From: David Howells <dhowells@redhat.com> To: torvalds@linux-foundation.org Cc: linux-man@vger.kernel.org, linux-api@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org Subject: [PATCH 06/24] kexec_load: Disable at runtime if the kernel is locked down Date: Wed, 11 Apr 2018 17:25:18 +0100 [thread overview] Message-ID: <152346391877.4030.6270466586590461223.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> 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: Matthew Garrett <mjg59@srcf.ucam.org> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Dave Young <dyoung@redhat.com> Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> Reviewed-by: James Morris <james.l.morris@oracle.com> cc: kexec@lists.infradead.org --- kernel/kexec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index aed8fb2564b3..1553ac765e73 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -199,6 +199,13 @@ static inline int kexec_load_check(unsigned long nr_segments, if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; + /* + * kexec can be used to circumvent module loading restrictions, so + * prevent loading in that case + */ + if (kernel_is_locked_down("kexec of unsigned images")) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions.
WARNING: multiple messages have this Message-ID (diff)
From: dhowells@redhat.com (David Howells) To: linux-security-module@vger.kernel.org Subject: [PATCH 06/24] kexec_load: Disable at runtime if the kernel is locked down Date: Wed, 11 Apr 2018 17:25:18 +0100 [thread overview] Message-ID: <152346391877.4030.6270466586590461223.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> 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: Matthew Garrett <mjg59@srcf.ucam.org> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Dave Young <dyoung@redhat.com> Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> Reviewed-by: James Morris <james.l.morris@oracle.com> cc: kexec at lists.infradead.org --- kernel/kexec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index aed8fb2564b3..1553ac765e73 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -199,6 +199,13 @@ static inline int kexec_load_check(unsigned long nr_segments, if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; + /* + * kexec can be used to circumvent module loading restrictions, so + * prevent loading in that case + */ + if (kernel_is_locked_down("kexec of unsigned images")) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2018-04-11 16:25 UTC|newest] Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-11 16:24 [PATCH 00/24] security: Add kernel lockdown David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:24 ` [PATCH 01/24] Add the ability to lock down access to the running kernel image David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:44 ` Jann Horn 2018-04-11 16:44 ` Jann Horn 2018-04-11 17:37 ` Randy Dunlap 2018-04-11 17:37 ` Randy Dunlap 2018-04-11 18:50 ` Miguel Ojeda 2018-04-11 18:50 ` Miguel Ojeda 2018-04-11 19:56 ` Greg KH 2018-04-11 19:56 ` Greg KH 2018-04-11 17:49 ` David Howells 2018-04-11 17:49 ` David Howells 2018-04-11 18:09 ` Linus Torvalds 2018-04-11 18:09 ` Linus Torvalds 2018-04-11 18:35 ` Justin Forbes 2018-04-11 18:35 ` Justin Forbes 2018-04-11 21:05 ` Jordan Glover 2018-04-11 21:05 ` Jordan Glover 2018-04-11 22:38 ` Linus Torvalds 2018-04-11 22:38 ` Linus Torvalds 2018-04-12 13:09 ` Justin Forbes 2018-04-12 13:09 ` Justin Forbes 2018-04-12 16:52 ` Linus Torvalds 2018-04-12 16:52 ` Linus Torvalds 2018-04-12 2:57 ` Andy Lutomirski 2018-04-12 2:57 ` Andy Lutomirski 2018-04-11 16:24 ` [PATCH 02/24] Add a SysRq option to lift kernel lockdown David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 17:05 ` Jann Horn 2018-04-11 17:05 ` Jann Horn 2018-04-13 20:22 ` Pavel Machek 2018-04-11 16:24 ` [PATCH 03/24] ima: require secure_boot rules in lockdown mode David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:25 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 05/24] Restrict /dev/{mem, kmem, port} when " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` David Howells [this message] 2018-04-11 16:25 ` [PATCH 06/24] kexec_load: Disable at runtime if " David Howells 2018-04-11 19:00 ` Eric W. Biederman 2018-04-11 19:00 ` Eric W. Biederman 2018-04-11 20:09 ` Mimi Zohar 2018-04-11 20:09 ` Mimi Zohar 2018-04-12 11:38 ` Mimi Zohar 2018-04-12 11:38 ` Mimi Zohar 2018-04-11 20:05 ` David Howells 2018-04-11 20:05 ` David Howells 2018-04-11 20:05 ` David Howells 2018-04-11 16:25 ` [PATCH 07/24] hibernate: Disable when " David Howells 2018-04-11 16:25 ` David Howells 2018-04-13 20:22 ` Pavel Machek 2018-04-19 14:38 ` David Howells 2018-04-19 14:38 ` David Howells 2018-04-22 14:34 ` Andy Lutomirski 2018-04-22 14:34 ` Andy Lutomirski 2018-04-26 7:26 ` Pavel Machek 2018-04-26 7:34 ` Rafael J. Wysocki 2018-04-26 7:34 ` Rafael J. Wysocki 2018-04-26 8:20 ` Jiri Kosina 2018-04-26 8:20 ` Jiri Kosina 2018-05-23 8:46 ` joeyli 2018-05-23 8:46 ` joeyli 2018-04-11 16:25 ` [PATCH 08/24] uswsusp: " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 09/24] PCI: Lock down BAR access " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 10/24] x86: Lock down IO port " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 11/24] x86/msr: Restrict MSR " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 12/24] ACPI: Limit access to custom_method " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:26 ` [PATCH 13/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 14/24] acpi: Disable ACPI table override if the kernel is " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 15/24] acpi: Disable APEI error injection " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 16/24] Prohibit PCMCIA CIS storage when " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 17/24] Lock down TIOCSSERIAL David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 18/24] Lock down module params that specify hardware parameters (eg. ioport) David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 17:22 ` Randy Dunlap 2018-04-11 17:22 ` Randy Dunlap 2018-04-11 16:26 ` [PATCH 19/24] x86/mmiotrace: Lock down the testmmiotrace module David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 20/24] Lock down /proc/kcore David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 21/24] Lock down kprobes David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:27 ` [PATCH 22/24] bpf: Restrict kernel image access functions when the kernel is locked down David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 16:27 ` [PATCH 23/24] Lock down perf David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 16:27 ` [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 17:26 ` Randy Dunlap 2018-04-11 17:26 ` Randy Dunlap 2018-04-11 18:50 ` Eric W. Biederman 2018-04-11 18:50 ` Eric W. Biederman 2018-04-11 19:54 ` Greg KH 2018-04-11 19:54 ` Greg KH 2018-04-11 20:08 ` David Howells 2018-04-11 20:08 ` David Howells 2018-04-11 20:08 ` David Howells 2018-04-11 20:09 ` David Howells 2018-04-11 20:09 ` David Howells 2018-04-11 20:33 ` Greg KH 2018-04-11 20:33 ` Greg KH 2018-04-12 2:54 ` Andy Lutomirski 2018-04-12 2:54 ` Andy Lutomirski 2018-04-12 8:23 ` Greg KH 2018-04-12 8:23 ` Greg KH 2018-04-12 14:19 ` Andy Lutomirski 2018-04-12 14:19 ` Andy Lutomirski 2018-04-13 20:22 ` Pavel Machek 2018-04-19 14:35 ` David Howells 2018-04-19 14:35 ` David Howells 2018-05-10 11:01 ` Pavel Machek
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