From patchwork Mon Jun 24 12:05:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tengda Wu X-Patchwork-Id: 13709388 X-Patchwork-Delegate: bpf@iogearbox.net Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 BB9F92E636 for ; Mon, 24 Jun 2024 12:05:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719230762; cv=none; b=IuWW3k8VBE9pfZeg32we7QsksiVb7K1awiYvPvRzr4/Agu97RnLXPcZmlS8ur2rzsjZJ3yqQLKR8mNXkoT+AIfXrW11Avh6LBFnzaFyQTV83m69floh5gbLZTOVoRJzkbHP2bDLAtzW3ZoUZQWjPg0M0rmYrZ4fkNqYbHU0CiG0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719230762; c=relaxed/simple; bh=iUDwmWowhQhoH7chaD0uFNN+JzCY9oTr05sCOGN6gEg=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=RB63DmYjhlIcXDWTBOj6suVWGlbxV+g6LABpV3Vh2Y6bUqHhNqPtLlTPwZjRc1h11fLZF8hw3cLYSbUIx1d1FbncoMFl8p2JNZk/CIrD/PW5pHjXUHPAYA2kTo7Ij2Pk4Cr75iaWEQaMBmtcsqq7j/TUX589Hex51kaK20XHKa0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4W769W6q6bz4f3jHg for ; Mon, 24 Jun 2024 20:05:35 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id A19161A0187 for ; Mon, 24 Jun 2024 20:05:46 +0800 (CST) Received: from huawei.com (unknown [7.197.88.80]) by APP1 (Coremail) with SMTP id cCh0CgAHMHwTYXlmPpXPAA--.52351S2; Mon, 24 Jun 2024 20:05:45 +0800 (CST) From: Tengda Wu To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , hffilwlqm@gmail.com Subject: [PATCH bpf v2] bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT Date: Mon, 24 Jun 2024 20:05:33 +0800 Message-Id: <20240624120533.873789-1-wutengda@huaweicloud.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgAHMHwTYXlmPpXPAA--.52351S2 X-Coremail-Antispam: 1UD129KBjvJXoW3WryfXF1rGF45uFyfXw4Utwb_yoW7ZrW3pF yDGr15Gr4kJ3y7Z3ZrAw1j9r15AFnrAF15tr43tw1ruF15Wr4xGr4UWay3Ar1agFZ8Ja93 t3Wjgr1DKw1UAaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv0b4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1F6r1fM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkIecxE wVCI4VW5JwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F4 0E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFyl IxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxV AFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6rW3Jr0E3s1lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU8 rWrJUUUUU== X-CM-SenderInfo: pzxwv0hjgdqx5xdzvxpfor3voofrz/ X-Patchwork-Delegate: bpf@iogearbox.net When loading a EXT program without specifying `attr->attach_prog_fd`, the `prog->aux->dst_prog` will be null. At this time, calling resolve_prog_type() anywhere will result in a null pointer dereference. Example stack trace: [ 8.107863] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 [ 8.108262] Mem abort info: [ 8.108384] ESR = 0x0000000096000004 [ 8.108547] EC = 0x25: DABT (current EL), IL = 32 bits [ 8.108722] SET = 0, FnV = 0 [ 8.108827] EA = 0, S1PTW = 0 [ 8.108939] FSC = 0x04: level 0 translation fault [ 8.109102] Data abort info: [ 8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 8.109836] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101354000 [ 8.110011] [0000000000000004] pgd=0000000000000000, p4d=0000000000000000 [ 8.112624] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 8.112783] Modules linked in: [ 8.113120] CPU: 0 PID: 99 Comm: may_access_dire Not tainted 6.10.0-rc3-next-20240613-dirty #1 [ 8.113230] Hardware name: linux,dummy-virt (DT) [ 8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 8.113429] pc : may_access_direct_pkt_data+0x24/0xa0 [ 8.113746] lr : add_subprog_and_kfunc+0x634/0x8e8 [ 8.113798] sp : ffff80008283b9f0 [ 8.113813] x29: ffff80008283b9f0 x28: ffff800082795048 x27: 0000000000000001 [ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000 [ 8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000 [ 8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff [ 8.113929] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720 [ 8.113944] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720 [ 8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9 : ffff80008021f4e4 [ 8.113991] x8 : 0101010101010101 x7 : 746f72705f6d656d x6 : 000000001e0e0f5f [ 8.114006] x5 : 000000000001864f x4 : ffff0000c12b8000 x3 : 000000000000001c [ 8.114020] x2 : 0000000000000002 x1 : 0000000000000000 x0 : 0000000000000000 [ 8.114126] Call trace: [ 8.114159] may_access_direct_pkt_data+0x24/0xa0 [ 8.114202] bpf_check+0x3bc/0x28c0 [ 8.114214] bpf_prog_load+0x658/0xa58 [ 8.114227] __sys_bpf+0xc50/0x2250 [ 8.114240] __arm64_sys_bpf+0x28/0x40 [ 8.114254] invoke_syscall.constprop.0+0x54/0xf0 [ 8.114273] do_el0_svc+0x4c/0xd8 [ 8.114289] el0_svc+0x3c/0x140 [ 8.114305] el0t_64_sync_handler+0x134/0x150 [ 8.114331] el0t_64_sync+0x168/0x170 [ 8.114477] Code: 7100707f 54000081 f9401c00 f9403800 (b9400403) [ 8.118672] ---[ end trace 0000000000000000 ]--- Fix this by adding dst_prog non-empty check in BPF_PROG_TYPE_EXT case when calling bpf_prog_load(). Note the BPF_PROG_TYPE_EXT type detection in libbpf also needs to be adapted by passing a valid attach_prog_fd, since an empty attach_prog_fd is no longer allowed when loading EXT program. Fixes: 4a9c7bbe2ed4 ("bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT") Signed-off-by: Tengda Wu Cc: stable@vger.kernel.org # v5.18+ --- v2: Fix libbpf_probe_prog_types test failure reported by CI by adapting libbpf code. (thanks for jirka's reminder) v1: https://lore.kernel.org/all/20240620060701.1465291-1-wutengda@huaweicloud.com/ kernel/bpf/syscall.c | 5 ++++- tools/lib/bpf/libbpf_probes.c | 13 ++++++++++++- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index f45ed6adc092..4490f8ccf006 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2632,9 +2632,12 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type, return 0; return -EINVAL; case BPF_PROG_TYPE_SYSCALL: - case BPF_PROG_TYPE_EXT: if (expected_attach_type) return -EINVAL; + return 0; + case BPF_PROG_TYPE_EXT: + if (expected_attach_type || !dst_prog) + return -EINVAL; fallthrough; default: return 0; diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 9dfbe7750f56..37f87c824933 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -112,6 +112,7 @@ static int probe_prog_load(enum bpf_prog_type prog_type, int fd, err, exp_err = 0; const char *exp_msg = NULL; char buf[4096]; + int attach_prog_fd = -1; switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: @@ -148,9 +149,17 @@ static int probe_prog_load(enum bpf_prog_type prog_type, opts.log_size = sizeof(buf); opts.log_level = 1; opts.attach_btf_id = 1; + /* choose socket_filter as the target program to attach, since it + * is the earliest and most likely BPF program to be supported. + */ + attach_prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, + "GPL", insns, insns_cnt, NULL); + if (attach_prog_fd < 0) + return attach_prog_fd; + opts.attach_prog_fd = attach_prog_fd; exp_err = -EINVAL; - exp_msg = "Cannot replace kernel functions"; + exp_msg = "FENTRY/FEXIT program can only be attached to another program annotated with BTF"; break; case BPF_PROG_TYPE_SYSCALL: opts.prog_flags = BPF_F_SLEEPABLE; @@ -192,6 +201,8 @@ static int probe_prog_load(enum bpf_prog_type prog_type, err = -errno; if (fd >= 0) close(fd); + if (attach_prog_fd >= 0) + close(attach_prog_fd); if (exp_err) { if (fd >= 0 || err != exp_err) return 0;