From fada7fdc83c0bf8755956bff707c42b609223301 Mon Sep 17 00:00:00 2001 From: Jonathan Lemon Date: Thu, 6 Jun 2019 13:59:40 -0700 Subject: [PATCH] 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. Remove selftest - will be added back in later patch. Signed-off-by: Jonathan Lemon Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov --- 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 ++++++++++++++++++++++ .../selftests/bpf/verifier/prevent_map_lookup.c | 15 -------- 7 files changed, 85 insertions(+), 19 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e5a309e6a400..1fe137afa898 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -280,6 +280,7 @@ 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 @@ -727,6 +728,13 @@ 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 5c2cb5bd84ce..8d1786357a09 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; } @@ -6299,6 +6316,7 @@ 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 */ @@ -6693,6 +6711,7 @@ 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; @@ -7826,6 +7845,9 @@ 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 413d75f4fc72..ef7338cebd18 100644 --- a/kernel/bpf/xskmap.c +++ b/kernel/bpf/xskmap.c @@ -152,6 +152,12 @@ 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); } @@ -218,6 +224,7 @@ 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 f2777dc0b624..a5e4ac7fcbe5 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/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 @@ -29,21 +29,6 @@ .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 = { BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), -- 2.11.0