- 31 May, 2014 1 commit
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Alexei Starovoitov authored
[ Upstream commit 773cd38f ] bpf_alloc_binary() adds 128 bytes of room to JITed program image and rounds it up to the nearest page size. If image size is close to page size (like 4000), it is rounded to two pages: round_up(4000 + 4 + 128) == 8192 then 'hole' is computed as 8192 - (4000 + 4) = 4188 If prandom_u32() % hole selects a number >= PAGE_SIZE - sizeof(*header) then kernel will crash during bpf_jit_free(): kernel BUG at arch/x86/mm/pageattr.c:887! Call Trace: [<ffffffff81037285>] change_page_attr_set_clr+0x135/0x460 [<ffffffff81694cc0>] ? _raw_spin_unlock_irq+0x30/0x50 [<ffffffff810378ff>] set_memory_rw+0x2f/0x40 [<ffffffffa01a0d8d>] bpf_jit_free_deferred+0x2d/0x60 [<ffffffff8106bf98>] process_one_work+0x1d8/0x6a0 [<ffffffff8106bf38>] ? process_one_work+0x178/0x6a0 [<ffffffff8106c90c>] worker_thread+0x11c/0x370 since bpf_jit_free() does: unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK; struct bpf_binary_header *header = (void *)addr; to compute start address of 'bpf_binary_header' and header->pages will pass junk to: set_memory_rw(addr, header->pages); Fix it by making sure that &header->image[prandom_u32() % hole] and &header are in the same page Fixes: 314beb9b ("x86: bpf_jit_comp: secure bpf jit against spraying attacks") Signed-off-by:
Alexei Starovoitov <ast@plumgrid.com> Acked-by:
Eric Dumazet <edumazet@google.com> Signed-off-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 16 Jan, 2014 1 commit
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Eric Dumazet authored
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:
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:
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- 08 Nov, 2013 1 commit
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Andrey Vagin authored
sk_filter isn't freed if bpf_func is equal to sk_run_filter. This memory leak was introduced by v3.12-rc3-224-gd45ed4a4 "net: fix unsafe set_memory_rw from softirq". Before this patch sk_filter was freed in sk_filter_release_rcu, now it should be freed in bpf_jit_free. Here is output of kmemleak: unreferenced object 0xffff8800b774eab0 (size 128): comm "systemd", pid 1, jiffies 4294669014 (age 124.062s) hex dump (first 32 bytes): 00 00 00 00 0b 00 00 00 20 63 7f b7 00 88 ff ff ........ c...... 60 d4 55 81 ff ff ff ff 30 d9 55 81 ff ff ff ff `.U.....0.U..... backtrace: [<ffffffff816444be>] kmemleak_alloc+0x4e/0xb0 [<ffffffff811845af>] __kmalloc+0xef/0x260 [<ffffffff81534028>] sock_kmalloc+0x38/0x60 [<ffffffff8155d4dd>] sk_attach_filter+0x5d/0x190 [<ffffffff815378a1>] sock_setsockopt+0x991/0x9e0 [<ffffffff81531bd6>] SyS_setsockopt+0xb6/0xd0 [<ffffffff8165f3e9>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff v2: add extra { } after else Fixes: d45ed4a4 ("net: fix unsafe set_memory_rw from softirq") Acked-by:
Daniel Borkmann <dborkman@redhat.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by:
Andrey Vagin <avagin@openvz.org> Acked-by:
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- 07 Oct, 2013 1 commit
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Alexei Starovoitov authored
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:
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- 20 May, 2013 1 commit
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Eric Dumazet authored
hpa bringed into my attention some security related issues with BPF JIT on x86. This patch makes sure the bpf generated code is marked read only, as other kernel text sections. It also splits the unused space (we vmalloc() and only use a fraction of the page) in two parts, so that the generated bpf code not starts at a known offset in the page, but a pseudo random one. Refs: http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html Reported-by:
H. Peter Anvin <hpa@zytor.com> Signed-off-by:
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- 18 May, 2013 1 commit
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Eric Dumazet authored
It looks like we can call module_free()/vfree() from softirq context, so no longer need a wrapper and a work_struct. Signed-off-by:
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- 21 Mar, 2013 1 commit
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Daniel Borkmann authored
If bpf_jit_enable > 1, then we dump the emitted JIT compiled image after creation. Currently, only SPARC and PowerPC has similar output as in the reference implementation on x86_64. Make a small helper function in order to reduce duplicated code and make the dump output uniform across architectures x86_64, SPARC, PPC, ARM (e.g. on ARM flen, pass and proglen are currently not shown, but would be interesting to know as well), also for future BPF JIT implementations on other archs. Cc: Mircea Gherzan <mgherzan@gmail.com> Cc: Matt Evans <matt@ozlabs.org> Cc: Eric Dumazet <eric.dumazet@google.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by:
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- 31 Jan, 2013 1 commit
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Eric Dumazet authored
Supporting access to skb->pkt_type is a bit tricky if we want to have a generic code, allowing pkt_type to be moved in struct sk_buff pkt_type is a bit field, so compiler cannot really help us to find its offset. Let's use a helper for this : It will throw a one time message if pkt_type no longer starts at a byte boundary or is no longer a 3bit field. Reported-by:
Willem de Bruijn <willemb@google.com> Signed-off-by:
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- 31 Oct, 2012 1 commit
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Eric Dumazet authored
This patch is a follow-up for patch "net: filter: add vlan tag access" to support the new VLAN_TAG/VLAN_TAG_PRESENT accessors in BPF JIT. Signed-off-by:
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- 24 Sep, 2012 1 commit
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Daniel Borkmann authored
This patch is a follow-up for patch "filter: add XOR instruction for use with X/K" that implements BPF x86 JIT parts for the BPF XOR operation. Signed-off-by:
Daniel Borkmann <daniel.borkmann@tik.ee.ethz.ch> Acked-by:
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- 10 Sep, 2012 1 commit
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Eric Dumazet authored
commit b6069a95 (filter: add MOD operation) added generic support for modulus operation in BPF. This patch brings JIT support for x86_64 Signed-off-by:
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- 06 Jun, 2012 1 commit
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Eric Dumazet authored
commit ffe06c17 (filter: add XOR operation) added generic support for XOR operation. This patch implements the XOR instruction in x86 jit. Signed-off-by:
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- 03 Apr, 2012 1 commit
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Jan Seiffert authored
Now the helper function from filter.c for negative offsets is exported, it can be used it in the jit to handle negative offsets. First modify the asm load helper functions to handle: - know positive offsets - know negative offsets - any offset then the compiler can be modified to explicitly use these helper when appropriate. This fixes the case of a negative X register and allows to lift the restriction that bpf programs with negative offsets can't be jited. Signed-of-by:
Jan Seiffert <kaffeemonster@googlemail.com> Signed-off-by:
Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:
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- 29 Mar, 2012 1 commit
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zhuangfeiran@ict.ac.cn authored
When K >= 0xFFFF0000, AND needs the two least significant bytes of K as its operand, but EMIT2() gives it the least significant byte of K and 0x2. EMIT() should be used here to replace EMIT2(). Signed-off-by:
Feiran Zhuang <zhuangfeiran@ict.ac.cn> Acked-by:
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- 19 Mar, 2012 1 commit
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Eric Dumazet authored
Matt Evans spotted that x86 bpf_jit was incorrectly handling negative constant offsets in BPF_S_LDX_B_MSH instruction. We need to abort JIT compilation like we do in common_load so that filter uses the interpreter code and can call __load_pointer() Reference: http://lists.openwall.net/netdev/2011/07/19/11 Thanks to Indan Zupancic to bring back this issue. Reported-by:
Matt Evans <matt@ozlabs.org> Reported-by:
Indan Zupancic <indan@nul.nu> Signed-off-by:
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- 18 Jan, 2012 1 commit
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Eric Dumazet authored
Several problems fixed in this patch : 1) Target of the conditional jump in case a divide by 0 is performed by a bpf is wrong. 2) Must 'generate' the full function prologue/epilogue at pass=0, or else we can stop too early in pass=1 if the proglen doesnt change. (if the increase of prologue/epilogue equals decrease of all instructions length because some jumps are converted to near jumps) 3) Change the wrong length detection at the end of code generation to issue a more explicit message, no need for a full stack trace. Reported-by:Phil Oester <kernel@linuxace.com> Signed-off-by:
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- 19 Dec, 2011 1 commit
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Markus Kötter authored
x86 jump instruction size is 2 or 5 bytes (near/long jump), not 2 or 6 bytes. In case a conditional jump is followed by a long jump, conditional jump target is one byte past the start of target instruction. Signed-off-by:
Markus Kötter <nepenthesdev@gmail.com> Signed-off-by:
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- 28 Apr, 2011 1 commit
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Eric Dumazet authored
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:
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