From 002345925e6c45861f60db6f4fc6236713fd8847 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 3 Feb 2010 15:36:43 -0800 Subject: 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 Acked-by: Serge Hallyn Acked-by: John Johansen Signed-off-by: James Morris --- security/commoncap.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'security/commoncap.c') diff --git a/security/commoncap.c b/security/commoncap.c index f800fdb3de9..677fad9d5cb 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -27,6 +27,7 @@ #include #include #include +#include /* * 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; -- cgit v1.2.3