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efi: add more logging for all EFI variable reads

This commit is contained in:
Lennart Poettering 2020-05-27 17:30:29 +02:00
parent 002914e688
commit 84190644ff
1 changed files with 10 additions and 7 deletions
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17
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
@ -96,7 +98,7 @@ 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)
@ -106,7 +108,8 @@ int efi_get_variable(
}
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) {
@ -116,7 +119,7 @@ int efi_get_variable(
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 (3 bytes, to properly protect UTF-16, even if truncated in the middle of a character) */