POSIX Capabilities are a way to split full superuser privileges into smaller partitions of privileges. Use this tag for questions on managing and using capabilities.

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1answer
700 views

Command to run a child process “offline” (no external network) on Linux

I have a program I would like to test in offline mode without taking down my actual network. This program would still need to connect to local sockets, including unix domain sockets and loopback. It ...
7
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9answers
929 views

How to prevent a process from writing files

I want to run a command on Linux in a way that it cannot create or open any files to write. It should still be able to read files as normal (so an empty chroot is not an option), and still be able to ...
6
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3answers
425 views

Why are web servers traditionally started as superuser?

Thinking about a future web server setup, it struck me that for some reason web servers usually start as root and then drop certain rights (setuid) for the worker processes. In addition there is often ...
6
votes
1answer
319 views

Capabilities for a script on Linux

If I want to set a capability (capabilities(7)), such as CAP_NET_BIND_SERVICE, on an executable file and that file is a script, do I have to set the capability (setcap(8)) on the interpreter starting ...
6
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1answer
502 views

Can capabilities be used in scripts without setcap'ing the interpreter binary?

Right now I'm using cap_net_bind_service MY_USERNAME in /etc/security/capability.conf. Now I just need to set cap_net_bind_service+i on the interpreter of my favouite scripting language to be able to ...
3
votes
1answer
51 views

Can capabilities be specified in Debian packages?

Since RPM 4.7, there has been the ability to specify that a file in an RPM package should be installed with capabilities set (via %caps). Is there a similar feature for Debian packages?
3
votes
1answer
770 views

How to replace setuid with file-system capabilities

Inspired by this question here is the follow-up: As some of you may know setuid-binaries are dangerous, since some exploits use these to escalate their rights up to root. Now it seems that there has ...
3
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1answer
82 views

Why doesn't Ubuntu use capabilities on ping?

After running, $ ls -l /bin/ping -rwsr-xr-x 1 root root 34740 Nov 5 2012 /bin/ping I wonder, why doesn't Ubuntu use capabilities (i.e. raw sockets) rather than setuid?
3
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2answers
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Passing capabilities through exec

I'm trying to understand how Linux capabilities are passed to a process that has been exec()'d by another one. From what I've read, in order for a capability to be kept after exec, it must be in the ...
2
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1answer
24 views

Security of capabilities vs setuid (LD_PRELOAD, etc)

I know that if a process is run setuid that it's protected against various things that could subvert the process, like LD_PRELOAD and ptrace (debugging). But I haven't been able to find anything on ...
2
votes
1answer
426 views

Is it possible to specify groups in /etc/security/capability.conf?

I've been inspired to start playing around with Linux capabilities again, my pet project is to replace the setuid on a lot of the binaries and provide access to additional privileged utilities to ...
2
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0answers
26 views

Can capabilities for files be specified via cmake/cpack?

Since RPM 4.7, there has been the ability to specify that a file in an RPM package should be installed with capabilities set (via %caps). Is there a way to specify something like this via cmake/cpack ...
1
vote
2answers
58 views

Can't get upstart service to honor capabilities(7)

I am developing a daemon started by upstart (Ubuntu 14.04) which needs to run as a non-privileged user (for security), but bind privileged port 443. I am using setcap to set the CAP_NET_BIND_SERVICE ...
1
vote
0answers
68 views

How to set local shared library path after setting file capabilities on Debian?

I have a custom application which comes with its own libstdc++.so.6 and it requires cap_net_admin and cap_net_raw to work properly. Before I set file capabilities it starts without problems but when I ...
1
vote
0answers
13 views

Is there a Linux capabilities(7) to allow a process to execute pam_authenticate?

I am writing a process that needs to periodically authenticate users (i.e. call pam_authenticate()). For security purposes I would prefer not to run this process with root privilege. I can use ...
1
vote
1answer
108 views

Principle of least privilege: Does Authbind helper really need setuid root, or can it run with cap_net_bind_services?

Does Authbind's helper really need setuid root, or can it run with the CAP_NET_BIND_SERVICES capability and still work?
1
vote
0answers
259 views

Unable to set capability CAP_SETFCAP by user

The question is about capabilities. I need to allow user to set capabilities using setcap. When I call it by root all goes fine, eg $ sudo setcap cap_dac_override,cap_dac_read_search+ep ./bin_file $ ...
0
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0answers
52 views

Fedora 14 root missing capability

I am trying to run a process that performs a clone() operation using a set of flags (CLONE_NEWIPC, CLONE_NEWNET, ...) that require CAP_SYS_ADMIN capability. This should not be a problem since I am ...