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authorSerge E. Hallyn <serge@hallyn.com>2010-11-25 17:11:32 +0000
committerJames Morris <jmorris@namei.org>2010-11-29 08:35:12 +1100
commitce6ada35bdf710d16582cc4869c26722547e6f11 (patch)
treec2b5fd46c883f4b7285b191bac55940022662b43
parent1d6d75684d869406e5bb2ac5d3ed9454f52d0cab (diff)
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>
-rw-r--r--include/linux/capability.h7
-rw-r--r--kernel/printk.c8
-rw-r--r--security/selinux/include/classmap.h2
3 files changed, 13 insertions, 4 deletions
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 90012b9ddbf3..fb16a3699b99 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -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)
diff --git a/kernel/printk.c b/kernel/printk.c
index 9a2264fc42ca..0712380737b3 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -283,8 +283,14 @@ 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);
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 8858d2b2d4b6..7ed3663332ec 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -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 } },

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