45d4c5a623
* Mon Sep 07 2020 Fedora Kernel Team <kernel-team@fedoraproject.org> [5.9.0-0.rc4.4] - Merge ark-patches Resolves: rhbz# Signed-off-by: Justin M. Forbes <jforbes@fedoraproject.org>
123 lines
4.5 KiB
Diff
123 lines
4.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Eugene Syromiatnikov <esyr@redhat.com>
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Date: Thu, 14 Jun 2018 16:36:02 -0400
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Subject: [PATCH] bpf: set unprivileged_bpf_disabled to 1 by default, add a
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boot parameter
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Message-id: <133022c6c389ca16060bd20ef69199de0800200b.1528991396.git.esyr@redhat.com>
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Patchwork-id: 8250
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O-Subject: [kernel team] [RHEL8 PATCH v4 2/5] [bpf] bpf: set unprivileged_bpf_disabled to 1 by default, add a boot parameter
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Bugzilla: 1561171
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RH-Acked-by: Jiri Benc <jbenc@redhat.com>
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RH-Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
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This patch sets kernel.unprivileged_bpf_disabled sysctl knob to 1
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by default, and provides an ability (in a form of a boot-time parameter)
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to reset it to 0, as it is impossible to do so in runtime. Since
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unprivileged BPF is considered unsupported, it also taints the kernel.
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1561171
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Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=16716594
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Upstream: RHEL only. The patch (in a more generic form) has been
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proposed upstream[1] and subsequently rejected.
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[1] https://lkml.org/lkml/2018/5/21/344
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Upstream Status: RHEL only
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Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
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Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
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---
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.../admin-guide/kernel-parameters.txt | 8 +++++++
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include/linux/kernel.h | 2 +-
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kernel/bpf/syscall.c | 21 ++++++++++++++++++-
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kernel/panic.c | 2 +-
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4 files changed, 30 insertions(+), 3 deletions(-)
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diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
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index a1068742a6df..aba9439caec9 100644
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--- a/Documentation/admin-guide/kernel-parameters.txt
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+++ b/Documentation/admin-guide/kernel-parameters.txt
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@@ -5370,6 +5370,14 @@
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unknown_nmi_panic
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[X86] Cause panic on unknown NMI.
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+ unprivileged_bpf_disabled=
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+ Format: { "0" | "1" }
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+ Sets the initial value of
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+ kernel.unprivileged_bpf_disabled sysctl knob.
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+ 0 - unprivileged bpf() syscall access is enabled.
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+ 1 - unprivileged bpf() syscall access is disabled.
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+ Default value is 1.
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+
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usbcore.authorized_default=
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[USB] Default USB device authorization:
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(default -1 = authorized except for wireless USB,
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diff --git a/include/linux/kernel.h b/include/linux/kernel.h
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index f14f238dc36a..156d1e44d9f7 100644
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--- a/include/linux/kernel.h
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+++ b/include/linux/kernel.h
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@@ -617,7 +617,7 @@ extern enum system_states {
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#define TAINT_RESERVED28 28
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#define TAINT_RESERVED29 29
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#define TAINT_RESERVED30 30
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-#define TAINT_RESERVED31 31
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+#define TAINT_UNPRIVILEGED_BPF 31
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/* End of Red Hat-specific taint flags */
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#define TAINT_FLAGS_COUNT 32
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#define TAINT_FLAGS_MAX ((1UL << TAINT_FLAGS_COUNT) - 1)
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diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
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index b999e7ff2583..5e5ac50d9137 100644
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--- a/kernel/bpf/syscall.c
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+++ b/kernel/bpf/syscall.c
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@@ -24,6 +24,7 @@
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#include <linux/ctype.h>
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#include <linux/nospec.h>
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#include <linux/audit.h>
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+#include <linux/init.h>
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#include <uapi/linux/btf.h>
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#include <linux/pgtable.h>
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#include <linux/bpf_lsm.h>
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@@ -48,7 +49,25 @@ static DEFINE_SPINLOCK(map_idr_lock);
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static DEFINE_IDR(link_idr);
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static DEFINE_SPINLOCK(link_idr_lock);
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-int sysctl_unprivileged_bpf_disabled __read_mostly;
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+/* RHEL-only: default to 1 */
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+int sysctl_unprivileged_bpf_disabled __read_mostly = 1;
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+
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+static int __init unprivileged_bpf_setup(char *str)
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+{
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+ unsigned long disabled;
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+ if (!kstrtoul(str, 0, &disabled))
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+ sysctl_unprivileged_bpf_disabled = !!disabled;
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+
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+ if (!sysctl_unprivileged_bpf_disabled) {
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+ pr_warn("Unprivileged BPF has been enabled "
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+ "(unprivileged_bpf_disabled=0 has been supplied "
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+ "in boot parameters), tainting the kernel");
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+ add_taint(TAINT_UNPRIVILEGED_BPF, LOCKDEP_STILL_OK);
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+ }
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+
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+ return 1;
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+}
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+__setup("unprivileged_bpf_disabled=", unprivileged_bpf_setup);
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static const struct bpf_map_ops * const bpf_map_types[] = {
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#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
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diff --git a/kernel/panic.c b/kernel/panic.c
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index fe1d3decf61c..2c483bec82d6 100644
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--- a/kernel/panic.c
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+++ b/kernel/panic.c
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@@ -399,7 +399,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
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[ TAINT_RESERVED28 ] = { '?', '-', false },
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[ TAINT_RESERVED29 ] = { '?', '-', false },
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[ TAINT_RESERVED30 ] = { '?', '-', false },
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- [ TAINT_RESERVED31 ] = { '?', '-', false },
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+ [ TAINT_UNPRIVILEGED_BPF ] = { 'u', ' ', false },
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};
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/**
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--
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2.26.2
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