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>
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>
For our master branch, a Qualys patch referenced below
was reverted as being unwarranted. That original patch
was not applied in this branch so there was no revert.
However, there was 1 specific problem their patch had,
in fact, prevented. Thus, this patch now addresses it.
Reference(s):
. original qualys patch
0109-top-Protect-scat-from-buffer-overflows.patch
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>
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>
This refactor was done in response to the Qualys patch
referenced below, which deals with some 'readeither()'
flaws under the master branch. Under our newlib branch
those flaws mostly disappear since the function is now
private. But without a redesign the #define is broken.
When the #define FALSE_THREADS is active, some special
strings showing "[ duplicate ENUM ]" will appear under
each child thread. Note that the real reason for those
appearing isn't being exercised, only their mechanics.
In reality, they only show when a user duplicates such
enums in a results stack & only 1 instance can own it.
Reference(s):
. original qualys patch
0084-proc-readproc.c-Work-around-a-design-flaw-in-readeit.patch
. QUICK_THREADS became FALSE_THREADS
commit c546d9dd44
Signed-off-by: Jim Warner <james.warner@comcast.net>
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):
. master branch increase to 64
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 55a42ae040
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
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
Signed-off-by: Jim Warner <james.warner@comcast.net>
Whereas an original patch (referenced below) 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
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
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch replaces an original patch referenced below
(omitted under this branch). 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
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
Signed-off-by: Jim Warner <james.warner@comcast.net>
In the new library 'cmd' is dynamically allocated just
like 'cmdline'. This will align us with the ref below.
Reference(s):
. master branch increase to 64
commit 2cfdbbe897
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().
- 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).
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()).
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()."
---------------------------- adapted for newlib branch
. the 'isBUSY' macro is quite different under newlib
Signed-off-by: Jim Warner <james.warner@comcast.net>
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.
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.
readeither() caches (in new_p) a pointer to the proc_t of a task-group
leader, but readeither()'s callers can do pretty much anything with the
proc_t structure passed to and/or returned by this function. For
example, they can 1/ free it or 2/ recycle it (by passing it to
readeither() as x).
1/ leads to a use-after-free, and 2/ leads to unexpected behavior when
taskreader()/simple_readtask() is called with new_p equal to x (this is
not a theoretical flaw: 2/ happens in readproctab3() when want_task()
returns false and p is a group leader).
As a workaround, we keep a copy of new_p's first member (tid) in static
storage, and the next times we enter readeither() we check this "canary"
against the tid in new_p: if they differ, we reset new_p to NULL, which
forces the allocation of a new proc_t (the new "leader", or reference).
This always detects 2/ (because free_acquired(x,1) memsets x and hence
new_p); always detects 1/ if freed via free_acquired() and/or freeproc()
(very likely, otherwise memory may be leaked); probably detects 1/ even
if freed directly via free() (because the canary is the first member of
proc_t, likely to be overwritten by free()); but can not detect 1/ if
free() does not write to new_p's chunk at all.
Moreover, accessing new_p->tid to check the canary in case 1/ is itself
a use-after-free, so a better long-term solution should be implemented
at some point (we wanted to avoid intrusive and backward-incompatible
changes in this library function, hence this imperfect workaround).
---------------------------- adapted for newlib branch
. adapted via 'patch' (rejected due to 'xcalloc' ref)
. with loss of both readproctab functions, most no longer true
Signed-off-by: Jim Warner <james.warner@comcast.net>
If QUICK_THREADS is not defined (it is not by default, but most
distributions enable it) and task_dir_missing is true (only on very old
kernels), then readtask() forgets to reset some of the struct proc_t t's
members, which later results in double-free()s in free_acquired().
For now, we simply synchronized the list of members to be reset with the
list of members freed in free_acquired().
---------------------------- adapted for newlib branch
. now 'cmd' is also dynamic
. just synchronized with those freed in free_acquired
. QUICK_THREADS is now FALSE_THREADS, serving different purpose
. entire patch will be effectively reverted with upcoming refactor
Signed-off-by: Jim Warner <james.warner@comcast.net>
Replace xmalloc() with xcalloc().
---------------------------- adapted for newlib branch
. trade xcalloc() for calloc()
. thus we must account for potential ENOMEM
Signed-off-by: Jim Warner <james.warner@comcast.net>
Replace memcpy+strcpy with snprintf.
---------------------------- adapted for newlib branch
. adapted via 'patch' (without rejections)
Signed-off-by: Jim Warner <james.warner@comcast.net>
Check the return value of snprintf(), otherwise dst may point
out-of-bounds when it reaches the end of the dst_buffer (the snprintf()
always returns 1 in that case, even if there is not enough space left),
and vMAX becomes negative and is passed to snprintf() as a size_t.
---------------------------- adapted for newlib branch
. adapted via 'patch (without rejections)
Signed-off-by: Jim Warner <james.warner@comcast.net>
This detects an integer overflow of "strlen + 1", prevents an integer
overflow of "tot + adj + (2 * pSZ)", and avoids calling snprintf with a
string longer than INT_MAX. Truncate rather than fail, since the callers
do not expect a failure of this function.
---------------------------- adapted for newlib branch
. logic is now in pids.c
. former 'vectorize_this_str' is now 'pids_vectorize_this'
Signed-off-by: Jim Warner <james.warner@comcast.net>
1/ Prevent an out-of-bounds write if sz is 0.
2/ Limit sz to INT_MAX, because the return value is an int, not an
unsigned int (and because if INT_MAX is equal to SSIZE_MAX, man 2 read
says "If count is greater than SSIZE_MAX, the result is unspecified.")
3/ Always null-terminate dst (unless sz is 0), because a return value of
0 because of an open() error (for example) is indistinguishable from a
return value of 0 because of an empty file.
4/ Use an unsigned int for i (just like n), not an int.
5/ Check for snprintf() truncation.
---------------------------- adapted for newlib branch
. adapted via 'patch (without rejections)
Signed-off-by: Jim Warner <james.warner@comcast.net>
Note: this is by far the most important and complex patch of the whole
series, please review it carefully; thank you very much!
For this patch, we decided to keep the original function's design and
skeleton, to avoid regressions and behavior changes, while fixing the
various bugs and overflows. And like the "Harden file2str()" patch, this
patch does not fail when about to overflow, but truncates instead: there
is information available about this process, so return it to the caller;
also, we used INT_MAX as a limit, but a lower limit could be used.
The easy changes:
- Replace sprintf() with snprintf() (and check for truncation).
- Replace "if (n == 0 && rbuf == 0)" with "if (n <= 0 && tot <= 0)" and
do break instead of return: it simplifies the code (only one place to
handle errors), and also guarantees that in the while loop either n or
tot is > 0 (or both), even if n is reset to 0 when about to overflow.
- Remove the "if (n < 0)" block in the while loop: it is (and was) dead
code, since we enter the while loop only if n >= 0.
- Rewrite the missing-null-terminator detection: in the original
function, if the size of the file is a multiple of 2047, a null-
terminator is appended even if the file is already null-terminated.
- Replace "if (n <= 0 && !end_of_file)" with "if (n < 0 || tot <= 0)":
originally, it was equivalent to "if (n < 0)", but we added "tot <= 0"
to handle the first break of the while loop, and to guarantee that in
the rest of the function tot is > 0.
- Double-force ("belt and suspenders") the null-termination of rbuf:
this is (and was) essential to the correctness of the function.
- Replace the final "while" loop with a "for" loop that behaves just
like the preceding "for" loop: in the original function, this would
lead to unexpected results (for example, if rbuf is |\0|A|\0|, this
would return the array {"",NULL} but should return {"","A",NULL}; and
if rbuf is |A|\0|B| (should never happen because rbuf should be null-
terminated), this would make room for two pointers in ret, but would
write three pointers to ret).
The hard changes:
- Prevent the integer overflow of tot in the while loop, but unlike
file2str(), file2strvec() cannot let tot grow until it almost reaches
INT_MAX, because it needs more space for the pointers: this is why we
introduced ARG_LEN, which also guarantees that we can add "align" and
a few sizeof(char*)s to tot without overflowing.
- Prevent the integer overflow of "tot + c + align": when INT_MAX is
(almost) reached, we write the maximal safe amount of pointers to ret
(ARG_LEN guarantees that there is always space for *ret = rbuf and the
NULL terminator).
---------------------------- adapted for newlib branch
. there were many formatting differences
. i introduced several myself (especially comments)
. stdlib 'realloc' used, not that home grown xrealloc
. stdlib 'realloc' required extra 'return NULL' statement
Signed-off-by: Jim Warner <james.warner@comcast.net>
1/ Replace sprintf() with snprintf() (and check for truncation).
2/ Prevent an integer overflow of ub->siz. The "tot_read--" is needed to
avoid an off-by-one overflow in "ub->buf[tot_read] = '\0'". It is safe
to decrement tot_read here, because we know that tot_read is equal to
ub->siz (and ub->siz is very large).
We believe that truncation is a better option than failure (implementing
failure instead should be as easy as replacing the "tot_read--" with
"tot_read = 0").
---------------------------- adapted for newlib branch
. no real changes, patch refused due to mem alloc & failure return
Signed-off-by: Jim Warner <james.warner@comcast.net>
1/ Use a "size_t num" instead of an "unsigned num" (also, do not store
the return value of sscanf() into num, it was unused anyway).
2/ Check the return value of strchr() and strrchr().
3/ Never jump over the terminating null byte with "S = tmp + 2".
---------------------------- adapted for newlib branch
. newlib doesn't use that 'unlikely' crap
. the cmd field is now also dynamic (like cmdline)
. thus we must account for potential ENOMEM
Signed-off-by: Jim Warner <james.warner@comcast.net>
1/ Prevent an integer overflow of t.
2/ Avoid an infinite loop if s contains characters other than comma,
spaces, +, -, and digits.
3/ Handle all possible return values of snprintf().
---------------------------- adapted for newlib branch
. we can't use xrealloc(), so we use realloc() instead
. and must account for a mem failure via a return of 1
Signed-off-by: Jim Warner <james.warner@comcast.net>
1/ Do not read past the terminating null byte when hashing the name.
2/ S[x] is used as an index, but S is "char *S" (signed) and hence may
index the array out-of-bounds. Bit-mask S[x] with 127 (the array has 128
entries).
3/ Use a size_t for j, not an int (strlen() returns a size_t).
Notes:
- These are (mostly) theoretical problems, because the contents of
/proc/PID/status are (mostly) trusted.
- The "name" member of the status_table_struct has 8 bytes, and
"RssShmem" occupies exactly 8 bytes, which means that "name" is not
null-terminated. This is fine right now, because status2proc() uses
memcmp(), not strcmp(), but it is worth mentioning.
---------------------------- adapted for newlib branch
. newlib doesn't use that 'unlikely' crap
. newlib also had a '#ifdef FALSE_THREADS'
Signed-off-by: Jim Warner <james.warner@comcast.net>
This function is unused (SIGNAL_STRING is defined by default, and if it
is not, procps does not compile -- for example, there is no "outbuf" in
help_pr_sig()) but fix it anyway. There are two bugs:
- it accepts non-hexadecimal characters (anything >= 0x30);
- "(c - (c>0x57) ? 0x57 : 0x30)" is always equal to 0x57.
---------------------------- adapted for newlib branch
. newlib doesn't use that 'unlikely' crap
Signed-off-by: Jim Warner <james.warner@comcast.net>
This solves several problems:
1/ outbuf[1] was written to, but not outbuf[0], which was left
uninitialized (well, SECURE_ESCAPE_ARGS() already fixes this, but do it
explicitly as well); we know it is safe to write one byte to outbuf,
because SECURE_ESCAPE_ARGS() guarantees it.
2/ If bytes was 1, the write to outbuf[1] was an off-by-one overflow.
3/ Do not call escape_str() with a 0 bufsize if bytes == overhead.
4/ Prevent various buffer overflows if bytes <= overhead.
Simply rearrange the old comparisons. The new comparisons are safe,
because we know from previous checks that:
1/ wlen > 0
2/ my_cells < *maxcells (also: my_cells >= 0 and *maxcells > 0)
3/ len > 1
4/ my_bytes+1 < bufsize (also: my_bytes >= 0 and bufsize > 0)
