kernel/linux.git/include/linux/filter.h, branch v3.14.76

net: filter: let bpf_tell_extensions return SKF_AD_MAX

2014-01-22T02:57:43+00:00

Michal Sekletar added in commit ea02f9411d9f ("net: introduce SO_BPF_EXTENSIONS") a facility where user space can enquire the BPF ancillary instruction set, which is imho a step into the right direction for letting user space high-level to BPF optimizers make an informed decision for possibly using these extensions. The original rationale was to return through a getsockopt(2) a bitfield of which instructions are supported and which are not, as of right now, we just return 0 to indicate a base support for SKF_AD_PROTOCOL up to SKF_AD_PAY_OFFSET. Limitations of this approach are that this API which we need to maintain for a long time can only support a maximum of 32 extensions, and needs to be additionally maintained/updated when each new extension that comes in. I thought about this a bit more and what we can do here to overcome this is to just return SKF_AD_MAX. Since we never remove any extension since we cannot break user space and always linearly increase SKF_AD_MAX on each newly added extension, user space can make a decision on what extensions are supported in the whole set of extensions and which aren't, by just checking which of them from the whole set have an offset < SKF_AD_MAX of the underlying kernel. Since SKF_AD_MAX must be updated each time we add new ones, we don't need to introduce an additional enum and got maintenance for free. At some point in time when SO_BPF_EXTENSIONS becomes ubiquitous for most kernels, then an application can simply make use of this and easily be run on newer or older underlying kernels without needing to be recompiled, of course. Since that is for 3.14, it's not too late to do this change. Cc: Michal Sekletar Cc: Eric Dumazet Signed-off-by: Daniel Borkmann Acked-by: Michal Sekletar Signed-off-by: David S. Miller

net: introduce SO_BPF_EXTENSIONS

2014-01-19T03:08:58+00:00

For user space packet capturing libraries such as libpcap, there's currently only one way to check which BPF extensions are supported by the kernel, that is, commit aa1113d9f85d ("net: filter: return -EINVAL if BPF_S_ANC* operation is not supported"). For querying all extensions at once this might be rather inconvenient. Therefore, this patch introduces a new option which can be used as an argument for getsockopt(), and allows one to obtain information about which BPF extensions are supported by the current kernel. As David Miller suggests, we do not need to define any bits right now and status quo can just return 0 in order to state that this versions supports SKF_AD_PROTOCOL up to SKF_AD_PAY_OFFSET. Later additions to BPF extensions need to add their bits to the bpf_tell_extensions() function, as documented in the comment. Signed-off-by: Michal Sekletar Cc: David Miller Reviewed-by: Daniel Borkmann Signed-off-by: David S. Miller

net: fix unsafe set_memory_rw from softirq

2013-10-07T19:16:45+00:00

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] [ 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: [] 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] [] dump_stack+0x55/0x76 [ 56.936067] [] print_usage_bug+0x1f7/0x208 [ 56.942445] [] ? save_stack_trace+0x2f/0x50 [ 56.948932] [] ? check_usage_backwards+0x150/0x150 [ 56.955470] [] mark_lock+0x282/0x2c0 [ 56.961945] [] __lock_acquire+0x45d/0x1d50 [ 56.968474] [] ? __lock_acquire+0x2de/0x1d50 [ 56.975140] [] ? cpumask_next_and+0x55/0x90 [ 56.981942] [] lock_acquire+0x92/0x1d0 [ 56.988745] [] ? vm_unmap_aliases+0x16a/0x380 [ 56.995619] [] _raw_spin_lock+0x41/0x50 [ 57.002493] [] ? vm_unmap_aliases+0x16a/0x380 [ 57.009447] [] vm_unmap_aliases+0x16a/0x380 [ 57.016477] [] ? vm_unmap_aliases+0x8c/0x380 [ 57.023607] [] change_page_attr_set_clr+0xc0/0x460 [ 57.030818] [] ? trace_hardirqs_on+0xd/0x10 [ 57.037896] [] ? kmem_cache_free+0xb0/0x2b0 [ 57.044789] [] ? free_object_rcu+0x93/0xa0 [ 57.051720] [] set_memory_rw+0x2f/0x40 [ 57.058727] [] bpf_jit_free+0x2c/0x40 [ 57.065577] [] sk_filter_release_rcu+0x1a/0x30 [ 57.072338] [] rcu_process_callbacks+0x202/0x7c0 [ 57.078962] [] __do_softirq+0xf7/0x3f0 [ 57.085373] [] 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 Acked-by: Eric Dumazet Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2013-06-19T23:49:39+00:00

Conflicts: drivers/net/wireless/ath/ath9k/Kconfig drivers/net/xen-netback/netback.c net/batman-adv/bat_iv_ogm.c net/wireless/nl80211.c The ath9k Kconfig conflict was a change of a Kconfig option name right next to the deletion of another option. The xen-netback conflict was overlapping changes involving the handling of the notify list in xen_netbk_rx_action(). Batman conflict resolution provided by Antonio Quartulli, basically keep everything in both conflict hunks. The nl80211 conflict is a little more involved. In 'net' we added a dynamic memory allocation to nl80211_dump_wiphy() to fix a race that Linus reported. Meanwhile in 'net-next' the handlers were converted to use pre and post doit handlers which use a flag to determine whether to hold the RTNL mutex around the operation. However, the dump handlers to not use this logic. Instead they have to explicitly do the locking. There were apparent bugs in the conversion of nl80211_dump_wiphy() in that we were not dropping the RTNL mutex in all the return paths, and it seems we very much should be doing so. So I fixed that whilst handling the overlapping changes. To simplify the initial returns, I take the RTNL mutex after we try to allocate 'tb'. Signed-off-by: David S. Miller

sock_diag: fix filter code sent to userspace

2013-06-11T05:23:32+00:00

Filters need to be translated to real BPF code for userland, like SO_GETFILTER. Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller

filter: do not output bpf image address for security reason

2013-05-20T06:56:41+00:00

Do not leak starting address of BPF JIT code for non root users, as it might help intruders to perform an attack. Signed-off-by: Eric Dumazet Cc: Ben Hutchings Cc: Daniel Borkmann Signed-off-by: David S. Miller

filter: fix va_list build error

2013-05-01T20:28:48+00:00

This patch fixes the following build error. In file included from include/linux/filter.h:52:0, from arch/arm/net/bpf_jit_32.c:14: include/linux/printk.h:54:2: error: unknown type name ‘va_list’ include/linux/printk.h:105:21: error: unknown type name ‘va_list’ include/linux/printk.h:108:30: error: unknown type name ‘va_list’ Signed-off-by: Xi Wang Signed-off-by: David S. Miller

include/linux: printk is needed in filter.h when CONFIG_BPF_JIT is defined

2013-03-30T03:31:34+00:00

for make V=1 EXTRA_CFLAGS=-W ARCH=arm allmodconfig printk is need when CONFIG_BPF_JIT is defined or it will report pr_err and print_hex_dump are implicit declaration Signed-off-by: Chen Gang Signed-off-by: David S. Miller

filter: bpf_jit_comp: refactor and unify BPF JIT image dump output

2013-03-21T21:25:56+00:00

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 Cc: Matt Evans Cc: Eric Dumazet Cc: David S. Miller Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

filter: add ANC_PAY_OFFSET instruction for loading payload start offset

2013-03-20T17:15:45+00:00

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 Signed-off-by: Daniel Borkmann Acked-by: Eric Dumazet Signed-off-by: David S. Miller