efivars.c revision ff47c895c8c2132ef98ef4182213a0ba79eefb73
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2013 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <unistd.h>
#include <fcntl.h>
#include "util.h"
#include "utf8.h"
#include "efivars.h"
#define EFI_VENDOR_LOADER SD_ID128_MAKE(4a,67,b0,82,0a,4c,41,cf,b6,c7,44,0b,29,bb,8c,4f)
bool is_efiboot(void) {
return access("/sys/firmware/efi", F_OK) >= 0;
}
int efi_get_variable(sd_id128_t vendor, const char *name, uint32_t *attribute, void **value, size_t *size) {
_cleanup_close_ int fd = -1;
_cleanup_free_ char *p = NULL;
uint32_t a;
ssize_t n;
struct stat st;
void *r;
assert(name);
assert(value);
assert(size);
if (asprintf(&p,
"/sys/firmware/efi/efivars/%s-%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
name, SD_ID128_FORMAT_VAL(vendor)) < 0)
return -ENOMEM;
fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
if (fstat(fd, &st) < 0)
return -errno;
if (st.st_size < 4)
return -EIO;
if (st.st_size > 4*1024*1024 + 4)
return -E2BIG;
n = read(fd, &a, sizeof(a));
if (n < 0)
return (int) n;
if (n != sizeof(a))
return -EIO;
r = malloc(st.st_size - 4 + 2);
if (!r)
return -ENOMEM;
n = read(fd, r, (size_t) st.st_size - 4);
if (n < 0) {
free(r);
return (int) -n;
}
if (n != (ssize_t) st.st_size - 4) {
free(r);
return -EIO;
}
/* Always NUL terminate (2 bytes, to protect UTF-16) */
((char*) r)[st.st_size - 4] = 0;
((char*) r)[st.st_size - 4 + 1] = 0;
*value = r;
*size = (size_t) st.st_size - 4;
if (attribute)
*attribute = a;
return 0;
}
static int read_usec(sd_id128_t vendor, const char *name, usec_t *u) {
_cleanup_free_ void *i = NULL;
_cleanup_free_ char *j = NULL;
size_t is;
int r;
uint64_t x;
assert(name);
assert(u);
r = efi_get_variable(EFI_VENDOR_LOADER, name, NULL, &i, &is);
if (r < 0)
return r;
j = utf16_to_utf8(i, is);
if (!j)
return -ENOMEM;
r = safe_atou64(j, &x);
if (r < 0)
return r;
*u = x;
return 0;
}
static int get_boot_usec(usec_t *firmware, usec_t *loader) {
uint64_t x, y;
int r;
assert(firmware);
assert(loader);
r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeInitUSec", &x);
if (r < 0)
return r;
r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeExecUSec", &y);
if (r < 0)
return r;
if (y == 0 || y < x)
return -EIO;
if (y > USEC_PER_HOUR)
return -EIO;
*firmware = x;
*loader = y;
return 0;
}
int efi_get_boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) {
usec_t x, y, a;
int r;
dual_timestamp _n;
assert(firmware);
assert(loader);
if (!n) {
dual_timestamp_get(&_n);
n = &_n;
}
r = get_boot_usec(&x, &y);
if (r < 0)
return r;
/* Let's convert this to timestamps where the firmware
* began/loader began working. To make this more confusing:
* since usec_t is unsigned and the kernel's monotonic clock
* begins at kernel initialization we'll actually initialize
* the monotonic timestamps here as negative of the actual
* value. */
firmware->monotonic = y;
loader->monotonic = y - x;
a = n->monotonic + firmware->monotonic;
firmware->realtime = n->realtime > a ? n->realtime - a : 0;
a = n->monotonic + loader->monotonic;
loader->realtime = n->realtime > a ? n->realtime - a : 0;
return 0;
}
int efi_get_loader_device_part_uuid(sd_id128_t *u) {
_cleanup_free_ void *s = NULL;
_cleanup_free_ char *p = NULL;
size_t ss;
int r, parsed[16];
unsigned i;
assert(u);
r = efi_get_variable(EFI_VENDOR_LOADER, "LoaderDevicePartUUID", NULL, &s, &ss);
if (r < 0)
return r;
p = utf16_to_utf8(s, ss);
if (!p)
return -ENOMEM;
if (sscanf(p, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
&parsed[0], &parsed[1], &parsed[2], &parsed[3],
&parsed[4], &parsed[5], &parsed[6], &parsed[7],
&parsed[8], &parsed[9], &parsed[10], &parsed[11],
&parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
return -EIO;
for (i = 0; i < ELEMENTSOF(parsed); i++)
u->bytes[i] = parsed[i];
return 0;
}