* [PATCH bpf-next 0/2] Split bpf_sock dst_port field
@ 2022-01-27 17:24 Jakub Sitnicki
2022-01-27 17:24 ` [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide Jakub Sitnicki
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Jakub Sitnicki @ 2022-01-27 17:24 UTC (permalink / raw)
To: bpf
Cc: netdev, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Menglong Dong, Martin KaFai Lau
This is a follow-up to discussion around the idea of making dst_port in struct
bpf_sock a 16-bit field that happened in [1]. I have fleshed it out further:
v1:
- keep dst_field offset unchanged to prevent existing BPF program breakage
(Martin)
- allow 8-bit loads from dst_port[0] and [1]
- add test coverage for the verifier and the context access converter
[1] https://lore.kernel.org/bpf/87sftbobys.fsf@cloudflare.com/
Jakub Sitnicki (2):
bpf: Make dst_port field in struct bpf_sock 16-bit wide
selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads
include/uapi/linux/bpf.h | 3 +-
net/core/filter.c | 9 ++-
tools/include/uapi/linux/bpf.h | 3 +-
.../selftests/bpf/prog_tests/sock_fields.c | 58 +++++++++----
.../selftests/bpf/progs/test_sock_fields.c | 41 ++++++++++
tools/testing/selftests/bpf/verifier/sock.c | 81 ++++++++++++++++++-
6 files changed, 172 insertions(+), 23 deletions(-)
--
2.31.1
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide 2022-01-27 17:24 [PATCH bpf-next 0/2] Split bpf_sock dst_port field Jakub Sitnicki @ 2022-01-27 17:24 ` Jakub Sitnicki 2022-01-28 18:17 ` Alexei Starovoitov 2022-01-27 17:24 ` [PATCH bpf-next 2/2] selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads Jakub Sitnicki 2022-01-28 6:31 ` [PATCH bpf-next 0/2] Split bpf_sock dst_port field Martin KaFai Lau 2 siblings, 1 reply; 6+ messages in thread From: Jakub Sitnicki @ 2022-01-27 17:24 UTC (permalink / raw) To: bpf Cc: netdev, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Menglong Dong, Martin KaFai Lau Menglong Dong reports that the documentation for the dst_port field in struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the field is a zero-padded 16-bit integer in network byte order. The value appears to the BPF user as if laid out in memory as so: offsetof(struct bpf_sock, dst_port) + 0 <port MSB> + 8 <port LSB> +16 0x00 +24 0x00 32-, 16-, and 8-bit wide loads from the field are all allowed, but only if the offset into the field is 0. 32-bit wide loads from dst_port are especially confusing. The loaded value, after converting to host byte order with bpf_ntohl(dst_port), contains the port number in the upper 16-bits. Remove the confusion by splitting the field into two 16-bit fields. For backward compatibility, allow 32-bit wide loads from offsetof(struct bpf_sock, dst_port). While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port. Reported-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> --- include/uapi/linux/bpf.h | 3 ++- net/core/filter.c | 9 ++++++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4a2f7041ebae..027e84b18b51 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5574,7 +5574,8 @@ struct bpf_sock { __u32 src_ip4; __u32 src_ip6[4]; __u32 src_port; /* host byte order */ - __u32 dst_port; /* network byte order */ + __be16 dst_port; /* network byte order */ + __u16 zero_padding; __u32 dst_ip4; __u32 dst_ip6[4]; __u32 state; diff --git a/net/core/filter.c b/net/core/filter.c index a06931c27eeb..ef8473163696 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -8265,6 +8265,7 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { const int size_default = sizeof(__u32); + int field_size; if (off < 0 || off >= sizeof(struct bpf_sock)) return false; @@ -8276,7 +8277,6 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, case offsetof(struct bpf_sock, family): case offsetof(struct bpf_sock, type): case offsetof(struct bpf_sock, protocol): - case offsetof(struct bpf_sock, dst_port): case offsetof(struct bpf_sock, src_port): case offsetof(struct bpf_sock, rx_queue_mapping): case bpf_ctx_range(struct bpf_sock, src_ip4): @@ -8285,6 +8285,13 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, case bpf_ctx_range_till(struct bpf_sock, dst_ip6[0], dst_ip6[3]): bpf_ctx_record_field_size(info, size_default); return bpf_ctx_narrow_access_ok(off, size, size_default); + case bpf_ctx_range(struct bpf_sock, dst_port): + field_size = size == size_default ? + size_default : sizeof_field(struct bpf_sock, dst_port); + bpf_ctx_record_field_size(info, field_size); + return bpf_ctx_narrow_access_ok(off, size, field_size); + case bpf_ctx_range(struct bpf_sock, zero_padding): + return false; } return size == size_default; -- 2.31.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide 2022-01-27 17:24 ` [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide Jakub Sitnicki @ 2022-01-28 18:17 ` Alexei Starovoitov 2022-01-30 11:58 ` Jakub Sitnicki 0 siblings, 1 reply; 6+ messages in thread From: Alexei Starovoitov @ 2022-01-28 18:17 UTC (permalink / raw) To: Jakub Sitnicki Cc: bpf, Network Development, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Menglong Dong, Martin KaFai Lau On Thu, Jan 27, 2022 at 9:24 AM Jakub Sitnicki <jakub@cloudflare.com> wrote: > > Menglong Dong reports that the documentation for the dst_port field in > struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the > field is a zero-padded 16-bit integer in network byte order. The value > appears to the BPF user as if laid out in memory as so: > > offsetof(struct bpf_sock, dst_port) + 0 <port MSB> > + 8 <port LSB> > +16 0x00 > +24 0x00 > > 32-, 16-, and 8-bit wide loads from the field are all allowed, but only if > the offset into the field is 0. > > 32-bit wide loads from dst_port are especially confusing. The loaded value, > after converting to host byte order with bpf_ntohl(dst_port), contains the > port number in the upper 16-bits. > > Remove the confusion by splitting the field into two 16-bit fields. For > backward compatibility, allow 32-bit wide loads from offsetof(struct > bpf_sock, dst_port). > > While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port. > > Reported-by: Menglong Dong <imagedong@tencent.com> > Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> > --- > include/uapi/linux/bpf.h | 3 ++- > net/core/filter.c | 9 ++++++++- > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 4a2f7041ebae..027e84b18b51 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -5574,7 +5574,8 @@ struct bpf_sock { > __u32 src_ip4; > __u32 src_ip6[4]; > __u32 src_port; /* host byte order */ > - __u32 dst_port; /* network byte order */ > + __be16 dst_port; /* network byte order */ > + __u16 zero_padding; I was wondering can we do '__u16 :16' here ? Should we do the same for bpf_sk_lookup->remote_port as well for consistency? Thanks for the idea and the patches! ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide 2022-01-28 18:17 ` Alexei Starovoitov @ 2022-01-30 11:58 ` Jakub Sitnicki 0 siblings, 0 replies; 6+ messages in thread From: Jakub Sitnicki @ 2022-01-30 11:58 UTC (permalink / raw) To: Alexei Starovoitov Cc: bpf, Network Development, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Menglong Dong, Martin KaFai Lau On Fri, Jan 28, 2022 at 07:17 PM CET, Alexei Starovoitov wrote: > On Thu, Jan 27, 2022 at 9:24 AM Jakub Sitnicki <jakub@cloudflare.com> wrote: >> >> Menglong Dong reports that the documentation for the dst_port field in >> struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the >> field is a zero-padded 16-bit integer in network byte order. The value >> appears to the BPF user as if laid out in memory as so: >> >> offsetof(struct bpf_sock, dst_port) + 0 <port MSB> >> + 8 <port LSB> >> +16 0x00 >> +24 0x00 >> >> 32-, 16-, and 8-bit wide loads from the field are all allowed, but only if >> the offset into the field is 0. >> >> 32-bit wide loads from dst_port are especially confusing. The loaded value, >> after converting to host byte order with bpf_ntohl(dst_port), contains the >> port number in the upper 16-bits. >> >> Remove the confusion by splitting the field into two 16-bit fields. For >> backward compatibility, allow 32-bit wide loads from offsetof(struct >> bpf_sock, dst_port). >> >> While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port. >> >> Reported-by: Menglong Dong <imagedong@tencent.com> >> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> >> --- >> include/uapi/linux/bpf.h | 3 ++- >> net/core/filter.c | 9 ++++++++- >> 2 files changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >> index 4a2f7041ebae..027e84b18b51 100644 >> --- a/include/uapi/linux/bpf.h >> +++ b/include/uapi/linux/bpf.h >> @@ -5574,7 +5574,8 @@ struct bpf_sock { >> __u32 src_ip4; >> __u32 src_ip6[4]; >> __u32 src_port; /* host byte order */ >> - __u32 dst_port; /* network byte order */ >> + __be16 dst_port; /* network byte order */ >> + __u16 zero_padding; > > I was wondering can we do '__u16 :16' here ? Great idea. Now done in v2: https://lore.kernel.org/bpf/20220130115518.213259-1-jakub@cloudflare.com/ > Should we do the same for bpf_sk_lookup->remote_port as well > for consistency? I can tend to that this upcoming week. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next 2/2] selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads 2022-01-27 17:24 [PATCH bpf-next 0/2] Split bpf_sock dst_port field Jakub Sitnicki 2022-01-27 17:24 ` [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide Jakub Sitnicki @ 2022-01-27 17:24 ` Jakub Sitnicki 2022-01-28 6:31 ` [PATCH bpf-next 0/2] Split bpf_sock dst_port field Martin KaFai Lau 2 siblings, 0 replies; 6+ messages in thread From: Jakub Sitnicki @ 2022-01-27 17:24 UTC (permalink / raw) To: bpf Cc: netdev, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Menglong Dong, Martin KaFai Lau Add coverage to the verifier tests and tests for reading bpf_sock fields to ensure that 32-bit, 16-bit, and 8-bit loads from dst_port field are allowed only at intended offsets and produce expected values. While 16-bit and 8-bit access to dst_port field is straight-forward, 32-bit wide loads need be allowed and produce a zero-padded 16-bit value for backward compatibility. Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> --- tools/include/uapi/linux/bpf.h | 3 +- .../selftests/bpf/prog_tests/sock_fields.c | 58 +++++++++---- .../selftests/bpf/progs/test_sock_fields.c | 41 ++++++++++ tools/testing/selftests/bpf/verifier/sock.c | 81 ++++++++++++++++++- 4 files changed, 162 insertions(+), 21 deletions(-) diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 4a2f7041ebae..027e84b18b51 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5574,7 +5574,8 @@ struct bpf_sock { __u32 src_ip4; __u32 src_ip6[4]; __u32 src_port; /* host byte order */ - __u32 dst_port; /* network byte order */ + __be16 dst_port; /* network byte order */ + __u16 zero_padding; __u32 dst_ip4; __u32 dst_ip6[4]; __u32 state; diff --git a/tools/testing/selftests/bpf/prog_tests/sock_fields.c b/tools/testing/selftests/bpf/prog_tests/sock_fields.c index 9fc040eaa482..9d211b5c22c4 100644 --- a/tools/testing/selftests/bpf/prog_tests/sock_fields.c +++ b/tools/testing/selftests/bpf/prog_tests/sock_fields.c @@ -1,9 +1,11 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2019 Facebook */ +#define _GNU_SOURCE #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> +#include <sched.h> #include <stdlib.h> #include <string.h> #include <errno.h> @@ -20,6 +22,7 @@ enum bpf_linum_array_idx { EGRESS_LINUM_IDX, INGRESS_LINUM_IDX, + READ_SK_DST_PORT_LINUM_IDX, __NR_BPF_LINUM_ARRAY_IDX, }; @@ -42,8 +45,16 @@ static __u64 child_cg_id; static int linum_map_fd; static __u32 duration; -static __u32 egress_linum_idx = EGRESS_LINUM_IDX; -static __u32 ingress_linum_idx = INGRESS_LINUM_IDX; +static bool create_netns(void) +{ + if (!ASSERT_OK(unshare(CLONE_NEWNET), "create netns")) + return false; + + if (!ASSERT_OK(system("ip link set dev lo up"), "bring up lo")) + return false; + + return true; +} static void print_sk(const struct bpf_sock *sk, const char *prefix) { @@ -91,19 +102,24 @@ static void check_result(void) { struct bpf_tcp_sock srv_tp, cli_tp, listen_tp; struct bpf_sock srv_sk, cli_sk, listen_sk; - __u32 ingress_linum, egress_linum; + __u32 idx, ingress_linum, egress_linum, linum; int err; - err = bpf_map_lookup_elem(linum_map_fd, &egress_linum_idx, - &egress_linum); + idx = EGRESS_LINUM_IDX; + err = bpf_map_lookup_elem(linum_map_fd, &idx, &egress_linum); CHECK(err < 0, "bpf_map_lookup_elem(linum_map_fd)", "err:%d errno:%d\n", err, errno); - err = bpf_map_lookup_elem(linum_map_fd, &ingress_linum_idx, - &ingress_linum); + idx = INGRESS_LINUM_IDX; + err = bpf_map_lookup_elem(linum_map_fd, &idx, &ingress_linum); CHECK(err < 0, "bpf_map_lookup_elem(linum_map_fd)", "err:%d errno:%d\n", err, errno); + idx = READ_SK_DST_PORT_LINUM_IDX; + err = bpf_map_lookup_elem(linum_map_fd, &idx, &linum); + ASSERT_OK(err, "bpf_map_lookup_elem(linum_map_fd, READ_SK_DST_PORT_IDX)"); + ASSERT_EQ(linum, 0, "failure in read_sk_dst_port on line"); + memcpy(&srv_sk, &skel->bss->srv_sk, sizeof(srv_sk)); memcpy(&srv_tp, &skel->bss->srv_tp, sizeof(srv_tp)); memcpy(&cli_sk, &skel->bss->cli_sk, sizeof(cli_sk)); @@ -262,7 +278,7 @@ static void test(void) char buf[DATA_LEN]; /* Prepare listen_fd */ - listen_fd = start_server(AF_INET6, SOCK_STREAM, "::1", 0, 0); + listen_fd = start_server(AF_INET6, SOCK_STREAM, "::1", 0xcafe, 0); /* start_server() has logged the error details */ if (CHECK_FAIL(listen_fd == -1)) goto done; @@ -330,8 +346,12 @@ static void test(void) void serial_test_sock_fields(void) { - struct bpf_link *egress_link = NULL, *ingress_link = NULL; int parent_cg_fd = -1, child_cg_fd = -1; + struct bpf_link *link; + + /* Use a dedicated netns to have a fixed listen port */ + if (!create_netns()) + return; /* Create a cgroup, get fd, and join it */ parent_cg_fd = test__join_cgroup(PARENT_CGROUP); @@ -352,15 +372,20 @@ void serial_test_sock_fields(void) if (CHECK(!skel, "test_sock_fields__open_and_load", "failed\n")) goto done; - egress_link = bpf_program__attach_cgroup(skel->progs.egress_read_sock_fields, - child_cg_fd); - if (!ASSERT_OK_PTR(egress_link, "attach_cgroup(egress)")) + link = bpf_program__attach_cgroup(skel->progs.egress_read_sock_fields, child_cg_fd); + if (!ASSERT_OK_PTR(link, "attach_cgroup(egress_read_sock_fields)")) + goto done; + skel->links.egress_read_sock_fields = link; + + link = bpf_program__attach_cgroup(skel->progs.ingress_read_sock_fields, child_cg_fd); + if (!ASSERT_OK_PTR(link, "attach_cgroup(ingress_read_sock_fields)")) goto done; + skel->links.ingress_read_sock_fields = link; - ingress_link = bpf_program__attach_cgroup(skel->progs.ingress_read_sock_fields, - child_cg_fd); - if (!ASSERT_OK_PTR(ingress_link, "attach_cgroup(ingress)")) + link = bpf_program__attach_cgroup(skel->progs.read_sk_dst_port, child_cg_fd); + if (!ASSERT_OK_PTR(link, "attach_cgroup(read_sk_dst_port")) goto done; + skel->links.read_sk_dst_port = link; linum_map_fd = bpf_map__fd(skel->maps.linum_map); sk_pkt_out_cnt_fd = bpf_map__fd(skel->maps.sk_pkt_out_cnt); @@ -369,8 +394,7 @@ void serial_test_sock_fields(void) test(); done: - bpf_link__destroy(egress_link); - bpf_link__destroy(ingress_link); + test_sock_fields__detach(skel); test_sock_fields__destroy(skel); if (child_cg_fd >= 0) close(child_cg_fd); diff --git a/tools/testing/selftests/bpf/progs/test_sock_fields.c b/tools/testing/selftests/bpf/progs/test_sock_fields.c index 81b57b9aaaea..246f1f001813 100644 --- a/tools/testing/selftests/bpf/progs/test_sock_fields.c +++ b/tools/testing/selftests/bpf/progs/test_sock_fields.c @@ -12,6 +12,7 @@ enum bpf_linum_array_idx { EGRESS_LINUM_IDX, INGRESS_LINUM_IDX, + READ_SK_DST_PORT_LINUM_IDX, __NR_BPF_LINUM_ARRAY_IDX, }; @@ -250,4 +251,44 @@ int ingress_read_sock_fields(struct __sk_buff *skb) return CG_OK; } +static __noinline bool sk_dst_port__load_word(struct bpf_sock *sk) +{ + __u32 *word = (__u32 *)&sk->dst_port; + return word[0] == bpf_htonl(0xcafe0000); +} + +static __noinline bool sk_dst_port__load_half(struct bpf_sock *sk) +{ + __u16 *half = (__u16 *)&sk->dst_port; + return half[0] == bpf_htons(0xcafe); +} + +static __noinline bool sk_dst_port__load_byte(struct bpf_sock *sk) +{ + __u8 *byte = (__u8 *)&sk->dst_port; + return byte[0] == 0xca && byte[1] == 0xfe; +} + +SEC("cgroup_skb/egress") +int read_sk_dst_port(struct __sk_buff *skb) +{ + __u32 linum, linum_idx; + struct bpf_sock *sk; + + linum_idx = READ_SK_DST_PORT_LINUM_IDX; + + sk = skb->sk; + if (!sk) + RET_LOG(); + + if (!sk_dst_port__load_word(sk)) + RET_LOG(); + if (!sk_dst_port__load_half(sk)) + RET_LOG(); + if (!sk_dst_port__load_byte(sk)) + RET_LOG(); + + return CG_OK; +} + char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/verifier/sock.c b/tools/testing/selftests/bpf/verifier/sock.c index ce13ece08d51..3d9d89c5fe65 100644 --- a/tools/testing/selftests/bpf/verifier/sock.c +++ b/tools/testing/selftests/bpf/verifier/sock.c @@ -121,7 +121,25 @@ .result = ACCEPT, }, { - "sk_fullsock(skb->sk): sk->dst_port [narrow load]", + "sk_fullsock(skb->sk): sk->dst_port [word load] (backward compatibility)", + .insns = { + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_sock, dst_port)), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = ACCEPT, +}, +{ + "sk_fullsock(skb->sk): sk->dst_port [half load]", .insns = { BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), @@ -139,7 +157,64 @@ .result = ACCEPT, }, { - "sk_fullsock(skb->sk): sk->dst_port [load 2nd byte]", + "sk_fullsock(skb->sk): sk->dst_port [half load] (invalid)", + .insns = { + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_sock, dst_port) + 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = REJECT, + .errstr = "invalid sock access", +}, +{ + "sk_fullsock(skb->sk): sk->dst_port [byte load]", + .insns = { + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_B, BPF_REG_2, BPF_REG_0, offsetof(struct bpf_sock, dst_port)), + BPF_LDX_MEM(BPF_B, BPF_REG_2, BPF_REG_0, offsetof(struct bpf_sock, dst_port) + 1), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = ACCEPT, +}, +{ + "sk_fullsock(skb->sk): sk->dst_port [byte load] (invalid)", + .insns = { + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_sock, dst_port) + 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = REJECT, + .errstr = "invalid sock access", +}, +{ + "sk_fullsock(skb->sk): sk->zero_padding [half load] (invalid)", .insns = { BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), @@ -149,7 +224,7 @@ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), - BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_sock, dst_port) + 1), + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_0, offsetof(struct bpf_sock, zero_padding)), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, -- 2.31.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 0/2] Split bpf_sock dst_port field 2022-01-27 17:24 [PATCH bpf-next 0/2] Split bpf_sock dst_port field Jakub Sitnicki 2022-01-27 17:24 ` [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide Jakub Sitnicki 2022-01-27 17:24 ` [PATCH bpf-next 2/2] selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads Jakub Sitnicki @ 2022-01-28 6:31 ` Martin KaFai Lau 2 siblings, 0 replies; 6+ messages in thread From: Martin KaFai Lau @ 2022-01-28 6:31 UTC (permalink / raw) To: Jakub Sitnicki Cc: bpf, netdev, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Menglong Dong On Thu, Jan 27, 2022 at 06:24:46PM +0100, Jakub Sitnicki wrote: > This is a follow-up to discussion around the idea of making dst_port in struct > bpf_sock a 16-bit field that happened in [1]. I have fleshed it out further: > > v1: > - keep dst_field offset unchanged to prevent existing BPF program breakage > (Martin) > - allow 8-bit loads from dst_port[0] and [1] > - add test coverage for the verifier and the context access converter lgtm. Thanks for the patches. Acked-by: Martin KaFai Lau <kafai@fb.com> ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-01-30 11:58 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-01-27 17:24 [PATCH bpf-next 0/2] Split bpf_sock dst_port field Jakub Sitnicki 2022-01-27 17:24 ` [PATCH bpf-next 1/2] bpf: Make dst_port field in struct bpf_sock 16-bit wide Jakub Sitnicki 2022-01-28 18:17 ` Alexei Starovoitov 2022-01-30 11:58 ` Jakub Sitnicki 2022-01-27 17:24 ` [PATCH bpf-next 2/2] selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads Jakub Sitnicki 2022-01-28 6:31 ` [PATCH bpf-next 0/2] Split bpf_sock dst_port field Martin KaFai Lau
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