The poll() changes were not well thought out, and completely
unexplained. They also caused a huge performance regression, because
"->poll()" was no longer a trivial file operation that just called down
to the underlying file operations, but instead did at least two indirect
calls.
Indirect calls are sadly slow now with the Spectre mitigation, but the
performance problem could at least be largely mitigated by changing the
"->get_poll_head()" operation to just have a per-file-descriptor pointer
to the poll head instead. That gets rid of one of the new indirections.
But that doesn't fix the new complexity that is completely unwarranted
for the regular case. The (undocumented) reason for the poll() changes
was some alleged AIO poll race fixing, but we don't make the common case
slower and more complex for some uncommon special case, so this all
really needs way more explanations and most likely a fundamental
redesign.
[ This revert is a revert of about 30 different commits, not reverted
individually because that would just be unnecessarily messy - Linus ]
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fchownat() doesn't even hold refcnt of fd until it figures out
fd is really needed (otherwise is ignored) and releases it after
it resolves the path. This means sock_close() could race with
sockfs_setattr(), which leads to a NULL pointer dereference
since typically we set sock->sk to NULL in ->release().
As pointed out by Al, this is unique to sockfs. So we can fix this
in socket layer by acquiring inode_lock in sock_close() and
checking against NULL in sockfs_setattr().
sock_release() is called in many places, only the sock_close()
path matters here. And fortunately, this should not affect normal
sock_close() as it is only called when the last fd refcnt is gone.
It only affects sock_close() with a parallel sockfs_setattr() in
progress, which is not common.
Fixes: 86741ec254 ("net: core: Add a UID field to struct sock.")
Reported-by: shankarapailoor <shankarapailoor@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull security system updates from James Morris:
- incorporate new socketpair() hook into LSM and wire up the SELinux
and Smack modules. From David Herrmann:
"The idea is to allow SO_PEERSEC to be called on AF_UNIX sockets
created via socketpair(2), and return the same information as if
you emulated socketpair(2) via a temporary listener socket.
Right now SO_PEERSEC will return the unlabeled credentials for a
socketpair, rather than the actual credentials of the creating
process."
- remove the unused security_settime LSM hook (Sargun Dhillon).
- remove some stack allocated arrays from the keys code (Tycho
Andersen)
* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
dh key: get rid of stack allocated array for zeroes
dh key: get rid of stack allocated array
big key: get rid of stack array allocation
smack: provide socketpair callback
selinux: provide socketpair callback
net: hook socketpair() into LSM
security: add hook for socketpair()
security: remove security_settime
Factor out two busy poll related helpers for late reuse, and remove
a command that isn't very helpful, especially with the __poll_t
annotations in place.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Use the newly created LSM-hook for socketpair(). The default hook
return-value is 0, so behavior stays the same unless LSMs start using
this hook.
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: James Morris <james.morris@microsoft.com>
Pull trivial tree updates from Jiri Kosina.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
kfifo: fix inaccurate comment
tools/thermal: tmon: fix for segfault
net: Spelling s/stucture/structure/
edd: don't spam log if no EDD information is present
Documentation: Fix early-microcode.txt references after file rename
tracing: Block comments should align the * on each line
treewide: Fix typos in printk
GenWQE: Fix a typo in two comments
treewide: Align function definition open/close braces
Pull networking updates from David Miller:
1) Support offloading wireless authentication to userspace via
NL80211_CMD_EXTERNAL_AUTH, from Srinivas Dasari.
2) A lot of work on network namespace setup/teardown from Kirill Tkhai.
Setup and cleanup of namespaces now all run asynchronously and thus
performance is significantly increased.
3) Add rx/tx timestamping support to mv88e6xxx driver, from Brandon
Streiff.
4) Support zerocopy on RDS sockets, from Sowmini Varadhan.
5) Use denser instruction encoding in x86 eBPF JIT, from Daniel
Borkmann.
6) Support hw offload of vlan filtering in mvpp2 dreiver, from Maxime
Chevallier.
7) Support grafting of child qdiscs in mlxsw driver, from Nogah
Frankel.
8) Add packet forwarding tests to selftests, from Ido Schimmel.
9) Deal with sub-optimal GSO packets better in BBR congestion control,
from Eric Dumazet.
10) Support 5-tuple hashing in ipv6 multipath routing, from David Ahern.
11) Add path MTU tests to selftests, from Stefano Brivio.
12) Various bits of IPSEC offloading support for mlx5, from Aviad
Yehezkel, Yossi Kuperman, and Saeed Mahameed.
13) Support RSS spreading on ntuple filters in SFC driver, from Edward
Cree.
14) Lots of sockmap work from John Fastabend. Applications can use eBPF
to filter sendmsg and sendpage operations.
15) In-kernel receive TLS support, from Dave Watson.
16) Add XDP support to ixgbevf, this is significant because it should
allow optimized XDP usage in various cloud environments. From Tony
Nguyen.
17) Add new Intel E800 series "ice" ethernet driver, from Anirudh
Venkataramanan et al.
18) IP fragmentation match offload support in nfp driver, from Pieter
Jansen van Vuuren.
19) Support XDP redirect in i40e driver, from Björn Töpel.
20) Add BPF_RAW_TRACEPOINT program type for accessing the arguments of
tracepoints in their raw form, from Alexei Starovoitov.
21) Lots of striding RQ improvements to mlx5 driver with many
performance improvements, from Tariq Toukan.
22) Use rhashtable for inet frag reassembly, from Eric Dumazet.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1678 commits)
net: mvneta: improve suspend/resume
net: mvneta: split rxq/txq init and txq deinit into SW and HW parts
ipv6: frags: fix /proc/sys/net/ipv6/ip6frag_low_thresh
net: bgmac: Fix endian access in bgmac_dma_tx_ring_free()
net: bgmac: Correctly annotate register space
route: check sysctl_fib_multipath_use_neigh earlier than hash
fix typo in command value in drivers/net/phy/mdio-bitbang.
sky2: Increase D3 delay to sky2 stops working after suspend
net/mlx5e: Set EQE based as default TX interrupt moderation mode
ibmvnic: Disable irqs before exiting reset from closed state
net: sched: do not emit messages while holding spinlock
vlan: also check phy_driver ts_info for vlan's real device
Bluetooth: Mark expected switch fall-throughs
Bluetooth: Set HCI_QUIRK_SIMULTANEOUS_DISCOVERY for BTUSB_QCA_ROME
Bluetooth: btrsi: remove unused including <linux/version.h>
Bluetooth: hci_bcm: Remove DMI quirk for the MINIX Z83-4
sh_eth: kill useless check in __sh_eth_get_regs()
sh_eth: add sh_eth_cpu_data::no_xdfar flag
ipv6: factorize sk_wmem_alloc updates done by __ip6_append_data()
ipv4: factorize sk_wmem_alloc updates done by __ip_append_data()
...
Pull removal of in-kernel calls to syscalls from Dominik Brodowski:
"System calls are interaction points between userspace and the kernel.
Therefore, system call functions such as sys_xyzzy() or
compat_sys_xyzzy() should only be called from userspace via the
syscall table, but not from elsewhere in the kernel.
At least on 64-bit x86, it will likely be a hard requirement from
v4.17 onwards to not call system call functions in the kernel: It is
better to use use a different calling convention for system calls
there, where struct pt_regs is decoded on-the-fly in a syscall wrapper
which then hands processing over to the actual syscall function. This
means that only those parameters which are actually needed for a
specific syscall are passed on during syscall entry, instead of
filling in six CPU registers with random user space content all the
time (which may cause serious trouble down the call chain). Those
x86-specific patches will be pushed through the x86 tree in the near
future.
Moreover, rules on how data may be accessed may differ between kernel
data and user data. This is another reason why calling sys_xyzzy() is
generally a bad idea, and -- at most -- acceptable in arch-specific
code.
This patchset removes all in-kernel calls to syscall functions in the
kernel with the exception of arch/. On top of this, it cleans up the
three places where many syscalls are referenced or prototyped, namely
kernel/sys_ni.c, include/linux/syscalls.h and include/linux/compat.h"
* 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux: (109 commits)
bpf: whitelist all syscalls for error injection
kernel/sys_ni: remove {sys_,sys_compat} from cond_syscall definitions
kernel/sys_ni: sort cond_syscall() entries
syscalls/x86: auto-create compat_sys_*() prototypes
syscalls: sort syscall prototypes in include/linux/compat.h
net: remove compat_sys_*() prototypes from net/compat.h
syscalls: sort syscall prototypes in include/linux/syscalls.h
kexec: move sys_kexec_load() prototype to syscalls.h
x86/sigreturn: use SYSCALL_DEFINE0
x86: fix sys_sigreturn() return type to be long, not unsigned long
x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm()
mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead()
mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff()
mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64()
fs: add ksys_fallocate() wrapper; remove in-kernel calls to sys_fallocate()
fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls
fs: add ksys_truncate() wrapper; remove in-kernel calls to sys_truncate()
fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscall
kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid()
kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare()
...
The non-compat codepaths for sys_...msg() verify that MSG_CMSG_COMPAT
is not set. By moving this check to the __sys_...msg() functions
(and making it dependent on a static flag passed to this function), we
can call the __sys...msg() functions instead of the syscall functions
in all cases. __sys_recvmmsg() does not need this trickery, as the
check is handled within the do_sys_recvmmsg() function internal to
net/socket.c.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
