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From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christopher Lameter <cl@linux.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	David Hildenbrand <david@redhat.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	James Bottomley <jejb@linux.ibm.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Mike Rapoport <rppt@kernel.org>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Roman Gushchin <guro@fb.com>, Shuah Khan <shuah@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@k ernel.org>,
	linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
	x86@kernel.org
Subject: [PATCH v9 7/9] PM: hibernate: disable when there are active secretmem users
Date: Tue, 17 Nov 2020 18:29:30 +0200	[thread overview]
Message-ID: <20201117162932.13649-8-rppt@kernel.org> (raw)
In-Reply-To: <20201117162932.13649-1-rppt@kernel.org>

From: Mike Rapoport <rppt@linux.ibm.com>

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.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 include/linux/secretmem.h |  6 ++++++
 kernel/power/hibernate.c  |  5 ++++-
 mm/secretmem.c            | 15 +++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index 70e7db9f94fe..907a6734059c 100644
--- 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 da0b41914177..559acef3fddb 100644
--- 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 abf6ecdf70cb..14ef439841c9 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -51,6 +51,13 @@ 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;
@@ -185,6 +192,12 @@ 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)
 {
 	struct secretmem_ctx *ctx = file->private_data;
@@ -211,6 +224,7 @@ bool vma_is_secretmem(struct vm_area_struct *vma)
 }
 
 static const struct file_operations secretmem_fops = {
+	.release	= secretmem_release,
 	.mmap		= secretmem_mmap,
 };
 
@@ -328,6 +342,7 @@ 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:
-- 
2.28.0
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  parent reply	other threads:[~2020-11-17 16:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-17 16:29 [PATCH v9 0/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 1/9] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 2/9] mmap: make mlock_future_check() global Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 3/9] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 4/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 5/9] secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 6/9] secretmem: add memcg accounting Mike Rapoport
2020-11-17 19:33   ` Roman Gushchin
2020-11-17 20:02     ` Shakeel Butt
2020-11-18  6:55       ` Mike Rapoport
2020-11-17 16:29 ` Mike Rapoport [this message]
2020-11-17 16:29 ` [PATCH v9 8/9] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
2020-11-17 17:15   ` Catalin Marinas
2020-11-18  6:57     ` Mike Rapoport
2020-11-17 16:29 ` [PATCH v9 9/9] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport

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