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Commit ce6ada35 authored by Serge E. Hallyn's avatar Serge E. Hallyn Committed by James Morris
Browse files

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: default avatarSerge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: default avatarAndrew G. Morgan <morgan@kernel.org>
Acked-By: default avatarKees 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: default avatarJames Morris <jmorris@namei.org>
parent 1d6d7568

include/linux/capability.h

+5 −2
Original line number Diff line number Diff line
@@ -246,7 +246,6 @@ struct cpu_vfs_cap_data { 
/* 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 @@ struct cpu_vfs_cap_data { 


#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)

kernel/printk.c

+7 −1
Original line number Diff line number Diff line
@@ -283,9 +283,15 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) 
			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);

	if (error)

security/selinux/include/classmap.h

+1 −1
Original line number Diff line number Diff line
@@ -142,7 +142,7 @@ struct security_class_mapping secclass_map[] = { 
	    "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 } },