[PATCH v17 03/15] sk_run_filter: add BPF_S_ANC_SECCOMP_LD_W

From: Will Drewry
Date: Thu Mar 29 2012 - 16:07:52 EST


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

v17: rebase
v16: -
v15: include seccomp.h explicitly for when seccomp_bpf_load exists.
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>
Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
---
include/linux/filter.h | 1 +
net/core/filter.c | 6 ++++++
2 files changed, 7 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 cf4989a..b6caa49 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -38,6 +38,7 @@
#include <linux/filter.h>
#include <linux/reciprocal_div.h>
#include <linux/ratelimit.h>
+#include <linux/seccomp.h>

/* No hurry in this branch */
static void *__load_pointer(const struct sk_buff *skb, int k, unsigned int size)
@@ -349,6 +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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