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At first Jakub Zawadzki noticed that some divisions by reciprocal_divide
were not correct. (off by one in some cases)
http://www.wireshark.org/~darkjames/reciprocal-buggy.c
He could also show this with BPF:
http://www.wireshark.org/~darkjames/set-and-dump-filter-k-bug.c
The reciprocal divide in linux kernel is not generic enough,
lets remove its use in BPF, as it is not worth the pain with
current cpus.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Mircea Gherzan <mgherzan@gmail.com>
Cc: Daniel Borkmann <dxchgb@gmail.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Matt Evans <matt@ozlabs.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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on x86 system with net.core.bpf_jit_enable = 1
sudo tcpdump -i eth1 'tcp port 22'
causes the warning:
[ 56.766097] Possible unsafe locking scenario:
[ 56.766097]
[ 56.780146] CPU0
[ 56.786807] ----
[ 56.793188] lock(&(&vb->lock)->rlock);
[ 56.799593] <Interrupt>
[ 56.805889] lock(&(&vb->lock)->rlock);
[ 56.812266]
[ 56.812266] *** DEADLOCK ***
[ 56.812266]
[ 56.830670] 1 lock held by ksoftirqd/1/13:
[ 56.836838] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff8118f44c>] vm_unmap_aliases+0x8c/0x380
[ 56.849757]
[ 56.849757] stack backtrace:
[ 56.862194] CPU: 1 PID: 13 Comm: ksoftirqd/1 Not tainted 3.12.0-rc3+ #45
[ 56.868721] Hardware name: System manufacturer System Product Name/P8Z77 WS, BIOS 3007 07/26/2012
[ 56.882004] ffffffff821944c0 ffff88080bbdb8c8 ffffffff8175a145 0000000000000007
[ 56.895630] ffff88080bbd5f40 ffff88080bbdb928 ffffffff81755b14 0000000000000001
[ 56.909313] ffff880800000001 ffff880800000000 ffffffff8101178f 0000000000000001
[ 56.923006] Call Trace:
[ 56.929532] [<ffffffff8175a145>] dump_stack+0x55/0x76
[ 56.936067] [<ffffffff81755b14>] print_usage_bug+0x1f7/0x208
[ 56.942445] [<ffffffff8101178f>] ? save_stack_trace+0x2f/0x50
[ 56.948932] [<ffffffff810cc0a0>] ? check_usage_backwards+0x150/0x150
[ 56.955470] [<ffffffff810ccb52>] mark_lock+0x282/0x2c0
[ 56.961945] [<ffffffff810ccfed>] __lock_acquire+0x45d/0x1d50
[ 56.968474] [<ffffffff810cce6e>] ? __lock_acquire+0x2de/0x1d50
[ 56.975140] [<ffffffff81393bf5>] ? cpumask_next_and+0x55/0x90
[ 56.981942] [<ffffffff810cef72>] lock_acquire+0x92/0x1d0
[ 56.988745] [<ffffffff8118f52a>] ? vm_unmap_aliases+0x16a/0x380
[ 56.995619] [<ffffffff817628f1>] _raw_spin_lock+0x41/0x50
[ 57.002493] [<ffffffff8118f52a>] ? vm_unmap_aliases+0x16a/0x380
[ 57.009447] [<ffffffff8118f52a>] vm_unmap_aliases+0x16a/0x380
[ 57.016477] [<ffffffff8118f44c>] ? vm_unmap_aliases+0x8c/0x380
[ 57.023607] [<ffffffff810436b0>] change_page_attr_set_clr+0xc0/0x460
[ 57.030818] [<ffffffff810cfb8d>] ? trace_hardirqs_on+0xd/0x10
[ 57.037896] [<ffffffff811a8330>] ? kmem_cache_free+0xb0/0x2b0
[ 57.044789] [<ffffffff811b59c3>] ? free_object_rcu+0x93/0xa0
[ 57.051720] [<ffffffff81043d9f>] set_memory_rw+0x2f/0x40
[ 57.058727] [<ffffffff8104e17c>] bpf_jit_free+0x2c/0x40
[ 57.065577] [<ffffffff81642cba>] sk_filter_release_rcu+0x1a/0x30
[ 57.072338] [<ffffffff811108e2>] rcu_process_callbacks+0x202/0x7c0
[ 57.078962] [<ffffffff81057f17>] __do_softirq+0xf7/0x3f0
[ 57.085373] [<ffffffff81058245>] run_ksoftirqd+0x35/0x70
cannot reuse jited filter memory, since it's readonly,
so use original bpf insns memory to hold work_struct
defer kfree of sk_filter until jit completed freeing
tested on x86_64 and i386
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Filters need to be translated to real BPF code for userland, like SO_GETFILTER.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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It is very useful to do dynamic truncation of packets. In particular,
we're interested to push the necessary header bytes to the user space and
cut off user payload that should probably not be transferred for some reasons
(e.g. privacy, speed, or others). With the ancillary extension PAY_OFFSET,
we can load it into the accumulator, and return it. E.g. in bpfc syntax ...
ld #poff ; { 0x20, 0, 0, 0xfffff034 },
ret a ; { 0x16, 0, 0, 0x00000000 },
... as a filter will accomplish this without having to do a big hackery in
a BPF filter itself. Follow-up JIT implementations are welcome.
Thanks to Eric Dumazet for suggesting and discussing this during the
Netfilter Workshop in Copenhagen.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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While a privileged program can open a raw socket, attach some
restrictive filter and drop its privileges (or send the socket to an
unprivileged program through some Unix socket), the filter can still
be removed or modified by the unprivileged program. This commit adds a
socket option to lock the filter (SO_LOCK_FILTER) preventing any
modification of a socket filter program.
This is similar to OpenBSD BIOCLOCK ioctl on bpf sockets, except even
root is not allowed change/drop the filter.
The state of the lock can be read with getsockopt(). No error is
triggered if the state is not changed. -EPERM is returned when a user
tries to remove the lock or to change/remove the filter while the lock
is active. The check is done directly in sk_attach_filter() and
sk_detach_filter() and does not affect only setsockopt() syscall.
Signed-off-by: Vincent Bernat <bernat@luffy.cx>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently, we return -EINVAL for malformed or wrong BPF filters.
However, this is not done for BPF_S_ANC* operations, which makes it
more difficult to detect if it's actually supported or not by the
BPF machine. Therefore, we should also return -EINVAL if K is within
the SKF_AD_OFF universe and the ancillary operation did not match.
Why exactly is it needed? If tools such as libpcap/tcpdump want to
make use of new ancillary operations (like filtering VLAN in kernel
space), there is currently no sane way to test if this feature /
BPF_S_ANC* op is present or not, since no error is returned. This
patch will make life easier for that and allow for a proper usage
for user space applications.
There was concern, if this patch will break userland. Short answer: Yes
and no. Long answer: It will "break" only for code that calls ...
{ BPF_LD | BPF_(W|H|B) | BPF_ABS, 0, 0, <K> },
... where <K> is in [0xfffff000, 0xffffffff] _and_ <K> is *not* an
ancillary. And here comes the BUT: assuming some *old* code will have
such an instruction where <K> is between [0xfffff000, 0xffffffff] and
it doesn't know ancillary operations, then this will give a
non-expected / unwanted behavior as well (since we do not return the
BPF machine with 0 after a failed load_pointer(), which was the case
before introducing ancillary operations, but load sth. into the
accumulator instead, and continue with the next instruction, for
instance). Thus, user space code would already have been broken by
introducing ancillary operations into the BPF machine per se. Code
that does such a direct load, e.g. "load word at packet offset
0xffffffff into accumulator" ("ld [0xffffffff]") is quite broken,
isn't it? The whole assumption of ancillary operations is that no-one
intentionally calls things like "ld [0xffffffff]" and expect this
word to be loaded from such a packet offset. Hence, we can also safely
make use of this feature testing patch and facilitate application
development. Therefore, at least from this patch onwards, we have
*for sure* a check whether current or in future implemented BPF_S_ANC*
ops are supported in the kernel. Patch was tested on x86_64.
(Thanks to Eric for the previous review.)
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: Ani Sinha <ani@aristanetworks.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The SO_ATTACH_FILTER option is set only. I propose to add the get
ability by using SO_ATTACH_FILTER in getsockopt. To be less
irritating to eyes the SO_GET_FILTER alias to it is declared. This
ability is required by checkpoint-restore project to be able to
save full state of a socket.
There are two issues with getting filter back.
First, kernel modifies the sock_filter->code on filter load, thus in
order to return the filter element back to user we have to decode it
into user-visible constants. Fortunately the modification in question
is interconvertible.
Second, the BPF_S_ALU_DIV_K code modifies the command argument k to
speed up the run-time division by doing kernel_k = reciprocal(user_k).
Bad news is that different user_k may result in same kernel_k, so we
can't get the original user_k back. Good news is that we don't have
to do it. What we need to is calculate a user2_k so, that
reciprocal(user2_k) == reciprocal(user_k) == kernel_k
i.e. if it's re-loaded back the compiled again value will be exactly
the same as it was. That said, the user2_k can be calculated like this
user2_k = reciprocal(kernel_k)
with an exception, that if kernel_k == 0, then user2_k == 1.
The optlen argument is treated like this -- when zero, kernel returns
the amount of sock_fprog elements in filter, otherwise it should be
large enough for the sock_fprog array.
changes since v1:
* Declared SO_GET_FILTER in all arch headers
* Added decode of vlan-tag codes
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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BPF filters lack ability to access skb->vlan_tci
This patch adds two new ancillary accessors :
SKF_AD_VLAN_TAG (44) mapped to vlan_tx_tag_get(skb)
SKF_AD_VLAN_TAG_PRESENT (48) mapped to vlan_tx_tag_present(skb)
This allows libpcap/tcpdump to use a kernel filter instead of
having to fallback to accept all packets, then filter them in
user space.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Ani Sinha <ani@aristanetworks.com>
Suggested-by: Daniel Borkmann <danborkmann@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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SKF_AD_ALU_XOR_X has been added a while ago, but as an 'ancillary'
operation that is invoked through a negative offset in K within BPF
load operations. Since BPF_MOD has recently been added, BPF_XOR should
also be part of the common ALU operations. Removing SKF_AD_ALU_XOR_X
might not be an option since this is exposed to user space.
Signed-off-by: Daniel Borkmann <daniel.borkmann@tik.ee.ethz.ch>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add a new ALU opcode, to compute a modulus.
Commit ffe06c17afbbb used an ancillary to implement XOR_X,
but here we reserve one of the available ALU opcode to implement both
MOD_X and MOD_K
Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: George Bakos <gbakos@alpinista.org>
Cc: Jay Schulist <jschlst@samba.org>
Cc: Jiri Pirko <jpirko@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change the skb allocation API to indicate RX usage and use this to fall
back to the PFMEMALLOC reserve when needed. SKBs allocated from the
reserve are tagged in skb->pfmemalloc. If an SKB is allocated from the
reserve and the socket is later found to be unrelated to page reclaim, the
packet is dropped so that the memory remains available for page reclaim.
Network protocols are expected to recover from this packet loss.
[a.p.zijlstra@chello.nl: Ideas taken from various patches]
[davem@davemloft.net: Use static branches, coding style corrections]
[sebastian@breakpoint.cc: Avoid unnecessary cast, fix !CONFIG_NET build]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix kernel-doc warnings in net/core:
Warning(net/core/skbuff.c:3368): No description found for parameter 'delta_truesize'
Warning(net/core/filter.c:628): No description found for parameter 'pfp'
Warning(net/core/filter.c:628): Excess function parameter 'sk' description in 'sk_unattached_filter_create'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
"New notable features:
- The seccomp work from Will Drewry
- PR_{GET,SET}_NO_NEW_PRIVS from Andy Lutomirski
- Longer security labels for Smack from Casey Schaufler
- Additional ptrace restriction modes for Yama by Kees Cook"
Fix up trivial context conflicts in arch/x86/Kconfig and include/linux/filter.h
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (65 commits)
apparmor: fix long path failure due to disconnected path
apparmor: fix profile lookup for unconfined
ima: fix filename hint to reflect script interpreter name
KEYS: Don't check for NULL key pointer in key_validate()
Smack: allow for significantly longer Smack labels v4
gfp flags for security_inode_alloc()?
Smack: recursive tramsmute
Yama: replace capable() with ns_capable()
TOMOYO: Accept manager programs which do not start with / .
KEYS: Add invalidation support
KEYS: Do LRU discard in full keyrings
KEYS: Permit in-place link replacement in keyring list
KEYS: Perform RCU synchronisation on keys prior to key destruction
KEYS: Announce key type (un)registration
KEYS: Reorganise keys Makefile
KEYS: Move the key config into security/keys/Kconfig
KEYS: Use the compat keyctl() syscall wrapper on Sparc64 for Sparc32 compat
Yama: remove an unused variable
samples/seccomp: fix dependencies on arch macros
Yama: add additional ptrace scopes
...
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Use of "unsigned int" is preferred to bare "unsigned" in net tree.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Introduces a new BPF ancillary instruction that all LD calls will be
mapped through when skb_run_filter() is being used for seccomp BPF. The
rewriting will be done using a secondary chk_filter function that is run
after skb_chk_filter.
The code change is guarded by CONFIG_SECCOMP_FILTER which is added,
along with the seccomp_bpf_load() function later in this series.
This is based on http://lkml.org/lkml/2012/3/2/141
Suggested-by: Indan Zupancic <indan@nul.nu>
Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Eric Paris <eparis@redhat.com>
v18: rebase
...
v15: include seccomp.h explicitly for when seccomp_bpf_load exists.
v14: First cut using a single additional instruction
... v13: made bpf functions generic.
Signed-off-by: James Morris <james.l.morris@oracle.com>
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Add XOR instruction fo BPF machine. Needed for computing packet hashes.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Today, BPF filters are bind to sockets. Since BPF machine becomes handy
for other purposes, this patch allows to create unattached filter.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The function is renamed to make it a little more clear what it does.
It is not added to any .h because it is not for general consumption, only for
bpf internal use (and so by the jits).
Signed-of-by: Jan Seiffert <kaffeemonster@googlemail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Remove all #inclusions of asm/system.h preparatory to splitting and killing
it. Performed with the following command:
perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`
Signed-off-by: David Howells <dhowells@redhat.com>
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This is just a cleanup.
My testing version of Smatch warns about this:
net/core/filter.c +380 check_load_and_stores(6)
warn: check 'flen' for negative values
flen comes from the user. We try to clamp the values here between 1
and BPF_MAXINSNS but the clamp doesn't work because it could be
negative. This is a bug, but it's not exploitable.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.
Convert all rcu_assign_pointer of NULL value.
//smpl
@@ expression P; @@
- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)
// </smpl>
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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As reported by Ingo Molnar, we still have configuration combinations
where use of the WARN_RATELIMIT interfaces break the build because
dependencies don't get met.
Instead of going down the long road of trying to make it so that
ratelimit.h can get included by kernel.h or asm-generic/bug.h,
just move the interface into ratelimit.h and make users have
to include that.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
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A mis-configured filter can spam the logs with lots of stack traces.
Rate-limit the warnings and add printout of the bogus filter information.
Original-patch-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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In order to speedup packet filtering, here is an implementation of a
JIT compiler for x86_64
It is disabled by default, and must be enabled by the admin.
echo 1 >/proc/sys/net/core/bpf_jit_enable
It uses module_alloc() and module_free() to get memory in the 2GB text
kernel range since we call helpers functions from the generated code.
EAX : BPF A accumulator
EBX : BPF X accumulator
RDI : pointer to skb (first argument given to JIT function)
RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
r9d : skb->len - skb->data_len (headlen)
r8 : skb->data
To get a trace of generated code, use :
echo 2 >/proc/sys/net/core/bpf_jit_enable
Example of generated code :
# tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24
flen=18 proglen=147 pass=3 image=ffffffffa00b5000
JIT code: ffffffffa00b5000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 60
JIT code: ffffffffa00b5010: 44 2b 4f 64 4c 8b 87 b8 00 00 00 be 0c 00 00 00
JIT code: ffffffffa00b5020: e8 24 7b f7 e0 3d 00 08 00 00 75 28 be 1a 00 00
JIT code: ffffffffa00b5030: 00 e8 fe 7a f7 e0 24 00 3d 00 14 a8 c0 74 49 be
JIT code: ffffffffa00b5040: 1e 00 00 00 e8 eb 7a f7 e0 24 00 3d 00 14 a8 c0
JIT code: ffffffffa00b5050: 74 36 eb 3b 3d 06 08 00 00 74 07 3d 35 80 00 00
JIT code: ffffffffa00b5060: 75 2d be 1c 00 00 00 e8 c8 7a f7 e0 24 00 3d 00
JIT code: ffffffffa00b5070: 14 a8 c0 74 13 be 26 00 00 00 e8 b5 7a f7 e0 24
JIT code: ffffffffa00b5080: 00 3d 00 14 a8 c0 75 07 b8 ff ff 00 00 eb 02 31
JIT code: ffffffffa00b5090: c0 c9 c3
BPF program is 144 bytes long, so native program is almost same size ;)
(000) ldh [12]
(001) jeq #0x800 jt 2 jf 8
(002) ld [26]
(003) and #0xffffff00
(004) jeq #0xc0a81400 jt 16 jf 5
(005) ld [30]
(006) and #0xffffff00
(007) jeq #0xc0a81400 jt 16 jf 17
(008) jeq #0x806 jt 10 jf 9
(009) jeq #0x8035 jt 10 jf 17
(010) ld [28]
(011) and #0xffffff00
(012) jeq #0xc0a81400 jt 16 jf 13
(013) ld [38]
(014) and #0xffffff00
(015) jeq #0xc0a81400 jt 16 jf 17
(016) ret #65535
(017) ret #0
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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Packet filter (BPF) doesnt need to disable softirqs, being fully
re-entrant and lock-less.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Fix new kernel-doc notation warning in net/core/filter.c:
Warning(net/core/filter.c:172): No description found for parameter 'fentry'
Warning(net/core/filter.c:172): Excess function parameter 'filter' description in 'sk_run_filter'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We can translate pseudo load instructions at filter check time to
dedicated instructions to speed up filtering and avoid one switch().
libpcap currently uses SKF_AD_PROTOCOL, but custom filters probably use
other ancillary accesses.
Note : I made the assertion that ancillary data was always accessed with
BPF_LD|BPF_?|BPF_ABS instructions, not with BPF_LD|BPF_?|BPF_IND ones
(offset given by K constant, not by K + X register)
On x86_64, this saves a few bytes of text :
# size net/core/filter.o.*
text data bss dec hex filename
4864 0 0 4864 1300 net/core/filter.o.new
4944 0 0 4944 1350 net/core/filter.o.old
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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__load_pointer() checks data we fetch from skb is included in head
portion, but assumes we fetch one byte, instead of up to four.
This wont crash because we have extra bytes (struct skb_shared_info)
after head, but this can read uninitialized bytes.
Fix this using size of the data (1, 2, 4 bytes) in the test.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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|
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
net/llc/af_llc.c
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|
sk_run_filter() doesnt write on skb, change its prototype to reflect
this.
Fix two af_packet comments.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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|
We added some security checks in commit 57fe93b374a6
(filter: make sure filters dont read uninitialized memory) to close a
potential leak of kernel information to user.
This added a potential extra cost at run time, while we can perform a
check of the filter itself, to make sure a malicious user doesnt try to
abuse us.
This patch adds a check_loads() function, whole unique purpose is to
make this check, allocating a temporary array of mask. We scan the
filter and propagate a bitmask information, telling us if a load M(K) is
allowed because a previous store M(K) is guaranteed. (So that
sk_run_filter() can possibly not read unitialized memory)
Note: this can uncover application bug, denying a filter attach,
previously allowed.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
|
|
Add SKF_AD_RXHASH and SKF_AD_CPU to filter ancillary mechanism,
to be able to build advanced filters.
This can help spreading packets on several sockets with a fast
selection, after RPS dispatch to N cpus for example, or to catch a
percentage of flows in one queue.
tcpdump -s 500 "cpu = 1" :
[0] ld CPU
[1] jeq #1 jt 2 jf 3
[2] ret #500
[3] ret #0
# take 12.5 % of flows (average)
tcpdump -s 1000 "rxhash & 7 = 2" :
[0] ld RXHASH
[1] and #7
[2] jeq #2 jt 3 jf 4
[3] ret #1000
[4] ret #0
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rui <wirelesser@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Pavel Emelyanov tried to fix a race between sk_filter_(de|at)tach and
sk_clone() in commit 47e958eac280c263397
Problem is we can have several clones sharing a common sk_filter, and
these clones might want to sk_filter_attach() their own filters at the
same time, and can overwrite old_filter->rcu, corrupting RCU queues.
We can not use filter->rcu without being sure no other thread could do
the same thing.
Switch code to a more conventional ref-counting technique : Do the
atomic decrement immediately and queue one rcu call back when last
reference is released.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
drivers/net/bonding/bond_main.c
net/core/net-sysfs.c
net/ipv6/addrconf.c
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At compile time, we can replace the DIV_K instruction (divide by a
constant value) by a reciprocal divide.
At exec time, the expensive divide is replaced by a multiply, a less
expensive operation on most processors.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Starting the translated instruction to 1 instead of 0 allows us to
remove one descrement at check time and makes codes[] array init
cleaner.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Remove pc variable to avoid arithmetic to compute fentry at each filter
instruction. Jumps directly manipulate fentry pointer.
As the last instruction of filter[] is guaranteed to be a RETURN, and
all jumps are before the last instruction, we dont need to check filter
bounds (number of instructions in filter array) at each iteration, so we
remove it from sk_run_filter() params.
On x86_32 remove f_k var introduced in commit 57fe93b374a6b871
(filter: make sure filters dont read uninitialized memory)
Note : We could use a CONFIG_ARCH_HAS_{FEW|MANY}_REGISTERS in order to
avoid too many ifdefs in this code.
This helps compiler to use cpu registers to hold fentry and A
accumulator.
On x86_32, this saves 401 bytes, and more important, sk_run_filter()
runs much faster because less register pressure (One less conditional
branch per BPF instruction)
# size net/core/filter.o net/core/filter_pre.o
text data bss dec hex filename
2948 0 0 2948 b84 net/core/filter.o
3349 0 0 3349 d15 net/core/filter_pre.o
on x86_64 :
# size net/core/filter.o net/core/filter_pre.o
text data bss dec hex filename
5173 0 0 5173 1435 net/core/filter.o
5224 0 0 5224 1468 net/core/filter_pre.o
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Fix kernel-doc warning for sk_filter_rcu_release():
Warning(net/core/filter.c:586): missing initial short description on line:
* sk_filter_rcu_release: Release a socket filter by rcu_head
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
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BPF_S_* are used internally, should not be exposed to the others.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Since repeating u16 value to u8 value conversion using switch() clause's
case statement is wasteful, this patch introduces u16 to u8 mapping table
and removes most of case statements. As a result, the size of net/core/filter.o
is reduced by about 29% on x86.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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There is a possibility malicious users can get limited information about
uninitialized stack mem array. Even if sk_run_filter() result is bound
to packet length (0 .. 65535), we could imagine this can be used by
hostile user.
Initializing mem[] array, like Dan Rosenberg suggested in his patch is
expensive since most filters dont even use this array.
Its hard to make the filter validation in sk_chk_filter(), because of
the jumps. This might be done later.
In this patch, I use a bitmap (a single long var) so that only filters
using mem[] loads/stores pay the price of added security checks.
For other filters, additional cost is a single instruction.
[ Since we access fentry->k a lot now, cache it in a local variable
and mark filter entry pointer as const. -DaveM ]
Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add __rcu annotation to :
(struct sock)->sk_filter
And use appropriate rcu primitives to reduce sparse warnings if
CONFIG_SPARSE_RCU_POINTER=y
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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sk_attach_filter() and sk_detach_filter() are run with socket locked.
Use the appropriate rcu_dereference_protected() instead of blocking BH,
and rcu_dereference_bh().
There is no point adding BH prevention and memory barrier.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Gcc is currenlty not in the ability to optimize the switch statement in
sk_run_filter() because of dense case labels. This patch replace the
OR'd labels with ordered sequenced case labels. The sk_chk_filter()
function is modified to patch/replace the original OPCODES in a
ordered but equivalent form. gcc is now in the ability to transform the
switch statement in sk_run_filter into a jump table of complexity O(1).
Until this patch gcc generates a sequence of conditional branches (O(n) of 567
byte .text segment size (arch x86_64):
7ff: 8b 06 mov (%rsi),%eax
801: 66 83 f8 35 cmp $0x35,%ax
805: 0f 84 d0 02 00 00 je adb <sk_run_filter+0x31d>
80b: 0f 87 07 01 00 00 ja 918 <sk_run_filter+0x15a>
811: 66 83 f8 15 cmp $0x15,%ax
815: 0f 84 c5 02 00 00 je ae0 <sk_run_filter+0x322>
81b: 77 73 ja 890 <sk_run_filter+0xd2>
81d: 66 83 f8 04 cmp $0x4,%ax
821: 0f 84 17 02 00 00 je a3e <sk_run_filter+0x280>
827: 77 29 ja 852 <sk_run_filter+0x94>
829: 66 83 f8 01 cmp $0x1,%ax
[...]
With the modification the compiler translate the switch statement into
the following jump table fragment:
7ff: 66 83 3e 2c cmpw $0x2c,(%rsi)
803: 0f 87 1f 02 00 00 ja a28 <sk_run_filter+0x26a>
809: 0f b7 06 movzwl (%rsi),%eax
80c: ff 24 c5 00 00 00 00 jmpq *0x0(,%rax,8)
813: 44 89 e3 mov %r12d,%ebx
816: e9 43 03 00 00 jmpq b5e <sk_run_filter+0x3a0>
81b: 41 89 dc mov %ebx,%r12d
81e: e9 3b 03 00 00 jmpq b5e <sk_run_filter+0x3a0>
Furthermore, I reordered the instructions to reduce cache line misses by
order the most common instruction to the start.
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add an SKF_AD_HATYPE field to the packet ancilliary data area, giving
access to skb->dev->type, as reported in the sll_hatype field.
When capturing packets on a PF_PACKET/SOCK_RAW socket bound to all
interfaces, there doesn't appear to be a way for the filter program to
actually find out the underlying hardware type the packet was captured
on. This patch adds such ability.
This patch also handles the case where skb->dev can be NULL, such as on
netlink sockets.
Signed-off-by: Paul Evans <leonerd@leonerd.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
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implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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Conflicts:
drivers/firmware/iscsi_ibft.c
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Update rcu_dereference() primitives to use new lockdep-based
checking. The rcu_dereference() in __in6_dev_get() may be
protected either by rcu_read_lock() or RTNL, per Eric Dumazet.
The rcu_dereference() in __sk_free() is protected by the fact
that it is never reached if an update could change it. Check
for this by using rcu_dereference_check() to verify that the
struct sock's ->sk_wmem_alloc counter is zero.
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-5-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
Eric Dumazet
Alexei Starovoitov
Nicolas Dichtel
Daniel Borkmann
Vincent Bernat
Pavel Emelyanov
Daniel Borkmann
Mel Gorman
Randy Dunlap
Linus Torvalds
Eric Dumazet
Will Drewry
David S. Miller
Jiri Pirko
Jan Seiffert
David Howells
Dan Carpenter
Stephen Hemminger
Joe Perches
Lucas De Marchi
Randy Dunlap
Changli Gao
Tetsuo Handa
Hagen Paul Pfeifer
Paul LeoNerd Evans
Tejun Heo
Paul E. McKenney