How to execute a process with CAP_SYS_RESOURCE

Question

I'm using Linux POSIX mqueue implementation, and I have a problem. For current kernel, the max message size is 1MB, but I need to have no limit.

man mq_overview says that if the process is privileged (a process that has CAP_SYS_RESOURCE capability) it has no limits. I thought that a process executed by root was already privileged, but I'm still getting "message too long" error (my message has 2MB).

How can I add CAP_SYS_RESOURCE capability to the process?

Answer 1

I don't know if it is possible to set it to a running process (I guess not) but you can grant the CAP_SYS_RESOURCE capability to an executable file using # setcap 'CAP_SYS_RESOURCE=+ep' /path/to/executable (as super user). In this example the +ep turns down into raise the CAP_SYS_RESOURCE capibility to be permitted and effective. However the man pages capabilities(7) and setcap(8) are useful sources for further information.

Answer 2

you can change the ceiling on the maximum message size on this file /proc/sys/fs/mqueue/msgsize_max I hope it works