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authorDan Ballard <dan@mindstab.net>2011-10-31 20:11:20 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 20:30:53 -0400
commit73efc0394e148d0e15583e13712637831f926720 (patch)
tree896c58a85f520bcccae4f16647cfb0f1ecd2c08e /kernel/sysctl.c
parent4ff819515b203f937cc6c8a0215a37a68d1ee71f (diff)
kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel
Userspace needs to know the highest valid capability of the running kernel, which right now cannot reliably be retrieved from the header files only. The fact that this value cannot be determined properly right now creates various problems for libraries compiled on newer header files which are run on older kernels. They assume capabilities are available which actually aren't. libcap-ng is one example. And we ran into the same problem with systemd too. Now the capability is exported in /proc/sys/kernel/cap_last_cap. [akpm@linux-foundation.org: make cap_last_cap const, per Ulrich] Signed-off-by: Dan Ballard <dan@mindstab.net> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Lennart Poettering <lennart@poettering.net> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Ulrich Drepper <drepper@akkadia.org> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2d2ecdcc8cdb..c49d66658ec0 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -57,6 +57,7 @@
57#include <linux/pipe_fs_i.h> 57#include <linux/pipe_fs_i.h>
58#include <linux/oom.h> 58#include <linux/oom.h>
59#include <linux/kmod.h> 59#include <linux/kmod.h>
60#include <linux/capability.h>
60 61
61#include <asm/uaccess.h> 62#include <asm/uaccess.h>
62#include <asm/processor.h> 63#include <asm/processor.h>
@@ -134,6 +135,7 @@ static int minolduid;
134static int min_percpu_pagelist_fract = 8; 135static int min_percpu_pagelist_fract = 8;
135 136
136static int ngroups_max = NGROUPS_MAX; 137static int ngroups_max = NGROUPS_MAX;
138static const int cap_last_cap = CAP_LAST_CAP;
137 139
138#ifdef CONFIG_INOTIFY_USER 140#ifdef CONFIG_INOTIFY_USER
139#include <linux/inotify.h> 141#include <linux/inotify.h>
@@ -740,6 +742,13 @@ static struct ctl_table kern_table[] = {
740 .mode = 0444, 742 .mode = 0444,
741 .proc_handler = proc_dointvec, 743 .proc_handler = proc_dointvec,
742 }, 744 },
745 {
746 .procname = "cap_last_cap",
747 .data = (void *)&cap_last_cap,
748 .maxlen = sizeof(int),
749 .mode = 0444,
750 .proc_handler = proc_dointvec,
751 },
743#if defined(CONFIG_LOCKUP_DETECTOR) 752#if defined(CONFIG_LOCKUP_DETECTOR)
744 { 753 {
745 .procname = "watchdog", 754 .procname = "watchdog",