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grub/grub-core/loader/linux.c
Matthew Garrett f4f4e3c715 verifiers: Core TPM support 
Add support for performing basic TPM measurements. Right now this only
supports extending PCRs statically and only on UEFI. In future we might
want to have some sort of mechanism for choosing which events get logged
to which PCRs, but this seems like a good default policy and we can wait
to see whether anyone  has a use case before adding more complexity.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-09-21 16:43:54 -04:00

307 lines
6.8 KiB
C
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#include <grub/types.h>
#include <grub/err.h>
#include <grub/linux.h>
#include <grub/misc.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/tpm.h>
struct newc_head
{
char magic[6];
char ino[8];
char mode[8];
char uid[8];
char gid[8];
char nlink[8];
char mtime[8];
char filesize[8];
char devmajor[8];
char devminor[8];
char rdevmajor[8];
char rdevminor[8];
char namesize[8];
char check[8];
} GRUB_PACKED;
struct grub_linux_initrd_component
{
grub_file_t file;
char *newc_name;
grub_off_t size;
};
struct dir
{
char *name;
struct dir *next;
struct dir *child;
};
static char
hex (grub_uint8_t val)
{
if (val < 10)
return '0' + val;
return 'a' + val - 10;
}
static void
set_field (char *var, grub_uint32_t val)
{
int i;
char *ptr = var;
for (i = 28; i >= 0; i -= 4)
*ptr++ = hex((val >> i) & 0xf);
}
static grub_uint8_t *
make_header (grub_uint8_t *ptr,
const char *name, grub_size_t len,
grub_uint32_t mode,
grub_off_t fsize)
{
struct newc_head *head = (struct newc_head *) ptr;
grub_uint8_t *optr;
grub_size_t oh = 0;
grub_memcpy (head->magic, "070701", 6);
set_field (head->ino, 0);
set_field (head->mode, mode);
set_field (head->uid, 0);
set_field (head->gid, 0);
set_field (head->nlink, 1);
set_field (head->mtime, 0);
set_field (head->filesize, fsize);
set_field (head->devmajor, 0);
set_field (head->devminor, 0);
set_field (head->rdevmajor, 0);
set_field (head->rdevminor, 0);
set_field (head->namesize, len);
set_field (head->check, 0);
optr = ptr;
ptr += sizeof (struct newc_head);
grub_memcpy (ptr, name, len);
ptr += len;
oh = ALIGN_UP_OVERHEAD (ptr - optr, 4);
grub_memset (ptr, 0, oh);
ptr += oh;
return ptr;
}
static void
free_dir (struct dir *root)
{
if (!root)
return;
free_dir (root->next);
free_dir (root->child);
grub_free (root->name);
grub_free (root);
}
static grub_size_t
insert_dir (const char *name, struct dir **root,
grub_uint8_t *ptr)
{
struct dir *cur, **head = root;
const char *cb, *ce = name;
grub_size_t size = 0;
while (1)
{
for (cb = ce; *cb == '/'; cb++);
for (ce = cb; *ce && *ce != '/'; ce++);
if (!*ce)
break;
for (cur = *root; cur; cur = cur->next)
if (grub_memcmp (cur->name, cb, ce - cb)
&& cur->name[ce - cb] == 0)
break;
if (!cur)
{
struct dir *n;
n = grub_zalloc (sizeof (*n));
if (!n)
return 0;
n->next = *head;
n->name = grub_strndup (cb, ce - cb);
if (ptr)
{
grub_dprintf ("linux", "Creating directory %s, %s\n", name, ce);
ptr = make_header (ptr, name, ce - name,
040777, 0);
}
size += ALIGN_UP ((ce - (char *) name)
+ sizeof (struct newc_head), 4);
*head = n;
cur = n;
}
root = &cur->next;
}
return size;
}
grub_err_t
grub_initrd_init (int argc, char *argv[],
struct grub_linux_initrd_context *initrd_ctx)
{
int i;
int newc = 0;
struct dir *root = 0;
initrd_ctx->nfiles = 0;
initrd_ctx->components = 0;
initrd_ctx->components = grub_zalloc (argc
* sizeof (initrd_ctx->components[0]));
if (!initrd_ctx->components)
return grub_errno;
initrd_ctx->size = 0;
for (i = 0; i < argc; i++)
{
const char *fname = argv[i];
initrd_ctx->size = ALIGN_UP (initrd_ctx->size, 4);
if (grub_memcmp (argv[i], "newc:", 5) == 0)
{
const char *ptr, *eptr;
ptr = argv[i] + 5;
while (*ptr == '/')
ptr++;
eptr = grub_strchr (ptr, ':');
if (eptr)
{
initrd_ctx->components[i].newc_name = grub_strndup (ptr, eptr - ptr);
if (!initrd_ctx->components[i].newc_name)
{
grub_initrd_close (initrd_ctx);
return grub_errno;
}
initrd_ctx->size
+= ALIGN_UP (sizeof (struct newc_head)
+ grub_strlen (initrd_ctx->components[i].newc_name),
4);
initrd_ctx->size += insert_dir (initrd_ctx->components[i].newc_name,
&root, 0);
newc = 1;
fname = eptr + 1;
}
}
else if (newc)
{
initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
+ sizeof ("TRAILER!!!") - 1, 4);
free_dir (root);
root = 0;
newc = 0;
}
initrd_ctx->components[i].file = grub_file_open (fname,
GRUB_FILE_TYPE_LINUX_INITRD
| GRUB_FILE_TYPE_NO_DECOMPRESS);
if (!initrd_ctx->components[i].file)
{
grub_initrd_close (initrd_ctx);
return grub_errno;
}
initrd_ctx->nfiles++;
initrd_ctx->components[i].size
= grub_file_size (initrd_ctx->components[i].file);
initrd_ctx->size += initrd_ctx->components[i].size;
}
if (newc)
{
initrd_ctx->size = ALIGN_UP (initrd_ctx->size, 4);
initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
+ sizeof ("TRAILER!!!") - 1, 4);
free_dir (root);
root = 0;
}
return GRUB_ERR_NONE;
}
grub_size_t
grub_get_initrd_size (struct grub_linux_initrd_context *initrd_ctx)
{
return initrd_ctx->size;
}
void
grub_initrd_close (struct grub_linux_initrd_context *initrd_ctx)
{
int i;
if (!initrd_ctx->components)
return;
for (i = 0; i < initrd_ctx->nfiles; i++)
{
grub_free (initrd_ctx->components[i].newc_name);
grub_file_close (initrd_ctx->components[i].file);
}
grub_free (initrd_ctx->components);
initrd_ctx->components = 0;
}
grub_err_t
grub_initrd_load (struct grub_linux_initrd_context *initrd_ctx,
char *argv[], void *target)
{
grub_uint8_t *ptr = target;
int i;
int newc = 0;
struct dir *root = 0;
grub_ssize_t cursize = 0;
for (i = 0; i < initrd_ctx->nfiles; i++)
{
grub_memset (ptr, 0, ALIGN_UP_OVERHEAD (cursize, 4));
ptr += ALIGN_UP_OVERHEAD (cursize, 4);
if (initrd_ctx->components[i].newc_name)
{
ptr += insert_dir (initrd_ctx->components[i].newc_name,
&root, ptr);
ptr = make_header (ptr, initrd_ctx->components[i].newc_name,
grub_strlen (initrd_ctx->components[i].newc_name),
0100777,
initrd_ctx->components[i].size);
newc = 1;
}
else if (newc)
{
ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!") - 1,
0, 0);
free_dir (root);
root = 0;
newc = 0;
}
cursize = initrd_ctx->components[i].size;
if (grub_file_read (initrd_ctx->components[i].file, ptr, cursize)
!= cursize)
{
if (!grub_errno)
grub_error (GRUB_ERR_FILE_READ_ERROR, N_("premature end of file %s"),
argv[i]);
grub_initrd_close (initrd_ctx);
return grub_errno;
}
// TODO figure out the GRUB_VERIFY_ equivalent for this one
//grub_tpm_measure (ptr, cursize, GRUB_BINARY_PCR, "Initrd");
//grub_print_error();
ptr += cursize;
}
if (newc)
{
grub_memset (ptr, 0, ALIGN_UP_OVERHEAD (cursize, 4));
ptr += ALIGN_UP_OVERHEAD (cursize, 4);
ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!") - 1, 0, 0);
}
free_dir (root);
root = 0;
return GRUB_ERR_NONE;
}
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