The apparmor.d manpage listed 'to' as an alternative for '->' in link
rules.
However, the parser doesn't accept 'to', none of our examples and tests
include it, and nobody ever complained about it. Therefore I'll call
this a documentation bug ;-) and simply adjust the manpage to only list
'->' as valid syntax.
Add userland support for matching based on extended file attributes. This
leverages DFA based matching already in the kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8e51f908https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73f488cd
Matching is exposed via flags on the profile:
/usr/bin/* xattrs=(user.foo=bar user.bar=foo) {
# ...
}
xattr values are appended to the existing xmatch via a null transition.
$ echo '/usr/bin/* xattrs=(user.foo=foo user.bar=bar) {}' | \
./parser/apparmor_parser -QT -D expr-tree
DFA: Expression Tree
/usr/bin/[^\0000/]([^\0000/])*(\0000bar)?(\0000foo)?< 0x1>
DFA: Expression Tree
(\a|(\n|(\0002|\t)))< 0x4>
Tested manually on a 4.19 kernel via QEMU+KVM.
TODO:
* ~~Add regression tests~~ (EDIT: done)
* ~~EDIT: add support in the tools~~ (EDIT: done)
Questions for reviewers:
* ~~parser/libapparmor: regex construction probably needs cleaning up~~ (EDIT: done)
* ~~parser/parser_regex.c: confused what xmatch length is for~~ (EDIT: done)
/cc @mjg59
PR: https://gitlab.com/apparmor/apparmor/merge_requests/270
Signed-off-by: John Johansen <john.johansen@canonical.com>
I slightly ;-) doubt we'll change the module name.
PR: https://gitlab.com/apparmor/apparmor/merge_requests/354
Signed-off-by: Christian Boltz <apparmor@cboltz.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Compiling the parser currently prints a deprecation warning. Remove
throw(int) annotations from function signatures. These aren't required
to catch exceptions. This gets us closer to possibly enabling '-Werror'
in the future.
For example, the following program catches the exception without a
throw(int) annotation:
#include <iostream>
void throw_an_error()
{
throw 3;
return;
}
int main ()
{
try
{
throw_an_error();
}
catch (int e)
{
std::cout << "caught exception " << e << '\n';
}
return 0;
}
This program prints:
$ g++ -o error error.cc
$ ./error
caught exception 3
PR: https://gitlab.com/apparmor/apparmor/merge_requests/356
Signed-off-by: Eric Chiang <ericchiang@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Note that $PARSER_OPTS has to stay without quotes because it can
sometimes be empty, and would (if quoted) be interpreted as empty
filename by apparmor_parser
Compiling the parser currently prints a deprecation warning. Remove
throw(int) annotations from function signatures. These aren't required
to catch exceptions.
For example, the following program catches the exception without a
throw(int) annotation:
#include <iostream>
void throw_an_error()
{
throw 3;
return;
}
int main ()
{
try
{
throw_an_error();
}
catch (int e)
{
std::cout << "caught exception " << e << '\n';
}
return 0;
}
This program prints:
$ g++ -o error error.cc
$ ./error
caught exception 3
Signed-off-by: Eric Chiang <ericchiang@google.com>
Extend the subshell so that the actual (possibly non-zero) value of
$retval gets returned. Before, the changed value was lost at "done"
(= leaving the subshell), and the initial $retval=0 was returned.
(found with shellcheck)
parser: determine xmatch priority based on smallest DFA match
The length of a xmatch is used to prioritize multiple profiles that
match the same path, with the intent that the more specific match wins.
Currently, the length of a xmatch is computed by the position of the
first regex character.
While trying to work around issues with no_new_privs by combining
profiles, we noticed that the xmatch length computation doesn't work as
expected for multiple regexs. Consider the following two profiles:
profile all /** { }
profile bins /{,usr/,usr/local/}bin/** { }
xmatch_len is currently computed as "1" for both profiles, even though
"bins" is clearly more specific.
When determining the length of a regex, compute the smallest possible
match and use that for xmatch priority instead of the position of the
first regex character.
PR: https://gitlab.com/apparmor/apparmor/merge_requests/326
Signed-off-by: John Johansen <john.johansen@canonical.com>
Update the indetation of work_spawn to correct for the changes made in
cb43e57d27 ("parser: Fix parser failing to handle errors when setting up work")
the indetation was not updated in that patch to make the changes made
easier to review and see in diffs.
Signed-off-by: John Johansen <john.johansen@canonical.com>
The parser is not correctly handling some error conditions when
dealing with work units. Failure to spawn work, access files, etc
should be returned where appropriate, and be able to abort processing
if abort_on_error is set.
In addition some errors are leading to a direct exit without checking
for abort_on_error.
BugLink: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=921866
BugLink: http://bugs.launchpad.net/bugs/1815294
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Eric Chiang <ericchiang@google.com>
The length of a xmatch is used to prioritize multiple profiles that
match the same path, with the intent that the more specific match wins.
Currently, the length of a xmatch is computed by the position of the
first regex character.
While trying to work around issues with no_new_privs by combining
profiles, we noticed that the xmatch length computation doesn't work as
expected for multiple regexs. Consider the following two profiles:
profile all /** { }
profile bins /{,usr/,usr/local/}bin/** { }
xmatch_len is currently computed as "1" for both profiles, even though
"bins" is clearly more specific.
When determining the length of a regex, compute the smallest possible
match and use that for xmatch priority instead of the position of the
first regex character.
This change updates parser/Makefile to respect target dependencies and
not rebuild apparmor_parser if nothing's changed. The goal is to allow
cross-compiled tests #17 to run on a target system without the tests
attempting to rebuild the parser.
Two changes were made:
* Generate af_names.h in a script so the script timestamp is compared.
* Use FORCE instead of PHONY for libapparmor_re/libapparmor_re.a
Changes to list_af_names are intended to exactly replicate the old
behavior.
Signed-off-by: Eric Chiang <ericchiang@google.com>
Commit 0d5ab43d59 removed support for loading
modules and introduced a caller, in apparmor_start(), that passes no argument to
is_apparmor_present(), which breaks that function when /bin/sh → /bin/dash.
Passing a module name as argument does not make sense since we dropped support
for the long obsolete "subdomain" module, so let's simplify
is_apparmor_present() and adjust its callers accordingly.
Bug-Debian: https://bugs.debian.org/917874
Since 04eb2fe3, __parse_profiles_dir can only return 0 or 1, so $STATUS can only
be 0 or 1, so trying to reset this variable to 0 when its value is 2 can only
cause confusion.
Expr tree simplification makes multiple passes at simplifying the
expression tree trying to use fatoring rules and heuristics to achieve
the minimum tree, so that dfa construction has fewer nodes to deal
with.
Unfortunately expr tree simplification can slow some policy compiles,
dependent on the type of expressions generated, down, and even worse
is currently subject to never terminating on some expressions as the
left and right passes keep undoing each others work.
Limiting the number of passes that expr tree simplification does can
provide most of its benefits (later passes generally have diminishing
returns), reduces the overhead it has on simple policy where it is of
little benefit, and insures that simplifications can not get stuck in
an infinite loop due to the left and right passes ping-ponging on each
others factoring.
Note: This also results in a performance improvement in evince
compiles, and general policy compiles because it achieves a better
balance between time spent on simplifying the tree to remove nodes and
time the dfa build requires to build with extra nodes and then
eliminate with minimization.
$ time apparmor_parser -QT /etc/apparmor.d/usr.bin.evince
real 0m2.744s
user 0m2.714s
sys 0m0.028s
vs.
$ time apparmor_parser -QT /etc/apparmor.d/usr.bin.evince
real 0m2.992s
user 0m2.979s
sys 0m0.012s
and
$ time apparmor_parser -QT /etc/apparmor.d/
real 0m3.568s
user 0m14.529s
sys 0m0.152s
vs.
$ time apparmor_parser -QT /etc/apparmor.d/
real 0m3.741s
user 0m15.400s
sys 0m0.179s
PR: https://gitlab.com/apparmor/apparmor/merge_requests/246
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
aa-eventd and its initscripts have been moved to deprecated/ in 2014 and
didn't get any serious updates for several more years, so it's most
probably useless and/or broken nowadays.
This also means we don't need to keep the AA_EV_BIN and AA_EV_PIDFILE
variables in rc.apparmor.functions anymore.
The apparmor kernel "module" has not been a loadable module for more
than a decade, it must be built into the kernel and due configuration
requirements it will never go back to being a loadable module.
Remove the long unfunctioning load_module support from the init script.
PR: https://gitlab.com/apparmor/apparmor/merge_requests/257
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: seth.arnold@canonical.com
Elaborate in class comment of firstpos, lastpos, followpos, and nullable
fields beyond just referencing the Dragon book. Also add the section of
the book these are explained in.
If a test is marked as TODO, but matches its EXRESULT, this means the
TODO is superfluous and (probably) a change fixed what the TODO was for.
Instead of more or less ignoring such superfluous TODOs, error out to
make the change visible instantly.
Both result in "superfluous TODO" (for unknown reason), but fail after
removing the TODO.
Disable the tests until we find out why they have this strange
behaviour, to unblock merging the "error out on superfluous TODO" patch.
Remove TODO notes from no-longer-failing tests
See merge request apparmor/apparmor!180
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: intrigeri <intrigeri@debian.org>
Imported from the Debian/Ubuntu packaging. We need this function so that
Debian/Ubuntu can switch to using this shell library instead of their own code.
