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 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 --- 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 3c6c037b3381..2de06446ebf9 100644 --- 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; @@ -186,6 +193,12 @@ 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; @@ -208,6 +221,7 @@ bool vma_is_secretmem(struct vm_area_struct *vma) }
static const struct file_operations secretmem_fops = { + .release = secretmem_release, .mmap = secretmem_mmap, };
@@ -323,6 +337,7 @@ 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: