diff options
| -rw-r--r-- | include/linux/mm.h | 15 | ||||
| -rw-r--r-- | include/linux/security.h | 17 | ||||
| -rw-r--r-- | kernel/sysctl.c | 7 | ||||
| -rw-r--r-- | mm/Kconfig | 6 | ||||
| -rw-r--r-- | mm/mmap.c | 3 | ||||
| -rw-r--r-- | mm/nommu.c | 3 | ||||
| -rw-r--r-- | security/Kconfig | 16 | ||||
| -rw-r--r-- | security/Makefile | 2 | ||||
| -rw-r--r-- | security/commoncap.c | 2 | ||||
| -rw-r--r-- | security/min_addr.c | 49 | ||||
| -rw-r--r-- | security/selinux/hooks.c | 2 |
11 files changed, 92 insertions, 30 deletions
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 @@ 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> @@ -575,19 +573,6 @@ static inline void set_page_links(struct page *page, enum zone_type zone, } /* - * 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 ac4bc37..dc3472c 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> @@ -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 --- 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 { @@ -225,9 +225,9 @@ config DEFAULT_MMAP_MIN_ADDR 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. @@ -88,9 +88,6 @@ int sysctl_overcommit_ratio = 50; /* default is 50% */ 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 @@ -69,9 +69,6 @@ int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 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 @@ config SECURITY_ROOTPLUG 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-$(CONFIG_SECURITY_SMACK) += smack subdir-$(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/commoncap.c b/security/commoncap.c index 6bcf6e8..e3097c0 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -1005,7 +1005,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, { int ret = 0; - if (addr < mmap_min_addr) { + 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 */ 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 e6d1432..8d8b69c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3036,7 +3036,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot, * at bad behaviour/exploit that we always want to get the AVC, even * if DAC would have also denied the operation. */ - if (addr < mmap_min_addr) { + if (addr < CONFIG_LSM_MMAP_MIN_ADDR) { rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT, MEMPROTECT__MMAP_ZERO, NULL); if (rc) |
