[PATCH v14 01/13] sk_run_filter: add BPF_S_ANC_SECCOMP_LD_W

[Will Drewry]

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

v14: First cut using a single additional instruction
... v13: made bpf functions generic.


Suggested-by: Indan Zupancic <indan@xxxxxx>
Signed-off-by: Will Drewry <wad@xxxxxxxxxxxx>
---
 include/linux/filter.h |    1 +
 net/core/filter.c      |    5 +++++
 2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 8eeb205..aaa2e80 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -228,6 +228,7 @@ enum {
 	BPF_S_ANC_HATYPE,
 	BPF_S_ANC_RXHASH,
 	BPF_S_ANC_CPU,
+	BPF_S_ANC_SECCOMP_LD_W,
 };
 
 #endif /* __KERNEL__ */
diff --git a/net/core/filter.c b/net/core/filter.c
index 5dea452..3000931 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -350,6 +350,11 @@ load_b:
 				A = 0;
 			continue;
 		}
+#ifdef CONFIG_SECCOMP_FILTER
+		case BPF_S_ANC_SECCOMP_LD_W:
+			A = seccomp_bpf_load(fentry->k);
+			continue;
+#endif
 		default:
 			WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
 				       fentry->code, fentry->jt,
-- 
1.7.5.4

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