Daniel Borkmann c2002f9837 bpf: fix checking xdp_adjust_head on tail calls ... Commit 17bedab272 ("bpf: xdp: Allow head adjustment in XDP prog") added the xdp_adjust_head bit to the BPF prog in order to tell drivers that the program that is to be attached requires support for the XDP bpf_xdp_adjust_head() helper such that drivers not supporting this helper can reject the program. There are also drivers that do support the helper, but need to check for xdp_adjust_head bit in order to move packet metadata prepended by the firmware away for making headroom. For these cases, the current check for xdp_adjust_head bit is insufficient since there can be cases where the program itself does not use the bpf_xdp_adjust_head() helper, but tail calls into another program that uses bpf_xdp_adjust_head(). As such, the xdp_adjust_head bit is still set to 0. Since the first program has no control over which program it calls into, we need to assume that bpf_xdp_adjust_head() helper is used upon tail calls. Thus, for the very same reasons in cb_access, set the xdp_adjust_head bit to 1 when the main program uses tail calls. Fixes: 17bedab272 ("bpf: xdp: Allow head adjustment in XDP prog") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2017-04-17 15:51:57 -04:00
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arraymap.c	bpf: mark all registered map/prog types as __ro_after_init	2017-02-17 13:40:04 -05:00
bpf_lru_list.c	bpf: Make unnecessarily global functions static	2017-01-10 21:00:59 -05:00
bpf_lru_list.h	bpf: Add percpu LRU list	2016-11-15 11:50:20 -05:00
cgroup.c	bpf: introduce BPF_F_ALLOW_OVERRIDE flag	2017-02-12 21:52:19 -05:00
core.c	bpf: reference may_access_skb() from __bpf_prog_run()	2017-04-11 10:54:27 -04:00
hashtab.c	bpf: fix hashmap extra_elems logic	2017-03-22 14:12:18 -07:00
helpers.c	bpf: rename ARG_PTR_TO_STACK	2017-01-09 16:56:27 -05:00
inode.c	bpf: add initial bpf tracepoints	2017-01-25 13:17:47 -05:00
lpm_trie.c	bpf: add get_next_key callback to LPM map	2017-03-05 17:55:29 -08:00
Makefile	bpf: add a longest prefix match trie map implementation	2017-01-23 16:10:38 -05:00
percpu_freelist.c	bpf: introduce percpu_freelist	2016-03-08 15:28:31 -05:00
percpu_freelist.h	bpf: introduce percpu_freelist	2016-03-08 15:28:31 -05:00
stackmap.c	bpf: mark all registered map/prog types as __ro_after_init	2017-02-17 13:40:04 -05:00
syscall.c	bpf: fix checking xdp_adjust_head on tail calls	2017-04-17 15:51:57 -04:00
verifier.c	bpf, verifier: fix rejection of unaligned access checks for map_value_adj	2017-04-01 12:36:37 -07:00