Re: [PATCH] Warn if MBR gap is small and user uses advanced modules

[Vladimir 'phcoder' Serbinenko]

On Wed, Mar 11, 2020 at 2:34 PM Daniel Kiper <address@hidden> wrote:
>
> Adding Michael, Mihai, Javier and Peter...
>
> Below you can find what more or less Vladimir and I agreed WRT small MBR
> gap. In general Vladimir convinced me to phase out small MBR gaps
> support gradually. This is first step in this journey. We think that we
> have to build some warnings into the code and extend documentation.
> Please chime in what you think about that...
>
> On Tue, Mar 10, 2020 at 01:23:10PM +0100, Vladimir 'phcoder' Serbinenko wrote:
> > Daniel, do you want to adjust the whitelist?
> >
> > We don't want to support small MBR gap in pair with anything but
> > the simplest config of biosdisk+part_msdos+simple filesystem. In this
> > path "simple filesystems" are all current filesystems except zfs and
> > btrfs
>
> Missing SOB...
>
> > ---
> >  grub-core/partmap/gpt.c     |  9 ++++++++-
> >  grub-core/partmap/msdos.c   |  7 ++++++-
> >  include/grub/partition.h    |  3 ++-
> >  include/grub/util/install.h |  7 +++++--
> >  util/grub-install-common.c  | 24 ++++++++++++++++++++++++
> >  util/grub-install.c         | 10 +++++++---
> >  util/grub-setup.c           |  2 +-
> >  util/setup.c                |  5 +++--
> >  8 files changed, 56 insertions(+), 11 deletions(-)
> >
> > diff --git a/grub-core/partmap/gpt.c b/grub-core/partmap/gpt.c
> > index 103f6796f..25a5a1934 100644
> > --- a/grub-core/partmap/gpt.c
> > +++ b/grub-core/partmap/gpt.c
> > @@ -25,6 +25,9 @@
> >  #include <grub/msdos_partition.h>
> >  #include <grub/gpt_partition.h>
> >  #include <grub/i18n.h>
> > +#ifdef GRUB_UTIL
> > +#include <grub/emu/misc.h>
> > +#endif
> >
> >  GRUB_MOD_LICENSE ("GPLv3+");
> >
> > @@ -169,7 +172,8 @@ static grub_err_t
> >  gpt_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
> >   unsigned int max_nsectors,
> >   grub_embed_type_t embed_type,
> > - grub_disk_addr_t **sectors)
> > + grub_disk_addr_t **sectors,
> > + int warn_short)
> >  {
> >    struct gpt_partition_map_embed_ctx ctx = {
> >      .start = 0,
> > @@ -191,6 +195,9 @@ gpt_partition_map_embed (struct grub_disk *disk,
> > unsigned int *nsectors,
> >          N_("this GPT partition label contains no BIOS Boot Partition;"
> >     " embedding won't be possible"));
> >
> > +  if (ctx.len < 450) {
>
> Could you define constant somewhere?
>
> Is it in sectors? Why 450? Should not it be 2048 if 1 MiB below?
Increased to 1900. So slighlty under 1MiB is accepted but not much
smaller. Made it a const
>
> ...and missing "&& warn_short" check...
It's intentional. On GPT we don't want BBP under 1MiB even if setup is simple.
>
> > +    grub_util_warn("Your BIOS Boot Partition is under 1 MiB, please
> > increase its size.");
> > +  }
> >    if (ctx.len < *nsectors)
>
> Could not we use this check somehow instead of adding new one?
No, it checks for different thing.
>
> >      return grub_error (GRUB_ERR_OUT_OF_RANGE,
> >          N_("your BIOS Boot Partition is too small;"
> > diff --git a/grub-core/partmap/msdos.c b/grub-core/partmap/msdos.c
> > index 7b8e45076..402bce050 100644
> > --- a/grub-core/partmap/msdos.c
> > +++ b/grub-core/partmap/msdos.c
> > @@ -236,7 +236,8 @@ static grub_err_t
> >  pc_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
> >   unsigned int max_nsectors,
> >   grub_embed_type_t embed_type,
> > - grub_disk_addr_t **sectors)
> > + grub_disk_addr_t **sectors,
> > + int warn_short)
> >  {
> >    grub_disk_addr_t end = ~0ULL;
> >    struct grub_msdos_partition_mbr mbr;
> > @@ -390,6 +391,10 @@ pc_partition_map_embed (struct grub_disk *disk,
> > unsigned int *nsectors,
> >        return GRUB_ERR_NONE;
> >      }
> >
> > +  if (end < 450 && warn_short) {
> > +    grub_util_warn("You have a short MBR gap and use advanced config.
> > Please increase post-MBR gap");
>
> Ditto?
Changed
>
> > +  }
> > +
> >    if (end <= 1)
> >      return grub_error (GRUB_ERR_FILE_NOT_FOUND,
> >          N_("this msdos-style partition label has no "
> > diff --git a/include/grub/partition.h b/include/grub/partition.h
> > index 7adb7ec6e..5697e28d5 100644
> > --- a/include/grub/partition.h
> > +++ b/include/grub/partition.h
> > @@ -55,7 +55,8 @@ struct grub_partition_map
> >    grub_err_t (*embed) (struct grub_disk *disk, unsigned int *nsectors,
> >          unsigned int max_nsectors,
> >          grub_embed_type_t embed_type,
> > -        grub_disk_addr_t **sectors);
> > +        grub_disk_addr_t **sectors,
> > +        int warn_short);
> >  #endif
> >  };
> >  typedef struct grub_partition_map *grub_partition_map_t;
> > diff --git a/include/grub/util/install.h b/include/grub/util/install.h
> > index 2631b1074..982115f57 100644
> > --- a/include/grub/util/install.h
> > +++ b/include/grub/util/install.h
> > @@ -193,13 +193,13 @@ grub_util_bios_setup (const char *dir,
> >         const char *boot_file, const char *core_file,
> >         const char *dest, int force,
> >         int fs_probe, int allow_floppy,
> > -       int add_rs_codes);
> > +       int add_rs_codes, int warn_short_mbr_gap);
> >  void
> >  grub_util_sparc_setup (const char *dir,
> >          const char *boot_file, const char *core_file,
> >          const char *dest, int force,
> >          int fs_probe, int allow_floppy,
> > -        int add_rs_codes);
> > +        int add_rs_codes, int warn_short_mbr_gap);
> >
> >  char *
> >  grub_install_get_image_targets_string (void);
> > @@ -265,4 +265,7 @@ grub_util_get_target_name (const struct
> > grub_install_image_target_desc *t);
> >  extern char *grub_install_copy_buffer;
> >  #define GRUB_INSTALL_COPY_BUFFER_SIZE 1048576
> >
> > +int
>
> extern int
>
> > +grub_install_is_short_mgrgap_supported(void);
> > +
> >  #endif
> > diff --git a/util/grub-install-common.c b/util/grub-install-common.c
> > index ca0ac612a..e4cff2871 100644
> > --- a/util/grub-install-common.c
> > +++ b/util/grub-install-common.c
> > @@ -234,6 +234,30 @@ char *grub_install_source_directory = NULL;
> >  char *grub_install_locale_directory = NULL;
> >  char *grub_install_themes_directory = NULL;
> >
> > +int
> > +grub_install_is_short_mgrgap_supported()
> > +{
> > +  int i, j;
> > +  static const char *whitelist[] =
> > +    {
> > +     "part_msdos", "biosdisk", "affs", "afs", "bfs", "archelp",
> > +     "cpio", "cpio_be", "newc", "odc", "ext2", "fat", "exfat",
> > +     "f2fs", "fshelp", "hfs", "hfsplus", "hfspluscomp",
> > +     "iso9660", "jfs", "minix", "minix2", "minix3", "minix_be",
> > +     "minix2_be", "minix2_be", "nilfs2", "ntfs", "ntfscomp",
> > +     "reiserfs", "romfs", "sfs", "squash4", "tar", "udf",
> > +     "ufs1", "ufs1_be", "ufs2", "xfs"
> > +    };
>
> The list LGTM...
>
> > +  for (i = 0; i < modules.n_entries; i++) {
> > +    for (j = 0; j < ARRAY_SIZE (whitelist); j++)
> > +      if (strcmp(modules.entries[i], whitelist[j]) == 0)
> > + break;
> > +    if (j == ARRAY_SIZE (whitelist))
> > +      return 0;
> > +  }
> > +  return 1;
> > +}
> > +
> >  void
> >  grub_install_push_module (const char *val)
> >  {
> > diff --git a/util/grub-install.c b/util/grub-install.c
> > index 8970b73aa..ba27657d9 100644
> > --- a/util/grub-install.c
> > +++ b/util/grub-install.c
> > @@ -1718,10 +1718,14 @@ main (int argc, char *argv[])
> >   install_device);
> >
> >   /*  Now perform the installation.  */
> > - if (install_bootsector)
> > + if (install_bootsector) {
> > +   int warn_short_mbr_gap = grub_install_is_short_mgrgap_supported();
> > +
> >     grub_util_bios_setup (platdir, "boot.img", "core.img",
> >   install_drive, force,
> > - fs_probe, allow_floppy, add_rs_codes);
> > + fs_probe, allow_floppy, add_rs_codes,
> > + warn_short_mbr_gap);
> > + }
> >   break;
> >        }
> >      case GRUB_INSTALL_PLATFORM_SPARC64_IEEE1275:
> > @@ -1748,7 +1752,7 @@ main (int argc, char *argv[])
> >     grub_util_sparc_setup (platdir, "boot.img", "core.img",
> >   install_drive, force,
> >   fs_probe, allow_floppy,
> > - 0 /* unused */ );
> > + 0 /* unused */, 0 /* unused */ );
> >   break;
> >        }
> >
> > diff --git a/util/grub-setup.c b/util/grub-setup.c
> > index 42b98ad3c..1783224dd 100644
> > --- a/util/grub-setup.c
> > +++ b/util/grub-setup.c
> > @@ -315,7 +315,7 @@ main (int argc, char *argv[])
> >      arguments.core_file ? : DEFAULT_CORE_FILE,
> >      dest_dev, arguments.force,
> >      arguments.fs_probe, arguments.allow_floppy,
> > -    arguments.add_rs_codes);
> > +    arguments.add_rs_codes, 0);
> >
> >    /* Free resources.  */
> >    grub_fini_all ();
> > diff --git a/util/setup.c b/util/setup.c
> > index 3be88aae1..da5f2c07f 100644
> > --- a/util/setup.c
> > +++ b/util/setup.c
> > @@ -254,7 +254,8 @@ SETUP (const char *dir,
> >         const char *boot_file, const char *core_file,
> >         const char *dest, int force,
> >         int fs_probe, int allow_floppy,
> > -       int add_rs_codes __attribute__ ((unused))) /* unused on sparc64 */
> > +       int add_rs_codes __attribute__ ((unused)), /* unused on sparc64 */
> > +       int warn_small)
> >  {
> >    char *core_path;
> >    char *boot_img, *core_img, *boot_path;
> > @@ -530,7 +531,7 @@ SETUP (const char *dir,
> >   GRUB_EMBED_PCBIOS, &sectors);
> >      else if (ctx.dest_partmap)
> >        err = ctx.dest_partmap->embed (dest_dev->disk, &nsec, maxsec,
> > -      GRUB_EMBED_PCBIOS, &sectors);
> > +      GRUB_EMBED_PCBIOS, &sectors, warn_small);
> >      else
> >        err = fs->fs_embed (dest_dev, &nsec, maxsec,
> >     GRUB_EMBED_PCBIOS, &sectors);
>
> ...plus some missing spaces in function names and other places...
>
> Additionally, please extend relevant doc section with explanation why we
> are doing that. And maybe with an schedule for phase out...
>
> Daniel



-- 
Regards
Vladimir 'phcoder' Serbinenko