berdav
/
cado
mirror of https://github.com/rd235/cado
1
0
Fork 0
Code Issues Releases Wiki Activity

Initial release (v.0.9)

This commit is contained in:
Renzo Davoli 2016-06-25 14:12:41 +02:00
parent 4311c2e564
commit 68a7dcfa2e
21 changed files with 1626 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

339
COPYING Normal file
View File

@ -0,0 +1,339 @@
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your
freedom to share and change it. By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
modification follow.
GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language. (Hereinafter, translation is included without limitation in
the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
a) You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.
c) If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License. (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,
b) Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,
c) Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.
5. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
6. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.
7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all. For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
9. The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.
10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this. Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.
NO WARRANTY
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.
12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
Appendix: How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) 19yy <name of author>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.

9
Makefile.am Normal file
View File

@ -0,0 +1,9 @@
bin_PROGRAMS = cado caprint
cado_SOURCES = cado.c pam_check.c get_user_groups.c capset_from_namelist.c read_conf.c set_ambient_cap.c
cado_LDADD = -lpam -lpam_misc -lcap
caprint_LDADD = -lcap
man_MANS = cado.1 caprint.1 cado.conf.5

194
README Normal file
View File

@ -0,0 +1,194 @@
introducing CADO: Capability DO.
Cado permits to delegate capabilities to users.
Cado is a capability based sudo. Sudo allows authorized users to run programs
as root (or as another user), cado allows authorized users to run programs with
specific (ambient) capabilities.
Cado is more selective than sudo, users can be authorized to have only specific capabilities (and not others).
INSTALL:
get the source code, from the root of the source tree run:
$ autoreconf -if
$ ./configure
$ make
$ sudo make install
It installs two programs in /usr/local/bin: cado and caprint.
If you want to install the programs in /usr/bin run "./configure --prefix=/usr" instead of "./configure".
Cado needs a configuration file: /etc/cado.conf with the following syntax:
* lines beginning with # are comments
* all the other lines have two fields separated by :, the first field is a capability or a list of
capabilities, the second field is a list of users or groups (group names have @ as a prefix).
Capabilities can be written with or without the cap_ prefix (net_admin means cap_net_admin).
Example of /etc/cado.conf file:
---------------------------------------------
# Capability Ambient DO configuration file
# cado.conf
net_admin: @netadmin,renzo
cap_kill: renzo
--------------------------------------------
The file above allows the user renzo and all the members of the group named netadmin to run programs
neeeding the cap_net_admin capability.
The user renzo can also run programs requiring cap_kill.
The file /etc/cado.conf can be owned by root and have no rw permission for users.
It is also possible to use lists of capabilities:
setgid,setuid: giovanni
or exadecimal masks:
c0: giovanni,@idgroup
$ ls -l /etc/cado.conf
-rw------- 1 root root 100 Jun 19 17:11 /etc/cado.conf
IMPORTANT.
Cado has been designed to work using the minimum set of capability required for its services.
(following the principle of least privilege).
Cado itself is not a seuid executable, it uses the capability mechanism and it has an options to
set its own capabilities. So after each change in the /etc/cado.conf, the capability set should be
recomputed using the following command:
$ sudo cado -s
or
$ sudo cado -sv
(this latter command is verbose and shows the set of capabilties assigned to the capo executable file).
using the example configuration file above, capo would be assigned the following capabilities:
$ sudo cado -sv
Capability needed by cado:
2 0000000000000004 cap_dac_read_search
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001024
$ /sbin/getcap /usr/local/bin/cado
/usr/local/bin/cado = cap_dac_read_search,cap_kill,cap_net_admin+p
-----------------------------------------------------------------
The syntax of cado is simple:
$ cado [options] set_of_capabilities command [args]
for example if the user renzo wants to run a shell having the cap_net_admin capability enabled he can type
the following command:
$ cado net_admin bash
Password:
$
the user will be requested to authenticate himself. If the user has the right to enable cap_net_admin (from the
cado.conf configuration file) and he typed in the correct password, cado starts a new shell with the requested
capability enabled.
It is possible define the set_of_capabilities using a list of capabilities (with or without the cap_prefix)
or exadecimal masks.
In the new shell the user can do all the operations permitted by the enabled capabilities,
in this case, for example, he will be allowed to change the networking configuration, add tuntap
interfaces and so on.
It is possible to show the ambient capability set of a program by reading the /proc/####/status file:
e.g.:
$ grep CapAmb /proc/$$/status
CapAmb: 0000000000001000
(cap_net_admin is the capability #12, the mask is 0x1000, i.e. 1ULL << 12)
-----------------------------------------------------------------
caprint is a simple program which shows the ambient capabilities of a running program.
(a pid of a running process can be specified as an optional parameter, otherwise it shows the capabilities
of caprint itself)
$ caprint
cap_net_admin
$ caprint -l
12 0000000000001000 cap_net_admin
There is an option -p that has been designed to add the current set of ambient capabilities to the shell prompt,
so it is easier for the user to recognize when a shell has some "extra power", so to avoid errors.
In .bashrc or .bash_profile (or in their system-side counterparts in /etc) it is possible to set rules like
the followings:
-----------
if which caprint >&/dev/null ; then
ambient=$(caprint -p)
fi
PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$$ambient '
-----------
The prompt becomes something like:
renzo@host:~$net_admin#
-------------------------------------------------------------------
Some secondary features:
The -v feature shows the set of available capabilities:
$ cado -v
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
$ cado -v net_admin,kill bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Password:
It is useful to show which capability/ies cannot be granted:
$ cado net_admin,kill,setuid bash
cado: Permission denied
$ cado -v net_admin,kill,setuid bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
7 0000000000000080 cap_setuid
12 0000000000001000 cap_net_admin
00000000000010a0
Unavailable ambient capabilities:
7 0000000000000080 cap_setuid
cado: Permission denied
It is possible to enable only the capability allowed by setting the -q option
(with or without -v). Using -q cado does not fail.
$ cado -qv net_admin,kill,setuid bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
7 0000000000000080 cap_setuid
12 0000000000001000 cap_net_admin
00000000000010a0
Unavailable ambient capabilities:
7 0000000000000080 cap_setuid
Password:
Granted ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
renzo@eipi:~/tests/cado/pre$kill,net_admin#

216
README.md
View File

@ -1,2 +1,218 @@
# cado
CADO: Capability DO (like a sudo providing users with just the capabilities they need)
Cado permits to delegate capabilities to users.
Cado is a capability based sudo. Sudo allows authorized users to run programs
as root (or as another user), cado allows authorized users to run programs with
specific (ambient) capabilities.
Cado is more selective than sudo, users can be authorized to have only specific capabilities (and not others).
INSTALL:
get the source code, from the root of the source tree run:
```
$ autoreconf -if
$ ./configure
$ make
$ sudo make install
```
It installs two programs in /usr/local/bin: cado and caprint.
If you want to install the programs in /usr/bin run "./configure --prefix=/usr" instead of "./configure".
Cado needs a configuration file: /etc/cado.conf with the following syntax:
- lines beginning with # are comments
- all the other lines have two fields separated by :, the first field is a capability or a list of
capabilities, the second field is a list of users or groups (group names have @ as a prefix).
Capabilities can be written with or without the cap_ prefix (net_admin means cap_net_admin).
Example of /etc/cado.conf file:
```
# Capability Ambient DO configuration file
# cado.conf
net_admin: @netadmin,renzo
cap_kill: renzo
```
The file above allows the user renzo and all the members of the group named netadmin to run programs
neeeding the cap_net_admin capability.
The user renzo can also run programs requiring cap_kill.
The file /etc/cado.conf can be owned by root and have no rw permission for users.
It is also possible to use lists of capabilities:
```
setgid,setuid: giovanni
```
or exadecimal masks:
```
c0: giovanni,@idgroup
```
IMPORTANT.
Cado has been designed to work using the minimum set of capability required for its services.
(following the principle of least privilege).
```
$ ls -l /etc/cado.conf
-rw------- 1 root root 100 Jun 19 17:11 /etc/cado.conf
```
Cado itself is not a seuid executable, it uses the capability mechanism and it has an options to
set its own capabilities. So after each change in the /etc/cado.conf, the capability set should be
recomputed using the following command:
```
$ sudo cado -s
```
or
```
$ sudo cado -sv
```
(this latter command is verbose and shows the set of capabilties assigned to the capo executable file).
using the example configuration file above, capo would be assigned the following capabilities:
```
$ sudo cado -sv
Capability needed by cado:
2 0000000000000004 cap_dac_read_search
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001024
$ /sbin/getcap /usr/local/bin/cado
/usr/local/bin/cado = cap_dac_read_search,cap_kill,cap_net_admin+p
```
---
The syntax of cado is simple:
```
$ cado [options] set_of_capabilities command [args]
```
for example if the user renzo wants to run a shell having the cap_net_admin capability enabled he can type
the following command:
```
$ cado net_admin bash
Password:
$
```
the user will be requested to authenticate himself. If the user has the right to enable cap_net_admin (from the
cado.conf configuration file) and he typed in the correct password, cado starts a new shell with the requested
capability enabled.
It is possible define the set_of_capabilities using a list of capabilities (with or without the cap_prefix)
or exadecimal masks.
In the new shell the user can do all the operations permitted by the enabled capabilities,
in this case, for example, he will be allowed to change the networking configuration, add tuntap
interfaces and so on.
It is possible to show the ambient capability set of a program by reading the /proc/####/status file:
e.g.:
```
$ grep CapAmb /proc/$$/status
CapAmb: 0000000000001000
```
(cap_net_admin is the capability #12, the mask is 0x1000, i.e. 1ULL << 12)
---
caprint is a simple program which shows the ambient capabilities of a running program.
(a pid of a running process can be specified as an optional parameter, otherwise it shows the capabilities
of caprint itself)
```
$ caprint
cap_net_admin
$ caprint -l
12 0000000000001000 cap_net_admin
```
There is an option -p that has been designed to add the current set of ambient capabilities to the shell prompt,
so it is easier for the user to recognize when a shell has some "extra power", so to avoid errors.
In .bashrc or .bash_profile (or in their system-side counterparts in /etc) it is possible to set rules like
the followings:
```
if which caprint >&/dev/null ; then
ambient=$(caprint -p)
fi
PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$$ambient '
```
The prompt becomes something like:
```
renzo@host:~$net_admin#
```
---
Some secondary features:
The -v feature shows the set of available capabilities:
```
$ cado -v
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
$ cado -v net_admin,kill bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Password:
```
It is useful to show which capability/ies cannot be granted:
```
$ cado net_admin,kill,setuid bash
cado: Permission denied
$ cado -v net_admin,kill,setuid bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
7 0000000000000080 cap_setuid
12 0000000000001000 cap_net_admin
00000000000010a0
Unavailable ambient capabilities:
7 0000000000000080 cap_setuid
cado: Permission denied
```
It is possible to enable only the capability allowed by setting the -q option
(with or without -v). Using -q cado does not fail.
```
$ cado -qv net_admin,kill,setuid bash
Allowed ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
Requested ambient capabilities:
5 0000000000000020 cap_kill
7 0000000000000080 cap_setuid
12 0000000000001000 cap_net_admin
00000000000010a0
Unavailable ambient capabilities:
7 0000000000000080 cap_setuid
Password:
Granted ambient capabilities:
5 0000000000000020 cap_kill
12 0000000000001000 cap_net_admin
0000000000001020
renzo@host:~/tests/cado/pre$kill,net_admin#
```

67
cado.1 Normal file
View File

@ -0,0 +1,67 @@
.TH CADO 1 "June 23, 2016" "VirtualSquare Labs"
.SH NAME
cado \- Capability Ambient DO
.SH SYNOPSIS
.B cado
[
.I OPTIONS
]
[
.I capability_list
.I command
[
.I args
]
]
.SH DESCRIPTION
Cado permits to delegate capabilities to users.
Cado is a capability based sudo. Sudo allows authorized users to run programs as root (or as another user),
cado allows authorized users to run programs with specific (ambient) capabilities.
Cado is more selective than sudo, users can be authorized to have only specific capabilities (and not others).
\fIcapability_list\fR is a comma separated list of capability names or capability masks (exadecimal numbers).
For brevity, the \fBcap_\fR prefix of capability names can be omitted (e.g. \fBnet_admin\fR and \fBcap_net_admin\fR
have the same meaning).
If it is allowed for the current user to run processes with the requested capabilities, the user is asked to
type their password (or to authenticate themselves as required by pam).
Once the authentication succeeds, \fBcado\fR executes the command granting the required ambient capabilities.
The file /etc/cado.conf (see \fBcado.conf\fR(5)) defines which capabilities can be provided by \fBcado\fR to each user.
Cado itself is not a seuid executable, it uses the capability mechanism and it has an options to
set its own capabilities. So after each change in the /etc/cado.conf, the capability set should be
recomputed by root using the command \fBcado -s\fR or \fBcado --setcap\fR.
.SH OPTIONS
.I cado
accepts the following options:
.TP
\fB\-v
.TQ
\fB\-\-verbose
run in verbose mode. \fBcado\fR shows the set of allowed capabilities, requested cababilities, unavailable capabilities and
(in case of -s) the set of capabilities assigned to \fBcado.conf\fR itself.
.TP
\fB\-q
.TQ
\fB\-\-quiet
do not fail in case the user asks for unavailable capabilities, \fBcado.conf\fR in this case grants the intersection between the
set of requested cababilities and the set of allowed capabilities
.TP
\fB\-s
.TQ
\fB\-\-setcap
\fBcado\fR computes the miminal set of capability required by itself and sets the file capability of the cado executable.
.TP
\fB\-h
.TQ
\fB\-\-help
print a short usage banner and exit.
.SH SEE ALSO
\fBcado.conf\fR(5),
\fBcaprint\fR(1),
\fBcapabilities\fR(7)

156
cado.c Normal file
View File

@ -0,0 +1,156 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <unistd.h>
#include <libgen.h>
#include <pam_check.h>
#include <get_user_groups.h>
#include <capset_from_namelist.h>
#include <read_conf.h>
#include <set_ambient_cap.h>
static void printcapset(uint64_t capset, char *indent) {
cap_value_t cap;
int count=0;
for (cap = 0; cap <= CAP_LAST_CAP; cap++) {
if (capset & (1ULL << cap)) {
count ++;
printf("%s%2d %016llx %s\n",indent,cap,1ULL<<cap,cap_to_name(cap));
}
}
if (count > 1)
printf("%s %016llx\n",indent,capset);
}
#define OPTSTRING "hqvs"
struct option long_options[]={
{"help", no_argument, NULL, 'h'},
{"quiet", no_argument, NULL, 'q'},
{"verbose", no_argument, NULL, 'v'},
{"setcap", no_argument, NULL, 'v'},
};
void usage(char *progname) {
fprintf(stderr,"%s - execute a command in a different capability ambient\n\n",progname);
fprintf(stderr,"usage: %s OPTIONS capability_list command [args]\n\n",progname);
fprintf(stderr,"Options:\n");
fprintf(stderr," -h, --help display help message and exit\n");
fprintf(stderr," -q, --quiet do not display warnings, do what it is allowed\n");
fprintf(stderr," -v, --verbose generate extra output\n");
fprintf(stderr," -s, --setcap set the minimun caps for %s (root access)\n",progname);
exit(1);
}
int main(int argc, char*argv[])
{
char *progname=basename(argv[0]);
char **user_groups=get_user_groups();
uint64_t okcaps=get_authorized_caps(user_groups);
uint64_t reqcaps=0;
uint64_t grantcap=0;
int verbose=0;
int quiet=0;
int setcap=0;
while (1) {
int c=getopt_long(argc, argv, OPTSTRING, long_options, NULL);
if (c < 0)
break;
switch (c) {
case 'h': usage(progname);
break;
case 'v': verbose=1;
break;
case 'q': quiet=1;
break;
case 's': setcap=1;
break;
}
}
if (setcap) {
if (geteuid() != 0) {
fprintf(stderr, "setcap requires root access\n");
exit(2);
}
okcaps = get_authorized_caps(NULL);
okcaps |= 1ULL << CAP_DAC_READ_SEARCH;
if (verbose) {
printf("Capability needed by %s:\n", progname);
printcapset(okcaps, " ");
}
if (set_self_capability(okcaps) < 0) {
fprintf(stderr, "Cannot set %s capabilities\n", progname);
exit(2);
}
exit(0);
}
if (verbose) {
printf("Allowed ambient capabilities:\n");
printcapset(okcaps, " ");
}
if (verbose && (argc == optind))
exit(0);
if (argc - optind < 2)
usage(progname);
if (capset_from_namelist(argv[optind], &reqcaps))
exit(2);
if (verbose) {
printf("Requested ambient capabilities:\n");
printcapset(reqcaps, " ");
}
if (reqcaps & ~okcaps) {
if (verbose) {
printf("Unavailable ambient capabilities:\n");
printcapset(reqcaps & ~okcaps, " ");
}
if (!quiet) {
fprintf(stderr,"%s: Permission denied\n",progname);
exit(2);
}
}
grantcap = reqcaps & okcaps;
optind++;
if (pam_check(user_groups[0]) != 0) {
fprintf(stderr,"%s: Authentication failure\n",progname);
exit(2);
}
set_ambient_cap(grantcap);
if (verbose && (reqcaps & ~okcaps)) {
printf("Granted ambient capabilities:\n");
printcapset(grantcap, " ");
}
execvp(argv[optind],argv+optind);
exit(2);
}

11
cado.conf Normal file
View File

@ -0,0 +1,11 @@
# Capability Ambient DO configuration file
# cado.conf example
# syntax list_of_capabilities: list_of_users_or_groups
# lists are comma separated
# items in list_of_capabilities can be capability names, short capability names (without the cap_ prefix) and exadecimal masks.
# using @ as a prefix of a name in list_of_users_or_groups means that it is a groupname instead of a username.
# net_admin: @netadmin,renzo
# net_admin,net_bind_service,net_raw,net_broadcast: @vxvdex
# cap_kill: renzo

43
cado.conf.5 Normal file
View File

@ -0,0 +1,43 @@
.TH CADO.CONF 5 "June 23, 2016" "VirtualSquare Labs"
.SH NAME
cado.conf \- Capability Ambient DO: configuration file
.SH DESCRIPTION
The \fB/etc/cado.conf\fR file is used to configure which ambient cabalities can be provided by \fBcado\fR to users.
\fBcado\fR uses the capability cap_dac_read_search to access \fB/etc/cado.conf\fR, so this configuration does not
need to be readable by users.
All lines beginning with the sign '#' are comments.
Non-comment lines have the following syntax
.nf
\fIlist_of_capabilities\fB:\fI list_of_users_and_groups\fR
.fi
Both \fIlist_of_capabilities\fR and \fIlist_of_users_and_groups\fR are comma separated lists of identifiers.
Items of \fIlist_of_capabilities\fR are capability names or capability masks (exadecimal numbers).
For brevity, the \fBcap_\fR prefix of capability names can be omitted (e.g. \fBnet_admin\fR and \fBcap_net_admin\fR
have the same meaning).
Items of \fIlist_of_users_and_groups\fR are usernames or groupnames (groupnames must be prefexed by '@').
Example of \fBcado.conf\fR file:
.ni
# Capability Ambient DO configuration file
# cado.conf
net_admin: @netadmin,renzo
net_admin,net_bind_service,net_raw,net_broadcast: @vxvdex
cap_kill: renzo
.fi
In this example the renzo's processes can be granted (by \fBcado\fR) cap_net_admin and cap_kill.
cap_net_admin can be acquired by processes owned by users belonging to the netadmin group.
Users in vxvdex can provide their processes with a subset of cap_net_admin, cap_net_bind_service, cap_net_raw and cap_net_broadcast
.SH SEE ALSO
\fBcado\fR(1),
\fBcaprint\fR(1),
\fBcapabilities\fR(7)

55
caprint.1 Normal file
View File

@ -0,0 +1,55 @@
.TH CAPRINT 1 "June 23, 2016" "VirtualSquare Labs"
.SH NAME
caprint \- Capability Ambient Print
.SH SYNOPSIS
.B caprint
[
OPTIONS
]
[
.I pid
]
.SH DESCRIPTION
\fBcaprint\fR shows the ambient capabilities of a running program (whose pid can be specified as an optional parameter, otherwise \fBcaprint\fR
shows the capabilities of caprint itself).
.SH OPTIONS
.I caprint
accepts the following options:
.TP
\fB\-l
.TQ
\fB\-\-long
run in verbose mode. \fBcaprint\fR shows the bitmask for each capability owned by the process and the resulting mask of the capability set.
.TP
\fB\-c
.TQ
\fB\-\-compact
emit a compact output (a single line composed of a comma separated list of the capability short names). This output can be copied as a
capability list for the command \fBcado\fR(1).
.TP
\fB\-p
.TQ
\fB\-\-prompt
this option has been created to provide users with a suitable shell prompt to warn the users of the extra capabilities granted to that shell
(and of the extra danger in case of running wrong commands).
As an example, it is possible to set the \fBbash\fR prompt editing the \fB.bashrc\fR in the user's home directory:
.nf
if which caprint >&/dev/null ; then
ambient=$(caprint -p)
fi
PS1='\\u@\\h:\\w\\$$ambient'
.fi
.TP
\fB\-h
.TQ
\fB\-\-help
print a short usage banner and exit.
.SH SEE ALSO
\fBcado\fR(1),
\fBcapabilities\fR(7),

131
caprint.c Normal file
View File

@ -0,0 +1,131 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/capability.h>
char *tag="CapAmb:\t";
uint64_t get_capamb(pid_t pid) {
FILE *f;
char filename[32];
int status=0;
int target=strlen(tag);
uint64_t capamb=0;
int c;
snprintf(filename,32,"/proc/%d/status",pid);
f=fopen(filename,"r");
if (f==NULL)
exit(2);
while ((c = getc(f)) != EOF) {
if (c == tag[status]) {
status++;
if (status == target) {
fscanf(f,"%llx",&capamb);
break;
}
} else
status=0;
}
fclose(f);
return capamb;
}
#define OPTSTRING "hpcl"
struct option long_options[]={
{"help", no_argument, NULL, 'h'},
{"prompt", no_argument, NULL, 'p'},
{"compact", no_argument, NULL, 'c'},
{"long", no_argument, NULL, 'l'},
};
void usage(char *progname) {
fprintf(stderr,"%s - show the current capability ambient\n\n",progname);
fprintf(stderr,"usage: %s OPTIONS [pid]\n\n",progname);
fprintf(stderr,"Options:\n");
fprintf(stderr," -h, --help display help message and exit\n");
fprintf(stderr," -p, --prompt single line output for the command prompt\n");
fprintf(stderr," -c, --compact single line without cap_ prefix\n");
fprintf(stderr," -l, --long display cap# and mask\n");
exit(1);
}
int main(int argc, char *argv[]) {
uint64_t capamb;
char *progname=basename(argv[0]);
int prompt=0;
int compact=0;
int longlist=0;
while (1) {
int c=getopt_long(argc, argv, OPTSTRING, long_options, NULL);
if (c < 0)
break;
switch (c) {
case 'h': usage(progname);
break;
case 'p': prompt=compact=1;
break;
case 'c': compact=1;
break;
case 'l': longlist=1;
break;
default:
usage(progname);
}
}
if (argc - optind > 1)
usage(progname);
if (optind < argc)
capamb=get_capamb(atoi(argv[optind]));
else
capamb=get_capamb(getpid());
if (capamb) {
cap_value_t cap;
char *sep="";
int count=0;
for (cap = 0; cap <= CAP_LAST_CAP; cap++) {
if (capamb & (1ULL << cap)) {
count++;
if (longlist)
printf("%2d %016llx %s\n",cap,1ULL<<cap,cap_to_name(cap));
else if (compact)
printf("%s%s",sep,cap_to_name(cap)+4);
else
printf("%s\n",cap_to_name(cap));
sep=",";
}
}
if (prompt) printf("#");
if (compact) printf("\n");
if (longlist && count > 1)
printf(" %016llx\n",capamb);
}
}

59
capset_from_namelist.c Normal file
View File

@ -0,0 +1,59 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/capability.h>
#include <capset_from_namelist.h>
static int addcap(char *name, uint64_t *capset) {
char *tail;
uint64_t exacaps=strtoull(name, &tail, 16);
if (*tail == 0) {
*capset |= exacaps;
return 0;
} else {
int rv;
cap_value_t thiscap;
if (strncmp(name,"cap_",4) == 0)
rv=cap_from_name(name, &thiscap);
else {
int xnamelen=strlen(name)+5;
char xname[xnamelen];
snprintf(xname,xnamelen,"cap_%s",name);
rv=cap_from_name(xname, &thiscap);
}
if (rv >= 0)
*capset |= 1ULL << thiscap;
return rv;
}
}
int capset_from_namelist(char *namelist, uint64_t *capset) {
int rv=0;
char *onecap;
char *tmptok;
for (; (onecap=strtok_r(namelist,",",&tmptok)) != NULL; namelist=NULL)
rv |= addcap(onecap,capset);
return rv;
}

8
capset_from_namelist.h Normal file
View File

@ -0,0 +1,8 @@
#ifndef CAP_FROM_NAMEX_H
#define CAP_FROM_NAMEX_H
#include <sys/capability.h>
#include <stdint.h>
int capset_from_namelist(char *namelist, uint64_t *capset);
#endif

29
configure.ac Normal file
View File

@ -0,0 +1,29 @@
# -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.
AC_PREREQ([2.69])
AC_INIT([cado], [0.9], [info@v2.cs.unibo.it])
AM_INIT_AUTOMAKE([foreign dist-bzip2])
AC_CONFIG_SRCDIR([pam_check.h])
AC_CONFIG_HEADERS([config.h])
# Checks for programs.
AC_PROG_CXX
AC_PROG_CC
AC_PROG_INSTALL
# Checks for libraries.
# Checks for header files.
AC_CHECK_HEADERS([fcntl.h stdint.h stdlib.h string.h unistd.h])
# Checks for typedefs, structures, and compiler characteristics.
AC_TYPE_UID_T
AC_TYPE_PID_T
AC_TYPE_SSIZE_T
AC_TYPE_UINT64_T
# Checks for library functions.
AC_CHECK_FUNCS([strdup strtoull])
AC_OUTPUT([Makefile])

60
get_user_groups.c Normal file
View File

@ -0,0 +1,60 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <get_user_groups.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <grp.h>
#include <pwd.h>
char **get_user_groups(void) {
uid_t uid=getuid();
struct passwd *pwd=getpwuid(uid);
int ngroups=0;
char **user_groups=NULL;
getgrouplist(pwd->pw_name, pwd->pw_gid, NULL, &ngroups);
if (ngroups > 0) {
gid_t gids[ngroups];
struct group *grp;
user_groups = calloc(ngroups+2, sizeof(char *));
if (user_groups) {
int i=0;
user_groups[i++] = strdup(pwd->pw_name);
if (getgrouplist(pwd->pw_name, pwd->pw_gid, gids, &ngroups) == ngroups) {
while ((grp=getgrent()) != NULL) {
int j;
for (j=0; j<ngroups; j++) {
if (grp->gr_gid == gids[j]) {
gids[j] = -1;
user_groups[i++] = strdup(grp->gr_name);
}
}
}
user_groups[i] = NULL;
endgrent();
}
}
}
return user_groups;
}

5
get_user_groups.h Normal file
View File

@ -0,0 +1,5 @@
#ifndef GET_USER_GROUPS_H
#define GET_USER_GROUPS_H
char **get_user_groups(void);
#endif

42
pam_check.c Normal file
View File

@ -0,0 +1,42 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/types.h>
#include <security/pam_appl.h>
#include <security/pam_misc.h>
#include <pwd.h>
#include <pam_check.h>
int pam_check(char *username)
{
pam_handle_t* pamh;
struct pam_conv pamc={.conv=&misc_conv, .appdata_ptr=NULL};
int rv;
pam_start ("capdo", username, &pamc, &pamh);
rv= pam_authenticate (pamh, 0);
pam_end (pamh, 0);
return rv;
}

4
pam_check.h Normal file
View File

@ -0,0 +1,4 @@
#ifndef PAM_CHECK_H
#define PAM_CHECK_H
int pam_check(char *username);
#endif

116
read_conf.c Normal file
View File

@ -0,0 +1,116 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <fcntl.h>
#include <read_conf.h>
#include <set_ambient_cap.h>
#include <capset_from_namelist.h>
#ifndef CONFDIR
#define CONFDIR "/etc"
#endif
#define CADO_CONF CONFDIR "/cado.conf"
static int groupmatch (char *group, char **grouplist) {
for (;*grouplist; grouplist++) {
//printf("%s %s\n",group, *grouplist);
if (strcmp(group, *grouplist) == 0)
return 1;
}
return 0;
}
uint64_t get_authorized_caps(char **user_groups) {
uint64_t ok_caps=0;
FILE *f;
if (user_groups) raise_cap_dac_read_search();
f=fopen(CADO_CONF, "r");
if (f) {
char *line=NULL;
ssize_t len,n=0;
while ((len=getline(&line, &n, f)) > 0) {
//printf("%s",line);
char *scan=line;
char *tok;
uint64_t capset;
char *tmptok;
while (isspace(*scan)) scan++;
if (*scan == 0 || *scan == '#') //comment
continue;
tok=strtok_r(scan, ":", &tmptok);
//printf("%s\n",tok);
capset=0;
if (capset_from_namelist(tok, &capset) < 0)
continue;
if (user_groups == NULL) {
ok_caps |= capset;
continue;
}
//printf("CAP %s %d\n",tok,thiscap);
while ((tok=strtok_r(NULL, ",\n ",&tmptok)) != NULL) {
//printf("XX %s\n",tok);
if (*tok=='@') {
if (groupmatch(tok+1, user_groups+1)) {
ok_caps |= capset;
break;
}
} else if (strcmp(tok, user_groups[0]) == 0) {
ok_caps |= capset;
break;
}
}
}
fclose(f);
if (line)
free(line);
}
if (user_groups) lower_cap_dac_read_search();
return ok_caps;
}
int set_self_capability(uint64_t capset) {
cap_value_t cap;
cap_t caps=cap_init();
int f,rv=-1;
for (cap = 0; cap <= CAP_LAST_CAP; cap++) {
if (capset & (1ULL << cap)) {
/*if (cap_set_flag(caps, CAP_PERMITTED, 1, &cap, CAP_SET) ||
cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, CAP_SET)) {*/
if (cap_set_flag(caps, CAP_PERMITTED, 1, &cap, CAP_SET)) {
fprintf(stderr, "Cannot set permitted cap %s\n",cap_to_name(cap));
exit(2);
}
}
}
if ((f=open("/proc/self/exe",O_RDONLY)) >= 0) {
if (cap_set_fd(f,caps) >= 0)
rv=0;
close(f);
}
cap_free(caps);
return rv;
}

9
read_conf.h Normal file
View File

@ -0,0 +1,9 @@
#ifndef READ_CONF_H
#define READ_CONF_H
#include <stdint.h>
uint64_t get_authorized_caps(char **user_groups);
int set_self_capability(uint64_t capset);
#endif

63
set_ambient_cap.c Normal file
View File

@ -0,0 +1,63 @@
/*
* cado: execute a command in a capability ambient
* Copyright (C) 2016 Renzo Davoli, University of Bologna
*
* This file is part of cado.
*
* Cado is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <set_ambient_cap.h>
void set_ambient_cap(uint64_t capset)
{
cap_value_t cap;
cap_t caps=cap_get_proc();
for (cap = 0; cap <= CAP_LAST_CAP; cap++) {
int op = (capset & (1ULL << cap)) ? CAP_SET : CAP_CLEAR;
if (cap_set_flag(caps, CAP_INHERITABLE, 1, &cap, op)) {
fprintf(stderr, "Cannot %s inheritable cap %s\n",op==CAP_SET?"set":"clear",cap_to_name(cap));
exit(2);
}
}
cap_set_proc(caps);
cap_free(caps);
for (cap = 0; cap <= CAP_LAST_CAP; cap++) {
int op = (capset & (1ULL << cap)) ? PR_CAP_AMBIENT_RAISE : PR_CAP_AMBIENT_LOWER;
if (prctl(PR_CAP_AMBIENT, op, cap, 0, 0)) {
perror("Cannot set cap");
exit(1);
}
}
}
void raise_cap_dac_read_search(void) {
cap_value_t cap=CAP_DAC_READ_SEARCH;
cap_t caps=cap_get_proc();
cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, CAP_SET);
cap_set_proc(caps);
}
void lower_cap_dac_read_search(void) {
cap_value_t cap=CAP_DAC_READ_SEARCH;
cap_t caps=cap_get_proc();
cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, CAP_CLEAR);
cap_set_proc(caps);
}

10
set_ambient_cap.h Normal file
View File

@ -0,0 +1,10 @@
#ifndef SET_AMBIENT_CAP_H
#define SET_AMBIENT_CAP_H
void set_ambient_cap(uint64_t capset);
void raise_cap_dac_read_search(void);
void lower_cap_dac_read_search(void);
#endif