The current checks allow out-of-range values (for example, if
getenv/atoi returns ~-2GB, maxcmd becomes ~+2GB after the subtraction).
This is not a security problem, none of this is under an attacker's
control.
With the Qualys security audit, we began to harden our
treatment of the top rcfile. In particular, the values
read were checked so as to prevent some malicious user
from editing it in order to achieve an evil objective.
However when it came to colors I was surprised to find
that at least one user edited the rcfile for 256-color
support. Unfortunately, our new checks prevented this.
So this commit will provide the means to exploit those
extra colors with no need to manually edit the rcfile.
Reference(s):
https://gitlab.com/procps-ng/procps/issues/96
Signed-off-by: Jim Warner <james.warner@comcast.net>
It's good that those Qualys folks were looking over my
shoulder. They suggested a change to that commit shown
below. This improvement was obviously a better choice.
Reference(s):
. original change
commit f9a8009e27
Signed-off-by: Jim Warner <james.warner@comcast.net>
Following that patch referenced below, the top SUPGRPS
field would produce a segmentation fault and ps SUPGRP
would often show "(null)". Such problems resulted from
some faulty logic in the status2proc() routine dealing
with 'Groups' (supgid) which served as a source field.
For many processes the original code produced an empty
string which prevented conversion to the expected "-".
Moreover, prior to release 3.3.15 such an empty string
will become 0 after strtol() which pwcache_get_group()
translates to 'root' yielding very misleading results.
So, now we'll check for empty '/proc/#/status/Groups:'
fields & consistently provide a "-" value for callers.
[ we'll also protect against future problems in that ]
[ new qualys logic by always ensuring valid 'supgrp' ]
[ pointers - logic which revealed our original flaw! ]
Reference(s):
. original qualys patch
0071-proc-readproc.c-Harden-supgrps_from_supgids.patch
Signed-off-by: Jim Warner <james.warner@comcast.net>
The free manpage used the correct unit names (e.g. membibyte) but the
incorrect unit (e.g. M ) for the human-readable option.
References:
https://bugs.debian.org/898774
Signed-off-by: Craig Small <csmall@enc.com.au>
This guards against rcfile 'Inspect' entries which may
include non-printable characters. While this shouldn't
occur, we have no real control over those crazy users.
[ and, while such data can't be used maliciously, it ]
[ does adversely impact such a user's screen display ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
When a Qualys patch was reverted as being unwarranted,
1 specific problem their patch had, in fact, prevented
was re-introduced. This patch corrects that oversight.
Reference(s):
. qualys patch revert
commit c502678715
Signed-off-by: Jim Warner <james.warner@comcast.net>
Until the Qualys security audit I had never considered
it a possibility that some malicious person might edit
the top config file to achieve some nefarious results.
And while the Qualys approach tended to concentrate on
the symptoms from such an effort, subsequent revisions
more properly concentrated on startup and that rcfile.
This commit completes those efforts with 1 more field.
Signed-off-by: Jim Warner <james.warner@comcast.net>
I've long since forgotten why the attempt to influence
groff line lengths was made. However, I did receive an
email regarding problems formatting postscript output.
Hopefully this patch will eliminate any such problems.
Signed-off-by: Jim Warner <james.warner@comcast.net>
The library now presents command names up to 64 characters, in line with
the kernel changes. ps command name selection (the -C option) now also
is 64 characters long.
References:
commit 2cfdbbe897
The referenced commit removed the warning for using pgrep with over
15 characters. The check for this warning needs to also be removed.
References:
commit c32ab58b94
The command name for running tasks is displayed by top
in a variable length field, so the increase from 16 to
64 bytes was not a problem. However, there's one place
where top is sensitive to length - insp_view_choice().
So, this patch just bumps a buffer used to display it.
Reference(s):
. increased 'comm' length
commit 2cfdbbe897
Signed-off-by: Jim Warner <james.warner@comcast.net>
This will protect some remaining rcfile variables from
a possible manual editing of top's configuration file.
[ and correct two #error related boo-boos introduced ]
[ with the system default rcfile in the commit shown ]
Reference(s):
. introduced /etc/topdefaultrc
commit 3e6a208ae5
Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit moves some overhead to the Batch mode path
where it's needed. And given the new 'else if' test we
can delete some now redundant logic in the other path.
Reference(s):
. original qualys patch
0117-top-Prevent-out-of-bounds-writes-in-PUFF.patch
commit 059ae8b512
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch addresses a potential (but unlikely) buffer
overflow by reducing, if necessary, a memcpy length by
3 bytes to provide for an eol '\0' and 2 unused buffer
positions which also might receive the '\0' character.
[ note to future analysis tool: just because you see ]
[ binary data being manipulated in the routine, that ]
[ doesn't mean such function was passed binary data! ]
Reference(s):
. original qualys patch
0116-top-Fix-out-of-bounds-read-write-in-show_special.patch
commit ed8f6d9cc6
Signed-off-by: Jim Warner <james.warner@comcast.net>
I'm reverting this patch to prepare for some alternate
solution. In that solution I will address point #1 but
point #2 is based on a wrong assumption. There will be
no binary data ever found in the 'glob' passed to this
show_special() function. It is now always simple text.
------------------------------------------------ original commit message
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.
------------------------------------------------------------------------
Reference(s):
. original qualys patch
0116-top-Fix-out-of-bounds-read-write-in-show_special.patch
commit ed8f6d9cc6
Signed-off-by: Jim Warner <james.warner@comcast.net>
Whereas that original patch (since reversed) addressed
some symptoms related to manually edited config files,
this solution deals with root causes. And it goes much
beyond any single top field by protecting all of top's
fields. Henceforth, a duplicated field is not allowed.
Reference(s):
. original qualys patch
0114-top-Prevent-buffer-overflow-in-calibrate_fields.patch
commit c424a64331
Signed-off-by: Jim Warner <james.warner@comcast.net>
Here, again, we have an example of attacking a problem
by addressing the symptoms. And that assertion made in
the original commit message is true if only if someone
had manually (maliciously) edited the top config file.
So let's reverse the original patch & thus prepare for
a proper solution addressing the cause, not a symptom.
Reference(s):
. original qualys patch
0114-top-Prevent-buffer-overflow-in-calibrate_fields.patch
commit c424a64331
Signed-off-by: Jim Warner <james.warner@comcast.net>
The whole idea was to make top's 'scat' function small
and very quick, unlike that standard 'strcat' routine.
To achieve that end we ignore the potential for buffer
overruns and trust callers to provide adequate dest's.
Reference(s):
. original qualys patch
0109-top-Protect-scat-from-buffer-overflows.patch
commit 9c745975b2
Signed-off-by: Jim Warner <james.warner@comcast.net>
This is as far as we need go with respect to the issue
of integer overflow addressed in that reference below.
That patch, of course, was reversed to prepare for us.
Reference(s):
. original qualys patch
0105-top-Prevent-integer-overflows-in-procs_refresh.patch
commit 131e5e2fe6
Signed-off-by: Jim Warner <james.warner@comcast.net>
That patch referenced below is being reverted because:
. By design, no other top macro looks like a function.
Instead, they all contain some minimal capitalization.
The 'grow_by_size' macro stands out like a sore thumb.
. We would need to approach 400+ million tasks for for
the 1st addressed problem to produce integer overflow.
. And a 2nd check against SSIZE_MAX remains a mystery.
Me thinks a system on which top is running will suffer
ENOMEM before we need to worry about integer overflow.
Reference(s):
. original qualys patch
0105-top-Prevent-integer-overflows-in-procs_refresh.patch
commit 131e5e2fe6
Signed-off-by: Jim Warner <james.warner@comcast.net>
Rather than validate the window's 'sortindx' each time
it was referenced (as was done in the patch below), we
now ensure the validity just once when the config file
is read. Thereafter, a running top will police bounds.
Reference(s):
. original qualys patch
0102-top-Check-sortindx.patch
commit d5b8ac7139
Signed-off-by: Jim Warner <james.warner@comcast.net>
Here's yet another example of dealing with a potential
problem at the symptom level, instead of addressing it
at the source. So, we will reverse that original patch
referenced below in preparation for a proper solution.
[ at the least, this ugly code should have used that ]
[ existing MAXTBL macro, making it a little prettier ]
Reference(s):
. original qualys patch
0102-top-Check-sortindx.patch
commit d5b8ac7139
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch replaces an original patch referenced below
which has now been reversed. We now validate variables
'graph_cpus', 'graph_mems' and 'summ_mscale' just once
at startup. Thereafter, top enforces the proper range.
[ we afford the same treatment to that 'task_mscale' ]
[ variable, which was ignored in the original patch. ]
Reference(s):
. original qualys patch
0099-top-Check-graph_cpus-graph_mems-and-summ_mscale.patch
commit cd8ba5670e
Signed-off-by: Jim Warner <james.warner@comcast.net>
The variables graph_cpus, graph_mems & summ_mscale are
all well managed in a running top. They were, however,
each vulnerable to tampering via the rcfile. So rather
than continually addressing the symptoms, we'll attack
the root cause just once at startup in the next patch.
Reference(s):
. original qualys patch
0099-top-Check-graph_cpus-graph_mems-and-summ_mscale.patch
commit cd8ba5670e
Signed-off-by: Jim Warner <james.warner@comcast.net>
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>
As comm length can be longer than 15 characters with newer kernels, it
doesn't make sense to have a warning when you make the match string
longer than this.
As a side-effect, it removes the false-positive you got when you used
long regex matches (see issue #92 )
References:
commit 2cfdbbe897procps-ng/procps#92
For many years, the comm length has been set to 16. Previously to that
it was 8. This means for things like kworkers they all have very cryptic
names. The kernel is now going to increase this size to 64, so the
procps library will follow this length increase.
System tools may also increase their default length to 64, or keep it at
16; there is only so much screen real estate.
References:
https://lkml.org/lkml/2018/5/17/16
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()."
