Header size is needed to distinguish between header and the dump data.
Incorporate the addition of new argument (hsize) in the pstore write
callback.
Signed-off-by: NAruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Seiji reported getting empty dmesg-* files, because the data was never
actually read in efi_pstore_read_func(), and so the memcpy() was copying
garbage data.

This patch necessitated adding __efivar_entry_get() which is callable
between efivar_entry_iter_{begin,end}(). We can also delete
__efivar_entry_size() because efi_pstore_read_func() was the only
caller.
Reported-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Tested-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

We need to remove the entry from the EFI variable list before we erase
it from the variable store and free the associated state, otherwise it's
possible to hit the following crash,

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: [<ffffffff8142ea0f>] __efivar_entry_iter+0xcf/0x120
  PGD 19483f067 PUD 195426067 PMD 0
  Oops: 0000 [#1] SMP
  [...]
  Call Trace:
   [<ffffffff81430ebf>] efi_pstore_erase+0xef/0x140
   [<ffffffff81003138>] ? math_error+0x288/0x2d0
   [<ffffffff811ea491>] pstore_unlink+0x41/0x60
   [<ffffffff811741ff>] vfs_unlink+0x9f/0x110
   [<ffffffff8117813b>] do_unlinkat+0x18b/0x280
   [<ffffffff8116d7e6>] ? sys_newfstatat+0x36/0x50
   [<ffffffff81178472>] sys_unlinkat+0x22/0x40
   [<ffffffff81543282>] system_call_fastpath+0x16/0x1b
Reported-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Tested-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

Seiji reports hitting the following crash when erasing pstore dump
variables,

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000fa4
  IP: [<ffffffff8142dadf>] __efivar_entry_iter+0x2f/0x120
  PGD 18482a067 PUD 190724067 PMD 0
  Oops: 0000 [#1] SMP
  [...]
  Call Trace:
   [<ffffffff8143001f>] efi_pstore_erase+0xdf/0x130
   [<ffffffff81200038>] ? cap_socket_create+0x8/0x10
   [<ffffffff811ea491>] pstore_unlink+0x41/0x60
   [<ffffffff811741ff>] vfs_unlink+0x9f/0x110
   [<ffffffff8117813b>] do_unlinkat+0x18b/0x280
   [<ffffffff81178472>] sys_unlinkat+0x22/0x40
   [<ffffffff81542402>] system_call_fastpath+0x16/0x1b

'entry' needs to be initialised in efi_pstore_erase() when iterating
with __efivar_entry_iter(), otherwise the garbage pointer will be
dereferenced, leading to crashes like the above.
Reported-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Tested-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

efivars.c has grown far too large and needs to be divided up. Create a
new directory and move the persistence storage code to efi-pstore.c now
that it uses the new efivar API. This helps us to greatly reduce the
size of efivars.c and paves the way for moving other code out of
efivars.c.

Note that because CONFIG_EFI_VARS can be built as a module efi-pstore
must also include support for building as a module.
Reviewed-by: NTom Gundersen <teg@jklm.no>
Tested-by: NTom Gundersen <teg@jklm.no>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>