Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759766AbYBZOza (ORCPT ); Tue, 26 Feb 2008 09:55:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753563AbYBZOzU (ORCPT ); Tue, 26 Feb 2008 09:55:20 -0500 Received: from twinlark.arctic.org ([208.69.40.136]:49477 "EHLO twinlark.arctic.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751522AbYBZOzS (ORCPT ); Tue, 26 Feb 2008 09:55:18 -0500 Message-ID: <47C42854.8030000@kernel.org> Date: Tue, 26 Feb 2008 06:55:16 -0800 From: "Andrew G. Morgan" User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: Kohei KaiGai CC: greg@kroah.com, serue@us.ibm.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] exporting capability name/code pairs (final#2) References: <47C25AE9.7080305@ak.jp.nec.com> <47C25BE3.9050905@ak.jp.nec.com> In-Reply-To: <47C25BE3.9050905@ak.jp.nec.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8761 Lines: 268 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Acked-by: Andrew G. Morgan Tested-by: Andrew G. Morgan 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 | -- | 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 | +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/ | + returns its symbolic representation, on reading. | + e.g) $ cat /sys/kernel/capability/codes/30 | + cap_audit_control | + | + - /sys/kernel/capability/name/ | + 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 $0`/../include/linux/capability.h" | +REGEXP='^#define CAP_[A-Z_]+[ ]+[0-9]+$' | +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($2), $2); }' | +echo | +echo 'static struct attribute *capability_name_attrs[] = {' | +cat "$CAPHEAD" | egrep "$REGEXP" \ | + | awk '{ printf("\t&%s_name_attr.attr,\n", tolower($2)); } END { print "\tNULL," }' | +echo '};' | + | +echo | +cat "$CAPHEAD" | egrep "$REGEXP" \ | + | awk '{ printf("SYSFS_CAP_CODE_ENTRY(%s,%s);\n", tolower($2), $2); }' | +echo | +echo 'static struct attribute *capability_code_attrs[] = {' | +cat "$CAPHEAD" | egrep "$REGEXP" \ | + | awk '{ printf("\t&%s_code_attr.attr,\n", tolower($2)); } END { print "\tNULL," }' | +echo '};' | + | +echo '#endif' | +echo '#endif' | +echo '#endif' | diff --git a/security/Makefile b/security/Makefile | index 9e8b025..4093e3e 100644 | --- a/security/Makefile | +++ b/security/Makefile | @@ -18,3 +18,12 @@ obj-$(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 | #include | #include | +#include | +#include | | /* 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); | -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) iD8DBQFHxChT+bHCR3gb8jsRAtnIAJ9EZKZ8Uw1WZE0GdGc2SRuuEdqm5QCcCUm2 Dp+6/phU4jLCDo6jsNKJd9A= =6DqN -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/