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=== Context Capabilities === As the Linux Capabilities have almost reached the maximum number that is possible without heavy modifications to the kernel, it was a natural step to add a context-specific capability system. The Linux-VServer context capability set acts as a mechanism to fine tune existing Linux capabilities. It is not visible to the processes within a context, as they would not know how to modify or verify it. In general there are two ways to use those capabilities: * Require one or a number of context capabilities to be set in addition to a given Linux capability, each one controlling a distinct part of the functionality.For example the CAP_NET_ADMIN could be split into RAW and PACKET sockets, so you could take away each of them separately by not providing the required context capability. * Consider the context capability sufficient for a specified functionality, even if the Linux Capability says something different.For example mount() requires CAP_SYS_ADMIN which adds a dozen other things we do not want, so we define a CCAP_MOUNT to allow mounts for certain contexts. The difference between the Context Flags and the Context Caps is more an abstract logical separation than a functional one, because they are handled very similarly. Again, a list of the Context Capabilities and their purpose: {| class="wikitablenowrap" ! [0] VXC_SET_UTSNAME | allow the context to change the host and domain name with the appropriate kernel Syscall |- ! [1] VXC_SET_RLIMIT | allow the context to modify the resource limits (within the vserver limits). |- ! [8] VXC_RAW_ICMP | allow raw icmp packets in a secure way (this makes ping work from inside) |- ! [16] VXC_SECURE_MOUNT | permit secure mounts, which at the moment means that the nodev mount option is added. |}
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