Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
security: define round_hint_to_min in !CONFIG_SECURITY
Security/SELinux: seperate lsm specific mmap_min_addr
SELinux: call cap_file_mmap in selinux_file_mmap
Capabilities: move cap_file_mmap to commoncap.c
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ba3a7cb..9a72cc7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -34,8 +34,6 @@
#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>
@@ -575,19 +573,6 @@
}
/*
- * 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()
*/
#include <linux/vmstat.h>
diff --git a/include/linux/security.h b/include/linux/security.h
index 5eff459..1f16eea 100644
--- 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>
@@ -66,6 +67,9 @@
extern int cap_inode_removexattr(struct dentry *dentry, const char *name);
extern int cap_inode_need_killpriv(struct dentry *dentry);
extern int cap_inode_killpriv(struct dentry *dentry);
+extern int cap_file_mmap(struct file *file, unsigned long reqprot,
+ unsigned long prot, unsigned long flags,
+ unsigned long addr, unsigned long addr_only);
extern int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags);
extern int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
@@ -92,6 +96,7 @@
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
*/
@@ -116,6 +121,21 @@
#define LSM_UNSAFE_PTRACE 2
#define LSM_UNSAFE_PTRACE_CAP 4
+/*
+ * 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);
+
#ifdef CONFIG_SECURITY
struct security_mnt_opts {
@@ -2197,9 +2217,7 @@
unsigned long addr,
unsigned long addr_only)
{
- if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))
- return -EACCES;
- return 0;
+ return cap_file_mmap(file, reqprot, prot, flags, addr, addr_only);
}
static inline int security_file_mprotect(struct vm_area_struct *vma,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 98e0232..58be760 100644
--- 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 @@
{
.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 --git a/mm/Kconfig b/mm/Kconfig
index c948d4c..fe5f674 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -225,9 +225,9 @@
For most ia64, ppc64 and x86 users with lots of address space
a value of 65536 is reasonable and should cause no problems.
On arm and other archs it should not be higher than 32768.
- Programs which use vm86 functionality would either need additional
- permissions from either the LSM or the capabilities module or have
- this protection disabled.
+ Programs which use vm86 functionality or have some need to map
+ this low address space will need CAP_SYS_RAWIO or disable this
+ protection by setting the value to 0.
This value can be changed after boot using the
/proc/sys/vm/mmap_min_addr tunable.
diff --git a/mm/mmap.c b/mm/mmap.c
index 34579b2..8101de4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -88,9 +88,6 @@
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
struct percpu_counter vm_committed_as;
-/* amount of vm to protect from userspace access */
-unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
-
/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
diff --git a/mm/nommu.c b/mm/nommu.c
index 53cab10..28754c4 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -69,9 +69,6 @@
int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
int heap_stack_gap = 0;
-/* amount of vm to protect from userspace access */
-unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
-
atomic_long_t mmap_pages_allocated;
EXPORT_SYMBOL(mem_map);
diff --git a/security/Kconfig b/security/Kconfig
index d23c839..9c60c34 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -113,6 +113,22 @@
If you are unsure how to answer this question, answer N.
+config LSM_MMAP_MIN_ADDR
+ int "Low address space for LSM to from user allocation"
+ depends on SECURITY && SECURITY_SELINUX
+ default 65535
+ help
+ This is the portion of low virtual memory which should be protected
+ from userspace allocation. Keeping a user from writing to low pages
+ can help reduce the impact of kernel NULL pointer bugs.
+
+ For most ia64, ppc64 and x86 users with lots of address space
+ a value of 65536 is reasonable and should cause no problems.
+ On arm and other archs it should not be higher than 32768.
+ Programs which use vm86 functionality or have some need to map
+ this low address space will need the permission specific to the
+ systems running LSM.
+
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig
diff --git a/security/Makefile b/security/Makefile
index c67557c..b56e7f9 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -8,7 +8,7 @@
subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo
# always enable default capabilities
-obj-y += commoncap.o
+obj-y += commoncap.o min_addr.o
# Object file lists
obj-$(CONFIG_SECURITY) += security.o capability.o
diff --git a/security/capability.c b/security/capability.c
index 21b6cea..88f752e 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -330,15 +330,6 @@
return 0;
}
-static int cap_file_mmap(struct file *file, unsigned long reqprot,
- unsigned long prot, unsigned long flags,
- unsigned long addr, unsigned long addr_only)
-{
- if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))
- return -EACCES;
- return 0;
-}
-
static int cap_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
unsigned long prot)
{
diff --git a/security/commoncap.c b/security/commoncap.c
index 48b7e02..e3097c0 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -984,3 +984,33 @@
cap_sys_admin = 1;
return __vm_enough_memory(mm, pages, cap_sys_admin);
}
+
+/*
+ * cap_file_mmap - check if able to map given addr
+ * @file: unused
+ * @reqprot: unused
+ * @prot: unused
+ * @flags: unused
+ * @addr: address attempting to be mapped
+ * @addr_only: unused
+ *
+ * If the process is attempting to map memory below mmap_min_addr they need
+ * CAP_SYS_RAWIO. The other parameters to this function are unused by the
+ * capability security module. Returns 0 if this mapping should be allowed
+ * -EPERM if not.
+ */
+int cap_file_mmap(struct file *file, unsigned long reqprot,
+ unsigned long prot, unsigned long flags,
+ unsigned long addr, unsigned long addr_only)
+{
+ int ret = 0;
+
+ if (addr < dac_mmap_min_addr) {
+ ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
+ SECURITY_CAP_AUDIT);
+ /* set PF_SUPERPRIV if it turns out we allow the low mmap */
+ if (ret == 0)
+ current->flags |= PF_SUPERPRIV;
+ }
+ return ret;
+}
diff --git a/security/min_addr.c b/security/min_addr.c
new file mode 100644
index 0000000..14cc7b3
--- /dev/null
+++ b/security/min_addr.c
@@ -0,0 +1,49 @@
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/security.h>
+#include <linux/sysctl.h>
+
+/* amount of vm to protect from userspace access by both DAC and the LSM*/
+unsigned long mmap_min_addr;
+/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */
+unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
+/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */
+
+/*
+ * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR)
+ */
+static void update_mmap_min_addr(void)
+{
+#ifdef CONFIG_LSM_MMAP_MIN_ADDR
+ if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR)
+ mmap_min_addr = dac_mmap_min_addr;
+ else
+ mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR;
+#else
+ mmap_min_addr = dac_mmap_min_addr;
+#endif
+}
+
+/*
+ * sysctl handler which just sets dac_mmap_min_addr = the new value and then
+ * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly
+ */
+int mmap_min_addr_handler(struct ctl_table *table, int write, struct file *filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
+
+ update_mmap_min_addr();
+
+ return ret;
+}
+
+int __init init_mmap_min_addr(void)
+{
+ update_mmap_min_addr();
+
+ return 0;
+}
+pure_initcall(init_mmap_min_addr);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 1e8cfc4..8d8b69c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3030,9 +3030,21 @@
int rc = 0;
u32 sid = current_sid();
- if (addr < mmap_min_addr)
+ /*
+ * notice that we are intentionally putting the SELinux check before
+ * the secondary cap_file_mmap check. This is such a likely attempt
+ * at bad behaviour/exploit that we always want to get the AVC, even
+ * if DAC would have also denied the operation.
+ */
+ if (addr < CONFIG_LSM_MMAP_MIN_ADDR) {
rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT,
MEMPROTECT__MMAP_ZERO, NULL);
+ if (rc)
+ return rc;
+ }
+
+ /* do DAC check on address space usage */
+ rc = cap_file_mmap(file, reqprot, prot, flags, addr, addr_only);
if (rc || addr_only)
return rc;