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- From e346414725a70e5c74ee87ca14e580c66f517666 Mon Sep 17 00:00:00 2001
- From: Alex Burmashev <alexander.burmashev@oracle.com>
- Date: Tue, 16 Feb 2021 11:12:12 +0100
- Subject: [PATCH] templates: Disable the os-prober by default
- The os-prober is enabled by default what may lead to potentially
- dangerous use cases and borderline opening attack vectors. This
- patch disables the os-prober, adds warning messages and updates
- GRUB_DISABLE_OS_PROBER configuration option documentation. This
- way we make it clear that the os-prober usage is not recommended.
- Simplistic nature of this change allows downstream vendors, who
- really want os-prober to be enabled out of the box in their
- relevant products, easily revert to it's old behavior.
- Reported-by: NyankoSec (<nyanko@10x.moe>, https://twitter.com/NyankoSec),
- working with SSD Secure Disclosure
- Signed-off-by: Alex Burmashev <alexander.burmashev@oracle.com>
- Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
- Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
- ---
- docs/grub.texi | 18 ++++++++++--------
- util/grub.d/30_os-prober.in | 5 ++++-
- 2 files changed, 14 insertions(+), 9 deletions(-)
- diff --git a/docs/grub.texi b/docs/grub.texi
- index e302797..45a9f80 100644
- --- a/docs/grub.texi
- +++ b/docs/grub.texi
- @@ -1481,10 +1481,13 @@ boot sequence. If you have problems, set this option to @samp{text} and
- GRUB will tell Linux to boot in normal text mode.
-
- @item GRUB_DISABLE_OS_PROBER
- -Normally, @command{grub-mkconfig} will try to use the external
- -@command{os-prober} program, if installed, to discover other operating
- -systems installed on the same system and generate appropriate menu entries
- -for them. Set this option to @samp{true} to disable this.
- +The @command{grub-mkconfig} has a feature to use the external
- +@command{os-prober} program to discover other operating systems installed on
- +the same machine and generate appropriate menu entries for them. It is disabled
- +by default since automatic and silent execution of @command{os-prober}, and
- +creating boot entries based on that data, is a potential attack vector. Set
- +this option to @samp{false} to enable this feature in the
- +@command{grub-mkconfig} command.
-
- @item GRUB_OS_PROBER_SKIP_LIST
- List of space-separated FS UUIDs of filesystems to be ignored from os-prober
- @@ -1812,10 +1815,9 @@ than zero; otherwise 0.
- @section Multi-boot manual config
-
- Currently autogenerating config files for multi-boot environments depends on
- -os-prober and has several shortcomings. While fixing it is scheduled for the
- -next release, meanwhile you can make use of the power of GRUB syntax and do it
- -yourself. A possible configuration is detailed here, feel free to adjust to your
- -needs.
- +os-prober and has several shortcomings. Due to that it is disabled by default.
- +It is advised to use the power of GRUB syntax and do it yourself. A possible
- +configuration is detailed here, feel free to adjust to your needs.
-
- First create a separate GRUB partition, big enough to hold GRUB. Some of the
- following entries show how to load OS installer images from this same partition,
- diff --git a/util/grub.d/30_os-prober.in b/util/grub.d/30_os-prober.in
- index 515a68c..99de043 100644
- --- a/util/grub.d/30_os-prober.in
- +++ b/util/grub.d/30_os-prober.in
- @@ -26,7 +26,8 @@ export TEXTDOMAINDIR="@localedir@"
-
- . "$pkgdatadir/grub-mkconfig_lib"
-
- -if [ "x${GRUB_DISABLE_OS_PROBER}" = "xtrue" ]; then
- +if [ "x${GRUB_DISABLE_OS_PROBER}" = "xfalse" ]; then
- + gettext_printf "os-prober will not be executed to detect other bootable partitions.\nSystems on them will not be added to the GRUB boot configuration.\nCheck GRUB_DISABLE_OS_PROBER documentation entry.\n"
- exit 0
- fi
-
- @@ -39,6 +40,8 @@ OSPROBED="`os-prober | tr ' ' '^' | paste -s -d ' '`"
- if [ -z "${OSPROBED}" ] ; then
- # empty os-prober output, nothing doing
- exit 0
- +else
- + grub_warn "$(gettext_printf "os-prober was executed to detect other bootable partitions.\nIt's output will be used to detect bootable binaries on them and create new boot entries.")"
- fi
-
- osx_entry() {
- --
- 2.14.2
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