On Thu, May 13, 2021 at 09:47:32PM +0300, Mike Rapoport wrote: > From: Mike Rapoport <[email protected]> > > 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.
Have we thought about how this is going to work in practice, e.g. on mobile systems? It seems to me that there are a variety of common applications which might want to use this which people don't expect to inhibit hibernate (e.g. authentication agents, web browsers). Are we happy to say that any userspace application can incidentally inhibit hibernate? Thanks, Mark. > Signed-off-by: Mike Rapoport <[email protected]> > Cc: Alexander Viro <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Arnd Bergmann <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Christopher Lameter <[email protected]> > Cc: Dan Williams <[email protected]> > Cc: Dave Hansen <[email protected]> > Cc: David Hildenbrand <[email protected]> > Cc: Elena Reshetova <[email protected]> > Cc: Hagen Paul Pfeifer <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: James Bottomley <[email protected]> > Cc: "Kirill A. Shutemov" <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Matthew Wilcox <[email protected]> > Cc: Michael Kerrisk <[email protected]> > Cc: Palmer Dabbelt <[email protected]> > Cc: Palmer Dabbelt <[email protected]> > Cc: Paul Walmsley <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Rick Edgecombe <[email protected]> > Cc: Roman Gushchin <[email protected]> > Cc: Shakeel Butt <[email protected]> > Cc: Shuah Khan <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Tycho Andersen <[email protected]> > Cc: Will Deacon <[email protected]> > --- > 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: > -- > 2.28.0 > _______________________________________________ Linux-nvdimm mailing list -- [email protected] To unsubscribe send an email to [email protected]
