Messages in this thread | | | Subject | Re: [PATCH v19 6/8] PM: hibernate: disable when there are active secretmem users | From | David Hildenbrand <> | Date | Fri, 14 May 2021 11:27:11 +0200 |
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On 13.05.21 20:47, Mike Rapoport wrote: > 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 e617b4afcc62..21c3771e6a56 100644 > --- a/include/linux/secretmem.h > +++ b/include/linux/secretmem.h > @@ -30,6 +30,7 @@ static inline bool page_is_secretmem(struct page *page) > } > > bool vma_is_secretmem(struct vm_area_struct *vma); > +bool secretmem_active(void); > > #else > > @@ -43,6 +44,11 @@ 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 1ae50089adf1..7c2499e4de22 100644 > --- a/mm/secretmem.c > +++ b/mm/secretmem.c > @@ -40,6 +40,13 @@ module_param_named(enable, secretmem_enable, bool, 0400); > MODULE_PARM_DESC(secretmem_enable, > "Enable secretmem and memfd_secret(2) system call"); > > +static atomic_t secretmem_users; > + > +bool secretmem_active(void) > +{ > + return !!atomic_read(&secretmem_users); > +} > + > static vm_fault_t secretmem_fault(struct vm_fault *vmf) > { > struct address_space *mapping = vmf->vma->vm_file->f_mapping; > @@ -94,6 +101,12 @@ 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; > @@ -116,6 +129,7 @@ bool vma_is_secretmem(struct vm_area_struct *vma) > } > > static const struct file_operations secretmem_fops = { > + .release = secretmem_release, > .mmap = secretmem_mmap, > }; > > @@ -202,6 +216,7 @@ SYSCALL_DEFINE1(memfd_secret, unsigned int, flags) > file->f_flags |= O_LARGEFILE; > > fd_install(fd, file); > + atomic_inc(&secretmem_users); > return fd; > > err_put_fd: >
It looks a bit racy, but I guess we don't really care about these corner cases.
Acked-by: David Hildenbrand <david@redhat.com>
-- Thanks,
David / dhildenb
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