From: David Howells <dhowells@redhat.com> To: linux-kernel@vger.kernel.org Cc: matthew.garrett@nebula.com, linux-efi@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, gregkh@linuxfoundation.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org Subject: [PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down Date: Wed, 05 Apr 2017 18:10:41 +0100 [thread overview] Message-ID: <149141224171.31282.11926701357832474000.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <149141219387.31282.6648284836568938717.stgit@warthog.procyon.org.uk> From: Matthew Garrett <matthew.garrett@nebula.com> Allowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: David Howells <dhowells@redhat.com> --- drivers/char/mem.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
WARNING: multiple messages have this Message-ID (diff)
From: dhowells@redhat.com (David Howells) To: linux-security-module@vger.kernel.org Subject: [PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down Date: Wed, 05 Apr 2017 18:10:41 +0100 [thread overview] Message-ID: <149141224171.31282.11926701357832474000.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <149141219387.31282.6648284836568938717.stgit@warthog.procyon.org.uk> From: Matthew Garrett <matthew.garrett@nebula.com> Allowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: David Howells <dhowells@redhat.com> --- drivers/char/mem.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); -- 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@ http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2017-04-05 17:11 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-04-05 17:09 [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 17:09 ` David Howells 2017-04-05 17:10 ` [PATCH 01/24] efi: Add EFI_SECURE_BOOT bit David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` [PATCH 02/24] Add the ability to lock down access to the running kernel image David Howells 2017-04-05 17:10 ` David Howells 2017-04-06 8:44 ` James Morris 2017-04-06 8:44 ` James Morris 2017-04-06 8:44 ` James Morris 2017-04-06 10:43 ` David Howells 2017-04-06 10:43 ` David Howells 2017-04-06 21:55 ` James Morris 2017-04-06 21:55 ` James Morris 2017-04-06 21:55 ` James Morris 2017-04-05 17:10 ` [PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` David Howells [this message] 2017-04-05 17:10 ` [PATCH 05/24] Restrict /dev/mem and /dev/kmem when " David Howells 2017-04-05 17:10 ` [PATCH 06/24] Add a sysrq option to exit secure boot mode David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` [PATCH 07/24] kexec: Disable at runtime if the kernel is locked down David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:11 ` [PATCH 08/24] Copy secure_boot flag in boot params across kexec reboot David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` [PATCH 10/24] hibernate: Disable when the kernel is locked down David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` [PATCH 11/24] uswsusp: " David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` [PATCH 12/24] PCI: Lock down BAR access " David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:11 ` [PATCH 13/24] x86: Lock down IO port " David Howells 2017-04-05 17:11 ` David Howells 2017-04-05 17:12 ` [PATCH 14/24] x86: Restrict MSR " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:34 ` Kees Cook 2017-04-05 17:34 ` Kees Cook 2017-04-05 17:34 ` Kees Cook 2017-04-05 17:12 ` [PATCH 15/24] asus-wmi: Restrict debugfs interface " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` [PATCH 16/24] ACPI: Limit access to custom_method " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` [PATCH 18/24] acpi: Disable ACPI table override if the kernel is " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 17:12 ` [PATCH 19/24] acpi: Disable APEI error injection " David Howells 2017-04-05 17:12 ` David Howells 2017-04-05 19:57 ` [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 19:57 ` David Howells 2017-04-05 19:57 ` David Howells 2017-04-06 8:25 ` James Morris 2017-04-06 8:25 ` James Morris 2017-04-06 8:25 ` James Morris 2017-04-06 8:37 ` David Howells 2017-04-06 8:37 ` David Howells 2017-04-06 8:37 ` David Howells -- strict thread matches above, loose matches on Subject: below -- 2017-04-05 20:14 David Howells 2017-04-05 20:15 ` [PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down David Howells 2017-04-05 20:15 ` David Howells 2017-04-05 17:07 [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 17:07 ` [PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down David Howells 2017-04-05 17:07 ` David Howells 2017-04-05 17:07 ` David Howells
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