While it's only documented (so far) in commit text and
an occasional email I've tried to maintain some coding
standards primarily for reference/navigation purposes.
They also served, I felt, as useful mental challenges.
Someday I will get around to formerly documenting them
but in the meantime here are the ones for this commit:
. functions are grouped into logical (i hope) sections
. functions & sections are ordered to avoid prototypes
. function names are alphabetical within every section
. all functions & sections must be referenced in top.h
This patch just attempts to honor the above standards,
while also covering this new behavior in the man page.
[ please note that the net result of these 2 patches ]
[ is simply to avoid pathname truncations should our ]
[ limit of 1024 be exceeded. they do not have a role ]
[ in solving the 'local privilege escalation' issue. ]
[ and we can never prevent a user from setting their ]
[ HOME var to a directory writable by some attacker! ]
[ the only real protection for that CVE-2018-1122 is ]
[ those soon to be enhanced rcfile integrity checks, ]
[ achieved through several of the following patches. ]
Reference(s):
. original qualys patch
0097-top-Do-not-default-to-the-cwd-in-configs_read.patch
commit b45c4803dd
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch prevents three problems:
1/ Because snprintf() returns "the number of characters (excluding the
terminating null byte) which would have been written to the final string
if enough space had been available", _eol may point past the end of _str
and write out-of-bounds (in Batch mode).
2/ _eol is never checked against _str, so "while (*(--_eol) == ' ');"
may point _eol below _str and write out-of-bounds (in Batch mode).
3/ Sanity-check Pseudo_row to protect the strcpy().
This patch fixes two problems:
1/ In the switch case 0, if sub_end is at the very end of lin[], the two
null-byte writes are off-by-two (a stack-based buffer overflow). Replace
this end-of-string "emulation" with an equivalent test on ch (and then
goto/break out of the loop).
2/ "sub_end += 2" jumps over the null-byte terminator in lin[] if the
line contains a raw (without a tilde) \001-\010 character. Detect such a
null-byte terminator and goto/break out of the loop.
Note: in the case of a raw \001-\010 character, the character at
"sub_end + 1" is never processed (it is skipped/jumped over); this is
not a security problem anymore (since 2/ was fixed), so we decided not
to change this behavior, for backward-compatibility.
- Make sure i is at least 1 before "i - 1" and "--i".
- Initialize endpflg (to 0, as it was originally, since it is static)
before the "for" loop (the "break" may leave endpflg uninitialized,
for example).
pflgsall[] can contain PFLAGSSIZ = 100 elements, each iteration of the
loop can write 3 elements to pflgsall[], and there are EU_MAXPFLGS = 58
iterations: a buffer overflow (it can be triggered via the configuration
file, for example, by filling "fieldscur" with the "sortindx" flag).
The safety of the critical function task_show() depends on the sanity of
Screen_cols. Just copy the tests on w_cols to Screen_cols (from the same
function adj_geometry()).
Several of these buffer overflows can actually be triggered (through the
configuration file for example): in config_file(), inspection_utility(),
and show_special().
The default action for SIGURG is to ignore the signal, for example.
This is very similar to the patch "ps/display.c: Always exit from
signal_handler()."
Every time sortindx is used as an index, or loaded from the
configuration file. Otherwise it leads to out-of-bounds reads and
arbitrary code execution.
Otherwise they may lead to out-of-bounds writes (snprintf() returns the
number of characters which would have been written if enough space had
been available).
Also, make sure buf is null-terminated after COLPLUSCH has been written.
Otherwise they lead to out-of-bounds reads and format-string bugs.
Since these variables are set/written to in several places (for example,
config_file()), check them in the only place where they are read/used.
Also, constify the static gtab[]s.
If the HOME environment variable is not set, or not absolute, use the
home directory returned by getpwuid(getuid()), if set and absolute
(instead of the cwd "."); otherwise, set p_home to NULL.
To keep the changes to a minimum, we rely on POSIX, which requires that
fopen() fails with ENOENT if the pathname (Rc_name) is an empty string.
This integrates well into the existing code, and makes write_rcfile()
work without a change.
Also, it makes the code in configs_read() easier to follow: only set and
use p_home if safe, and only set Rc_name if safe (in all the other cases
it is the empty string, and the fopen() calls fail). Plus, check for
snprintf() truncation (and if it happens, reset Rc_name to the empty
string).
Important note: top.1 should probably be updated, since it mentions the
fallback to the current working directory.
With a little luck, this should be the final tweak for
our support of extra wide characters. Currently, those
characters don't always display the '+' indicator when
they've been truncated. Now, it should always be seen.
[ plus it's done a tad more efficiently via snprintf ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
As it turns out, that Ukrainian 'demo' text supporting
the '=' command was 152 bytes long, up from an English
version of 80 bytes. Unfortunately, the buffer used to
format all such strings was insufficient at 128 bytes.
Depending on the width of one's terminal, some strange
result could be experienced when a multi-byte sequence
was truncated. So, this just makes that buffer bigger.
Signed-off-by: Jim Warner <james.warner@comcast.net>
After wrestling with extra wide characters, supporting
languages like zh_CN, sometimes default/minimum column
widths might force a truncation of translated headers.
So, this commit explores one way that such truncations
could be avoided. It is designed so as to have minimal
impact on existing code, ultimately affecting just one
function. But it's off by default via its own #define.
Signed-off-by: Jim Warner <james.warner@comcast.net>
When I recently added extra wide character support for
locales like zh_CN, I didn't worry about some overhead
associated with the new calls to 'mbtowc' & 'wcwidth'.
That's because such overhead was usually incurred with
user interactions, not a normal iterative top display.
There was, however, one area where this overhead would
impact the normal iterative top mode - that's with the
Summary display. So I peeked at the glibc source code.
As it turns out, the costs of executing those 'mbtowc'
and 'wcwidth' functions were not at all insignificant.
So, this patch will avoid them in the vast majority of
instances, while still enabling extra wide characters.
Signed-off-by: Jim Warner <james.warner@comcast.net>
There is (should be) no justification for changing the
width of the percentage columns (%CPU, %MEM) depending
on the BOOST_PERCNT #define. So this patch will ensure
that both columns are fixed at their former maximum 5.
Signed-off-by: Jim Warner <james.warner@comcast.net>
With the documentation update in the commit referenced
below, we should also account for such threads as they
will already be represented in the task/thread totals.
[ and do it in a way that might avoid future changes ]
Reference(s):
commit a238a687ce
Signed-off-by: Jim Warner <james.warner@comcast.net>
Back when top was refactored to support UTF-8 encoding
it was acknowledged that languages like zh_CN were not
supported. That was because a single 'character' might
require more than a single 'column' when it's printed.
Well I've now figured out how to accommodate languages
like that. My adaptation is represented in this patch.
[ and just in case someone wishes to avoid the extra ]
[ runtime costs, a #define OFF_XTRAWIDE is included. ]
Along the way, I've cleaned up some miscellaneous code
supporting the 'Inspect' feature so that the rightmost
screen column was always used rather than being blank.
[ interestingly, my xterm & urxvt terminal emulators ]
[ are able to split extra wide characters then print ]
[ 1/2 of such graphics in the last column. the gnome ]
[ terminal emulator does not duplicate such behavior ]
[ but prints 1 extra character in same width window. ]
Reference(s):
. Sep, 2017 - original utf8 support
commit 7ef38420a4
Signed-off-by: Jim Warner <james.warner@comcast.net>
When the new approach for startup defaults was adopted
in the reference below, a file might be left open that
technically should be closed. This situation arises in
the unlikely event the #define RCFILE_NOERR is active.
Without that #define, the program will exit early thus
rendering the open file issue moot. However, even with
that #define there was no real harm with an open file.
It simply meant a 2nd FILE struct would have been used
when, or if, the rcfile was written via a 'W' command.
Anyway, this patch ensures such a file will be closed.
Reference(s):
. Dec, 2017 - /etc/topdefaultrc introduced
commit 3e6a208ae5
Signed-off-by: Jim Warner <james.warner@comcast.net>
Those references below offer more detail regarding the
default startup changes beginning with version 3.3.10.
It is important to remember that all such changes were
supposed to impact only new users or users who had not
saved the personal config file (via that 'W' command).
However, I introduced a bug wherein the rcfile was not
fully honored. This gave the changes a bad reputation.
That bug was corrected in release 3.3.11 but the issue
of default startup options keeps resurfacing. And it's
clear there's no consensus on what should be included.
Our --disable-modern-top configure option is of little
help since it remains an all-or-nothing approach. What
we need is an answer offering unlimited customization.
So, this commit will provide distribution packagers or
system administrators with a much more flexible way to
set their own preferred startup default configuration.
A new rcfile is being introduced: '/etc/topdefaultrc',
whose format/content is the same as a personal rcfile.
Thus once a 'proper' enterprise configuration has been
established and saved via 'W', it can be copied to the
/etc/ directory. Thereafter, startup in the absence of
a saved rcfile will use that configuration as default.
Now if a distribution packager or system administrator
wishes to expose their users to some of top's advanced
capabilities they can do so gradually. Perhaps setting
up graph mode for summary area task and memory display
while retaining the %CPU sort could be tried. Or maybe
showing colors, but better customized for a particular
terminal emulator. Such possibilities are now endless.
[ in exploiting this new capability, i hope that the ]
[ other windows (alt display mode) aren't overlooked ]
Reference(s):
. Sep, 2014 - Not fully honoring rcfile bug discussed
https://www.freelists.org/post/procps/top-saved-rcfile-bug
. Oct, 2014 - Attempt to defend new startup defaults
https://bugzilla.redhat.com/show_bug.cgi?id=1153049
. Jul, 2015 - Forest vs. %CPU views discussion
https://gitlab.com/procps-ng/procps/issues/6
. Oct, 2017 - Question the use of --disable-modern-top
https://bugzilla.redhat.com/show_bug.cgi?id=1499410
. Oct, 2017 - Forest vs. %CPU views discussion again
https://www.freelists.org/post/procps/Forest-mode-by-default-in-top-seems-a-bit-strange
. Dec, 2017 - Rehash of 3.3.10 startup defaults change
https://gitlab.com/procps-ng/procps/issues/78
Signed-off-by: Jim Warner <james.warner@comcast.net>
Way back in November of 2011, the library was equipped
with an overridable error message handler function. It
was done expressly for a program like top which alters
the tty. But that support was withdrawn shortly after.
This was all done in the lead up to v3.3.2. That's the
release where NLS support was added and it represented
a hectic time. In hindsight, the changes went too far.
So this commit, in a minimal fashion, restores ability
to address a potential fatal library error. After all,
any properly behaving library would never unilaterally
subject a caller to a stderr message and then an exit.
[ when exposing 1 variable in libprocps.sym, 2 other ]
[ existing symbols were repositioned alphabetically. ]
Reference(s):
. generalized library memory provisions
commit 7126cc4491
. top exploit library memory provisions
commit 88087ec5a5
. library xalloc type functions made private
commit 2865ded64e
. restored prior top memory logic
commit 05f5deb97c
Signed-off-by: Jim Warner <james.warner@comcast.net>
After noticing that the 'uk' translation expanded what
was supposed to be a 3 line header into 5 lines, seems
appropriate to offer more guidance on max lines count.
Signed-off-by: Jim Warner <james.warner@comcast.net>
And I thought those strange characters I saw with only
certain translations in Fields Management descriptions
were resulting from my terminal emulator deficiencies.
Turns out that ol' top wasn't addressing possibilities
of such descriptions ending with multi-byte sequences.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Initially, I was going to ignore that coverity warning
CID #177876. But, since top may be running SETUID it's
best if it can be avoided instead. The fix was simple.
We'll trade the access() call for a real fopen() call.
This time-of-check-time-of-use warning should go away.
------------------------------------------------------
When XDG support was originally introduced in top, the
author made a poor choice in access(). A real question
that needed asking was 'does the file exist'. However,
the question that was asked was 'can this real user ID
or this real group ID access the file'. Then, when the
fopen() is finally issued, top would use the effective
user ID or the effective group ID to access that file.
That's what opened the potential TOCTOU vulnerability,
which was important only if top was running SUID/SGID.
Signed-off-by: Jim Warner <james.warner@comcast.net>
By eliminating the call to 'fmtmk', the 'utf8_justify'
function could more easily be used in libproc someday.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Gosh, all this time we used indents of 4 spaces, not 3
spaces which were always the top standard indentation.
[ and we made our 'utf8_embody' a little more robust ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
The top man page was changed back on 10/20/15, in that
commit shown below. There, freelists.org was suggested
as the bug reports recipient. But, the program was not
changed from the original Debian bug reports approach.
Reference(s):
commit b1f7b2a509
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch better exploits short-circuit evaluation in
two 'if' tests. In every case, the 1st of 2 conditions
in each 'if' test must take place but it always proves
true with each iteration for 1 of the 'if' statements.
Thus, the 2nd condition will have to be evaluated too.
By reordering 2 tests in each 'if', we can ensure that
the 2nd condition will then be tested much less often.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Upon reflection, there was absolutely no justification
for that call to strlen() which was then followed by a
call to snprintf(). The latter provides this needed #.
[ also make that 'delta' value a little more visible ]
[ instead of hiding it at the end of a its code line ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
Now that top can properly handle translated multi-byte
strings I've been reviewing translated efforts so far,
and weighing output against related translation hints.
In one case, a translation hint has not kept pace with
the current program state. In addition, that same hint
could be expanded to suggest translation alternatives.
[ frankly I never expected the translators to tackle ]
[ some of those 'special' strings. the task appeared ]
[ just too daunting. but they have done a great job! ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
With the help of our Swedish translator, hopefully the
final buglet has now been vanquished in the multi-byte
translation support. This one was a real nasty bugger.
Although it didn't occur with every terminal emulator,
occasionally random text lines were being chopped off.
As it turns out, those terminals were blameless. There
were two separate places in top's show_special routine
where potential multi-byte sequences were inadequately
addressed. Solution: exploit existing utf-8 functions.
[ it also became apparent that the translation hints ]
[ in the top_nls module were deficient. so a special ]
[ caution was added regarding the final line of txt. ]
Reference(s):
https://gitlab.com/procps-ng/procps/issues/68
Signed-off-by: Jim Warner <james.warner@comcast.net>
Unlike the insp_mkrow_raw function the insp_mkrow_utf8
routine is not equipped to print non-ctl, non-printing
characters like '<7f>'. However, technically that very
value currently slips through the cracks. So with this
patch top will now print a space in the unlikely event
a character with the value of 127 is ever encountered.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Since all the necessary utf-8 plumbing is now in place
this commit will extend multi-byte support to user and
group names. Now top will be on a par with the ps guy.
[ plus, it's also my way of showing appreciation for ]
[ all those investments silently made by translators ]
Reference(s):
https://gitlab.com/procps-ng/procps/issues/68
Signed-off-by: Jim Warner <james.warner@comcast.net>
