Messages in this thread Patch in this message | | | Date | Fri, 22 Feb 2008 00:38:40 -0800 | From | "Andrew G. Morgan" <> | Subject | Re: [PATCH 2/3] exporting capability name/code pairs (final) |
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KaiGai,
I've just tried to build this with a separate obj tree: make O=/path.../ ~ the build failed as follows:
~ CC security/dummy.o ~ CC security/inode.o ~ CAPS security/cap_names.h /bin/sh: security/../scripts/mkcapnames.sh: No such file or directory make[3]: *** [security/cap_names.h] Error 127 make[2]: *** [security] Error 2 make[1]: *** [sub-make] Error 2 make: *** [all] Error 2
when I replace $(src)/../scripts/... with $(srctree)/scripts/... I get it to compile, but (x86_64) see this warning fly by:
~ CC security/commoncap.o /home/morgan/gits/linux-2.6/security/commoncap.c: In function `capability_name_show': /home/morgan/gits/linux-2.6/security/commoncap.c:652: warning: cast from pointer to integer of different size
Cheers
Andrew
Kohei KaiGai wrote: | [2/3] Exporting capability code/name pairs | | This patch enables to export code/name pairs of capabilities the running | kernel supported. | | A newer kernel sometimes adds new capabilities, like CAP_MAC_ADMIN | at 2.6.25. However, we have no interface to disclose what capabilities | are supported on the running kernel. Thus, we have to maintain libcap | version in appropriate one synchronously. | | This patch enables libcap to collect the list of capabilities at run time, | and provide them for users. It helps to improve portability of library. | | It exports these information as regular files under /sys/kernel/capability. | The numeric node exports its name, the symbolic node exports its code. | | Please consider to put this patch on the queue of 2.6.25. | | Thanks, | | ------------ BEGIN EXAMPLE ---- | [kaigai@saba ~]$ ls -R /sys/kernel/capability/ | /sys/kernel/capability/: | codes names version | | /sys/kernel/capability/codes: | 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 | | /sys/kernel/capability/names: | 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/version | 0x20071026 | [kaigai@saba ~]$ cat /sys/kernel/capability/codes/30 | cap_audit_control | [kaigai@saba ~]$ cat /sys/kernel/capability/names/cap_sys_pacct | 20 | [kaigai@saba ~]$ | ------------ END EXAMPLE ------ | | 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..402ef06 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 supported. | + | + - /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 $0`/../include/linux/capability.h" | +REGEXP='^#define CAP_[A-Z_]+[ ]+[0-9]+$' | +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($2)); } END { print "\tNULL," }' | +echo '};' | + | +echo '#endif' | +echo '#endif' | +echo '#endif' | diff --git a/security/Makefile b/security/Makefile | index 9e8b025..c1ffc00 100644 | --- a/security/Makefile | +++ b/security/Makefile | @@ -18,3 +18,12 @@ obj-$(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 $(src)/../scripts/mkcapnames.sh > $@ | +targets += cap_names.h | +$(obj)/cap_names.h: $(src)/../scripts/mkcapnames.sh $(src)/../include/linux/capability.h FORCE | + $(call if_changed,cap_names) | diff --git a/security/commoncap.c b/security/commoncap.c | index 5aba826..2f3b49a 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, "%d\n", (int) 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, (int)(_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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