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Message-ID: <20160807040702.GA9279@ircssh.c.rugged-nimbus-611.internal>
Date: Sat, 6 Aug 2016 21:07:03 -0700
From: Sargun Dhillon <sargun@...gun.me>
To: netdev@...r.kernel.org
Cc: alexei.starovoitov@...il.com, daniel@...earbox.net
Subject: [net-next 1/2] bpf: Add bpf_current_in_cgroup helper
This adds a kprobe helper that's similar to the skb_in_cgroup helper. It
checks whether the probe is currently executing in the context of the
cgroup at the given index a CGROUP_ARRAY.
Signed-off-by: Sargun Dhillon <sargun@...gun.me>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Daniel Borkmann <daniel@...earbox.net>
---
include/linux/bpf.h | 24 ++++++++++++++++++++++++
include/uapi/linux/bpf.h | 11 +++++++++++
kernel/bpf/arraymap.c | 2 +-
kernel/bpf/verifier.c | 4 +++-
kernel/trace/bpf_trace.c | 34 ++++++++++++++++++++++++++++++++++
net/core/filter.c | 11 ++++-------
6 files changed, 77 insertions(+), 9 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 1113423..9adf712 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -319,4 +319,28 @@ extern const struct bpf_func_proto bpf_get_stackid_proto;
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+#ifdef CONFIG_CGROUPS
+/* Helper to fetch a cgroup pointer based on index.
+ * @map: a cgroup arraymap
+ * @idx: index of the item you want to fetch
+ *
+ * Returns pointer on success,
+ * Error code if item not found, or out-of-bounds access
+ */
+static inline struct cgroup *fetch_arraymap_ptr(struct bpf_map *map, int idx)
+{
+ struct cgroup *cgrp;
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+
+ if (unlikely(idx >= array->map.max_entries))
+ return ERR_PTR(-E2BIG);
+
+ cgrp = READ_ONCE(array->ptrs[idx]);
+ if (unlikely(!cgrp))
+ return ERR_PTR(-EAGAIN);
+
+ return cgrp;
+}
+#endif /* CONFIG_CGROUPS */
+
#endif /* _LINUX_BPF_H */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index da218fe..23a5b99 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -375,6 +375,17 @@ enum bpf_func_id {
*/
BPF_FUNC_probe_write_user,
+ /**
+ * bpf_current_in_cgroup(map, index) - Check cgroup2 membership of skb
+ * @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
+ * @index: index of the cgroup in the bpf_map
+ * Return:
+ * == 0 current failed the cgroup2 descendant test
+ * == 1 current succeeded the cgroup2 descendant test
+ * < 0 error
+ */
+ BPF_FUNC_current_in_cgroup,
+
__BPF_FUNC_MAX_ID,
};
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 633a650..a2ac051 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -538,7 +538,7 @@ static int __init register_perf_event_array_map(void)
}
late_initcall(register_perf_event_array_map);
-#ifdef CONFIG_SOCK_CGROUP_DATA
+#ifdef CONFIG_CGROUPS
static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
struct file *map_file /* not used */,
int fd)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f72f23b..e16559b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1052,7 +1052,8 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
goto error;
break;
case BPF_MAP_TYPE_CGROUP_ARRAY:
- if (func_id != BPF_FUNC_skb_in_cgroup)
+ if (func_id != BPF_FUNC_skb_in_cgroup &&
+ func_id != BPF_FUNC_current_in_cgroup)
goto error;
break;
default:
@@ -1074,6 +1075,7 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
goto error;
break;
+ case BPF_FUNC_current_in_cgroup:
case BPF_FUNC_skb_in_cgroup:
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
goto error;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index b20438f..f2a6bc5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -376,6 +376,36 @@ static const struct bpf_func_proto bpf_get_current_task_proto = {
.ret_type = RET_INTEGER,
};
+#ifdef CONFIG_CGROUPS
+static u64 bpf_current_in_cgroup(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ struct bpf_map *map = (struct bpf_map *)(long)r1;
+ struct css_set *cset;
+ struct cgroup *cgrp;
+ u32 idx = (u32)r2;
+
+ if (unlikely(in_interrupt()))
+ return -EINVAL;
+
+ cgrp = fetch_arraymap_ptr(map, idx);
+
+ if (unlikely(IS_ERR(cgrp)))
+ return PTR_ERR(cgrp);
+
+ cset = task_css_set(current);
+
+ return cgroup_is_descendant(cset->dfl_cgrp, cgrp);
+}
+
+static const struct bpf_func_proto bpf_current_in_cgroup_proto = {
+ .func = bpf_current_in_cgroup,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_ANYTHING,
+};
+#endif /* CONFIG_CGROUPS */
+
static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
@@ -407,6 +437,10 @@ static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
return &bpf_perf_event_read_proto;
case BPF_FUNC_probe_write_user:
return bpf_get_probe_write_proto();
+#ifdef CONFIG_CGROUPS
+ case BPF_FUNC_current_in_cgroup:
+ return &bpf_current_in_cgroup_proto;
+#endif
default:
return NULL;
}
diff --git a/net/core/filter.c b/net/core/filter.c
index 5708999..922fdb4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2302,21 +2302,18 @@ static u64 bpf_skb_in_cgroup(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
struct sk_buff *skb = (struct sk_buff *)(long)r1;
struct bpf_map *map = (struct bpf_map *)(long)r2;
- struct bpf_array *array = container_of(map, struct bpf_array, map);
struct cgroup *cgrp;
struct sock *sk;
- u32 i = (u32)r3;
+ u32 idx = (u32)r3;
sk = skb->sk;
if (!sk || !sk_fullsock(sk))
return -ENOENT;
- if (unlikely(i >= array->map.max_entries))
- return -E2BIG;
+ cgrp = fetch_arraymap_ptr(map, idx);
- cgrp = READ_ONCE(array->ptrs[i]);
- if (unlikely(!cgrp))
- return -EAGAIN;
+ if (unlikely(IS_ERR(cgrp)))
+ return PTR_ERR(cgrp);
return cgroup_is_descendant(sock_cgroup_ptr(&sk->sk_cgrp_data), cgrp);
}
--
2.7.4
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