From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
David Howells <dhowells@redhat.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Matthew Garrett <mjg59@google.com>,
netdev@vger.kernel.org, Chun-Yi Lee <jlee@suse.com>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode
Date: Mon, 15 Jul 2019 12:59:40 -0700 [thread overview]
Message-ID: <20190715195946.223443-24-matthewgarrett@google.com> (raw)
In-Reply-To: <20190715195946.223443-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
bpf_read() and bpf_read_str() could potentially be abused to (eg) allow
private keys in kernel memory to be leaked. Disable them if the kernel
has been locked down in confidentiality mode.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: netdev@vger.kernel.org
cc: Chun-Yi Lee <jlee@suse.com>
cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
include/linux/security.h | 1 +
kernel/trace/bpf_trace.c | 10 ++++++++++
security/lockdown/lockdown.c | 1 +
3 files changed, 12 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index 987d8427f091..8dd1741a52cd 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -118,6 +118,7 @@ enum lockdown_reason {
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
LOCKDOWN_KPROBES,
+ LOCKDOWN_BPF_READ,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca1255d14576..605908da61c5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -142,7 +142,12 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret)
+ goto out;
+
ret = probe_kernel_read(dst, unsafe_ptr, size);
+out:
if (unlikely(ret < 0))
memset(dst, 0, size);
@@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret)
+ goto out;
+
/*
* The strncpy_from_unsafe() call will likely not fill the entire
* buffer, but that's okay in this circumstance as we're probing
@@ -579,6 +588,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
* is returned that can be used for bpf_perf_event_output() et al.
*/
ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
+out:
if (unlikely(ret < 0))
memset(dst, 0, size);
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index ccb3e9a2a47c..d14b89784412 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_KPROBES] = "use of kprobes",
+ [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.510.g264f2c817a-goog
next prev parent reply other threads:[~2019-07-15 20:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 19:59 [PATCH V35 00/29] Kernel lockdown functionality Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 01/29] security: Support early LSMs Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 10/29] hibernate: Disable when " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 12/29] x86: Lock down IO port " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-07-16 2:59 ` Dave Young
2019-07-16 20:34 ` Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-07-15 23:26 ` James Morris
2019-07-15 19:59 ` [PATCH V35 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 21/29] Lock down /proc/kcore Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-07-15 19:59 ` Matthew Garrett [this message]
2019-07-15 22:54 ` [PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is " Daniel Borkmann
2019-07-16 20:32 ` Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 24/29] Lock down perf when " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-07-15 23:17 ` James Morris
2019-07-15 19:59 ` [PATCH V35 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-07-16 23:14 ` Steven Rostedt
2019-07-16 23:22 ` Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-07-15 19:59 ` [PATCH V35 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
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