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i previously used error status and set return values
indirectly. i still do that, but where possible, i
also now return the real value.
this is because these string functions can no longer
return with error status; on error, they all abort.
this forces the program maintainer to keep their code
reliable, and removes the need to check the error status
after using syscalls, because these libc wrappers mitigate
that and make use of libc for you, including errors.
this is part of a general effort to promote safe use
of the C programming language, especially in libreboot!
Signed-off-by: Leah Rowe <leah@libreboot.org>
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This reverts commit e54862fcccca0325da8ae2879c1fa965267d3df0.
nope. not ready yet. will fix it later.
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i added a fake -t option, which doesn't actually
read optarg, so that -t usage can just override
the normal template. mkhtemp isn't ready for
distros yet, but it's ready for lbmk.
i hacked the makefile to also copy the binary to
mktemp, and i set PATH in lbmk so that this binary
is used insttead of the one on your system.
that way, upstream projects use it.
Signed-off-by: Leah Rowe <leah@libreboot.org>
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the functions no longer return errors, so i don't
need to handle them.
furthermore, the handling in state.c is redundant,
so i've removed that too.
Signed-off-by: Leah Rowe <leah@libreboot.org>
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Signed-off-by: Leah Rowe <leah@libreboot.org>
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i now use a singleton hook function per program:
nvmutil, mkhtemp and lottery
call this at the startup of your program:
(void) errhook(exit_cleanup);
then provide that function. make it static,
so that each program has its own version.
if you're writing a program that handles lots
of files for example, and you want to do certain
cleanup on exit (including error exit), this can
be quite useful.
Signed-off-by: Leah Rowe <leah@libreboot.org>
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i no longer care about openbsd 5.9. we assume unveil
is available, as has been the case for the past 12
years.
i use wrappers for unveil and pledge, which means that
i call them on every os. on OSes that don't have these,
i just return. it's somewhat inelegant, but also means
that i see errors more easily, e.g. misnamed variables
inside previous ifdef OpenBSD blocks.
Signed-off-by: Leah Rowe <leah@libreboot.org>
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Signed-off-by: Leah Rowe <leah@libreboot.org>
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This will also be used in lbmk itself at some point,
which currently just uses regular mktemp, for tmpdir
handling during the build process.
Renamed util/nvmutil to util/libreboot-utils, which
now contains two tools. The new tool, mkhtemp, is a
hardened implementation of mktemp, which nvmutil
also uses now. Still experimental, but good enough
for nvmutil.
Mkhtemp attempts to provide TOCTOU resistance on
Linux, by using modern features in Linux such as
Openat2 (syscall) with O_EXCL and O_TMPFILE,
and many various security checks e.g.
inode/dev during creation. Checks are done constantly,
to try to detect race conditions. The code is very
strict about things like sticky bits in world writeable
directories, also ownership (it can be made to bar even
root access on files and directories it doesn't own).
It's a security-first implementation of mktemp, likely
even more secure than the OpenBSD mkstemp, but more
auditing and testing is needed - more features are
also planned, including a compatibility mode to make
it also work like traditional mktemp/mkstemp. The
intention, once this becomes stable, is that it will
become a modern drop-in replacement for mkstemp on
Linux and BSD systems.
Some legacy code has been removed, and in general
cleaned up. I wrote mkhtemp for nvmutil, as part of
its atomic write behaviour, but mktemp was the last
remaining liability, so I rewrote that too!
Docs/manpage/website will be made for mkhtemp once
the code is mature.
Other changes have also been made. This is from another
experimental branch of Libreboot, that I'm pushing
early. For example, nvmutil's state machine has been
tidied up, moving more logic back into main.
Mktemp is historically prone to race conditions,
e.g. symlink attacks, directory replacement, remounting
during operation, all sorts of things. Mkhtemp has
been written to solve, or otherwise mitigate, that
problem. Mkhtemp is currently experimental and will
require a major cleanup at some point, but it
already works well enough, and you can in fact use
it; at this time, the -d, -p and -q flags are
supported, and you can add a custom template at
the end, e.g.
mkhtemp -p test -d
Eventually, I will make this have complete parity
with the GNU and BSD implementations, so that it is
fully useable on existing setups, while optionally
providing the hardening as well.
A lot of code has also been tidied up. I didn't
track the changes I made with this one, because
it was a major re-write of nvmutil; it is now
libreboot-utils, and I will continue to write
more programs in here over time. It's basically
now a bunch of hardened wrappers around various
libc functions, e.g. there is also a secure I/O
wrapper for read/write.
There is a custom randomisation function, rlong,
which simply uses arc4random or getrandom, on
BSD and Linux respectively. Efforts are made to
make it as reliable as possible, to the extent
that it never returns with failure; in the unlikely
event that it fails, it aborts. It also sleeps
between failure, to mitigate certain DoS attacks.
You can just go in util/libreboot-utils and
type make, then you will have the nvmutil and
mkhtemp binaries, which you can just use. It
all works. Everything was massively rewritten.
Signed-off-by: Leah Rowe <leah@libreboot.org>
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