From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-api@vger.kernel.org, luto@kernel.org,
Matthew Garrett <mjg59@srcf.ucam.org>,
Matthew Garrett <mjg59@google.com>,
Dave Young <dyoung@redhat.com>,
kexec@lists.infradead.org
Subject: [PATCH V32 04/27] kexec_load: Disable at runtime if the kernel is locked down
Date: Wed, 3 Apr 2019 17:32:26 -0700 [thread overview]
Message-ID: <20190404003249.14356-5-matthewgarrett@google.com> (raw)
In-Reply-To: <20190404003249.14356-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
The kexec_load() syscall permits the loading and execution of arbitrary
code in ring 0, which is something that lock-down is meant to prevent. It
makes sense to disable kexec_load() in this situation.
This does not affect kexec_file_load() syscall which can check for a
signature on the image to be booted.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Dave Young <dyoung@redhat.com>
cc: kexec@lists.infradead.org
---
kernel/kexec.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 68559808fdfa..57047acc9a36 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -207,6 +207,14 @@ static inline int kexec_load_check(unsigned long nr_segments,
if (result < 0)
return result;
+ /*
+ * kexec can be used to circumvent module loading restrictions, so
+ * prevent loading in that case
+ */
+ if (kernel_is_locked_down("kexec of unsigned images",
+ LOCKDOWN_INTEGRITY))
+ return -EPERM;
+
/*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
--
2.21.0.392.gf8f6787159e-goog
next prev parent reply other threads:[~2019-04-04 0:33 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-04 0:32 [PATCH V32 0/27] Lockdown patches for 5.2 Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-04-16 8:40 ` Andrew Donnellan
2019-04-18 6:38 ` Daniel Axtens
2019-04-18 19:35 ` Matthew Garrett
2019-04-29 0:06 ` Daniel Axtens
2019-04-29 4:54 ` Daniel Axtens
2019-04-30 5:15 ` Andrew Donnellan
2019-04-29 22:56 ` Matthew Garrett
2019-05-02 21:07 ` James Morris
2019-05-02 21:15 ` Matthew Garrett
2019-05-02 23:19 ` James Morris
2019-05-03 0:34 ` Andy Lutomirski
2019-04-04 0:32 ` [PATCH V32 02/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 03/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-04-04 0:32 ` Matthew Garrett [this message]
2019-04-04 0:32 ` [PATCH V32 05/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 06/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 07/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 08/27] hibernate: Disable when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 09/27] uswsusp: " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 10/27] PCI: Lock down BAR access " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 11/27] x86: Lock down IO port " Matthew Garrett
2019-04-04 7:49 ` Thomas Gleixner
2019-04-04 0:32 ` [PATCH V32 12/27] x86/msr: Restrict MSR " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 13/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 14/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 15/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 16/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 17/27] Lock down TIOCSSERIAL Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 18/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 19/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-04-04 1:33 ` Steven Rostedt
2019-04-04 7:47 ` Thomas Gleixner
2019-04-04 0:32 ` [PATCH V32 20/27] Lock down /proc/kcore Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 21/27] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 22/27] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-04-30 19:19 ` Jann Horn
2019-04-04 0:32 ` [PATCH V32 23/27] Lock down perf when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 24/27] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 25/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 27/27] tracefs: Restrict tracefs " Matthew Garrett
2019-04-04 13:39 ` Steven Rostedt
2019-04-04 20:09 ` Matthew Garrett
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