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Merge pull request #15935 from poettering/cache-more-efi-vars

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logind + efi-loader: cache more efi vars
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2020-05-30 15:44:26 +02:00
committed by GitHub
parent d308cd4bfa 84190644ff
commit 956508cb5d
10 changed files with 211 additions and 64 deletions
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33
src/basic/efivars.c
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@@ -69,19 +69,21 @@ int efi_get_variable(
return 0;
}
if (DEBUG_LOGGING)
if (DEBUG_LOGGING) {
log_debug("Reading EFI variable %s.", p);
begin = now(CLOCK_MONOTONIC);
}
fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return log_debug_errno(errno, "open(\"%s\") failed: %m", p);
if (fstat(fd, &st) < 0)
return -errno;
return log_debug_errno(errno, "fstat(\"%s\") failed: %m", p);
if (st.st_size < 4)
return -ENODATA;
return log_debug_errno(SYNTHETIC_ERRNO(ENODATA), "EFI variable %s is shorter than 4 bytes, refusing.", p);
if (st.st_size > 4*1024*1024 + 4)
return -E2BIG;
return log_debug_errno(SYNTHETIC_ERRNO(E2BIG), "EFI variable %s is ridiculously large, refusing.", p);
if (ret_value || ret_attribute) {
/* The kernel ratelimits reads from the efivarfs because EFI is inefficient, and we'll
@@ -96,31 +98,34 @@ int efi_get_variable(
n = read(fd, &a, sizeof(a));
if (n >= 0)
break;
log_debug_errno(errno, "read from \"%s\" failed: %m", p);
log_debug_errno(errno, "Reading from \"%s\" failed: %m", p);
if (errno != EINTR)
return -errno;
if (try >= EFI_N_RETRIES)
return -EBUSY;
usleep(EFI_RETRY_DELAY);
(void) usleep(EFI_RETRY_DELAY);
}
if (n != sizeof(a))
return -EIO;
return log_debug_errno(SYNTHETIC_ERRNO(EIO),
"Read %zi bytes from EFI variable %s, expected %zu.", n, p, sizeof(a));
}
if (ret_value) {
buf = malloc(st.st_size - 4 + 2);
buf = malloc(st.st_size - 4 + 3);
if (!buf)
return -ENOMEM;
n = read(fd, buf, (size_t) st.st_size - 4);
if (n < 0)
return -errno;
return log_debug_errno(errno, "Failed to read value of EFI variable %s: %m", p);
assert(n <= st.st_size - 4);
/* Always NUL terminate (2 bytes, to protect UTF-16) */
/* Always NUL terminate (3 bytes, to properly protect UTF-16, even if truncated in the middle of a character) */
((char*) buf)[n] = 0;
((char*) buf)[n + 1] = 0;
((char*) buf)[n + 2] = 0;
} else
/* Assume that the reported size is accurate */
n = st.st_size - 4;
@@ -229,6 +234,14 @@ int efi_set_variable(
if (r < 0)
goto finish;
/* For some reason efivarfs doesn't update mtime automatically. Let's do it manually then. This is
* useful for processes that cache EFI variables to detect when changes occurred. */
if (futimens(fd, (struct timespec[2]) {
{ .tv_nsec = UTIME_NOW },
{ .tv_nsec = UTIME_NOW }
}) < 0)
log_debug_errno(errno, "Failed to update mtime/atime on %s, ignoring: %m", p);
r = 0;
finish: