>> Cheers
>>
>> Andrew
>>
>> Kohei KaiGai wrote:
>> | [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.
>> |
>> | Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
>> | --
>> | Documentation/ABI/testing/sysfs-kernel-capability | 23 +++++
>> | scripts/mkcapnames.sh | 44 +++++++++
>> | security/Makefile | 9 ++
>> | security/commoncap.c | 99
>> +++++++++++++++++++++
>> | 4 files changed, 175 insertions(+), 0 deletions(-)
>> |
>> | diff --git a/Documentation/ABI/testing/sysfs-kernel-capability
>> b/Documentation/ABI/testing/sysfs-kernel-capability
>> | index e69de29..d4a14e7 100644
>> | --- a/Documentation/ABI/testing/sysfs-kernel-capability
>> | +++ b/Documentation/ABI/testing/sysfs-kernel-capability
>> | @@ -0,0 +1,23 @@
>> | +What: /sys/kernel/capability
>> | +Date: Feb 2008
>> | +Contact: KaiGai Kohei <kaigai@ak.jp.nec.com>
>> | +Description:
>> | + The entries under /sys/kernel/capability are used to export
>> | + the list of capabilities the running kernel supports.
>> | +
>> | + - /sys/kernel/capability/version
>> | + returns the most preferable version number for the
>> | + running kernel.
>> | + e.g) $ cat /sys/kernel/capability/version
>> | + 0x20071026
>> | +
>> | + - /sys/kernel/capability/code/<numerical representation>
>> | + returns its symbolic representation, on reading.
>> | + e.g) $ cat /sys/kernel/capability/codes/30
>> | + cap_audit_control
>> | +
>> | + - /sys/kernel/capability/name/<symbolic representation>
>> | + returns its numerical representation, on reading.
>> | + e.g) $ cat /sys/kernel/capability/names/cap_sys_pacct
>> | + 20
>> | +
>> | diff --git a/scripts/mkcapnames.sh b/scripts/mkcapnames.sh
>> | index e69de29..5d36d52 100644
>> | --- a/scripts/mkcapnames.sh
>> | +++ b/scripts/mkcapnames.sh
>> | @@ -0,0 +1,44 @@
>> | +#!/bin/sh
>> | +
>> | +#
>> | +# generate a cap_names.h file from include/linux/capability.h
>> | +#
>> | +
>> | +CAPHEAD="`dirname __PLACEHOLDER__1_`/../include/linux/capability.h"
>> | +REGEXP='^#define CAP_[A-Z_]+[ ]+[0-9]+$'
>> | +NUMCAP=`cat "$CAPHEAD" | egrep -c "$REGEXP"`
>> | +
>> | +echo '#ifndef CAP_NAMES_H'
>> | +echo '#define CAP_NAMES_H'
>> | +echo
>> | +echo '/*'
>> | +echo ' * Do NOT edit this file directly.'
>> | +echo ' * This file is generated from include/linux/capability.h
>> automatically'
>> | +echo ' */'
>> | +echo
>> | +echo '#if !defined(SYSFS_CAP_NAME_ENTRY) ||
>> !defined(SYSFS_CAP_CODE_ENTRY)'
>> | +echo '#error cap_names.h should be included from security/capability.c'
>> | +echo '#else'
>> | +echo "#if $NUMCAP != CAP_LAST_CAP + 1"
>> | +echo '#error mkcapnames.sh cannot collect capabilities correctly'
>> | +echo '#else'
>> | +cat "$CAPHEAD" | egrep "$REGEXP" \
>> | + | awk '{ printf("SYSFS_CAP_NAME_ENTRY(%s,%s);\n", tolower(),
>> ); }'
>> | +echo
>> | +echo 'static struct attribute *capability_name_attrs[] = {'
>> | +cat "$CAPHEAD" | egrep "$REGEXP" \
>> | + | awk '{ printf("\t&%s_name_attr.attr,\n", tolower()); } END {
>> print "\tNULL," }'
>> | +echo '};'
>> | +
>> | +echo
>> | +cat "$CAPHEAD" | egrep "$REGEXP" \
>> | + | awk '{ printf("SYSFS_CAP_CODE_ENTRY(%s,%s);\n", tolower(),
>> ); }'
>> | +echo
>> | +echo 'static struct attribute *capability_code_attrs[] = {'
>> | +cat "$CAPHEAD" | egrep "$REGEXP" \
>> | + | awk '{ printf("\t&%s_code_attr.attr,\n", tolower()); } END {
>> print "\tNULL," }'
>> | +echo '};'
>> | +
>> | +echo '#endif'
>> | +echo '#endif'
>> | +echo '#endif'
>> | diff --git a/security/Makefile b/security/Makefile
>> | index 9e8b025..4093e3e 100644
>> | --- a/security/Makefile
>> | +++ b/security/Makefile
>> | @@ -18,3 +18,12 @@ obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o
>> | obj-$(CONFIG_SECURITY_SMACK) += commoncap.o smack/built-in.o
>> | obj-$(CONFIG_SECURITY_CAPABILITIES) += commoncap.o capability.o
>> | obj-$(CONFIG_SECURITY_ROOTPLUG) += commoncap.o root_plug.o
>> | +
>> | +# cap_names.h contains the code/name pair of capabilities.
>> | +# It is generated using include/linux/capability.h automatically.
>> | +$(obj)/commoncap.o: $(obj)/cap_names.h
>> | +quiet_cmd_cap_names = CAPS $@
>> | + cmd_cap_names = /bin/sh $(srctree)/scripts/mkcapnames.sh > $@
>> | +targets += cap_names.h
>> | +$(obj)/cap_names.h: $(srctree)/scripts/mkcapnames.sh
>> $(srctree)/include/linux/capability.h FORCE
>> | + $(call if_changed,cap_names)
>> | diff --git a/security/commoncap.c b/security/commoncap.c
>> | index 5aba826..9483fa9 100644
>> | --- a/security/commoncap.c
>> | +++ b/security/commoncap.c
>> | @@ -24,6 +24,8 @@
>> | #include <linux/hugetlb.h>
>> | #include <linux/mount.h>
>> | #include <linux/sched.h>
>> | +#include <linux/kobject.h>
>> | +#include <linux/sysfs.h>
>> |
>> | /* Global security state */
>> |
>> | @@ -637,3 +639,100 @@ int cap_vm_enough_memory(struct mm_struct *mm,
>> long pages)
>> | return __vm_enough_memory(mm, pages, cap_sys_admin);
>> | }
>> |
>> | +/*
>> | + * Export the list of capabilities on /sys/kernel/capability
>> | + */
>> | +static struct kobject *capability_kobj;
>> | +
>> | +static ssize_t capability_name_show(struct kobject *kobj,
>> | + struct kobj_attribute *attr,
>> | + char *buffer)
>> | +{
>> | + /* It returns numerical representation of capability. */
>> | + return scnprintf(buffer, PAGE_SIZE, "%ld\n", (long) attr->data);
>> | +}
>> | +
>> | +static ssize_t capability_code_show(struct kobject *kobj,
>> | + struct kobj_attribute *attr,
>> | + char *buffer)
>> | +{
>> | + /* It returns symbolic representation of capability. */
>> | + return scnprintf(buffer, PAGE_SIZE, "%s\n", (char *) attr->data);
>> | +}
>> | +
>> | +static ssize_t capability_version_show(struct kobject *kobj,
>> | + struct kobj_attribute *attr,
>> | + char *buffer)
>> | +{
>> | + return scnprintf(buffer, PAGE_SIZE, "0x%08x\n",
>> | + _LINUX_CAPABILITY_VERSION);
>> | +}
>> | +
>> | +#define SYSFS_CAP_NAME_ENTRY(_name,_code) \
>> | + static struct kobj_attribute _name##_name_attr = \
>> | + __ATTR_DATA(_name, 0444, capability_name_show, NULL, (long)(_code))
>> | +
>> | +#define SYSFS_CAP_CODE_ENTRY(_name,_code) \
>> | + static struct kobj_attribute _name##_code_attr = \
>> | + __ATTR_DATA(_code, 0444, capability_code_show, NULL,
>> __stringify(_name))
>> | +
>> | +/*
>> | + * capability_attrs[] is generated automatically by
>> scripts/mkcapnames.sh
>> | + * This script parses include/linux/capability.h
>> | + */
>> | +#include "cap_names.h"
>> | +
>> | +static struct attribute_group capability_name_attr_group = {
>> | + .name = "names",
>> | + .attrs = capability_name_attrs,
>> | +};
>> | +
>> | +static struct attribute_group capability_code_attr_group = {
>> | + .name = "codes",
>> | + .attrs = capability_code_attrs,
>> | +};
>> | +
>> | +static struct kobj_attribute cap_version_attr =
>> | + __ATTR(version, 0444, capability_version_show, NULL);
>> | +
>> | +static int __init capability_export_names(void)
>> | +{
>> | + int rc = -ENOMEM;
>> | +
>> | + /* make /sys/kernel/capability */
>> | + capability_kobj = kobject_create_and_add("capability", kernel_kobj);
>> | + if (!capability_kobj)
>> | + goto error0;
>> | +
>> | + /* make /sys/kernel/capability/names */
>> | + rc = sysfs_create_group(capability_kobj,
>> | + &capability_name_attr_group);
>> | + if (rc)
>> | + goto error1;
>> | +
>> | + /* make /sys/kernel/capability/codes */
>> | + rc = sysfs_create_group(capability_kobj,
>> | + &capability_code_attr_group);
>> | + if (rc)
>> | + goto error2;
>> | +
>> | + /* make /sys/kernel/capability/version */
>> | + rc = sysfs_create_file(capability_kobj,
>> | + &cap_version_attr.attr);
>> | + if (rc)
>> | + goto error3;
>> | +
>> | + return 0;
>> | +
>> | +error3:
>> | + sysfs_remove_group(capability_kobj, &capability_code_attr_group);
>> | +error2:
>> | + sysfs_remove_group(capability_kobj, &capability_name_attr_group);
>> | +error1:
>> | + kobject_put(capability_kobj);
>> | +error0:
>> | + printk(KERN_ERR "Unable to export capabilities\n");
>> | +
>> | + return rc;
>> | +}
>> | +__initcall(capability_export_names);
>> |
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>>
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