-P was introduced in 4.4BSD-Lite2 around 1994. It overwrote file contents
with a pass of 0xff, 0x00, then 0xff, in a low effort attempt to "really
delete" files.
It has no user-visible effect; at the end of the day, the file is unlinked via
the filesystem. Furthermore, the utility of overwriting files with patterned
data is extremely limited due to caveats at every layer of the stack[0] and
therefore mostly futile. At the least, three passes is likely wasteful on
modern hardware[1]. It could also be seen as a violation of the "Unix
Philosophy" to do one thing per tiny, composable program.
Since 1994, FreeBSD has left it alone; OpenBSD replaced it with a single
pass of arc4random(3) output in 2012[2]; and NetBSD implemented partial, but
explicitly incomplete support for U.S. DoD 5220.22-M, "National Industrial
Security Program Operating Manual" in 2004[3].
NetBSD's enhanced comment above rm_overwrite makes a strong case for removing
the flag entirely:
> This is an expensive way to keep people from recovering files from your
> non-snapshotted FFS filesystems using fsdb(8). Really. No more.
>
> It is impossible to actually conform to the exact procedure given in
> [NISPOM] if one is overwriting a file, not an entire disk, because the
> procedure requires examination and comparison of the disk's defect lists.
> Any program that claims to securely erase *files* while conforming to the
> standard, then, is not correct.
>
> Furthermore, the presence of track caches, disk and controller write
> caches, and so forth make it extremely difficult to ensure that data have
> actually been written to the disk, particularly when one tries to repeatedly
> overwrite the same sectors in quick succession. We call fsync(), but
> controllers with nonvolatile cache, as well as IDE disks that just plain lie
> about the stable storage of data, will defeat this.
>
> [NISPOM] requires physical media destruction, rather than any technique of
> the sort attempted here, for secret data.
As a first step towards evental removal, make it a placebo. It's not like
it was serving any security function. It is not defined in or mentioned by
POSIX.
If you are security conscious and need to erase your files, use a
woodchipper. At a minimum, the entire disk needs to be overwritten, not
just one file.
[0]: https://www.ru.nl/publish/pages/909282/draft-paper.pdf
[1]: https://commons.erau.edu/cgi/viewcontent.cgi?article=1131&context=jdfsl
[2]: https://github.com/openbsd/src/commit/7c5c57ba81b5fe8ff2d4899ff643af18c
[3]: https://github.com/NetBSD/src/commit/fdf0a7a25e59af958fca1e2159921562cd
Reviewed by: markj, Daniel O'Connor <darius AT dons.net.au> (previous version)
Differential Revision: https://reviews.freebsd.org/D17906
Restore the original behavior of unlink(1), passing the provided filename
directly to unlink(2), handling the first argument being "--" correctly.
This fixes "unlink -foo", broken in r97533.
PR: 228448
Submitted by: Brennan Vincent <brennan@umanwizard.com> (original version)
Submitted by: Yuri Pankov
Reported by: Brennan Vincent <brennan@umanwizard.com>
Reviewed by: emaste, kevans, vangyzen, 0mp
Approved by: re (delphij)
Differential Revision: https://reviews.freebsd.org/D17132
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
The wrong index was being checked for == ' ' in the resulting stringified
mode from strmode(3) -- it should have been the 11th value, not the 10th.
MFC after: 3 days
PR: 76711
Submitted by: Vasil Dimov <vd@datamax.bg>
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
Note: tcsh(1) has a MK_TCSH=no test, so this should be a separate
package, which requires pre-install/post-install scripts, to be
added later.
Sponsored by: The FreeBSD Foundation
edition 2013. No need anymore to disable the protection if one set
the POXILY_CORRECT environment variable.
Reviewed by: imp
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D4092
Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.
Still need to add real targets under targets/ to build packages.
Differential Revision: D2796
Reviewed by: brooks imp
fflag to ignore fts_read errors, but stop deleting from that directory
because no further progress can be made.
When building a kernel with a high -j value on a high core count
machine, during the cleanobj phase we can wind up doing multiple rm
-rf at the same time for modules that have subdirectories. This
exposed this race (sometimes) as fts_read can return an error if the
directory is removed by another rm -rf. Since the intent of the -f
flag was to ignore errors, even if this was a bug in fts_read, we
should ignore the error like we've been instructed to do.
directory entry then use the struct stat from that instead of doing
it again, and skip the rm_overwrite() call if fts_read() indicated
that the entry couldn't be a regular file.
Obtained from: OpenBSD
MFC after: 1 week
that the file we have opened is the one we expected. Also open in
non-blocking mode to avoid a potential hang with FIFOs.
Obtained from: NetBSD via OpenBSD
For these simple utilities, it doesn't harm to make all global variables
static. In fact, this allows the compiler to perform better forms of
optimisation and analysis.
Formerly, this tried to clear the flags on the symlink's target
instead of the symlink itself.
As before, this only happens for root or for the unlink(1) variant of rm.
PR: bin/111226 (part of)
Submitted by: Martin Kammerhofer
Approved by: ed (mentor)
MFC after: 3 weeks
instead of removing the file and issue a warning about
the removal, do not do any operation at all in case -P
is specified when the dinode has hard links.
With -f and -P specified together, we assume that the
user wants rm to overwrite the contents of the file
and remove it (destroy the contents of file but leave
its hard links as is).
The reason of doing it this way is that, in case where
a hard link is created by a malicious user (currently
this is permitted even if the user has no access to the
file). Losing the link can potentially mean that the
actual owner would lose control completely to the user
who wants to obtain access in a future day.
Discussed with: Peter Jermey
is hard links. Overwritting when links > 1 would cause data
loss, which is usually undesired.
Inspired by: discussion on -hackers@
Suggested by: elessar at bsdforen de
Obtained from: OpenBSD
earlier, and more gracefully. Previously, this combination would be
ignored early in the code where permissions are tested and fail later
with a very unhelpful "permission denied" error.
Instead, test for this flag in the same block that generates the
"override?" messages for read-only files, but instead of trying
to guess what the user has in mind, generate an error and exit.
Update the man page to reflect this new behavior.
Not objected to by: freebsd-hackers@
