Most OS platforms have already provided solutions to
Y2038 32-bit signed time_t 5 - 10 years ago (or more!)
Notable exceptions are Linux i686 and FreeBSD i386.
Since 32-bit systems tend to be embedded systems,
and since many distros take years to pick up new software,
this commit aims to provide Y2038 mitigations for lighttpd
running on 32-bit systems with Y2038-unsafe 32-bit signed time_t
* Y2038: lighttpd 1.4.60 and later report Y2038 safety
$ lighttpd -V
+ Y2038 support # Y2038-SAFE
$ lighttpd -V
- Y2038 support (unsafe 32-bit signed time_t) # Y2038-UNSAFE
* Y2038: general platform info
* Y2038-SAFE: lighttpd 64-bit builds on platforms using 64-bit time_t
- all major 64-bit platforms (known to this author) use 64-bit time_t
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 64-bit time_t
- Linux x32 ABI (different from i686)
- FreeBSD all 32-bit and 64-bit architectures *except* 32-bit i386
- NetBSD 6.0 (released Oct 2012) all 32-bit and 64-bit architectures
- OpenBSD 5.5 (released May 2014) all 32-bit and 64-bit architectures
- Microsoft Windows XP and Visual Studio 2005 (? unsure ?)
Another reference suggests Visual Studio 2015 defaults to 64-bit time_t
- MacOS 10.15 Catalina (released 2019) drops support for 32-bit apps
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 32-bit unsigned time_t
- e.g. OpenVMS (unknown if lighttpd builds on this platform)
* Y2038-UNSAFE: lighttpd 32-bit builds on platforms using 32-bit signed time_t
- Linux 32-bit (including i686)
- glibc 32-bit library support not yet available for 64-bit time_t
- https://sourceware.org/glibc/wiki/Y2038ProofnessDesign
- Linux kernel 5.6 on 32-bit platforms does support 64-bit time_t
https://itsubuntu.com/linux-kernel-5-6-to-fix-the-year-2038-issue-unix-y2k/
- https://www.gnu.org/software/libc/manual/html_node/64_002dbit-time-symbol-handling.html
"Note: at this point, 64-bit time support in dual-time
configurations is work-in-progress, so for these
configurations, the public API only makes the 32-bit time
support available. In a later change, the public API will
allow user code to choose the time size for a given
compilation unit."
- compiling with -D_TIME_BITS=64 currently has no effect
- glibc recent (Jul 2021) mailing list discussion
- https://public-inbox.org/bug-gnulib/878s2ozq70.fsf@oldenburg.str.redhat.com/T/
- FreeBSD i386
- DragonFlyBSD 32-bit
* Y2038 mitigations attempted on Y2038-UNSAFE platforms (32-bit signed time_t)
* lighttpd prefers system monotonic clock instead of realtime clock
in places where realtime clock is not required
* lighttpd treats negative time_t values as after 19 Jan 2038 03:14:07 GMT
* (lighttpd presumes that lighttpd will not encounter dates before 1970
during normal operation.)
* lighttpd casts struct stat st.st_mtime (and st.st_*time) through uint64_t
to convert negative timestamps for comparisions with 64-bit timestamps
(treating negative timestamp values as after 19 Jan 2038 03:14:07 GMT)
* lighttpd provides unix_time64_t (int64_t) and
* lighttpd provides struct unix_timespec64 (unix_timespec64_t)
(struct timespec equivalent using unix_time64_t tv_sec member)
* lighttpd provides gmtime64_r() and localtime64_r() wrappers
for platforms 32-bit platforms using 32-bit time_t and
lighttpd temporarily shifts the year in order to use
gmtime_r() and localtime_r() (or gmtime() and localtime())
from standard libraries, before readjusting year and passing
struct tm to formatting functions such as strftime()
* lighttpd provides TIME64_CAST() macro to cast signed 32-bit time_t to
unsigned 32-bit and then to unix_time64_t
* Note: while lighttpd tries handle times past 19 Jan 2038 03:14:07 GMT
on 32-bit platforms using 32-bit signed time_t, underlying libraries and
underlying filesystems might not behave properly after 32-bit signed time_t
overflows (19 Jan 2038 03:14:08 GMT). If a given 32-bit OS does not work
properly using negative time_t values, then lighttpd likely will not work
properly on that system.
* Other references and blogs
- https://en.wikipedia.org/wiki/Year_2038_problem
- https://en.wikipedia.org/wiki/Time_formatting_and_storage_bugs
- http://www.lieberbiber.de/2017/03/14/a-look-at-the-year-20362038-problems-and-time-proofness-in-various-systems/
reduce code duplication
make it easier to add new algos
mod_authn_file:
- leverage r->tmp_buf instead of temporary allocating buffer_init()
- mod_authn_file_htpasswd_basic()
- compare binary SHA1 (shorter) rather than base64 (longer)
- split crypt() from mod_authn_file_htpasswd_basic() to separate func
- apr_md5_encode() modifications for slightly better performance
This commit is a large set of code changes and results in removal of
hundreds, perhaps thousands, of CPU instructions, a portion of which
are on hot code paths.
Most (buffer *) used by lighttpd are not NULL, especially since buffers
were inlined into numerous larger structs such as request_st and chunk.
In the small number of instances where that is not the case, a NULL
check is often performed earlier in a function where that buffer is
later used with a buffer_* func. In the handful of cases that remained,
a NULL check was added, e.g. with r->http_host and r->conf.server_tag.
- check for empty strings at config time and set value to NULL if blank
string will be ignored at runtime; at runtime, simple pointer check
for NULL can be used to check for a value that has been set and is not
blank ("")
- use buffer_is_blank() instead of buffer_string_is_empty(),
and use buffer_is_unset() instead of buffer_is_empty(),
where buffer is known not to be NULL so that NULL check can be skipped
- use buffer_clen() instead of buffer_string_length() when buffer is
known not to be NULL (to avoid NULL check at runtime)
- use buffer_truncate() instead of buffer_string_set_length() to
truncate string, and use buffer_extend() to extend
Examples where buffer known not to be NULL:
- cpv->v.b from config_plugin_values_init is not NULL if T_CONFIG_BOOL
(though we might set it to NULL if buffer_is_blank(cpv->v.b))
- address of buffer is arg (&foo)
(compiler optimizer detects this in most, but not all, cases)
- buffer is checked for NULL earlier in func
- buffer is accessed in same scope without a NULL check (e.g. b->ptr)
internal behavior change:
callers must not pass a NULL buffer to some funcs.
- buffer_init_buffer() requires non-null args
- buffer_copy_buffer() requires non-null args
- buffer_append_string_buffer() requires non-null args
- buffer_string_space() requires non-null arg
no need for extra work for precision allocation to avoid 0-3 extra chars
note: callers passing precise buffer size for without padding will need
to be modified to pass a slightly larger buffer, e.g. mod_secdownload
cast to unsigned before << 4 to avoid (pedantic) undefined behavior
of (time_t) (which is signed integral type) on 32-bit signed time_t
The high bit gets shifted into the sign-bit, which is technically
undefined behavior in C, but is defined behavior in C++.
x-ref:
"pedantic warning from -fsanitize=undefined"
https://redmine.lighttpd.net/issues/3069
use NSS crypto if no other crypto avail, but NSS crypto is available
"NSS crypto support" is not included in tests/LightyTest.pm:has_crypto()
due to NSS libraries (freebl3) lacking public export for HMAC funcs
provide implementations for conventional digest interfaces
but use the newer openssl digest interfaces under the hood
<rant>
It is baffling that the openssl library -- with *thousands* of public
interfaces -- does not provide these, and suggests that openssl
developers do not frequently write apps which utilize these interfaces.
</rant>
Prefer some WolfSSL native APIs when building with WolfSSL.
However, some functionality in WolfSSL is available only through the
WolfSSL compatibility layer for OpenSSL, so the effort to create a
native mod_wolfssl halted here.
(experimental)
mod_gnutls supports most ssl.* config options supported by mod_openssl
x-ref:
"GnuTLS support for the mod_ssl"
https://redmine.lighttpd.net/issues/109
(experimental)
mod_mbedtls supports most ssl.* config options supported by mod_openssl
thx Ward Willats for the initial discussion and attempt in the comments
https://redmine.lighttpd.net/boards/3/topics/7029
./configure --with-nettle to use Nettle crypto lib for algorithms,
instead of OpenSSL or wolfSSL. Note: Nettle does not provide TLS.
x-ref:
"How to use SHA-256 without OpenSSL?"
https://redmine.lighttpd.net/boards/2/topics/8903
NB: r->tmp_buf == srv->tmp_buf (pointer is copied for quicker access)
NB: request read and write chunkqueues currently point to connection
chunkqueues; per-request and per-connection chunkqueues are
not distinct from one another
con->read_queue == r->read_queue
con->write_queue == r->write_queue
NB: in the future, a separate connection config may be needed for
connection-level module hooks. Similarly, might need to have
per-request chunkqueues separate from per-connection chunkqueues.
Should probably also have a request_reset() which is distinct from
connection_reset().
convert all log_error_write() to log_error() and pass (log_error_st *)
use con->errh in preference to srv->errh (even though currently same)
avoid passing (server *) when previously used only for logging (errh)
secdownload.path-segments = <number>
include only given number of path segments in hash digest calculation
secdownload.hash-querystr = "enable" | "disable"
include the query string in the hash digest calculation
x-ref:
"secdownload.path_elements support"
https://redmine.lighttpd.net/issues/646
"mod_secdownload option to include url GET parameters in md5"
https://redmine.lighttpd.net/issues/1904
issue warning at startup, instead of fatal error, if SHA used in
secdownload.algorithm = "..." but mod_secdownload was built without
SSL crypto. When lighttpd is built without openssl, this allows most
tests/* to be run and pass, except the ones in tests/mod-secdownload.t
which use "hmac-sha1" or "hmac-sha256".
(alternatively, could have made, used isolated tests/secdownload.conf)
also change passing of fixed-sized arrays: need to pass pointer to array
as otherwise size does not get enforced
From: Glenn Strauss <gstrauss@gluelogic.com>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3135 152afb58-edef-0310-8abb-c4023f1b3aa9
Impact is probably low on most platforms, as it will probably overwrite
one byte of "HASH HA1" which isn't used afterwards anymore.
Reference: Fortify Open Review Project - lighttpd 1.4.39
ID 22708159 - Buffer Overflow: Off-by-One
From: Stefan Bühler <stbuehler@web.de>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3096 152afb58-edef-0310-8abb-c4023f1b3aa9
Mohammed Sadiq
