diff options
| author | Kees Cook <kees.cook@canonical.com> | 2010-02-03 15:36:43 -0800 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2010-02-04 14:20:12 +1100 |
| commit | 002345925e6c45861f60db6f4fc6236713fd8847 (patch) | |
| tree | d7849eafe1755116597166bbebf43e2bee86cb76 /security/commoncap.c | |
| parent | 0719aaf5ead7555b7b7a4a080ebf2826a871384e (diff) | |
| download | lwn-002345925e6c45861f60db6f4fc6236713fd8847.tar.gz lwn-002345925e6c45861f60db6f4fc6236713fd8847.zip | |
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.c | 7 |
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; |