security: Define CAP_SYSLOG
Privileged syslog operations currently require CAP_SYS_ADMIN. Split
this off into a new CAP_SYSLOG privilege which we can sanely take away
from a container through the capability bounding set.
With this patch, an lxc container can be prevented from messing with
the host's syslog (i.e. dmesg -c).
Changelog: mar 12 2010: add selinux capability2:cap_syslog perm
Changelog: nov 22 2010:
. port to new kernel
. add a WARN_ONCE if userspace isn't using CAP_SYSLOG
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Acked-By: Kees Cook <kees.cook@canonical.com>
Cc: James Morris <jmorris@namei.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: "Christopher J. PeBenito" <cpebenito@tresys.com>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 90012b9..fb16a36 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -246,7 +246,6 @@
/* Allow configuration of the secure attention key */
/* Allow administration of the random device */
/* Allow examination and configuration of disk quotas */
-/* Allow configuring the kernel's syslog (printk behaviour) */
/* Allow setting the domainname */
/* Allow setting the hostname */
/* Allow calling bdflush() */
@@ -352,7 +351,11 @@
#define CAP_MAC_ADMIN 33
-#define CAP_LAST_CAP CAP_MAC_ADMIN
+/* Allow configuring the kernel's syslog (printk behaviour) */
+
+#define CAP_SYSLOG 34
+
+#define CAP_LAST_CAP CAP_SYSLOG
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
diff --git a/kernel/printk.c b/kernel/printk.c
index 9a2264f..0712380 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -283,8 +283,14 @@
return -EPERM;
if ((type != SYSLOG_ACTION_READ_ALL &&
type != SYSLOG_ACTION_SIZE_BUFFER) &&
- !capable(CAP_SYS_ADMIN))
+ !capable(CAP_SYSLOG)) {
+ /* remove after 2.6.38 */
+ if (capable(CAP_SYS_ADMIN))
+ WARN_ONCE(1, "Attempt to access syslog with "
+ "CAP_SYS_ADMIN but no CAP_SYSLOG "
+ "(deprecated and denied).\n");
return -EPERM;
+ }
}
error = security_syslog(type);
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 8858d2b..7ed3663 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -142,7 +142,7 @@
"node_bind", "name_connect", NULL } },
{ "memprotect", { "mmap_zero", NULL } },
{ "peer", { "recv", NULL } },
- { "capability2", { "mac_override", "mac_admin", NULL } },
+ { "capability2", { "mac_override", "mac_admin", "syslog", NULL } },
{ "kernel_service", { "use_as_override", "create_files_as", NULL } },
{ "tun_socket",
{ COMMON_SOCK_PERMS, NULL } },