Commit 80efa5c8 authored by Xiongfeng Wang's avatar Xiongfeng Wang Committed by Zheng Zengkai
Browse files

userswap: add a kernel parameter to enable userswap 



hulk inclusion
category: bugfix
bugzilla: 175146
CVE: NA

------------------------------------

Disable userswap by default and add a kernel parameter to enable it.

Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>

 Conflicts:
	include/linux/userfaultfd_k.h
Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 84ff5e27

fs/userfaultfd.c

+15 −2
Original line number Diff line number Diff line
@@ -31,6 +31,9 @@ 
int sysctl_unprivileged_userfaultfd __read_mostly = 1;



static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;

#ifdef CONFIG_USERSWAP

int enable_userswap;

#endif



enum userfaultfd_state {

	UFFD_STATE_WAIT_API,
@@ -863,6 +866,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file) 
	for (vma = mm->mmap; vma; vma = vma->vm_next) {

		userfault_flags = VM_UFFD_MISSING | VM_UFFD_WP;

#ifdef CONFIG_USERSWAP

		if (enable_userswap)

			userfault_flags |= VM_USWAP;

#endif

		cond_resched();
@@ -1295,7 +1299,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
	 * register the whole vma overlapping with the address range to avoid

	 * splitting the vma.

	 */

	if (uffdio_register.mode & UFFDIO_REGISTER_MODE_USWAP) {

	if (enable_userswap && (uffdio_register.mode & UFFDIO_REGISTER_MODE_USWAP)) {

		uffdio_register.mode &= ~UFFDIO_REGISTER_MODE_USWAP;

		if (!uffdio_register.mode)

			goto out;
@@ -2024,6 +2028,15 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) 
	return fd;

}



#ifdef CONFIG_USERSWAP

static int __init enable_userswap_setup(char *str)

{

	enable_userswap = true;

	return 1;

}

__setup("enable_userswap", enable_userswap_setup);

#endif



static int __init userfaultfd_init(void)

{

	userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache",

include/linux/userfaultfd_k.h

+3 −0
Original line number Diff line number Diff line
@@ -31,6 +31,9 @@ 
#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)



extern int sysctl_unprivileged_userfaultfd;

#ifdef CONFIG_USERSWAP

extern int enable_userswap;

#endif



extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);

mm/mmap.c

+3 −3
Original line number Diff line number Diff line
@@ -1598,7 +1598,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, 
			prot |= PROT_EXEC;



#ifdef CONFIG_USERSWAP

	if (flags & MAP_REPLACE) {

	if (enable_userswap && (flags & MAP_REPLACE)) {

		if (offset_in_page(addr) || (len % PAGE_SIZE))

			return -EINVAL;

		page_num = len / PAGE_SIZE;
@@ -1765,7 +1765,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, 


#ifdef CONFIG_USERSWAP

	/* mark the vma as special to avoid merging with other vmas */

	if (flags & MAP_REPLACE)

	if (enable_userswap && (flags & MAP_REPLACE))

		vm_flags |= VM_SPECIAL;

#endif
@@ -1777,7 +1777,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, 
#ifndef CONFIG_USERSWAP

	return addr;

#else

	if (!(flags & MAP_REPLACE))

	if (!enable_userswap || !(flags & MAP_REPLACE))

		return addr;



	if (IS_ERR_VALUE(addr)) {