Security/SELinux: seperate lsm specific mmap_min_addr

Currently SELinux enforcement of controls on the ability to map low memory
is determined by the mmap_min_addr tunable.  This patch causes SELinux to
ignore the tunable and instead use a seperate Kconfig option specific to how
much space the LSM should protect.

The tunable will now only control the need for CAP_SYS_RAWIO and SELinux
permissions will always protect the amount of low memory designated by
CONFIG_LSM_MMAP_MIN_ADDR.

This allows users who need to disable the mmap_min_addr controls (usual reason
being they run WINE as a non-root user) to do so and still have SELinux
controls preventing confined domains (like a web server) from being able to
map some area of low memory.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ba3a7cb..9a72cc7 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -34,8 +34,6 @@ extern int sysctl_legacy_va_layout;
 #define sysctl_legacy_va_layout 0
 #endif
 
-extern unsigned long mmap_min_addr;
-
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -574,19 +572,6 @@ static inline void set_page_links(struct page *page, enum zone_type zone,
        set_page_section(page, pfn_to_section_nr(pfn));
 }
 
-/*
- * If a hint addr is less than mmap_min_addr change hint to be as
- * low as possible but still greater than mmap_min_addr
- */
-static inline unsigned long round_hint_to_min(unsigned long hint)
-{
-       hint &= PAGE_MASK;
-       if (((void *)hint != NULL) &&
-           (hint < mmap_min_addr))
-               return PAGE_ALIGN(mmap_min_addr);
-       return hint;
-}
-
 /*
  * Some inline functions in vmstat.h depend on page_zone()
  */

diff --git a/include/linux/security.h b/include/linux/security.h
index 963a48f..7b43115 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -28,6 +28,7 @@
 #include <linux/resource.h>
 #include <linux/sem.h>
 #include <linux/shm.h>
+#include <linux/mm.h> /* PAGE_ALIGN */
 #include <linux/msg.h>
 #include <linux/sched.h>
 #include <linux/key.h>
@@ -95,6 +96,7 @@ extern int cap_netlink_send(struct sock *sk, struct sk_buff *skb);
 extern int cap_netlink_recv(struct sk_buff *skb, int cap);
 
 extern unsigned long mmap_min_addr;
+extern unsigned long dac_mmap_min_addr;
 /*
  * Values used in the task_security_ops calls
  */
@@ -147,6 +149,21 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
        opts->num_mnt_opts = 0;
 }
 
+/*
+ * If a hint addr is less than mmap_min_addr change hint to be as
+ * low as possible but still greater than mmap_min_addr
+ */
+static inline unsigned long round_hint_to_min(unsigned long hint)
+{
+       hint &= PAGE_MASK;
+       if (((void *)hint != NULL) &&
+           (hint < mmap_min_addr))
+               return PAGE_ALIGN(mmap_min_addr);
+       return hint;
+}
+
+extern int mmap_min_addr_handler(struct ctl_table *table, int write, struct file *filp,
+                                void __user *buffer, size_t *lenp, loff_t *ppos);
 /**
  * struct security_operations - main security structure
  *

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 98e0232..58be760 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -49,6 +49,7 @@
 #include <linux/acpi.h>
 #include <linux/reboot.h>
 #include <linux/ftrace.h>
+#include <linux/security.h>
 #include <linux/slow-work.h>
 #include <linux/perf_counter.h>
 
@@ -1306,10 +1307,10 @@ static struct ctl_table vm_table[] = {
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "mmap_min_addr",
-               .data           = &mmap_min_addr,
-               .maxlen         = sizeof(unsigned long),
+               .data           = &dac_mmap_min_addr,
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = &proc_doulongvec_minmax,
+               .proc_handler   = &mmap_min_addr_handler,
        },
 #ifdef CONFIG_NUMA
        {

diff --cc mm/Kconfig
Simple merge

diff --cc mm/mmap.c
Simple merge

diff --cc mm/nommu.c
Simple merge

diff --cc security/Kconfig
Simple merge

diff --cc security/Makefile
Simple merge

diff --cc security/commoncap.c
Simple merge

diff --cc security/min_addr.c
Simple merge

diff --cc security/selinux/hooks.c
Simple merge