Bug #963756
The kernel has an extended test for change_profile when used with
onexec, that allows it to only work against set executables.
The parser is not correctly mapping change_profile for this test
update the mapping so change_onexec will work when confined.
Note: the parser does not currently support the extended syntax
that the kernel test allows for, this just enables it to work
for the generic case.
Signed-off-by: John Johansen <john.johansen@canonical.com>
The changes are around how user data is handled.
1. permissions are mapped before data is matched
2. If data is to be mapped a AA_CONT_MATCH flag is set in the permissions
which allows data matching to continue.
3. If data auditing is to occur the AA_AUDIT_MNT_DATA flag is set
This allows better control over matching and auditing of data which can
be binary and should not be matched or audited
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>
Currently the backend doesn't like it (blows up) when the a vector entry is
empty. For the case where no flags match build_mnt_flags generates an
alternation of an impossible entry and nothing
(impossible|)
This provides the effect of a null entry without having an empty vector
entry. Unfortunately the impossible entry is not correct.
Note: how this is done needs to be changed and fixed in the next release
this is just a minimal patch to get it working for 2.8
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>
When generating the flag set the parser was not generating the complete
set when flags where not consecutive. This is because the len value
was not being reset for each flag considered, so once it was set for
a flag, then the next flag would have to be set to reset it else the
output string was still incremented by the old len value.
Eg.
echo "/t { mount options=rbind, }" | apparmor_parser -QT -D rule-exprs
results in
rule: \x07[^\000]*\x00[^\000]*\x00[^\000]*\x00\x0d ->
however \x0d only covers the bind and not the recursive flag
This is fixed by adding a continue to the flags generation loop for the
else case.
resulting the dump from above generating
rule: \x07[^\000]*\x00[^\000]*\x00[^\000]*\x00\x0d\x0f ->
\x0d\x0f covers both of the required flags
Also fix the flags output to allow for the allow any flags case. This
was being screened out. By masking the flags even when no flags where
specified.
this results in a difference of
echo "/t { mount, }" | apparmor_parser -QT -D rule-exprs
rule: \x07[^\000]*\x00[^\000]*\x00[^\000]*\x00(\x01|)(\x02|)(\x03|)(\x04|)(\x05|)\x00[^\000]*
becoming
\x07[^\000]*\x00[^\000]*\x00[^\000]*\x00[^\000]*\x00[^\000]*
which is simplified and covers all permissions vs. the first rule output
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>
Add the ability to control mounting and unmounting
The basic form of the rules are.
[audit] [deny] mount [conds]* [device] [ -> [conds] path],
[audit] [deny] remount [conds]* [path],
[audit] [deny] umount [conds]* [path],
[audit] [deny] pivotroot [oldroot=<value>] <path> -> <profile>
remount is just a short cut for mount options=remount
where [conds] can be
fstype=<expr>
options=<expr>
conds follow the extended conditional syntax of allowing either:
* a single value after the equals, which has the same character range as
regular IDS (ie most anything but it can't be terminated with a , (comma)
and if spaces or other characters are needed it can be quoted
eg.
options=foo
options = foo
options="foo bar"
* a list of values after the equals, the list of values is enclosed within
parenthesis () and its has a slightly reduced character set but again
elements can be quoted.
the separation between elements is whitespace and commas.
eg.
options=(foo bar)
options=(foo, bar)
options=(foo , bar)
options=(foo,bar)
The rules are flexible and follow a similar pattern as network, capability,
etc.
mount, # allow all mounts, but not umount or pivotroot
mount fstype=procfs, # allow mounting procfs anywhere
mount options=(bind, ro) /foo -> /bar, # readonly bind mount
mount /dev/sda -> /mnt,
mount /dev/sd** -> /mnt/**,
mount fstype=overlayfs options=(rw,upperdir=/tmp/upper/,lowerdir=/) overlay -> /mnt/
umount,
umount /m*,
Currently variables and regexs are are supported on the device and mount
point. ie.
mount <devince> -> <mount point>,
Regexes are supported in fstype and options. The options have a further
caveat that regexs only work if the option is fs specific option.
eg. options=(upperdir=/tmp/*,lowerdir=/)
regex's will not currently work against the standard options like ro, rw
nosuid
Conditionals (fstype) can only be applied to the device (source) at this
time and will be disregarded in situations where the mount is manipulating
an existing mount (bind, remount).
Options can be specified multiple times
mount option=rw option=(nosuid,upperdir=/foo),
and will be combined together into a single set of values
The ordering of the standard mount options (rw,ro, ...) does not matter
but the ordering of fs specific options does.
Specifying that the value of a particular option does not matter can be
acheived by providing both the positive and negative forms of and option
option=(rw,ro) options=(suid,nosuid)
For the fs specific options specifying that a particular value does not
matter is achieve using a regex with alternations.
Improvements to the syntax and order restrictions are planned for the
future.
Signed-off-by: John Johansen <john.johansen@canonical.com>
policydb is the new matching format, that combines the matching portions
of different rules into a single dfa/hfa. This patch only lays some ground
work it does not add encoding of any rules into the policydb
Signed-off-by: John Johansen <john.johansen@canonical.com>
This is a rather large rearrangement of how a subset of the parser global
variables are defined. Right now, there are unit tests built without
linking against parser_main.c. As a result, none of the globals defined in
parser_main.c could be used in the code that is built for unit tests
(misc, regex, symtab, variable). To get a clean build, either stubs needed
to be added to "#ifdef UNIT_TEST" blocks in each .c file, or we had to
depend on link-time optimizations that would throw out the unused routines.
First, this is a problem because all the compile-time warnings had to be
explicitly silenced, so reviewing the build logs becomes difficult on
failures, and we can potentially (in really unlucky situations) test
something that isn't actually part of the "real" parser.
Second, not all compilers will allow this kind of linking (e.g. mips gcc),
and the missing symbols at link time will fail the entire build even though
they're technically not needed.
To solve all of this, I've moved all of the global variables used in lex,
yacc, and main to parser_common.c, and adjusted the .h files. On top of
this, I made sure to fully link the tst builds so all symbols are resolved
(including aare lib) and removedonly tst build-log silencing (for now,
deferring to another future patchset to consolidate the build silencing).
Signed-off-by: Kees Cook <kees.cook@canonical.com>
Split out the aare_rule bits that encapsulate the convertion of apparmor
rules into the final compressed dfa.
This patch will not compile because of the it needs hfa to export an interface
but hfa is going to be split so just delay until hfa and transtable are
split and they can each export their own interface.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>
attachment specification doesn't contain globbing.
eg.
# profile name and attachment the same - attaches as expected
profile /usr/lib/chromium-browser/chromium-browser
# profile without attachment specification - does not attach as expected
profile chromium-browser
# profile with name and attachment specification where the attachment specification uses globbing - attaches as expected
profile chromium-browser /usr/lib/chromium-browser/chromium-broswer*
# profile with name and attachment specification without globbing - FAILS to attach when it should
profile chromium-browser /usr/lib/chromium-browser/chromium-browser
This occurs because the xmatch_len is not set correctly for the profiles that specify
a name and an attachment specification, where the attachment specification does not
contain globbing characters.
In this situation the correct length for the xmatch_len is the length of the name, as
the shortest possible unambiguous match is the name length.
This patch does not fix a related bug where an attachment specification of ** will not
match (/**) will.
Add the ability to specify the name and attachment of the profile
separately. It does not allow for the attachment specification to
begin with a variable however since variables in profile names is not
currently support this shouldn't be and issue.
Signed-off-by: John Johansen <john.johansen@canonical.com>
commits were made (as well as a few other minor warnings elsewhere).
The Makefile change is to avoid passing -Wstrict-prototypes and
-Wnested-externs to the C++ compiler, which the compiler yells about and
then ignores.
Since we compile with -Wmissing-field-initializers I dropped the
unreferenced zero-width fields in the header structs, and then explicitly
initialized the remaining fields.
I tagged several unused function parameters to silence those warnings.
And finally, I dropped the unused filter_escapes() too.
tree. It is limited in that it doesn't currently handle the permissions of a rule.
conversion output presents an aare -> prce conversion followed by 1 or more expression
tree rules, governed by what the rule does.
eg.
aare: /** -> /[^/\x00][^\x00]*
rule: /[^/\x00][^\x00]* -> /[^\0000/]([^\0000])*
eg.
echo "/foo { /** rwlkmix, } " | ./apparmor_parser -QT -D rule-exprs -D expr-tree
aare: /foo -> /foo
aare: /** -> /[^/\x00][^\x00]*
rule: /[^/\x00][^\x00]* -> /[^\0000/]([^\0000])*
rule: /[^/\x00][^\x00]*\x00/[^/].* -> /[^\0000/]([^\0000])*\0000/[^/](.)*
DFA: Expression Tree
(/[^\0000/]([^\0000])*(((((((((((((<513>|<2>)|<4>)|<8>)|<16>)|<32>)|<64>)|<8404992>)|<32768>)|<65536>)|<131072>)|<262144>)|<524288>)|<1048576>)|/[^\0000/]([^\0000])*\0000/[^/](.)*((<16>|<32>)|<262144>))
This simple example shows many things
1. The profile name under goes pcre conversion. But since no regular expressions where found
it doesn't generate any expr rules
2. /** is converted into the pcre expression /[^\0000/]([^\0000])*
3. The pcre expression /[^\0000/]([^\0000])* is converted into two rules that are then
converted into expression trees.
The reason for this can not be seen by the output as this is actually triggered by
permissions separation for the rule. In this case the link permission is separated
into what is shown as the second rule: statement.
4. DFA: Expression Tree dump shows how these rules are combined together
You will notice that the rule conversion statement is fairly redundant currently as it just
show pcre to expression tree pcre. This will change when direct aare parsing occurs,
but currently serves to verify the pcre conversion step.
It is not the prettiest patch, as its touching some ugly code that is schedule to be cleaned
up/replaced. eg. convert_aaregex_to_pcre is going to replaced with native parse conversion
from an aare straight to the expression tree, and dfaflag passing will become part of the
rule set.
Instead of updating the profile name, allow a profile to have multiple
alternate names. Aliases are now added as alternate names and matched
through the xmatch dfa.
This will allow turning on and off various debug dumps as needed.
Multiple dump options can be specified as needed by using multiple
options.
eg. apparmor_parser -D variables
apparmor_parser -D dfa-tree -D dfa-simple-tree
The help option has also been updated to take an optional argument
to display help about give parameters, currently only dump is supported.
eg. apparmor_parser -h # standard help
apparmor_parser -h=dump # dump info about --dump options
Also Enable the dfa expression tree dumps
Change_profile was broken so that it couldn't parse expressions that
weren't path based or started with a variable. Furthermore if the name
held any expressions it was not hanlded correctly, as it was being passed
directly to dfa conversion without going through glob -> pcre conversion.
Change the globbing conversion to include [^\x00]. This reduces cases of
artifical overlap between globbing rules, and link rules. Link rules
are encoded to use a \0 char to seperate the 2 match parts of the rule.
Before this fix a glob * or ** could match against the \0 seperator
resulting the generation of dfa states for that overlap. This of course
can never happen as \0 is not a valid path name character.
In one example stress policy when adding the rule
owner /** rwl,
this change made the difference between having a dfa with 55152 states
and one with 30019
key words. Deny is also used to subtract permissions from the
profiles permission set.
the audit key word can be prepended to any file, network, or capability
rule, to force a selective audit when that rule is matched. Audit
permissions accumulate just like standard permissions.
eg.
audit /bin/foo rw,
will force an audit message when the file /bin/foo is opened for
read or write.
audit /etc/shadow w,
/etc/shadow r,
will force an audit message when /etc/shadow is opened for writing.
The audit message is per permission bit so only opening the file
for read access will not, force an audit message.
audit can also be used in block form instead of prepending audit
to every rule.
audit {
/bin/foo rw,
/etc/shadow w,
}
/etc/shadow r, # don't audit r access to /etc/shadow
the deny key word can be prepended to file, network and capability
rules, to result in a denial of permissions when matching that rule.
The deny rule specifically does 3 things
- it gives AppArmor the ability to remember what has been denied
so that the tools don't prompt for what has been denied in
previous profiling sessions.
- it subtracts globally from the allowed permissions. Deny permissions
accumulate in the the deny set just as allow permissions accumulate
then, the deny set is subtracted from the allow set.
- it quiets known rejects. The default audit behavior of deny rules
is to quiet known rejects so that audit logs are not flooded
with already known rejects. To have known rejects logged prepend
the audit keyword to the deny rule. Deny rules do not have a
block form.
eg.
deny /foo/bar rw,
audit deny /etc/shadow w,
audit {
deny owner /blah w,
deny other /foo w,
deny /etc/shadow w,
}
This causes the dfa engine to not strip trailing /
and to handle /*/ /**/ and /* and /** cases specially so that directories
don't get matched unintentionally
aare pcre
/foo/* -> /foo/[^/][^/]* so the dir /foo/ will not match the rule
/foo/** -> /foo/[^/].*
/*/foo -> /[^/][^/]*/foo so the rule won't match //foo
/**/foo -> /[^/].*/foo
rules that contain more than a * or ** between dir / elements do not
get converted, ie.
/foo*
/foo**
/foo*/
/foo**/
/*foo
/**foo
/*foo/
/**foo/
there is a known case where this patch is incomplete. When there
exists an alternation that can be empty and * or ** ie.
/{foo,}*
/{foo,*}
