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Subject[PATCH 0/3] exporting capability name/code pairs (for 2.6.26)
The following three patches enables to export code/name pairs of
capabilities the running kernel supports, and add a documentation
and samples to use this feature.
It was too late for 2.6.25 merge window, so I submit them again
for the next development cycle.

[PATCH 1/3] add a private data field within kobj_attribute structure.

This patch add a private data field, declared as void *, within kobj_attribute
structure. The _show() and _store() method in the sysfs attribute entries can
refer this information to identify what entry is accessed.
It makes easier to share a single method implementation with several similar
entries, like ones to export the list of capabilities the running kernel

[PATCH 2/3] exporting capability name/code pairs

This patch enables to export code/name pairs of capabilities the running
kernel supported.

A newer kernel sometimes adds new capabilities, like CAP_MAC_ADMIN
at 2.6.25. However, we have no interface to disclose what capabilities
are supported on the running kernel. Thus, we have to maintain libcap
version in appropriate one synchronously.

This patch enables libcap to collect the list of capabilities at run time,
and provide them for users. It helps to improve portability of library.

It exports these information as regular files under /sys/kernel/capability.
The numeric node exports its name, the symbolic node exports its code.

[PATCH 3/3] a new example to use kobject/kobj_attribute

This patch can provide a new exmple to use kobject and attribute.
The _show() and _store() method can refer/store the private data field of
kobj_attribute structure to know what entries are accessed by users.
It will make easier to share a single _show()/_store() method with several

Example of execution:
[kaigai@saba ~]$ uname -r
[kaigai@saba ~]$ ls -R /sys/kernel/capability/
codes names version

0 10 12 14 16 18 2 21 23 25 27 29 30 32 4 6 8
1 11 13 15 17 19 20 22 24 26 28 3 31 33 5 7 9

cap_audit_control cap_kill cap_net_raw cap_sys_nice
cap_audit_write cap_lease cap_setfcap cap_sys_pacct
cap_chown cap_linux_immutable cap_setgid cap_sys_ptrace
cap_dac_override cap_mac_admin cap_setpcap cap_sys_rawio
cap_dac_read_search cap_mac_override cap_setuid cap_sys_resource
cap_fowner cap_mknod cap_sys_admin cap_sys_time
cap_fsetid cap_net_admin cap_sys_boot cap_sys_tty_config
cap_ipc_lock cap_net_bind_service cap_sys_chroot
cap_ipc_owner cap_net_broadcast cap_sys_module
[kaigai@saba ~]$ cat /sys/kernel/capability/names/cap_sys_pacct
[kaigai@saba ~]$ cat /sys/kernel/capability/codes/16
[kaigai@saba ~]$

OSS Platform Development Division, NEC
KaiGai Kohei <>

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