PM: hibernate: disable when there are active secretmem users

It is unsafe to allow saving of secretmem areas to the hibernation snapshot
as they would be visible after the resume and this essentially will defeat
the purpose of secret memory mappings.

Prevent hibernation whenever there are active secret memory users.

Link: https://lkml.kernel.org/r/20201203062949.5484-9-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index 70e7db9f94fe26cab889bace3b319a2923b6c110..907a6734059c9714b1a5beefb4e138c49b27defa 100644 (file)
--- a/include/linux/secretmem.h
+++ b/include/linux/secretmem.h
@@ -6,6 +6,7 @@
 
 bool vma_is_secretmem(struct vm_area_struct *vma);
 bool page_is_secretmem(struct page *page);
+bool secretmem_active(void);
 
 #else
 
@@ -19,6 +20,11 @@ static inline bool page_is_secretmem(struct page *page)
        return false;
 }
 
+static inline bool secretmem_active(void)
+{
+       return false;
+}
+
 #endif /* CONFIG_SECRETMEM */
 
 #endif /* _LINUX_SECRETMEM_H */

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index da0b419141779960541d743b42b7269e77cc66bf..559acef3fddb8974348d19d3c2ad8a742b32a678 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -31,6 +31,7 @@
 #include <linux/genhd.h>
 #include <linux/ktime.h>
 #include <linux/security.h>
+#include <linux/secretmem.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -81,7 +82,9 @@ void hibernate_release(void)
 
 bool hibernation_available(void)
 {
-       return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
+       return nohibernate == 0 &&
+               !security_locked_down(LOCKDOWN_HIBERNATION) &&
+               !secretmem_active();
 }
 
 /**

diff --git a/mm/secretmem.c b/mm/secretmem.c
index 2390901d3ff77df1360301c769d8779a04686a8b..7236f4d9458ada910443c2f982642cd711a8040b 100644 (file)
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -45,6 +45,13 @@ struct secretmem_ctx {
 
 static struct cma *secretmem_cma;
 
+static atomic_t secretmem_users;
+
+bool secretmem_active(void)
+{
+       return !!atomic_read(&secretmem_users);
+}
+
 static int secretmem_account_pages(struct page *page, gfp_t gfp, int order)
 {
        int err;
@@ -179,6 +186,12 @@ static const struct vm_operations_struct secretmem_vm_ops = {
        .fault = secretmem_fault,
 };
 
+static int secretmem_release(struct inode *inode, struct file *file)
+{
+       atomic_dec(&secretmem_users);
+       return 0;
+}
+
 static int secretmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
        unsigned long len = vma->vm_end - vma->vm_start;
@@ -201,6 +214,7 @@ bool vma_is_secretmem(struct vm_area_struct *vma)
 }
 
 static const struct file_operations secretmem_fops = {
+       .release        = secretmem_release,
        .mmap           = secretmem_mmap,
 };
 
@@ -318,6 +332,7 @@ SYSCALL_DEFINE1(memfd_secret, unsigned long, flags)
        file->f_flags |= O_LARGEFILE;
 
        fd_install(fd, file);
+       atomic_inc(&secretmem_users);
        return fd;
 
 err_put_fd: