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authorKees Cook <kees.cook@canonical.com>2010-02-03 15:36:43 -0800
committerJames Morris <jmorris@namei.org>2010-02-04 14:20:12 +1100
commit002345925e6c45861f60db6f4fc6236713fd8847 (patch)
treed7849eafe1755116597166bbebf43e2bee86cb76 /security/commoncap.c
parent0719aaf5ead7555b7b7a4a080ebf2826a871384e (diff)
downloadlinux-stericsson-002345925e6c45861f60db6f4fc6236713fd8847.tar.gz
syslog: distinguish between /proc/kmsg and syscalls
This allows the LSM to distinguish between syslog functions originating from /proc/kmsg access and direct syscalls. By default, the commoncaps will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg file descriptor. For example the kernel syslog reader can now drop privileges after opening /proc/kmsg, instead of staying privileged with CAP_SYS_ADMIN. MAC systems that implement security_syslog have unchanged behavior. Signed-off-by: Kees Cook <kees.cook@canonical.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/commoncap.c')
-rw-r--r--security/commoncap.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index f800fdb3de94..677fad9d5cba 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/prctl.h>
#include <linux/securebits.h>
+#include <linux/syslog.h>
/*
* If a non-root user executes a setuid-root binary in
@@ -888,12 +889,16 @@ error:
/**
* cap_syslog - Determine whether syslog function is permitted
* @type: Function requested
+ * @from_file: Whether this request came from an open file (i.e. /proc)
*
* Determine whether the current process is permitted to use a particular
* syslog function, returning 0 if permission is granted, -ve if not.
*/
-int cap_syslog(int type)
+int cap_syslog(int type, bool from_file)
{
+ /* /proc/kmsg can open be opened by CAP_SYS_ADMIN */
+ if (type != 1 && from_file)
+ return 0;
if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;