From nobody Wed Nov 27 21:39:35 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CFA521DC046; Tue, 8 Oct 2024 11:49:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728388197; cv=none; b=UOm3eZVVaHTJirSJg2vtaW6JUOr0q9vMYKDlr0NxYYlFg26FNSvCziauy7xhdLSgZrxyRKH6L44/bluoTLk5/FlDrBLVCId7G84DAnaSLiCI+2vCX+hNpZpfctdvylNzyvxjJoPpaBHc3hxxVK2pd6Xb5D9eZkSSaxjFLA6Gac0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728388197; c=relaxed/simple; bh=d+3xGC5kWs3uQkS1AdUBbn/V4ucQF3MN+94QVKIFWKI=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=XkxFnTY5zbWzJsPybhtJ1vwE+L6S74hxEOwgrz0k14gWmDSQTgsa9I40wADVbflg/TKQDnHTNtjZQVVXZt5k6Ic9kXo6Bn/vEkxgDyV0hhVtw5vUYl4TqpMrqluD5ScY9ZCBRa7kGCe4PGS9UDGc5TUbzUmYY6M5WAHNw5Al7ZI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ktSWF1iQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ktSWF1iQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A7CBC4CEC7; Tue, 8 Oct 2024 11:49:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728388197; bh=d+3xGC5kWs3uQkS1AdUBbn/V4ucQF3MN+94QVKIFWKI=; h=From:To:Subject:Date:In-Reply-To:References:From; b=ktSWF1iQqb9QUns8+W5nEFVixO8ixm17R8tETSHZ65wkPICLjUmnGZ46w+Y9sGCdq nrn4DYlMubXteJFksCdoYoCzTaUe8F+hzszHrzJgp2pIjcEJL8QGpCFvtz8ra0BH1q O6QHL07oB762YBXOiweuVUBO9XNgTc00aHoIOmihsy+ppUG4Am+G+GR9eJZW/JMMke n37Sxs9rW1sf9ohX6gbQTu9Ldeb/UbjwWORRMRw0qSQGbytF6mo6UUxju7IOKVTw0S lMfdZjBEPwA+mVlty5FtmCluZ6BJhZ1wrxwEh1stPrVDDTSvdS+uCfCvvRdYW5uaD3 Tm3bfRKhu6Y3A== From: Puranjay Mohan To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, puranjay12@gmail.com Subject: [PATCH bpf-next v4 1/2] bpf: implement bpf_send_signal_task() kfunc Date: Tue, 8 Oct 2024 11:49:39 +0000 Message-Id: <20241008114940.44305-2-puranjay@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20241008114940.44305-1-puranjay@kernel.org> References: <20241008114940.44305-1-puranjay@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Implement bpf_send_signal_task kfunc that is similar to bpf_send_signal_thread and bpf_send_signal helpers but can be used to send signals to other threads and processes. It also supports sending a cookie with the signal similar to sigqueue(). If the receiving process establishes a handler for the signal using the SA_SIGINFO flag to sigaction(), then it can obtain this cookie via the si_value field of the siginfo_t structure passed as the second argument to the handler. Signed-off-by: Puranjay Mohan Acked-by: Andrii Nakryiko --- kernel/bpf/helpers.c | 1 + kernel/trace/bpf_trace.c | 52 +++++++++++++++++++++++++++++++++------- 2 files changed, 45 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 4053f279ed4cc..2fd3feefb9d94 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3035,6 +3035,7 @@ BTF_ID_FLAGS(func, bpf_task_get_cgroup1, KF_ACQUIRE |= KF_RCU | KF_RET_NULL) #endif BTF_ID_FLAGS(func, bpf_task_from_pid, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_throw) +BTF_ID_FLAGS(func, bpf_send_signal_task, KF_TRUSTED_ARGS) BTF_KFUNCS_END(generic_btf_ids) =20 static const struct btf_kfunc_id_set generic_kfunc_set =3D { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a582cd25ca876..d9662e84510d3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -802,6 +802,8 @@ struct send_signal_irq_work { struct task_struct *task; u32 sig; enum pid_type type; + bool has_siginfo; + struct kernel_siginfo info; }; =20 static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work); @@ -809,27 +811,46 @@ static DEFINE_PER_CPU(struct send_signal_irq_work, se= nd_signal_work); static void do_bpf_send_signal(struct irq_work *entry) { struct send_signal_irq_work *work; + struct kernel_siginfo *siginfo; =20 work =3D container_of(entry, struct send_signal_irq_work, irq_work); - group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, work->type); + siginfo =3D work->has_siginfo ? &work->info : SEND_SIG_PRIV; + + group_send_sig_info(work->sig, siginfo, work->task, work->type); put_task_struct(work->task); } =20 -static int bpf_send_signal_common(u32 sig, enum pid_type type) +static int bpf_send_signal_common(u32 sig, enum pid_type type, struct task= _struct *task, u64 value) { struct send_signal_irq_work *work =3D NULL; + struct kernel_siginfo info; + struct kernel_siginfo *siginfo; + + if (!task) { + task =3D current; + siginfo =3D SEND_SIG_PRIV; + } else { + clear_siginfo(&info); + info.si_signo =3D sig; + info.si_errno =3D 0; + info.si_code =3D SI_KERNEL; + info.si_pid =3D 0; + info.si_uid =3D 0; + info.si_value.sival_ptr =3D (void *)(unsigned long)value; + siginfo =3D &info; + } =20 /* Similar to bpf_probe_write_user, task needs to be * in a sound condition and kernel memory access be * permitted in order to send signal to the current * task. */ - if (unlikely(current->flags & (PF_KTHREAD | PF_EXITING))) + if (unlikely(task->flags & (PF_KTHREAD | PF_EXITING))) return -EPERM; if (unlikely(!nmi_uaccess_okay())) return -EPERM; /* Task should not be pid=3D1 to avoid kernel panic. */ - if (unlikely(is_global_init(current))) + if (unlikely(is_global_init(task))) return -EPERM; =20 if (irqs_disabled()) { @@ -847,19 +868,21 @@ static int bpf_send_signal_common(u32 sig, enum pid_t= ype type) * to the irq_work. The current task may change when queued * irq works get executed. */ - work->task =3D get_task_struct(current); + work->task =3D get_task_struct(task); + work->has_siginfo =3D siginfo =3D=3D &info; + copy_siginfo(&work->info, &info); work->sig =3D sig; work->type =3D type; irq_work_queue(&work->irq_work); return 0; } =20 - return group_send_sig_info(sig, SEND_SIG_PRIV, current, type); + return group_send_sig_info(sig, siginfo, task, type); } =20 BPF_CALL_1(bpf_send_signal, u32, sig) { - return bpf_send_signal_common(sig, PIDTYPE_TGID); + return bpf_send_signal_common(sig, PIDTYPE_TGID, NULL, 0); } =20 static const struct bpf_func_proto bpf_send_signal_proto =3D { @@ -871,7 +894,7 @@ static const struct bpf_func_proto bpf_send_signal_prot= o =3D { =20 BPF_CALL_1(bpf_send_signal_thread, u32, sig) { - return bpf_send_signal_common(sig, PIDTYPE_PID); + return bpf_send_signal_common(sig, PIDTYPE_PID, NULL, 0); } =20 static const struct bpf_func_proto bpf_send_signal_thread_proto =3D { @@ -3484,3 +3507,16 @@ static int __init bpf_kprobe_multi_kfuncs_init(void) } =20 late_initcall(bpf_kprobe_multi_kfuncs_init); + +__bpf_kfunc_start_defs(); + +__bpf_kfunc int bpf_send_signal_task(struct task_struct *task, int sig, en= um pid_type type, + u64 value) +{ + if (type !=3D PIDTYPE_PID && type !=3D PIDTYPE_TGID) + return -EINVAL; + + return bpf_send_signal_common(sig, type, task, value); +} + +__bpf_kfunc_end_defs(); --=20 2.40.1