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verifiers: Verify commands executed by grub

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Pass all commands executed by GRUB to the verifiers layer. Most verifiers will
ignore this, but some (such as the TPM verifier) want to be able to measure and
log each command executed in order to ensure that the boot state is as expected.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Matthew Garrett 2018-11-29 11:28:08 -08:00 • committed by Vincent Batts
parent 90bb89f280
commit 8d6447d496
2 changed files with 18 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

31
grub-core/script/execute.c
View file

@ -28,6 +28,7 @@
#include <grub/extcmd.h>
#include <grub/i18n.h>
#include <grub/tpm.h>
#include <grub/verify.h>
/* Max digits for a char is 3 (0xFF is 255), similarly for an int it
is sizeof (int) * 3, and one extra for a possible -ve sign. */
@ -941,26 +942,29 @@ grub_script_execute_cmdline (struct grub_script_cmd *cmd)
if (grub_script_arglist_to_argv (cmdline->arglist, &argv) || ! argv.args[0])
return grub_errno;
for (i = 0; i < argv.argc; i++) {
cmdlen += grub_strlen (argv.args[i]) + 1;
}
for (i = 0; i < argv.argc; i++)
{
cmdlen += grub_strlen (argv.args[i]) + 1;
}
cmdstring = grub_malloc (cmdlen);
if (!cmdstring)
{
return grub_error (GRUB_ERR_OUT_OF_MEMORY,
N_("cannot allocate command buffer"));
}
{
return grub_error (GRUB_ERR_OUT_OF_MEMORY,
N_("cannot allocate command buffer"));
}
for (i = 0; i < argv.argc; i++) {
offset += grub_snprintf (cmdstring + offset, cmdlen - offset, "%s ",
argv.args[i]);
}
cmdstring[cmdlen-1]= '\0';
for (i = 0; i < argv.argc; i++)
{
offset += grub_snprintf (cmdstring + offset, cmdlen - offset, "%s ",
argv.args[i]);
}
cmdstring[cmdlen - 1] = '\0';
grub_tpm_measure ((unsigned char *)cmdstring, cmdlen, GRUB_ASCII_PCR,
"grub_cmd", cmdstring);
grub_print_error();
grub_free(cmdstring);
grub_verify_string (cmdstring, GRUB_VERIFY_COMMAND);
grub_free (cmdstring);
invert = 0;
argc = argv.argc - 1;
args = argv.args + 1;
@ -1185,4 +1189,3 @@ grub_script_execute (struct grub_script *script)
return grub_script_execute_cmd (script->cmd);
}

1
include/grub/verify.h
View file

@ -34,6 +34,7 @@ enum grub_verify_string_type
{
GRUB_VERIFY_KERNEL_CMDLINE,
GRUB_VERIFY_MODULE_CMDLINE,
GRUB_VERIFY_COMMAND,
};
struct grub_file_verifier