From patchwork Thu Jul 25 00:32:50 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13741479 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15CE123CB for ; Thu, 25 Jul 2024 00:33:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721867595; cv=none; b=PreImbceFTkdGJqrSkN3P5KDjkqRapdCVnaavA9/MjJgodUPLhhrqiQEn98ZTnHOU6anMtcVXNRLuubX03TSSrKYVYqyr6eu4++CttezTUYeaI1lMmTEEzytlK1xpNrDISFwjWfwmfjhuWLYUPWMUPvDStd62cyWdgZ+GvFY9r8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721867595; c=relaxed/simple; bh=ZtLiyxSKMb5P4riIoAMXhNKy3CtATILLYQLu02n68MY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=kve+5xrjFeypbFdEeR/3BLkBMU7FcdO/x/YPSY2QY1KMxf4t8r9oYupGpO4Ow2QwtTk3RA9V37YYL1EhPbTqgveMWB/QWKjGh7oWYhfYs03GS8udk1bhKZmLyU0IQsAQWj7NvPl/zwFOqPiLCfcWZOfssAlPDVHZedwfLi0mcHg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nUkgrEYD; arc=none smtp.client-ip=91.218.175.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nUkgrEYD" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1721867590; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+ZYRxJYlTl5TcpclwDh+0QBzN9UK/ckcG5I/pF9JewU=; b=nUkgrEYDP/yc/TLFbdbyvjDqRYKcgpdUlPflr8Gz710gTU9uAlT6GGvuIIAcFBjvmimQww 5INNZ1p3G7btIDqcG95NoJaCmLfj2COFCRI4zn0jBM0cLhC5YdbeuhWsn3U6fx2PniCiAc nfTMWM01Q6DEQ00xAY2gRB1XCk/LCe0= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, wutengda@huaweicloud.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 1/2] bpf: Fix updating attached freplace prog to PROG_ARRAY map Date: Thu, 25 Jul 2024 08:32:50 +0800 Message-ID: <20240725003251.37855-2-leon.hwang@linux.dev> In-Reply-To: <20240725003251.37855-1-leon.hwang@linux.dev> References: <20240725003251.37855-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net The commit f7866c3587337731 ("bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT") fixed the following panic, which was caused by updating attached freplace prog to PROG_ARRAY map. But, it does not support updating attached freplace prog to PROG_ARRAY map. [309049.036402] BUG: kernel NULL pointer dereference, address: 0000000000000004 [309049.036419] #PF: supervisor read access in kernel mode [309049.036426] #PF: error_code(0x0000) - not-present page [309049.036432] PGD 0 P4D 0 [309049.036437] Oops: 0000 [#1] PREEMPT SMP NOPTI [309049.036444] CPU: 2 PID: 788148 Comm: test_progs Not tainted 6.8.0-31-generic #31-Ubuntu [309049.036465] Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023 [309049.036477] RIP: 0010:bpf_prog_map_compatible+0x2a/0x140 [309049.036488] Code: 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 49 89 fe 41 55 41 54 53 44 8b 6e 04 48 89 f3 41 83 fd 1c 75 0c 48 8b 46 38 48 8b 40 70 <44> 8b 68 04 f6 43 03 01 75 1c 48 8b 43 38 44 0f b6 a0 89 00 00 00 [309049.036505] RSP: 0018:ffffb2e080fd7ce0 EFLAGS: 00010246 [309049.036513] RAX: 0000000000000000 RBX: ffffb2e0807c1000 RCX: 0000000000000000 [309049.036521] RDX: 0000000000000000 RSI: ffffb2e0807c1000 RDI: ffff990290259e00 [309049.036528] RBP: ffffb2e080fd7d08 R08: 0000000000000000 R09: 0000000000000000 [309049.036536] R10: 0000000000000000 R11: 0000000000000000 R12: ffff990290259e00 [309049.036543] R13: 000000000000001c R14: ffff990290259e00 R15: ffff99028e29c400 [309049.036551] FS: 00007b82cbc28140(0000) GS:ffff9903b3f00000(0000) knlGS:0000000000000000 [309049.036559] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [309049.036566] CR2: 0000000000000004 CR3: 0000000101286002 CR4: 00000000003706f0 [309049.036573] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [309049.036581] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [309049.036588] Call Trace: [309049.036592] [309049.036597] ? show_regs+0x6d/0x80 [309049.036604] ? __die+0x24/0x80 [309049.036619] ? page_fault_oops+0x99/0x1b0 [309049.036628] ? do_user_addr_fault+0x2ee/0x6b0 [309049.036634] ? exc_page_fault+0x83/0x1b0 [309049.036641] ? asm_exc_page_fault+0x27/0x30 [309049.036649] ? bpf_prog_map_compatible+0x2a/0x140 [309049.036656] prog_fd_array_get_ptr+0x2c/0x70 [309049.036664] bpf_fd_array_map_update_elem+0x37/0x130 [309049.036671] bpf_map_update_value+0x1d3/0x260 [309049.036677] map_update_elem+0x1fa/0x360 [309049.036683] __sys_bpf+0x54c/0xa10 [309049.036689] __x64_sys_bpf+0x1a/0x30 [309049.036694] x64_sys_call+0x1936/0x25c0 [309049.036700] do_syscall_64+0x7f/0x180 [309049.036706] ? do_syscall_64+0x8c/0x180 [309049.036712] ? do_syscall_64+0x8c/0x180 [309049.036717] ? irqentry_exit+0x43/0x50 [309049.036723] ? common_interrupt+0x54/0xb0 [309049.036729] entry_SYSCALL_64_after_hwframe+0x73/0x7b Since commit 1c123c567fb138eb ("bpf: Resolve fext program type when checking map compatibility"), freplace prog can be used as tail-callee of its target prog. And the commit 3aac1ead5eb6b76f ("bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach") sets prog->aux->dst_prog as NULL when attach freplace prog to its target. Then, as for following example: tailcall_freplace.c: // SPDX-License-Identifier: GPL-2.0 \#include \#include \#include "bpf_legacy.h" struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); __uint(max_entries, 1); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } jmp_table SEC(".maps"); int count = 0; __noinline int subprog(struct __sk_buff *skb) { volatile int ret = 1; count++; bpf_tail_call_static(skb, &jmp_table, 0); return ret; } SEC("freplace") int entry(struct __sk_buff *skb) { return subprog(skb); } char __license[] SEC("license") = "GPL"; tc_bpf2bpf.c: // SPDX-License-Identifier: GPL-2.0 \#include \#include \#include "bpf_legacy.h" __noinline int subprog(struct __sk_buff *skb) { volatile int ret = 1; return ret; } SEC("tc") int entry(struct __sk_buff *skb) { return subprog(skb); } char __license[] SEC("license") = "GPL"; And freplace entry prog's target is the tc subprog. After loading, the freplace jmp_table's owner type is BPF_PROG_TYPE_SCHED_CLS. Next, after attaching freplace prog to tc subprog, its prog->aux-> dst_prog is NULL. Next, when update freplace prog to jmp_table, bpf_prog_map_compatible() returns false because resolve_prog_type() returns BPF_PROG_TYPE_EXT instead of BPF_PROG_TYPE_SCHED_CLS. With this patch, resolve_prog_type() returns BPF_PROG_TYPE_SCHED_CLS to support updating attached freplace prog to PROG_ARRY map for this example. Fixes: f7866c358733 ("bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT") Cc: Toke Høiland-Jørgensen Cc: Martin KaFai Lau Signed-off-by: Leon Hwang --- include/linux/bpf_verifier.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 5cea15c81b8a8..387e034e73d0e 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -874,8 +874,8 @@ static inline u32 type_flag(u32 type) /* only use after check_attach_btf_id() */ static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog) { - return (prog->type == BPF_PROG_TYPE_EXT && prog->aux->dst_prog) ? - prog->aux->dst_prog->type : prog->type; + return prog->type == BPF_PROG_TYPE_EXT ? + prog->aux->saved_dst_prog_type : prog->type; } static inline bool bpf_prog_check_recur(const struct bpf_prog *prog) From patchwork Thu Jul 25 00:32:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13741480 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AD811193 for ; Thu, 25 Jul 2024 00:33:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721867601; cv=none; b=tZQuu0U5PApgtrGykSG5RW1a/DXBAeo7OJKCu1bb8yAHapCmSrxvKKbr7vAhErk1MHQ4Xj+9M5uXE+7t3NfVsb6ptZp6xeNFhdh9V/Y3T3x13p+8HkZRpyF4axrXJv+f0LAyJEHsJS/7gaFC7kGId2E5zJ0P8bNT7B/dSvMl9jM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721867601; c=relaxed/simple; bh=E2VIj11pKoFdDYnJVTQbGx7YNios2qUz1J9z0VI2VLU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=S9W8gmQye3YLuOD52Z+6WqJHrXHO3rnLuwdys2ah+bJoHiLFbHOgz5XZl52I8NdXBr0PidZ1hQ7ZPtyIz/4yRazK9I2FA/VcQ9MMwf7VqZAPff2UKfRicEixgky1Ni9NhTZrsUSHNns3q89J9riPQkz9ukqo/JsIuJWhGkYlluY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=gqzAkxks; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="gqzAkxks" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1721867597; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WkSmsKt6HKmdu9ujaqGEMcW/QMInfbqNA1B/6UjAG1Q=; b=gqzAkxksB0pVzejrkMzlbM6BjCr77qFJ5Zar5IK6IUrJFvLh2pWfnQPGN4NpoNiCiiJg0q ttMe3NEtWJOLtCSwT1R5lK6Cx3H/1Lo1DtItT+ohf2fNIbF3RTQz73UbrdWgVoVIrIGS+l PWtwyCOP0PKcbRaEVuY5zLi68GJqX00= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, wutengda@huaweicloud.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 2/2] selftests/bpf: Add testcase for updating attached freplace prog to PROG_ARRAY map Date: Thu, 25 Jul 2024 08:32:51 +0800 Message-ID: <20240725003251.37855-3-leon.hwang@linux.dev> In-Reply-To: <20240725003251.37855-1-leon.hwang@linux.dev> References: <20240725003251.37855-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net Add a selftest to confirm the issue, which gets -EINVAL when update attached freplace prog to PROG_ARRAY map, has been fixed. cd tools/testing/selftests/bpf; ./test_progs -t tailcalls 327/25 tailcalls/tailcall_freplace:OK 327 tailcalls:OK Summary: 1/25 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Leon Hwang --- .../selftests/bpf/prog_tests/tailcalls.c | 76 ++++++++++++++++++- .../selftests/bpf/progs/tailcall_freplace.c | 33 ++++++++ .../testing/selftests/bpf/progs/tc_bpf2bpf.c | 23 ++++++ 3 files changed, 131 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/progs/tailcall_freplace.c create mode 100644 tools/testing/selftests/bpf/progs/tc_bpf2bpf.c diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c index e01fabb8cc415..f1145601c0005 100644 --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c @@ -5,7 +5,8 @@ #include "tailcall_poke.skel.h" #include "tailcall_bpf2bpf_hierarchy2.skel.h" #include "tailcall_bpf2bpf_hierarchy3.skel.h" - +#include "tailcall_freplace.skel.h" +#include "tc_bpf2bpf.skel.h" /* test_tailcall_1 checks basic functionality by patching multiple locations * in a single program for a single tail call slot with nop->jmp, jmp->nop @@ -1495,6 +1496,77 @@ static void test_tailcall_bpf2bpf_hierarchy_3(void) RUN_TESTS(tailcall_bpf2bpf_hierarchy3); } +/* test_tailcall_freplace checks that the attached freplace prog is OK to + * update to PROG_ARRAY map. + */ +static void test_tailcall_freplace(void) +{ + struct tailcall_freplace *fr_skel = NULL; + struct tc_bpf2bpf *tc_skel = NULL; + struct bpf_link *fr_link = NULL; + int prog_fd, map_fd; + char buff[128] = {}; + int err, key; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .data_in = buff, + .data_size_in = sizeof(buff), + .repeat = 1, + ); + + fr_skel = tailcall_freplace__open(); + if (!ASSERT_OK_PTR(fr_skel, "open fr_skel")) + goto out; + + tc_skel = tc_bpf2bpf__open_and_load(); + if (!ASSERT_OK_PTR(tc_skel, "open tc_skel")) + goto out; + + prog_fd = bpf_program__fd(tc_skel->progs.entry); + if (!ASSERT_GE(prog_fd, 0, "tc_skel entry prog_id")) + goto out; + + err = bpf_program__set_attach_target(fr_skel->progs.entry, + prog_fd, "subprog"); + if (!ASSERT_OK(err, "set_attach_target")) + goto out; + + err = tailcall_freplace__load(fr_skel); + if (!ASSERT_OK(err, "load fr_skel")) + goto out; + + fr_link = bpf_program__attach_freplace(fr_skel->progs.entry, + prog_fd, "subprog"); + if (!ASSERT_OK_PTR(fr_link, "attach_freplace")) + goto out; + + prog_fd = bpf_program__fd(fr_skel->progs.entry); + if (!ASSERT_GE(prog_fd, 0, "fr_skel entry prog_fd")) + goto out; + + map_fd = bpf_map__fd(fr_skel->maps.jmp_table); + if (!ASSERT_GE(map_fd, 0, "fr_skel jmp_table map_fd")) + goto out; + + key = 0; + err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY); + if (!ASSERT_OK(err, "update jmp_table")) + goto out; + + prog_fd = bpf_program__fd(tc_skel->progs.entry); + if (!ASSERT_GE(prog_fd, 0, "prog_fd")) + goto out; + + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "test_run"); + ASSERT_EQ(topts.retval, 34, "test_run retval"); + +out: + bpf_link__destroy(fr_link); + tc_bpf2bpf__destroy(tc_skel); + tailcall_freplace__destroy(fr_skel); +} + void test_tailcalls(void) { if (test__start_subtest("tailcall_1")) @@ -1543,4 +1615,6 @@ void test_tailcalls(void) test_tailcall_bpf2bpf_hierarchy_fentry_entry(); test_tailcall_bpf2bpf_hierarchy_2(); test_tailcall_bpf2bpf_hierarchy_3(); + if (test__start_subtest("tailcall_freplace")) + test_tailcall_freplace(); } diff --git a/tools/testing/selftests/bpf/progs/tailcall_freplace.c b/tools/testing/selftests/bpf/progs/tailcall_freplace.c new file mode 100644 index 0000000000000..80b5fa386ed9c --- /dev/null +++ b/tools/testing/selftests/bpf/progs/tailcall_freplace.c @@ -0,0 +1,33 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include "bpf_legacy.h" + +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(max_entries, 1); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u32)); +} jmp_table SEC(".maps"); + +int count = 0; + +__noinline +int subprog(struct __sk_buff *skb) +{ + count++; + + bpf_tail_call_static(skb, &jmp_table, 0); + + return count; +} + +SEC("freplace") +int entry(struct __sk_buff *skb) +{ + return subprog(skb); +} + +char __license[] SEC("license") = "GPL"; + diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c new file mode 100644 index 0000000000000..4810961554585 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include "bpf_legacy.h" + +__noinline +int subprog(struct __sk_buff *skb) +{ + volatile int ret = 1; + + asm volatile (""::"r+"(ret)); + return ret; +} + +SEC("tc") +int entry(struct __sk_buff *skb) +{ + return subprog(skb); +} + +char __license[] SEC("license") = "GPL"; +