

Florian Weimer has mentioned the following:
: glibc ld.so currently maps DSOs without hints.  This means that the kernel
: will map right next to each other, and the offsets between them a completely
: predictable.  We would like to change that and supply a random address in a
: window of the address space.  If there is a conflict, we do not want the
: kernel to pick a non-random address. Instead, we would try again with a
: random address.

John Hubbard has mentioned CUDA example
: a) Searches /proc/<pid>/maps for a "suitable" region of available
: VA space.  "Suitable" generally means it has to have a base address
: within a certain limited range (a particular device model might
: have odd limitations, for example), it has to be large enough, and
: alignment has to be large enough (again, various devices may have
: constraints that lead us to do this).
:
: This is of course subject to races with other threads in the process.
:
: Let's say it finds a region starting at va.
:
: b) Next it does:
:     p = mmap(va, ...)
:
: *without* setting MAP_FIXED, of course (so va is just a hint), to
: attempt to safely reserve that region. If p != va, then in most cases,
: this is a failure (almost certainly due to another thread getting a
: mapping from that region before we did), and so this layer now has to
: call munmap(), before returning a "failure: retry" to upper layers.
:
:     IMPROVEMENT: --> if instead, we could call this:
:
:             p = mmap(va, ... MAP_FIXED_NOREPLACE ...)
:
:         , then we could skip the munmap() call upon failure. This
:         is a small thing, but it is useful here. (Thanks to Piotr
:         Jaroszynski and Mark Hairgrove for helping me get that detail
:         exactly right, btw.)
:
: c) After that, CUDA suballocates from p, via:
:
:      q = mmap(sub_region_start, ... MAP_FIXED ...)
:
: Interestingly enough, "freeing" is also done via MAP_FIXED, and
: setting PROT_NONE to the subregion. Anyway, I just included (c) for
: general interest.

Atomic address range probing in the multithreaded programs in general
sounds like an interesting thing to me.

The second patch simply replaces MAP_FIXED use in elf loader by
MAP_FIXED_NOREPLACE.  I believe other places which rely on MAP_FIXED
should follow.  Actually real MAP_FIXED usages should be docummented
properly and they should be more of an exception.

[1] http://lkml.kernel.org/r/20171116101900.13621-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/20171129144219.22867-1-mhocko@kernel.org
[3] http://lkml.kernel.org/r/20171107162217.382cd754@canb.auug.org.au
[4] http://lkml.kernel.org/r/1510048229.12079.7.camel@abdul.in.ibm.com
[5] http://lkml.kernel.org/r/20171023082608.6167-1-mhocko@kernel.org
[6] http://lkml.kernel.org/r/20171113094203.aofz2e7kueitk55y@dhcp22.suse.cz
[7] http://lkml.kernel.org/r/87efp1w7vy.fsf@concordia.ellerman.id.au

This patch (of 2):

MAP_FIXED is used quite often to enforce mapping at the particular range.
The main problem of this flag is, however, that it is inherently dangerous
because it unmaps existing mappings covered by the requested range.  This
can cause silent memory corruptions.  Some of them even with serious
security implications.  While the current semantic might be really
desiderable in many cases there are others which would want to enforce the
given range but rather see a failure than a silent memory corruption on a
clashing range.  Please note that there is no guarantee that a given range
is obeyed by the mmap even when it is free - e.g.  arch specific code is
allowed to apply an alignment.

Introduce a new MAP_FIXED_NOREPLACE flag for mmap to achieve this
behavior.  It has the same semantic as MAP_FIXED wrt.  the given address
request with a single exception that it fails with EEXIST if the requested
address is already covered by an existing mapping.  We still do rely on
get_unmaped_area to handle all the arch specific MAP_FIXED treatment and
check for a conflicting vma after it returns.

The flag is introduced as a completely new one rather than a MAP_FIXED
extension because of the backward compatibility.  We really want a
never-clobber semantic even on older kernels which do not recognize the
flag.  Unfortunately mmap sucks wrt.  flags evaluation because we do not
EINVAL on unknown flags.  On those kernels we would simply use the
traditional hint based semantic so the caller can still get a different
address (which sucks) but at least not silently corrupt an existing
mapping.  I do not see a good way around that.

[mpe@ellerman.id.au: fix whitespace]
[fail on clashing range with EEXIST as per Florian Weimer]
[set MAP_FIXED before round_hint_to_min as per Khalid Aziz]
Link: http://lkml.kernel.org/r/20171213092550.2774-2-mhocko@kernel.orgReviewed-by: NKhalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Evans <jasone@google.com>
Cc: David Goldblatt <davidtgoldblatt@gmail.com>
Cc: Edward Tomasz Napierała <trasz@FreeBSD.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clean up unusual formatting in the note about locking.

Link: http://lkml.kernel.org/r/20180324002630.13046-1-Valentin.Vidic@CARNet.hrSigned-off-by: NValentin Vidic <Valentin.Vidic@CARNet.hr>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Sean Young <sean@mess.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a permission discrepancy when consulting msq ipc object
metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl
command.  The later does permission checks for the object vs S_IRUGO.
As such there can be cases where EACCESS is returned via syscall but the
info is displayed anyways in the procfs files.

While this might have security implications via info leaking (albeit no
writing to the msq metadata), this behavior goes way back and showing
all the objects regardless of the permissions was most likely an
overlook - so we are stuck with it.  Furthermore, modifying either the
syscall or the procfs file can cause userspace programs to break (ie
ipcs).  Some applications require getting the procfs info (without root
privileges) and can be rather slow in comparison with a syscall -- up to
500x in some reported cases for shm.

This patch introduces a new MSG_STAT_ANY command such that the msq ipc
object permissions are ignored, and only audited instead.  In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.

Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Reported-by: NRobert Kettler <robert.kettler@outlook.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a permission discrepancy when consulting shm ipc object
metadata between /proc/sysvipc/sem (0444) and the SEM_STAT semctl
command.  The later does permission checks for the object vs S_IRUGO.
As such there can be cases where EACCESS is returned via syscall but the
info is displayed anyways in the procfs files.

While this might have security implications via info leaking (albeit no
writing to the sma metadata), this behavior goes way back and showing
all the objects regardless of the permissions was most likely an
overlook - so we are stuck with it.  Furthermore, modifying either the
syscall or the procfs file can cause userspace programs to break (ie
ipcs).  Some applications require getting the procfs info (without root
privileges) and can be rather slow in comparison with a syscall -- up to
500x in some reported cases for shm.

This patch introduces a new SEM_STAT_ANY command such that the sem ipc
object permissions are ignored, and only audited instead.  In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.

Link: http://lkml.kernel.org/r/20180215162458.10059-3-dave@stgolabs.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Reported-by: NRobert Kettler <robert.kettler@outlook.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "sysvipc: introduce STAT_ANY commands", v2.

The following patches adds the discussed (see [1]) new command for shm
as well as for sems and msq as they are subject to the same
discrepancies for ipc object permission checks between the syscall and
via procfs.  These new commands are justified in that (1) we are stuck
with this semantics as changing syscall and procfs can break userland;
and (2) some users can benefit from performance (for large amounts of
shm segments, for example) from not having to parse the procfs
interface.

Once merged, I will submit the necesary manpage updates.  But I'm thinking
something like:

: diff --git a/man2/shmctl.2 b/man2/shmctl.2
: index 7bb503999941..bb00bbe21a57 100644
: --- a/man2/shmctl.2
: +++ b/man2/shmctl.2
: @@ -41,6 +41,7 @@
:  .\" 2005-04-25, mtk -- noted aberrant Linux behavior w.r.t. new
:  .\"	attaches to a segment that has already been marked for deletion.
:  .\" 2005-08-02, mtk: Added IPC_INFO, SHM_INFO, SHM_STAT descriptions.
: +.\" 2018-02-13, dbueso: Added SHM_STAT_ANY description.
:  .\"
:  .TH SHMCTL 2 2017-09-15 "Linux" "Linux Programmer's Manual"
:  .SH NAME
: @@ -242,6 +243,18 @@ However, the
:  argument is not a segment identifier, but instead an index into
:  the kernel's internal array that maintains information about
:  all shared memory segments on the system.
: +.TP
: +.BR SHM_STAT_ANY " (Linux-specific)"
: +Return a
: +.I shmid_ds
: +structure as for
: +.BR SHM_STAT .
: +However, the
: +.I shm_perm.mode
: +is not checked for read access for
: +.IR shmid ,
: +resembing the behaviour of
: +/proc/sysvipc/shm.
:  .PP
:  The caller can prevent or allow swapping of a shared
:  memory segment with the following \fIcmd\fP values:
: @@ -287,7 +300,7 @@ operation returns the index of the highest used entry in the
:  kernel's internal array recording information about all
:  shared memory segments.
:  (This information can be used with repeated
: -.B SHM_STAT
: +.B SHM_STAT/SHM_STAT_ANY
:  operations to obtain information about all shared memory segments
:  on the system.)
:  A successful
: @@ -328,7 +341,7 @@ isn't accessible.
:  \fIshmid\fP is not a valid identifier, or \fIcmd\fP
:  is not a valid command.
:  Or: for a
: -.B SHM_STAT
: +.B SHM_STAT/SHM_STAT_ANY
:  operation, the index value specified in
:  .I shmid
:  referred to an array slot that is currently unused.

This patch (of 3):

There is a permission discrepancy when consulting shm ipc object metadata
between /proc/sysvipc/shm (0444) and the SHM_STAT shmctl command.  The
later does permission checks for the object vs S_IRUGO.  As such there can
be cases where EACCESS is returned via syscall but the info is displayed
anyways in the procfs files.

While this might have security implications via info leaking (albeit no
writing to the shm metadata), this behavior goes way back and showing all
the objects regardless of the permissions was most likely an overlook - so
we are stuck with it.  Furthermore, modifying either the syscall or the
procfs file can cause userspace programs to break (ie ipcs).  Some
applications require getting the procfs info (without root privileges) and
can be rather slow in comparison with a syscall -- up to 500x in some
reported cases.

This patch introduces a new SHM_STAT_ANY command such that the shm ipc
object permissions are ignored, and only audited instead.  In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.

[1] https://lkml.org/lkml/2017/12/19/220

Link: http://lkml.kernel.org/r/20180215162458.10059-2-dave@stgolabs.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Robert Kettler <robert.kettler@outlook.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since the stack rlimit is used in multiple places during exec and it can
be changed via other threads (via setrlimit()) or processes (via
prlimit()), the assumption that the value doesn't change cannot be made.
This leads to races with mm layout selection and argument size
calculations.  This changes the exec path to use the rlimit stored in
bprm instead of in current.  Before starting the thread, the bprm stack
rlimit is stored back to current.

Link: http://lkml.kernel.org/r/1518638796-20819-4-git-send-email-keescook@chromium.org
Fixes: 64701dee ("exec: Use sane stack rlimit under secureexec")
Signed-off-by: NKees Cook <keescook@chromium.org>
Reported-by: NBen Hutchings <ben.hutchings@codethink.co.uk>
Reported-by: NAndy Lutomirski <luto@kernel.org>
Reported-by: NBrad Spengler <spender@grsecurity.net>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Greg KH <greg@kroah.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Provide a final callback into fs/exec.c before start_thread() takes
over, to handle any last-minute changes, like the coming restoration of
the stack limit.

Link: http://lkml.kernel.org/r/1518638796-20819-3-git-send-email-keescook@chromium.orgSigned-off-by: NKees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Greg KH <greg@kroah.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>