forked from Minki/linux
84ac013046
syzkaller reports the following issue: BUG: unable to handle page fault for address: ffff888021f7e005 PGD11401067
P4D11401067
PUD 11402067 PMD 21f7d063 PTE 800fffffde081060 Oops: 0002 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3761 Comm: syz-executor281 Not tainted 5.19.0-rc4-syzkaller-00014-g941e3e791269 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:64 Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 RSP: 0018:ffffc9000329fa90 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 0000000000001000 RCX: 0000000000000ffb RDX: 0000000000000ffb RSI: 0000000000000000 RDI: ffff888021f7e005 RBP: ffffea000087df80 R08: 0000000000000001 R09: ffff888021f7e005 R10: ffffed10043efdff R11: 0000000000000000 R12: 0000000000000005 R13: 0000000000000000 R14: 0000000000001000 R15: 0000000000000ffb FS: 00007fb29d8b2700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888021f7e005 CR3: 0000000026e7b000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> zero_user_segments include/linux/highmem.h:272 [inline] folio_zero_range include/linux/highmem.h:428 [inline] truncate_inode_partial_folio+0x76a/0xdf0 mm/truncate.c:237 truncate_inode_pages_range+0x83b/0x1530 mm/truncate.c:381 truncate_inode_pages mm/truncate.c:452 [inline] truncate_pagecache+0x63/0x90 mm/truncate.c:753 simple_setattr+0xed/0x110 fs/libfs.c:535 secretmem_setattr+0xae/0xf0 mm/secretmem.c:170 notify_change+0xb8c/0x12b0 fs/attr.c:424 do_truncate+0x13c/0x200 fs/open.c:65 do_sys_ftruncate+0x536/0x730 fs/open.c:193 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fb29d900899 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb29d8b2318 EFLAGS: 00000246 ORIG_RAX: 000000000000004d RAX: ffffffffffffffda RBX: 00007fb29d988408 RCX: 00007fb29d900899 RDX: 00007fb29d900899 RSI: 0000000000000005 RDI: 0000000000000003 RBP: 00007fb29d988400 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb29d98840c R13: 00007ffca01a23bf R14: 00007fb29d8b2400 R15: 0000000000022000 </TASK> Modules linked in: CR2: ffff888021f7e005 ---[ end trace 0000000000000000 ]--- Eric Biggers suggested that this happens when secretmem_setattr()->simple_setattr() races with secretmem_fault() so that a page that is faulted in by secretmem_fault() (and thus removed from the direct map) is zeroed by inode truncation right afterwards. Use mapping->invalidate_lock to make secretmem_fault() and secretmem_setattr() mutually exclusive. [rppt@linux.ibm.com: v3] Link: https://lkml.kernel.org/r/20220714091337.412297-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20220707165650.248088-1-rppt@kernel.org Reported-by: syzbot+9bd2b7adbd34b30b87e4@syzkaller.appspotmail.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Suggested-by: Eric Biggers <ebiggers@kernel.org> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
294 lines
6.3 KiB
C
294 lines
6.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright IBM Corporation, 2021
|
|
*
|
|
* Author: Mike Rapoport <rppt@linux.ibm.com>
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/memfd.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/printk.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/pseudo_fs.h>
|
|
#include <linux/secretmem.h>
|
|
#include <linux/set_memory.h>
|
|
#include <linux/sched/signal.h>
|
|
|
|
#include <uapi/linux/magic.h>
|
|
|
|
#include <asm/tlbflush.h>
|
|
|
|
#include "internal.h"
|
|
|
|
#undef pr_fmt
|
|
#define pr_fmt(fmt) "secretmem: " fmt
|
|
|
|
/*
|
|
* Define mode and flag masks to allow validation of the system call
|
|
* parameters.
|
|
*/
|
|
#define SECRETMEM_MODE_MASK (0x0)
|
|
#define SECRETMEM_FLAGS_MASK SECRETMEM_MODE_MASK
|
|
|
|
static bool secretmem_enable __ro_after_init;
|
|
module_param_named(enable, secretmem_enable, bool, 0400);
|
|
MODULE_PARM_DESC(secretmem_enable,
|
|
"Enable secretmem and memfd_secret(2) system call");
|
|
|
|
static atomic_t secretmem_users;
|
|
|
|
bool secretmem_active(void)
|
|
{
|
|
return !!atomic_read(&secretmem_users);
|
|
}
|
|
|
|
static vm_fault_t secretmem_fault(struct vm_fault *vmf)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
struct inode *inode = file_inode(vmf->vma->vm_file);
|
|
pgoff_t offset = vmf->pgoff;
|
|
gfp_t gfp = vmf->gfp_mask;
|
|
unsigned long addr;
|
|
struct page *page;
|
|
vm_fault_t ret;
|
|
int err;
|
|
|
|
if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode))
|
|
return vmf_error(-EINVAL);
|
|
|
|
filemap_invalidate_lock_shared(mapping);
|
|
|
|
retry:
|
|
page = find_lock_page(mapping, offset);
|
|
if (!page) {
|
|
page = alloc_page(gfp | __GFP_ZERO);
|
|
if (!page) {
|
|
ret = VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
err = set_direct_map_invalid_noflush(page);
|
|
if (err) {
|
|
put_page(page);
|
|
ret = vmf_error(err);
|
|
goto out;
|
|
}
|
|
|
|
__SetPageUptodate(page);
|
|
err = add_to_page_cache_lru(page, mapping, offset, gfp);
|
|
if (unlikely(err)) {
|
|
put_page(page);
|
|
/*
|
|
* If a split of large page was required, it
|
|
* already happened when we marked the page invalid
|
|
* which guarantees that this call won't fail
|
|
*/
|
|
set_direct_map_default_noflush(page);
|
|
if (err == -EEXIST)
|
|
goto retry;
|
|
|
|
ret = vmf_error(err);
|
|
goto out;
|
|
}
|
|
|
|
addr = (unsigned long)page_address(page);
|
|
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
|
|
}
|
|
|
|
vmf->page = page;
|
|
ret = VM_FAULT_LOCKED;
|
|
|
|
out:
|
|
filemap_invalidate_unlock_shared(mapping);
|
|
return ret;
|
|
}
|
|
|
|
static const struct vm_operations_struct secretmem_vm_ops = {
|
|
.fault = secretmem_fault,
|
|
};
|
|
|
|
static int secretmem_release(struct inode *inode, struct file *file)
|
|
{
|
|
atomic_dec(&secretmem_users);
|
|
return 0;
|
|
}
|
|
|
|
static int secretmem_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long len = vma->vm_end - vma->vm_start;
|
|
|
|
if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
|
|
return -EINVAL;
|
|
|
|
if (mlock_future_check(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
|
|
return -EAGAIN;
|
|
|
|
vma->vm_flags |= VM_LOCKED | VM_DONTDUMP;
|
|
vma->vm_ops = &secretmem_vm_ops;
|
|
|
|
return 0;
|
|
}
|
|
|
|
bool vma_is_secretmem(struct vm_area_struct *vma)
|
|
{
|
|
return vma->vm_ops == &secretmem_vm_ops;
|
|
}
|
|
|
|
static const struct file_operations secretmem_fops = {
|
|
.release = secretmem_release,
|
|
.mmap = secretmem_mmap,
|
|
};
|
|
|
|
static bool secretmem_isolate_page(struct page *page, isolate_mode_t mode)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static int secretmem_migratepage(struct address_space *mapping,
|
|
struct page *newpage, struct page *page,
|
|
enum migrate_mode mode)
|
|
{
|
|
return -EBUSY;
|
|
}
|
|
|
|
static void secretmem_free_folio(struct folio *folio)
|
|
{
|
|
set_direct_map_default_noflush(&folio->page);
|
|
folio_zero_segment(folio, 0, folio_size(folio));
|
|
}
|
|
|
|
const struct address_space_operations secretmem_aops = {
|
|
.dirty_folio = noop_dirty_folio,
|
|
.free_folio = secretmem_free_folio,
|
|
.migratepage = secretmem_migratepage,
|
|
.isolate_page = secretmem_isolate_page,
|
|
};
|
|
|
|
static int secretmem_setattr(struct user_namespace *mnt_userns,
|
|
struct dentry *dentry, struct iattr *iattr)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
struct address_space *mapping = inode->i_mapping;
|
|
unsigned int ia_valid = iattr->ia_valid;
|
|
int ret;
|
|
|
|
filemap_invalidate_lock(mapping);
|
|
|
|
if ((ia_valid & ATTR_SIZE) && inode->i_size)
|
|
ret = -EINVAL;
|
|
else
|
|
ret = simple_setattr(mnt_userns, dentry, iattr);
|
|
|
|
filemap_invalidate_unlock(mapping);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static const struct inode_operations secretmem_iops = {
|
|
.setattr = secretmem_setattr,
|
|
};
|
|
|
|
static struct vfsmount *secretmem_mnt;
|
|
|
|
static struct file *secretmem_file_create(unsigned long flags)
|
|
{
|
|
struct file *file = ERR_PTR(-ENOMEM);
|
|
struct inode *inode;
|
|
|
|
inode = alloc_anon_inode(secretmem_mnt->mnt_sb);
|
|
if (IS_ERR(inode))
|
|
return ERR_CAST(inode);
|
|
|
|
file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem",
|
|
O_RDWR, &secretmem_fops);
|
|
if (IS_ERR(file))
|
|
goto err_free_inode;
|
|
|
|
mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
|
|
mapping_set_unevictable(inode->i_mapping);
|
|
|
|
inode->i_op = &secretmem_iops;
|
|
inode->i_mapping->a_ops = &secretmem_aops;
|
|
|
|
/* pretend we are a normal file with zero size */
|
|
inode->i_mode |= S_IFREG;
|
|
inode->i_size = 0;
|
|
|
|
return file;
|
|
|
|
err_free_inode:
|
|
iput(inode);
|
|
return file;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(memfd_secret, unsigned int, flags)
|
|
{
|
|
struct file *file;
|
|
int fd, err;
|
|
|
|
/* make sure local flags do not confict with global fcntl.h */
|
|
BUILD_BUG_ON(SECRETMEM_FLAGS_MASK & O_CLOEXEC);
|
|
|
|
if (!secretmem_enable)
|
|
return -ENOSYS;
|
|
|
|
if (flags & ~(SECRETMEM_FLAGS_MASK | O_CLOEXEC))
|
|
return -EINVAL;
|
|
if (atomic_read(&secretmem_users) < 0)
|
|
return -ENFILE;
|
|
|
|
fd = get_unused_fd_flags(flags & O_CLOEXEC);
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
file = secretmem_file_create(flags);
|
|
if (IS_ERR(file)) {
|
|
err = PTR_ERR(file);
|
|
goto err_put_fd;
|
|
}
|
|
|
|
file->f_flags |= O_LARGEFILE;
|
|
|
|
atomic_inc(&secretmem_users);
|
|
fd_install(fd, file);
|
|
return fd;
|
|
|
|
err_put_fd:
|
|
put_unused_fd(fd);
|
|
return err;
|
|
}
|
|
|
|
static int secretmem_init_fs_context(struct fs_context *fc)
|
|
{
|
|
return init_pseudo(fc, SECRETMEM_MAGIC) ? 0 : -ENOMEM;
|
|
}
|
|
|
|
static struct file_system_type secretmem_fs = {
|
|
.name = "secretmem",
|
|
.init_fs_context = secretmem_init_fs_context,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
|
|
static int secretmem_init(void)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (!secretmem_enable)
|
|
return ret;
|
|
|
|
secretmem_mnt = kern_mount(&secretmem_fs);
|
|
if (IS_ERR(secretmem_mnt))
|
|
ret = PTR_ERR(secretmem_mnt);
|
|
|
|
/* prevent secretmem mappings from ever getting PROT_EXEC */
|
|
secretmem_mnt->mnt_flags |= MNT_NOEXEC;
|
|
|
|
return ret;
|
|
}
|
|
fs_initcall(secretmem_init);
|