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0001-cli_lock-Add-build-option-to-block-command...
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File 0001-cli_lock-Add-build-option-to-block-command-line-inte.patch of Package grub2
From c7dd3dd296592fef6166170121b54aafe634369f Mon Sep 17 00:00:00 2001 From: Alec Brown <alec.r.brown@oracle.com> Date: Wed, 24 Jan 2024 06:26:37 +0000 Subject: [PATCH 1/2] cli_lock: Add build option to block command line interface Add functionality to disable command line interface access and editing of GRUB menu entries if GRUB image is built with --disable-cli. Signed-off-by: Alec Brown <alec.r.brown@oracle.com> Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> --- docs/grub.texi | 6 ++++-- grub-core/kern/main.c | 28 ++++++++++++++++++++++++++++ grub-core/kern/rescue_reader.c | 13 +++++++++++++ grub-core/normal/auth.c | 3 +++ grub-core/normal/menu_text.c | 31 +++++++++++++++++-------------- include/grub/kernel.h | 3 ++- include/grub/misc.h | 2 ++ include/grub/util/install.h | 8 ++++++-- util/grub-install-common.c | 11 ++++++++--- util/grub-mkimage.c | 9 ++++++++- util/mkimage.c | 16 +++++++++++++++- 11 files changed, 106 insertions(+), 24 deletions(-) diff --git a/docs/grub.texi b/docs/grub.texi index 00c5fdc44..e89007920 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -6523,8 +6523,10 @@ the GRUB command line, edit menu entries, and execute any menu entry. If @samp{superusers} is set, then use of the command line and editing of menu entries are automatically restricted to superusers. Setting @samp{superusers} to empty string effectively disables both access to CLI and editing of menu -entries. Note: The environment variable needs to be exported to also affect -the section defined by the @samp{submenu} command (@pxref{submenu}). +entries. Building a grub image with @samp{--disable-cli} option will also +disable access to CLI and editing of menu entries, as well as disabling rescue +mode. Note: The environment variable needs to be exported to also affect the +section defined by the @samp{submenu} command (@pxref{submenu}). Other users may be allowed to execute specific menu entries by giving a list of usernames (as above) using the @option{--users} option to the diff --git a/grub-core/kern/main.c b/grub-core/kern/main.c index 02df49206..07b6940d2 100644 --- a/grub-core/kern/main.c +++ b/grub-core/kern/main.c @@ -30,11 +30,14 @@ #include <grub/reader.h> #include <grub/parser.h> #include <grub/verify.h> +#include <grub/types.h> #ifdef GRUB_MACHINE_PCBIOS #include <grub/machine/memory.h> #endif +static bool cli_disabled = false; + grub_addr_t grub_modules_get_end (void) { @@ -237,6 +240,28 @@ grub_load_normal_mode (void) grub_command_execute ("normal", 0, 0); } +bool +grub_is_cli_disabled (void) +{ + return cli_disabled; +} + +static void +check_is_cli_disabled (void) +{ + struct grub_module_header *header; + header = 0; + + FOR_MODULES (header) + { + if (header->type == OBJ_TYPE_DISABLE_CLI) + { + cli_disabled = true; + return; + } + } +} + static void reclaim_module_space (void) { @@ -294,6 +319,9 @@ grub_main (void) grub_boot_time ("After loading embedded modules."); + /* Check if the CLI should be disabled */ + check_is_cli_disabled (); + /* It is better to set the root device as soon as possible, for convenience. */ grub_set_prefix_and_root (); diff --git a/grub-core/kern/rescue_reader.c b/grub-core/kern/rescue_reader.c index dcd7d4439..4259857ba 100644 --- a/grub-core/kern/rescue_reader.c +++ b/grub-core/kern/rescue_reader.c @@ -78,6 +78,19 @@ grub_rescue_read_line (char **line, int cont, void __attribute__ ((noreturn)) grub_rescue_run (void) { + /* Stall if the CLI has been disabled */ + if (grub_is_cli_disabled ()) + { + grub_printf ("Rescue mode has been disabled...\n"); + + do + { + /* Do not optimize out the loop. */ + asm volatile (""); + } + while (1); + } + grub_printf ("Entering rescue mode...\n"); while (1) diff --git a/grub-core/normal/auth.c b/grub-core/normal/auth.c index 517fc623f..d94020186 100644 --- a/grub-core/normal/auth.c +++ b/grub-core/normal/auth.c @@ -209,6 +209,9 @@ grub_auth_check_authentication (const char *userlist) char entered[GRUB_AUTH_MAX_PASSLEN]; struct grub_auth_user *user; + if (grub_is_cli_disabled ()) + return GRUB_ACCESS_DENIED; + grub_memset (login, 0, sizeof (login)); if (is_authenticated (userlist)) diff --git a/grub-core/normal/menu_text.c b/grub-core/normal/menu_text.c index ae92050d7..56c6f7797 100644 --- a/grub-core/normal/menu_text.c +++ b/grub-core/normal/menu_text.c @@ -194,21 +194,24 @@ command-line or ESC to discard edits and return to the GRUB menu."), grub_free (msg_translated); #endif - if (nested) + if (!grub_is_cli_disabled ()) { - ret += grub_print_message_indented_real - (_("Press enter to boot the selected OS, " - "`e' to edit the commands before booting " - "or `c' for a command-line. ESC to return previous menu."), - STANDARD_MARGIN, STANDARD_MARGIN, term, dry_run); - } - else - { - ret += grub_print_message_indented_real - (_("Press enter to boot the selected OS, " - "`e' to edit the commands before booting " - "or `c' for a command-line."), - STANDARD_MARGIN, STANDARD_MARGIN, term, dry_run); + if (nested) + { + ret += grub_print_message_indented_real + (_("Press enter to boot the selected OS, " + "`e' to edit the commands before booting " + "or `c' for a command-line. ESC to return previous menu."), + STANDARD_MARGIN, STANDARD_MARGIN, term, dry_run); + } + else + { + ret += grub_print_message_indented_real + (_("Press enter to boot the selected OS, " + "`e' to edit the commands before booting " + "or `c' for a command-line."), + STANDARD_MARGIN, STANDARD_MARGIN, term, dry_run); + } } } return ret; diff --git a/include/grub/kernel.h b/include/grub/kernel.h index d3aafc884..9f3e2031f 100644 --- a/include/grub/kernel.h +++ b/include/grub/kernel.h @@ -31,7 +31,8 @@ enum OBJ_TYPE_GPG_PUBKEY, OBJ_TYPE_X509_PUBKEY, OBJ_TYPE_DTB, - OBJ_TYPE_DISABLE_SHIM_LOCK + OBJ_TYPE_DISABLE_SHIM_LOCK, + OBJ_TYPE_DISABLE_CLI }; /* The module header. */ diff --git a/include/grub/misc.h b/include/grub/misc.h index 1b35a167f..1578f36c3 100644 --- a/include/grub/misc.h +++ b/include/grub/misc.h @@ -391,6 +391,8 @@ grub_uint64_t EXPORT_FUNC(grub_divmod64) (grub_uint64_t n, grub_uint64_t d, grub_uint64_t *r); +extern bool EXPORT_FUNC(grub_is_cli_disabled) (void); + /* Must match softdiv group in gentpl.py. */ #if !defined(GRUB_MACHINE_EMU) && (defined(__arm__) || defined(__ia64__) || \ (defined(__riscv) && (__riscv_xlen == 32))) diff --git a/include/grub/util/install.h b/include/grub/util/install.h index 38c6da73b..a4aac7b85 100644 --- a/include/grub/util/install.h +++ b/include/grub/util/install.h @@ -72,6 +72,8 @@ { "appended-signature-size", GRUB_INSTALL_OPTIONS_APPENDED_SIGNATURE_SIZE,\ "SIZE", 0, N_("Add a note segment reserving SIZE bytes for an appended signature"), \ 1}, \ + { "disable-cli", GRUB_INSTALL_OPTIONS_DISABLE_CLI, 0, 0, \ + N_("disabled command line interface access"), 0 }, \ { "verbose", 'v', 0, 0, \ N_("print verbose messages."), 1 } @@ -136,7 +138,8 @@ enum grub_install_options { GRUB_INSTALL_OPTIONS_DTB, GRUB_INSTALL_OPTIONS_SBAT, GRUB_INSTALL_OPTIONS_DISABLE_SHIM_LOCK, - GRUB_INSTALL_OPTIONS_APPENDED_SIGNATURE_SIZE + GRUB_INSTALL_OPTIONS_APPENDED_SIGNATURE_SIZE, + GRUB_INSTALL_OPTIONS_DISABLE_CLI }; extern char *grub_install_source_directory; @@ -199,7 +202,8 @@ grub_install_generate_image (const char *dir, const char *prefix, const struct grub_install_image_target_desc *image_target, int note, size_t appsig_size, grub_compression_t comp, const char *dtb_file, - const char *sbat_path, const int disable_shim_lock); + const char *sbat_path, const int disable_shim_lock, + const int disable_cli); const struct grub_install_image_target_desc * grub_install_get_image_target (const char *arg); diff --git a/util/grub-install-common.c b/util/grub-install-common.c index 75fa03995..344dca664 100644 --- a/util/grub-install-common.c +++ b/util/grub-install-common.c @@ -469,6 +469,7 @@ static char **x509keys; static size_t nx509keys; static grub_compression_t compression; static size_t appsig_size; +static int disable_cli; int grub_install_parse (int key, char *arg) @@ -514,6 +515,9 @@ grub_install_parse (int key, char *arg) * (nx509keys + 1)); x509keys[nx509keys++] = xstrdup (arg); return 1; + case GRUB_INSTALL_OPTIONS_DISABLE_CLI: + disable_cli = 1; + return 1; case GRUB_INSTALL_OPTIONS_VERBOSITY: verbosity++; @@ -707,12 +711,13 @@ grub_install_make_image_wrap_file (const char *dir, const char *prefix, grub_util_info ("grub-mkimage --directory '%s' --prefix '%s' --output '%s'" " --format '%s' --compression '%s'" - " --appended-signature-size %zu%s%s%s\n", + " --appended-signature-size %zu%s%s%s%s\n", dir, prefix, outname, mkimage_target, compnames[compression], appsig_size, note ? " --note" : "", - disable_shim_lock ? " --disable-shim-lock" : "", s); + disable_shim_lock ? " --disable-shim-lock" : "", + disable_cli ? " --disable-cli" : "", s); free (s); tgt = grub_install_get_image_target (mkimage_target); @@ -724,7 +729,7 @@ grub_install_make_image_wrap_file (const char *dir, const char *prefix, pubkeys, npubkeys, x509keys, nx509keys, config_path, tgt, note, appsig_size, compression, dtb, sbat, - disable_shim_lock); + disable_shim_lock, disable_cli); while (dc--) grub_install_pop_module (); } diff --git a/util/grub-mkimage.c b/util/grub-mkimage.c index 7d61ef3ea..351a5e430 100644 --- a/util/grub-mkimage.c +++ b/util/grub-mkimage.c @@ -84,6 +84,7 @@ static struct argp_option options[] = { {"compression", 'C', "(xz|none|auto)", 0, N_("choose the compression to use for core image"), 0}, {"sbat", 's', N_("FILE"), 0, N_("SBAT metadata"), 0}, {"disable-shim-lock", GRUB_INSTALL_OPTIONS_DISABLE_SHIM_LOCK, 0, 0, N_("disable shim_lock verifier"), 0}, + {"disable-cli", GRUB_INSTALL_OPTIONS_DISABLE_CLI, 0, 0, N_("disable command line interface access"), 0}, {"verbose", 'v', 0, 0, N_("print verbose messages."), 0}, {"appended-signature-size", 'S', N_("SIZE"), 0, N_("Add a note segment reserving SIZE bytes for an appended signature"), 0}, { 0, 0, 0, 0, 0, 0 } @@ -133,6 +134,7 @@ struct arguments int note; int disable_shim_lock; size_t appsig_size; + int disable_cli; const struct grub_install_image_target_desc *image_target; grub_compression_t comp; }; @@ -259,6 +261,10 @@ argp_parser (int key, char *arg, struct argp_state *state) arguments->disable_shim_lock = 1; break; + case GRUB_INSTALL_OPTIONS_DISABLE_CLI: + arguments->disable_cli = 1; + break; + case 'v': verbosity++; break; @@ -347,7 +353,8 @@ main (int argc, char *argv[]) arguments.image_target, arguments.note, arguments.appsig_size, arguments.comp, arguments.dtb, - arguments.sbat, arguments.disable_shim_lock); + arguments.sbat, arguments.disable_shim_lock, + arguments.disable_cli); if (grub_util_file_sync (fp) < 0) grub_util_error (_("cannot sync `%s': %s"), arguments.output ? : "stdout", diff --git a/util/mkimage.c b/util/mkimage.c index 0737935fd..d6cc13475 100644 --- a/util/mkimage.c +++ b/util/mkimage.c @@ -889,7 +889,8 @@ grub_install_generate_image (const char *dir, const char *prefix, const struct grub_install_image_target_desc *image_target, int note, size_t appsig_size, grub_compression_t comp, const char *dtb_path, const char *sbat_path, - int disable_shim_lock) + int disable_shim_lock, + int disable_cli) { char *kernel_img, *core_img; size_t total_module_size, core_size; @@ -964,6 +965,9 @@ grub_install_generate_image (const char *dir, const char *prefix, if (disable_shim_lock) total_module_size += sizeof (struct grub_module_header); + if (disable_cli) + total_module_size += sizeof (struct grub_module_header); + if (config_path) { config_size = ALIGN_ADDR (grub_util_get_image_size (config_path) + 1); @@ -1130,6 +1134,16 @@ grub_install_generate_image (const char *dir, const char *prefix, offset += sizeof (*header); } + if (disable_cli) + { + struct grub_module_header *header; + + header = (struct grub_module_header *) (kernel_img + offset); + header->type = grub_host_to_target32 (OBJ_TYPE_DISABLE_CLI); + header->size = grub_host_to_target32 (sizeof (*header)); + offset += sizeof (*header); + } + if (config_path) { struct grub_module_header *header; -- 2.46.0
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