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Message-ID: <20190605155756.3779466-2-jonathan.lemon@gmail.com>
Date: Wed, 5 Jun 2019 08:57:56 -0700
From: Jonathan Lemon <jonathan.lemon@...il.com>
To: <bjorn.topel@...el.com>, <magnus.karlsson@...el.com>,
<toke@...hat.com>, <brouer@...hat.com>
CC: <kernel-team@...com>, <netdev@...r.kernel.org>,
<daniel@...earbox.net>, <ast@...nel.org>
Subject: [PATCH 1/1] bpf: Allow bpf_map_lookup_elem() on an xskmap
Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue. Instead of doing this,
have bpf_map_lookup_elem() return a xdp_sock.
Rearrange some xdp_sock members to eliminate structure holes.
Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>
---
include/linux/bpf.h | 8 ++++
include/net/xdp_sock.h | 4 +-
include/uapi/linux/bpf.h | 4 ++
kernel/bpf/verifier.c | 26 +++++++++++-
kernel/bpf/xskmap.c | 7 ++++
net/core/filter.c | 40 +++++++++++++++++++
tools/include/uapi/linux/bpf.h | 4 ++
.../bpf/verifier/prevent_map_lookup.c | 15 -------
tools/testing/selftests/bpf/verifier/sock.c | 18 +++++++++
9 files changed, 107 insertions(+), 19 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index ff3e00ff84d2..66b175bdc645 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -276,6 +276,7 @@ enum bpf_reg_type {
PTR_TO_TCP_SOCK, /* reg points to struct tcp_sock */
PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */
+ PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */
};
/* The information passed from prog-specific *_is_valid_access
@@ -670,6 +671,13 @@ void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
void __cpu_map_flush(struct bpf_map *map);
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
struct net_device *dev_rx);
+bool bpf_xdp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
+ struct bpf_insn_access_aux *info);
+u32 bpf_xdp_sock_convert_ctx_access(enum bpf_access_type type,
+ const struct bpf_insn *si,
+ struct bpf_insn *insn_buf,
+ struct bpf_prog *prog,
+ u32 *target_size);
/* Return map's numa specified by userspace */
static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index d074b6d60f8a..ae0f368a62bb 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -58,11 +58,11 @@ struct xdp_sock {
struct xdp_umem *umem;
struct list_head flush_node;
u16 queue_id;
- struct xsk_queue *tx ____cacheline_aligned_in_smp;
- struct list_head list;
bool zc;
/* Protects multiple processes in the control path */
struct mutex mutex;
+ struct xsk_queue *tx ____cacheline_aligned_in_smp;
+ struct list_head list;
/* Mutual exclusion of NAPI TX thread and sendmsg error paths
* in the SKB destructor callback.
*/
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7c6aef253173..ae0907d8c03a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3083,6 +3083,10 @@ struct bpf_sock_tuple {
};
};
+struct bpf_xdp_sock {
+ __u32 queue_id;
+};
+
#define XDP_PACKET_HEADROOM 256
/* User return codes for XDP prog type.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2778417e6e0c..abe177405989 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -334,7 +334,8 @@ static bool type_is_sk_pointer(enum bpf_reg_type type)
{
return type == PTR_TO_SOCKET ||
type == PTR_TO_SOCK_COMMON ||
- type == PTR_TO_TCP_SOCK;
+ type == PTR_TO_TCP_SOCK ||
+ type == PTR_TO_XDP_SOCK;
}
static bool reg_type_may_be_null(enum bpf_reg_type type)
@@ -406,6 +407,7 @@ static const char * const reg_type_str[] = {
[PTR_TO_TCP_SOCK] = "tcp_sock",
[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
[PTR_TO_TP_BUFFER] = "tp_buffer",
+ [PTR_TO_XDP_SOCK] = "xdp_sock",
};
static char slot_type_char[] = {
@@ -1363,6 +1365,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
+ case PTR_TO_XDP_SOCK:
return true;
default:
return false;
@@ -1843,6 +1846,9 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
case PTR_TO_TCP_SOCK:
valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
break;
+ case PTR_TO_XDP_SOCK:
+ valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
+ break;
default:
valid = false;
}
@@ -2007,6 +2013,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
case PTR_TO_TCP_SOCK:
pointer_desc = "tcp_sock ";
break;
+ case PTR_TO_XDP_SOCK:
+ pointer_desc = "xdp_sock ";
+ break;
default:
break;
}
@@ -2905,10 +2914,14 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
* appear.
*/
case BPF_MAP_TYPE_CPUMAP:
- case BPF_MAP_TYPE_XSKMAP:
if (func_id != BPF_FUNC_redirect_map)
goto error;
break;
+ case BPF_MAP_TYPE_XSKMAP:
+ if (func_id != BPF_FUNC_redirect_map &&
+ func_id != BPF_FUNC_map_lookup_elem)
+ goto error;
+ break;
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
if (func_id != BPF_FUNC_map_lookup_elem)
@@ -3799,6 +3812,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
+ case PTR_TO_XDP_SOCK:
verbose(env, "R%d pointer arithmetic on %s prohibited\n",
dst, reg_type_str[ptr_reg->type]);
return -EACCES;
@@ -5038,6 +5052,9 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
if (reg->map_ptr->inner_map_meta) {
reg->type = CONST_PTR_TO_MAP;
reg->map_ptr = reg->map_ptr->inner_map_meta;
+ } else if (reg->map_ptr->map_type ==
+ BPF_MAP_TYPE_XSKMAP) {
+ reg->type = PTR_TO_XDP_SOCK;
} else {
reg->type = PTR_TO_MAP_VALUE;
}
@@ -6289,6 +6306,7 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
+ case PTR_TO_XDP_SOCK:
/* Only valid matches are exact, which memcmp() above
* would have accepted
*/
@@ -6683,6 +6701,7 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type)
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
+ case PTR_TO_XDP_SOCK:
return false;
default:
return true;
@@ -7816,6 +7835,9 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
case PTR_TO_TCP_SOCK:
convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
break;
+ case PTR_TO_XDP_SOCK:
+ convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
+ break;
default:
continue;
}
diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c
index 686d244e798d..b5c58e9c4835 100644
--- a/kernel/bpf/xskmap.c
+++ b/kernel/bpf/xskmap.c
@@ -153,6 +153,12 @@ void __xsk_map_flush(struct bpf_map *map)
}
static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return __xsk_map_lookup_elem(map, *(u32 *)key);
+}
+
+static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
{
return ERR_PTR(-EOPNOTSUPP);
}
@@ -220,6 +226,7 @@ const struct bpf_map_ops xsk_map_ops = {
.map_free = xsk_map_free,
.map_get_next_key = xsk_map_get_next_key,
.map_lookup_elem = xsk_map_lookup_elem,
+ .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
.map_update_elem = xsk_map_update_elem,
.map_delete_elem = xsk_map_delete_elem,
.map_check_btf = map_check_no_btf,
diff --git a/net/core/filter.c b/net/core/filter.c
index 55bfc941d17a..f2d9d77b4b57 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5680,6 +5680,46 @@ BPF_CALL_1(bpf_skb_ecn_set_ce, struct sk_buff *, skb)
return INET_ECN_set_ce(skb);
}
+bool bpf_xdp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
+ struct bpf_insn_access_aux *info)
+{
+ if (off < 0 || off >= offsetofend(struct bpf_xdp_sock, queue_id))
+ return false;
+
+ if (off % size != 0)
+ return false;
+
+ switch (off) {
+ default:
+ return size == sizeof(__u32);
+ }
+}
+
+u32 bpf_xdp_sock_convert_ctx_access(enum bpf_access_type type,
+ const struct bpf_insn *si,
+ struct bpf_insn *insn_buf,
+ struct bpf_prog *prog, u32 *target_size)
+{
+ struct bpf_insn *insn = insn_buf;
+
+#define BPF_XDP_SOCK_GET(FIELD) \
+ do { \
+ BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_sock, FIELD) > \
+ FIELD_SIZEOF(struct bpf_xdp_sock, FIELD)); \
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_sock, FIELD),\
+ si->dst_reg, si->src_reg, \
+ offsetof(struct xdp_sock, FIELD)); \
+ } while (0)
+
+ switch (si->off) {
+ case offsetof(struct bpf_xdp_sock, queue_id):
+ BPF_XDP_SOCK_GET(queue_id);
+ break;
+ }
+
+ return insn - insn_buf;
+}
+
static const struct bpf_func_proto bpf_skb_ecn_set_ce_proto = {
.func = bpf_skb_ecn_set_ce,
.gpl_only = false,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7c6aef253173..ae0907d8c03a 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3083,6 +3083,10 @@ struct bpf_sock_tuple {
};
};
+struct bpf_xdp_sock {
+ __u32 queue_id;
+};
+
#define XDP_PACKET_HEADROOM 256
/* User return codes for XDP prog type.
diff --git a/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c b/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
index bbdba990fefb..da7a4b37cb98 100644
--- a/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
+++ b/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
@@ -28,21 +28,6 @@
.errstr = "cannot pass map_type 18 into func bpf_map_lookup_elem",
.prog_type = BPF_PROG_TYPE_SOCK_OPS,
},
-{
- "prevent map lookup in xskmap",
- .insns = {
- BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
- BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
- BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
- BPF_LD_MAP_FD(BPF_REG_1, 0),
- BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
- BPF_EXIT_INSN(),
- },
- .fixup_map_xskmap = { 3 },
- .result = REJECT,
- .errstr = "cannot pass map_type 17 into func bpf_map_lookup_elem",
- .prog_type = BPF_PROG_TYPE_XDP,
-},
{
"prevent map lookup in stack trace",
.insns = {
diff --git a/tools/testing/selftests/bpf/verifier/sock.c b/tools/testing/selftests/bpf/verifier/sock.c
index b31cd2cf50d0..9ed192e14f5f 100644
--- a/tools/testing/selftests/bpf/verifier/sock.c
+++ b/tools/testing/selftests/bpf/verifier/sock.c
@@ -498,3 +498,21 @@
.result = REJECT,
.errstr = "cannot pass map_type 24 into func bpf_map_lookup_elem",
},
+{
+ "bpf_map_lookup_elem(xskmap, &key); xs->queue_id",
+ .insns = {
+ BPF_ST_MEM(BPF_W, BPF_REG_10, -8, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+ BPF_EXIT_INSN(),
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_xdp_sock, queue_id)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_xskmap = { 3 },
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .result = ACCEPT,
+},
--
2.17.1
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