From d900f3d20cc3169ce42ec72acc850e662a4d4db2 Mon Sep 17 00:00:00 2001 From: Liu Jian Date: Fri, 3 Mar 2023 16:09:46 +0800 Subject: bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser() When the buffer length of the recvmsg system call is 0, we got the flollowing soft lockup problem: watchdog: BUG: soft lockup - CPU#3 stuck for 27s! [a.out:6149] CPU: 3 PID: 6149 Comm: a.out Kdump: loaded Not tainted 6.2.0+ #30 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:remove_wait_queue+0xb/0xc0 Code: 5e 41 5f c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 57 <41> 56 41 55 41 54 55 48 89 fd 53 48 89 f3 4c 8d 6b 18 4c 8d 73 20 RSP: 0018:ffff88811b5978b8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88811a7d3780 RCX: ffffffffb7a4d768 RDX: dffffc0000000000 RSI: ffff88811b597908 RDI: ffff888115408040 RBP: 1ffff110236b2f1b R08: 0000000000000000 R09: ffff88811a7d37e7 R10: ffffed10234fa6fc R11: 0000000000000001 R12: ffff88811179b800 R13: 0000000000000001 R14: ffff88811a7d38a8 R15: ffff88811a7d37e0 FS: 00007f6fb5398740(0000) GS:ffff888237180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000000 CR3: 000000010b6ba002 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcp_msg_wait_data+0x279/0x2f0 tcp_bpf_recvmsg_parser+0x3c6/0x490 inet_recvmsg+0x280/0x290 sock_recvmsg+0xfc/0x120 ____sys_recvmsg+0x160/0x3d0 ___sys_recvmsg+0xf0/0x180 __sys_recvmsg+0xea/0x1a0 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc The logic in tcp_bpf_recvmsg_parser is as follows: msg_bytes_ready: copied = sk_msg_recvmsg(sk, psock, msg, len, flags); if (!copied) { wait data; goto msg_bytes_ready; } In this case, "copied" always is 0, the infinite loop occurs. According to the Linux system call man page, 0 should be returned in this case. Therefore, in tcp_bpf_recvmsg_parser(), if the length is 0, directly return. Also modify several other functions with the same problem. Fixes: 1f5be6b3b063 ("udp: Implement udp_bpf_recvmsg() for sockmap") Fixes: 9825d866ce0d ("af_unix: Implement unix_dgram_bpf_recvmsg()") Fixes: c5d2177a72a1 ("bpf, sockmap: Fix race in ingress receive verdict with redirect to self") Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Liu Jian Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Cc: Jakub Sitnicki Link: https://lore.kernel.org/bpf/20230303080946.1146638-1-liujian56@huawei.com --- net/ipv4/tcp_bpf.c | 6 ++++++ net/ipv4/udp_bpf.c | 3 +++ net/unix/unix_bpf.c | 3 +++ 3 files changed, 12 insertions(+) (limited to 'net') diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index cf26d65ca389..ebf917511937 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -186,6 +186,9 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); + if (!len) + return 0; + psock = sk_psock_get(sk); if (unlikely(!psock)) return tcp_recvmsg(sk, msg, len, flags, addr_len); @@ -244,6 +247,9 @@ static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); + if (!len) + return 0; + psock = sk_psock_get(sk); if (unlikely(!psock)) return tcp_recvmsg(sk, msg, len, flags, addr_len); diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c index e5dc91d0e079..0735d820e413 100644 --- a/net/ipv4/udp_bpf.c +++ b/net/ipv4/udp_bpf.c @@ -68,6 +68,9 @@ static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); + if (!len) + return 0; + psock = sk_psock_get(sk); if (unlikely(!psock)) return sk_udp_recvmsg(sk, msg, len, flags, addr_len); diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c index e9bf15513961..2f9d8271c6ec 100644 --- a/net/unix/unix_bpf.c +++ b/net/unix/unix_bpf.c @@ -54,6 +54,9 @@ static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg, struct sk_psock *psock; int copied; + if (!len) + return 0; + psock = sk_psock_get(sk); if (unlikely(!psock)) return __unix_recvmsg(sk, msg, len, flags); -- cgit v1.2.3 From 294635a8165a31408a8b3a24f9c74849ca3d8701 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Fri, 24 Feb 2023 17:36:07 +0100 Subject: bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit &xdp_buff and &xdp_frame are bound in a way that xdp_buff->data_hard_start == xdp_frame It's always the case and e.g. xdp_convert_buff_to_frame() relies on this. IOW, the following: for (u32 i = 0; i < 0xdead; i++) { xdpf = xdp_convert_buff_to_frame(&xdp); xdp_convert_frame_to_buff(xdpf, &xdp); } shouldn't ever modify @xdpf's contents or the pointer itself. However, "live packet" code wrongly treats &xdp_frame as part of its context placed *before* the data_hard_start. With such flow, data_hard_start is sizeof(*xdpf) off to the right and no longer points to the XDP frame. Instead of replacing `sizeof(ctx)` with `offsetof(ctx, xdpf)` in several places and praying that there are no more miscalcs left somewhere in the code, unionize ::frm with ::data in a flex array, so that both starts pointing to the actual data_hard_start and the XDP frame actually starts being a part of it, i.e. a part of the headroom, not the context. A nice side effect is that the maximum frame size for this mode gets increased by 40 bytes, as xdp_buff::frame_sz includes everything from data_hard_start (-> includes xdpf already) to the end of XDP/skb shared info. Also update %MAX_PKT_SIZE accordingly in the selftests code. Leave it hardcoded for 64 bit && 4k pages, it can be made more flexible later on. Minor: align `&head->data` with how `head->frm` is assigned for consistency. Minor #2: rename 'frm' to 'frame' in &xdp_page_head while at it for clarity. (was found while testing XDP traffic generator on ice, which calls xdp_convert_frame_to_buff() for each XDP frame) Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN") Acked-by: Toke Høiland-Jørgensen Signed-off-by: Alexander Lobakin Link: https://lore.kernel.org/r/20230224163607.2994755-1-aleksander.lobakin@intel.com Signed-off-by: Martin KaFai Lau --- net/bpf/test_run.c | 19 +++++++++++++------ .../selftests/bpf/prog_tests/xdp_do_redirect.c | 7 ++++--- 2 files changed, 17 insertions(+), 9 deletions(-) (limited to 'net') diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 6f3d654b3339..f81b24320a36 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -97,8 +97,11 @@ reset: struct xdp_page_head { struct xdp_buff orig_ctx; struct xdp_buff ctx; - struct xdp_frame frm; - u8 data[]; + union { + /* ::data_hard_start starts here */ + DECLARE_FLEX_ARRAY(struct xdp_frame, frame); + DECLARE_FLEX_ARRAY(u8, data); + }; }; struct xdp_test_data { @@ -113,6 +116,10 @@ struct xdp_test_data { u32 frame_cnt; }; +/* tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c:%MAX_PKT_SIZE + * must be updated accordingly this gets changed, otherwise BPF selftests + * will fail. + */ #define TEST_XDP_FRAME_SIZE (PAGE_SIZE - sizeof(struct xdp_page_head)) #define TEST_XDP_MAX_BATCH 256 @@ -132,8 +139,8 @@ static void xdp_test_run_init_page(struct page *page, void *arg) headroom -= meta_len; new_ctx = &head->ctx; - frm = &head->frm; - data = &head->data; + frm = head->frame; + data = head->data; memcpy(data + headroom, orig_ctx->data_meta, frm_len); xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq); @@ -223,7 +230,7 @@ static void reset_ctx(struct xdp_page_head *head) head->ctx.data = head->orig_ctx.data; head->ctx.data_meta = head->orig_ctx.data_meta; head->ctx.data_end = head->orig_ctx.data_end; - xdp_update_frame_from_buff(&head->ctx, &head->frm); + xdp_update_frame_from_buff(&head->ctx, head->frame); } static int xdp_recv_frames(struct xdp_frame **frames, int nframes, @@ -285,7 +292,7 @@ static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog, head = phys_to_virt(page_to_phys(page)); reset_ctx(head); ctx = &head->ctx; - frm = &head->frm; + frm = head->frame; xdp->frame_cnt++; act = bpf_prog_run_xdp(prog, ctx); diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c index 2666c84dbd01..7271a18ab3e2 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c @@ -65,12 +65,13 @@ static int attach_tc_prog(struct bpf_tc_hook *hook, int fd) } /* The maximum permissible size is: PAGE_SIZE - sizeof(struct xdp_page_head) - - * sizeof(struct skb_shared_info) - XDP_PACKET_HEADROOM = 3368 bytes + * SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - XDP_PACKET_HEADROOM = + * 3408 bytes for 64-byte cacheline and 3216 for 256-byte one. */ #if defined(__s390x__) -#define MAX_PKT_SIZE 3176 +#define MAX_PKT_SIZE 3216 #else -#define MAX_PKT_SIZE 3368 +#define MAX_PKT_SIZE 3408 #endif static void test_max_pkt_size(int fd) { -- cgit v1.2.3