From nobody Thu Nov 28 00:32:50 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 6D41D1C878B; Mon, 7 Oct 2024 10:34:52 +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=1728297292; cv=none; b=NyKr7Hid/Mrc+R9uultufE79K/wSxbeDJAP4PZFcWb3M5Bu00ILjC6RBaK3kVEuo/S4phfcZJ1rgno4FHozJkkMqYu9Ttx9AcCLGw82evWi6/+2z7CrajP8TiMDb2w021V+ODRobir3Z1MvSHihEzUQSPizZmZq7e8TyWoTOZMQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728297292; c=relaxed/simple; bh=zLBswqHmt+tMJ0oWb6dIQHlYuJg5CCE1zs0HIuD9lzg=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=UHCBj9ObibVQR3vo4UMLXZFG60n0Ic45efH6jnJhw/kjF/MiBxXpCDyJ1qr7ixW3kaQyPE2q1Vf2FOmgBJpdKUkEe0HQDO7x3RF4DclD8gkHZ5NwJkc8zjQdYrNw4SUtEQ37ERlSyh7dvNEjhgFu661k4jiTIwwkhT8rO5nCKk0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hqHnNV93; 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="hqHnNV93" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7D57C4CECC; Mon, 7 Oct 2024 10:34:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728297292; bh=zLBswqHmt+tMJ0oWb6dIQHlYuJg5CCE1zs0HIuD9lzg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=hqHnNV932lUsJI/DfMjunFOdZOtGtaQ2jPIAUz8mZQvwYq8p3iR460aqJ190Qnx1k DCy1KH+hRdAv2d98yQ2qJhQZHrMabrrgPh+OSXbFRLRknigWGTv9N7yY5MIfNGfM1I khRa4T6+5oDwivtaQKyB58zGyw8DFy/XPo7Fir6mLTMvmxWgXRSNRCHoJHtJo6x1j8 hiorTdrb181D9Z6T6WpU3x6MbwD/xsE+5u/DtPCGUWaz2S5S0RNqjFRWcK2FuZvvVd /EAhGPHromJOyqT501nN01n+kc/E86tpfGbbcUKyrfeea+zH2dvD0QyEvCRaDX7yb0 5tTvcc8mxzshQ== 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 v3 1/2] bpf: implement bpf_send_signal_task() kfunc Date: Mon, 7 Oct 2024 10:34:25 +0000 Message-Id: <20241007103426.128923-2-puranjay@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20241007103426.128923-1-puranjay@kernel.org> References: <20241007103426.128923-1-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 --- kernel/bpf/helpers.c | 1 + kernel/trace/bpf_trace.c | 54 ++++++++++++++++++++++++++++++++++------ 2 files changed, 47 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..ae8c9fa8b04d1 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; + kernel_siginfo_t info; }; =20 static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work); @@ -811,25 +813,43 @@ static void do_bpf_send_signal(struct irq_work *entry) struct send_signal_irq_work *work; =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); + if (work->has_siginfo) + group_send_sig_info(work->sig, &work->info, work->task, work->type); + else + group_send_sig_info(work->sig, SEND_SIG_PRIV, 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 *tsk, u64 value) { struct send_signal_irq_work *work =3D NULL; + kernel_siginfo_t info; + bool has_siginfo =3D false; + + if (!tsk) { + tsk =3D current; + } else { + has_siginfo =3D true; + 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 *)value; + } =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(tsk->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(tsk))) return -EPERM; =20 if (irqs_disabled()) { @@ -847,19 +867,24 @@ 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(tsk); + work->has_siginfo =3D has_siginfo; + work->info =3D 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); + if (has_siginfo) + return group_send_sig_info(sig, &info, tsk, type); + + return group_send_sig_info(sig, SEND_SIG_PRIV, tsk, 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 +896,7 @@ 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 +3509,16 @@ 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