From: David Howells <dhowells@redhat.com> To: linux-security-module@vger.kernel.org Cc: gnomes@lxorguk.ukuu.org.uk, linux-efi@vger.kernel.org, dhowells@redhat.com, linux-kernel@vger.kernel.org, jforbes@redhat.com Subject: [PATCH 13/30] x86/msr: Restrict MSR access when the kernel is locked down Date: Thu, 9 Nov 2017 17:32:15 +0000 [thread overview] Message-ID: <151024873510.28329.5219612113295367113.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <151024863544.28329.2436580122759221600.stgit@warthog.procyon.org.uk> From: Matthew Garrett <matthew.garrett@nebula.com> Writing to MSRs should not be allowed if the kernel is locked down, since it could lead to execution of arbitrary code in kernel mode. Based on a patch by Kees Cook. MSR accesses are logged for the purposes of building up a whitelist as per Alan Cox's suggestion. Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> cc: x86@kernel.org --- arch/x86/kernel/msr.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index ef688804f80d..dfb61d358196 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -84,6 +84,11 @@ static ssize_t msr_write(struct file *file, const char __user *buf, int err = 0; ssize_t bytes = 0; + if (kernel_is_locked_down("Direct MSR access")) { + pr_info("Direct access to MSR %x\n", reg); + return -EPERM; + } + if (count % 8) return -EINVAL; /* Invalid chunk size */ @@ -135,6 +140,11 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) err = -EFAULT; break; } + if (kernel_is_locked_down("Direct MSR access")) { + pr_info("Direct access to MSR %x\n", regs[1]); /* Display %ecx */ + err = -EPERM; + break; + } err = wrmsr_safe_regs_on_cpu(cpu, regs); if (err) break;
WARNING: multiple messages have this Message-ID (diff)
From: dhowells@redhat.com (David Howells) To: linux-security-module@vger.kernel.org Subject: [PATCH 13/30] x86/msr: Restrict MSR access when the kernel is locked down Date: Thu, 9 Nov 2017 17:32:15 +0000 [thread overview] Message-ID: <151024873510.28329.5219612113295367113.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <151024863544.28329.2436580122759221600.stgit@warthog.procyon.org.uk> From: Matthew Garrett <matthew.garrett@nebula.com> Writing to MSRs should not be allowed if the kernel is locked down, since it could lead to execution of arbitrary code in kernel mode. Based on a patch by Kees Cook. MSR accesses are logged for the purposes of building up a whitelist as per Alan Cox's suggestion. Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> cc: x86 at kernel.org --- arch/x86/kernel/msr.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index ef688804f80d..dfb61d358196 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -84,6 +84,11 @@ static ssize_t msr_write(struct file *file, const char __user *buf, int err = 0; ssize_t bytes = 0; + if (kernel_is_locked_down("Direct MSR access")) { + pr_info("Direct access to MSR %x\n", reg); + return -EPERM; + } + if (count % 8) return -EINVAL; /* Invalid chunk size */ @@ -135,6 +140,11 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) err = -EFAULT; break; } + if (kernel_is_locked_down("Direct MSR access")) { + pr_info("Direct access to MSR %x\n", regs[1]); /* Display %ecx */ + err = -EPERM; + break; + } err = wrmsr_safe_regs_on_cpu(cpu, regs); if (err) break; -- 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:[~2017-11-09 17:32 UTC|newest] Thread overview: 130+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-09 17:30 [PATCH 00/30] security, efi: Add kernel lockdown David Howells 2017-11-09 17:30 ` David Howells 2017-11-09 17:30 ` [PATCH 01/30] Add the ability to lock down access to the running kernel image David Howells 2017-11-09 17:30 ` David Howells 2017-11-09 17:30 ` [PATCH 02/30] Add a SysRq option to lift kernel lockdown David Howells 2017-11-09 17:30 ` David Howells 2017-11-09 17:30 ` David Howells 2017-11-09 17:31 ` [PATCH 03/30] ima: require secure_boot rules in lockdown mode David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 04/30] Enforce module signatures if the kernel is locked down David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 05/30] Restrict /dev/{mem, kmem, port} when " David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 06/30] kexec: Disable at runtime if " David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 07/30] Copy secure_boot flag in boot params across kexec reboot David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 08/30] kexec_file: Restrict at runtime if the kernel is locked down David Howells 2017-11-09 17:31 ` David Howells 2018-01-11 11:59 ` Jiri Bohac 2018-01-11 11:59 ` Jiri Bohac 2018-01-11 11:59 ` Jiri Bohac 2018-01-11 12:01 ` [PATCH 08a/30] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Jiri Bohac 2018-01-11 12:01 ` Jiri Bohac 2018-01-11 12:01 ` Jiri Bohac 2018-01-11 12:02 ` [PATCH 08b/30] kexec_file: Restrict at runtime if the kernel is locked down Jiri Bohac 2018-01-11 12:02 ` Jiri Bohac 2018-01-16 16:31 ` [PATCH 08a/30] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE David Howells 2018-01-16 16:31 ` David Howells 2018-01-16 16:31 ` David Howells 2018-01-16 19:39 ` Jiri Bohac 2018-01-16 19:39 ` Jiri Bohac 2018-01-17 16:34 ` David Howells 2018-01-17 16:34 ` David Howells 2018-01-19 12:54 ` Jiri Bohac 2018-01-19 12:54 ` Jiri Bohac 2018-01-19 12:54 ` Jiri Bohac 2018-02-21 16:20 ` David Howells 2018-02-21 16:20 ` David Howells 2018-01-11 12:43 ` [PATCH 08/30] kexec_file: Restrict at runtime if the kernel is locked down David Howells 2018-01-11 12:43 ` David Howells 2018-01-11 12:43 ` David Howells 2018-01-11 12:47 ` David Howells 2018-01-11 12:47 ` David Howells 2018-01-11 15:44 ` Jiri Bohac 2018-01-11 15:44 ` Jiri Bohac 2018-01-11 15:44 ` Jiri Bohac 2018-01-17 16:16 ` David Howells 2018-01-17 16:16 ` David Howells 2018-01-17 16:16 ` David Howells 2017-11-09 17:31 ` [PATCH 09/30] hibernate: Disable when " David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:31 ` [PATCH 10/30] uswsusp: " David Howells 2017-11-09 17:31 ` David Howells 2017-11-09 17:32 ` [PATCH 11/30] PCI: Lock down BAR access " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` [PATCH 12/30] x86: Lock down IO port " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` David Howells [this message] 2017-11-09 17:32 ` [PATCH 13/30] x86/msr: Restrict MSR " David Howells 2017-11-09 17:32 ` [PATCH 14/30] asus-wmi: Restrict debugfs interface " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` [PATCH 15/30] ACPI: Limit access to custom_method " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` [PATCH 16/30] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` [PATCH 17/30] acpi: Disable ACPI table override if the kernel is " David Howells 2017-11-09 17:32 ` David Howells 2017-11-09 17:32 ` [PATCH 18/30] acpi: Disable APEI error injection " David Howells 2017-11-09 17:32 ` David Howells 2019-11-07 8:21 ` Joey Lee 2022-05-28 0:11 ` joeyli 2017-11-09 17:33 ` [PATCH 19/30] scsi: Lock down the eata driver David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 20/30] Prohibit PCMCIA CIS storage when the kernel is locked down David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 21/30] Lock down TIOCSSERIAL David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 22/30] Lock down module params that specify hardware parameters (eg. ioport) David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 23/30] x86/mmiotrace: Lock down the testmmiotrace module David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 24/30] debugfs: Disallow use of debugfs files when the kernel is locked down David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 25/30] Lock down /proc/kcore David Howells 2017-11-09 17:33 ` David Howells 2017-11-09 17:33 ` [PATCH 26/30] Lock down ftrace David Howells 2017-11-09 17:33 ` David Howells 2017-11-10 9:23 ` Jiri Kosina 2017-11-10 9:23 ` Jiri Kosina 2017-11-10 9:23 ` Jiri Kosina 2017-11-10 10:07 ` David Howells 2017-11-10 10:07 ` David Howells 2017-11-10 10:07 ` David Howells 2017-11-10 10:15 ` Jiri Kosina 2017-11-10 10:15 ` Jiri Kosina 2017-11-10 10:15 ` Jiri Kosina 2017-11-10 10:21 ` David Howells 2017-11-10 10:21 ` David Howells 2017-11-10 10:21 ` David Howells 2017-11-10 10:23 ` Jiri Kosina 2017-11-10 10:23 ` Jiri Kosina 2017-11-10 11:06 ` David Howells 2017-11-10 11:06 ` David Howells 2017-11-10 11:06 ` David Howells 2017-11-09 17:34 ` [PATCH 27/30] Lock down kprobes David Howells 2017-11-09 17:34 ` David Howells 2017-11-09 17:34 ` [PATCH 28/30] bpf: Restrict kernel image access functions when the kernel is locked down David Howells 2017-11-09 17:34 ` David Howells 2017-11-09 17:34 ` [PATCH 29/30] efi: Add an EFI_SECURE_BOOT flag to indicate secure boot mode David Howells 2017-11-09 17:34 ` David Howells 2017-11-09 17:34 ` [PATCH 30/30] efi: Lock down the kernel if booted in " David Howells 2017-11-09 17:34 ` David Howells 2017-11-09 17:34 ` David Howells 2018-02-22 13:07 ` [PATCH 04/30] Enforce module signatures if the kernel is locked down David Howells 2018-02-22 13:07 ` David Howells 2018-02-22 18:44 ` Jiri Bohac 2018-02-22 18:44 ` Jiri Bohac 2018-02-22 14:20 ` [PATCH 08/30] kexec_file: Restrict at runtime " David Howells 2018-02-22 14:20 ` David Howells 2018-02-22 19:08 ` Jiri Bohac 2018-02-22 19:08 ` Jiri Bohac 2018-02-22 14:21 ` David Howells 2018-02-22 14:21 ` David Howells 2018-02-22 19:14 ` Jiri Bohac 2018-02-22 19:14 ` Jiri Bohac 2018-03-03 1:18 ` [PATCH 00/30] security, efi: Add kernel lockdown Andrew Morton 2018-03-03 1:18 ` Andrew Morton
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