kernel/linux.git/include/uapi/linux/magic.h, branch v6.6.131

mm: Convert all PageMovable users to movable_operations

2022-08-02T16:34:03+00:00

These drivers are rather uncomfortably hammered into the address_space_operations hole. They aren't filesystems and don't behave like filesystems. They just need their own movable_operations structure, which we can point to directly from page->mapping. Signed-off-by: Matthew Wilcox (Oracle)

fuse: move FUSE_SUPER_MAGIC definition to magic.h

2022-02-21T13:57:26+00:00

...to help userland apps that need to identify FUSE mounts. Signed-off-by: Jeff Layton Signed-off-by: Miklos Szeredi

Merge tag 'ceph-for-5.17-rc1' of git://github.com/ceph/ceph-client

2022-01-20T11:46:20+00:00

Pull ceph updates from Ilya Dryomov: "The highlight is the new mount "device" string syntax implemented by Venky Shankar. It solves some long-standing issues with using different auth entities and/or mounting different CephFS filesystems from the same cluster, remounting and also misleading /proc/mounts contents. The existing syntax of course remains to be maintained. On top of that, there is a couple of fixes for edge cases in quota and a new mount option for turning on unbuffered I/O mode globally instead of on a per-file basis with ioctl(CEPH_IOC_SYNCIO)" * tag 'ceph-for-5.17-rc1' of git://github.com/ceph/ceph-client: ceph: move CEPH_SUPER_MAGIC definition to magic.h ceph: remove redundant Lsx caps check ceph: add new "nopagecache" option ceph: don't check for quotas on MDS stray dirs ceph: drop send metrics debug message rbd: make const pointer spaces a static const array ceph: Fix incorrect statfs report for small quota ceph: mount syntax module parameter doc: document new CephFS mount device syntax ceph: record updated mon_addr on remount ceph: new device mount syntax libceph: rename parse_fsid() to ceph_parse_fsid() and export libceph: generalize addr/ip parsing based on delimiter

Merge tag '5.17-rc-part1-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

2022-01-17T07:53:21+00:00

Pull cifs updates from Steve French: - multichannel patches mostly related to improving reconnect behavior - minor cleanup patches * tag '5.17-rc-part1-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6: cifs: fix FILE_BOTH_DIRECTORY_INFO definition cifs: move superblock magic defitions to magic.h cifs: Fix smb311_update_preauth_hash() kernel-doc comment cifs: avoid race during socket reconnect between send and recv cifs: maintain a state machine for tcp/smb/tcon sessions cifs: fix hang on cifs_get_next_mid() cifs: take cifs_tcp_ses_lock for status checks cifs: reconnect only the connection and not smb session where possible cifs: add WARN_ON for when chan_count goes below minimum cifs: adjust DebugData to use chans_need_reconnect for conn status cifs: use the chans_need_reconnect bitmap for reconnect status cifs: track individual channel status using chans_need_reconnect cifs: remove redundant assignment to pointer p

cifs: move superblock magic defitions to magic.h

2022-01-15T16:08:44+00:00

Help userland apps to identify cifs and smb2 mounts. Signed-off-by: Jeff Layton Signed-off-by: Steve French

ceph: move CEPH_SUPER_MAGIC definition to magic.h

2022-01-13T12:40:07+00:00

The uapi headers are missing the ceph definition. Move it there so userland apps can ID cephfs. Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov

exfat: move super block magic number to magic.h

2022-01-10T02:00:03+00:00

Move exfat superblock magic number from local definition to magic.h. It is also needed by userspace programs that call fstatfs(). Acked-by: Christian Brauner Signed-off-by: Namjae Jeon

mm: introduce memfd_secret system call to create "secret" memory areas

2021-07-08T18:48:21+00:00

Introduce "memfd_secret" system call with the ability to create memory areas visible only in the context of the owning process and not mapped not only to other processes but in the kernel page tables as well. The secretmem feature is off by default and the user must explicitly enable it at the boot time. Once secretmem is enabled, the user will be able to create a file descriptor using the memfd_secret() system call. The memory areas created by mmap() calls from this file descriptor will be unmapped from the kernel direct map and they will be only mapped in the page table of the processes that have access to the file descriptor. Secretmem is designed to provide the following protections: * Enhanced protection (in conjunction with all the other in-kernel attack prevention systems) against ROP attacks. Seceretmem makes "simple" ROP insufficient to perform exfiltration, which increases the required complexity of the attack. Along with other protections like the kernel stack size limit and address space layout randomization which make finding gadgets is really hard, absence of any in-kernel primitive for accessing secret memory means the one gadget ROP attack can't work. Since the only way to access secret memory is to reconstruct the missing mapping entry, the attacker has to recover the physical page and insert a PTE pointing to it in the kernel and then retrieve the contents. That takes at least three gadgets which is a level of difficulty beyond most standard attacks. * Prevent cross-process secret userspace memory exposures. Once the secret memory is allocated, the user can't accidentally pass it into the kernel to be transmitted somewhere. The secreremem pages cannot be accessed via the direct map and they are disallowed in GUP. * Harden against exploited kernel flaws. In order to access secretmem, a kernel-side attack would need to either walk the page tables and create new ones, or spawn a new privileged uiserspace process to perform secrets exfiltration using ptrace. The file descriptor based memory has several advantages over the "traditional" mm interfaces, such as mlock(), mprotect(), madvise(). File descriptor approach allows explicit and controlled sharing of the memory areas, it allows to seal the operations. Besides, file descriptor based memory paves the way for VMMs to remove the secret memory range from the userspace hipervisor process, for instance QEMU. Andy Lutomirski says: "Getting fd-backed memory into a guest will take some possibly major work in the kernel, but getting vma-backed memory into a guest without mapping it in the host user address space seems much, much worse." memfd_secret() is made a dedicated system call rather than an extension to memfd_create() because it's purpose is to allow the user to create more secure memory mappings rather than to simply allow file based access to the memory. Nowadays a new system call cost is negligible while it is way simpler for userspace to deal with a clear-cut system calls than with a multiplexer or an overloaded syscall. Moreover, the initial implementation of memfd_secret() is completely distinct from memfd_create() so there is no much sense in overloading memfd_create() to begin with. If there will be a need for code sharing between these implementation it can be easily achieved without a need to adjust user visible APIs. The secret memory remains accessible in the process context using uaccess primitives, but it is not exposed to the kernel otherwise; secret memory areas are removed from the direct map and functions in the follow_page()/get_user_page() family will refuse to return a page that belongs to the secret memory area. Once there will be a use case that will require exposing secretmem to the kernel it will be an opt-in request in the system call flags so that user would have to decide what data can be exposed to the kernel. Removing of the pages from the direct map may cause its fragmentation on architectures that use large pages to map the physical memory which affects the system performance. However, the original Kconfig text for CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "... can improve the kernel's performance a tiny bit ..." (commit 00d1c5e05736 ("x86: add gbpages switches")) and the recent report [1] showed that "... although 1G mappings are a good default choice, there is no compelling evidence that it must be the only choice". Hence, it is sufficient to have secretmem disabled by default with the ability of a system administrator to enable it at boot time. Pages in the secretmem regions are unevictable and unmovable to avoid accidental exposure of the sensitive data via swap or during page migration. Since the secretmem mappings are locked in memory they cannot exceed RLIMIT_MEMLOCK. Since these mappings are already locked independently from mlock(), an attempt to mlock()/munlock() secretmem range would fail and mlockall()/munlockall() will ignore secretmem mappings. However, unlike mlock()ed memory, secretmem currently behaves more like long-term GUP: secretmem mappings are unmovable mappings directly consumed by user space. With default limits, there is no excessive use of secretmem and it poses no real problem in combination with ZONE_MOVABLE/CMA, but in the future this should be addressed to allow balanced use of large amounts of secretmem along with ZONE_MOVABLE/CMA. A page that was a part of the secret memory area is cleared when it is freed to ensure the data is not exposed to the next user of that page. The following example demonstrates creation of a secret mapping (error handling is omitted): fd = memfd_secret(0); ftruncate(fd, MAP_SIZE); ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); [1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/ [akpm@linux-foundation.org: suppress Kconfig whine] Link: https://lkml.kernel.org/r/20210518072034.31572-5-rppt@kernel.org Signed-off-by: Mike Rapoport Acked-by: Hagen Paul Pfeifer Acked-by: James Bottomley Cc: Alexander Viro Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christopher Lameter Cc: Dan Williams Cc: Dave Hansen Cc: Elena Reshetova Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: James Bottomley Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Cc: Mark Rutland Cc: Michael Kerrisk Cc: Palmer Dabbelt Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Rick Edgecombe Cc: Roman Gushchin Cc: Shakeel Butt Cc: Shuah Khan Cc: Thomas Gleixner Cc: Tycho Andersen Cc: Will Deacon Cc: David Hildenbrand Cc: kernel test robot Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

/dev/mem: Revoke mappings when a driver claims the region

2020-05-27T09:10:05+00:00

Close the hole of holding a mapping over kernel driver takeover event of a given address range. Commit 90a545e98126 ("restrict /dev/mem to idle io memory ranges") introduced CONFIG_IO_STRICT_DEVMEM with the goal of protecting the kernel against scenarios where a /dev/mem user tramples memory that a kernel driver owns. However, this protection only prevents *new* read(), write() and mmap() requests. Established mappings prior to the driver calling request_mem_region() are left alone. Especially with persistent memory, and the core kernel metadata that is stored there, there are plentiful scenarios for a /dev/mem user to violate the expectations of the driver and cause amplified damage. Teach request_mem_region() to find and shoot down active /dev/mem mappings that it believes it has successfully claimed for the exclusive use of the driver. Effectively a driver call to request_mem_region() becomes a hole-punch on the /dev/mem device. The typical usage of unmap_mapping_range() is part of truncate_pagecache() to punch a hole in a file, but in this case the implementation is only doing the "first half" of a hole punch. Namely it is just evacuating current established mappings of the "hole", and it relies on the fact that /dev/mem establishes mappings in terms of absolute physical address offsets. Once existing mmap users are invalidated they can attempt to re-establish the mapping, or attempt to continue issuing read(2) / write(2) to the invalidated extent, but they will then be subject to the CONFIG_IO_STRICT_DEVMEM checking that can block those subsequent accesses. Cc: Arnd Bergmann Cc: Ingo Molnar Cc: Kees Cook Cc: Matthew Wilcox Cc: Russell King Cc: Andrew Morton Cc: Greg Kroah-Hartman Fixes: 90a545e98126 ("restrict /dev/mem to idle io memory ranges") Signed-off-by: Dan Williams Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/159009507306.847224.8502634072429766747.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman

fs: New zonefs file system

2020-02-07T05:39:38+00:00

zonefs is a very simple file system exposing each zone of a zoned block device as a file. Unlike a regular file system with zoned block device support (e.g. f2fs), zonefs does not hide the sequential write constraint of zoned block devices to the user. Files representing sequential write zones of the device must be written sequentially starting from the end of the file (append only writes). As such, zonefs is in essence closer to a raw block device access interface than to a full featured POSIX file system. The goal of zonefs is to simplify the implementation of zoned block device support in applications by replacing raw block device file accesses with a richer file API, avoiding relying on direct block device file ioctls which may be more obscure to developers. One example of this approach is the implementation of LSM (log-structured merge) tree structures (such as used in RocksDB and LevelDB) on zoned block devices by allowing SSTables to be stored in a zone file similarly to a regular file system rather than as a range of sectors of a zoned device. The introduction of the higher level construct "one file is one zone" can help reducing the amount of changes needed in the application as well as introducing support for different application programming languages. Zonefs on-disk metadata is reduced to an immutable super block to persistently store a magic number and optional feature flags and values. On mount, zonefs uses blkdev_report_zones() to obtain the device zone configuration and populates the mount point with a static file tree solely based on this information. E.g. file sizes come from the device zone type and write pointer offset managed by the device itself. The zone files created on mount have the following characteristics. 1) Files representing zones of the same type are grouped together under a common sub-directory: * For conventional zones, the sub-directory "cnv" is used. * For sequential write zones, the sub-directory "seq" is used. These two directories are the only directories that exist in zonefs. Users cannot create other directories and cannot rename nor delete the "cnv" and "seq" sub-directories. 2) The name of zone files is the number of the file within the zone type sub-directory, in order of increasing zone start sector. 3) The size of conventional zone files is fixed to the device zone size. Conventional zone files cannot be truncated. 4) The size of sequential zone files represent the file's zone write pointer position relative to the zone start sector. Truncating these files is allowed only down to 0, in which case, the zone is reset to rewind the zone write pointer position to the start of the zone, or up to the zone size, in which case the file's zone is transitioned to the FULL state (finish zone operation). 5) All read and write operations to files are not allowed beyond the file zone size. Any access exceeding the zone size is failed with the -EFBIG error. 6) Creating, deleting, renaming or modifying any attribute of files and sub-directories is not allowed. 7) There are no restrictions on the type of read and write operations that can be issued to conventional zone files. Buffered, direct and mmap read & write operations are accepted. For sequential zone files, there are no restrictions on read operations, but all write operations must be direct IO append writes. mmap write of sequential files is not allowed. Several optional features of zonefs can be enabled at format time. * Conventional zone aggregation: ranges of contiguous conventional zones can be aggregated into a single larger file instead of the default one file per zone. * File ownership: The owner UID and GID of zone files is by default 0 (root) but can be changed to any valid UID/GID. * File access permissions: the default 640 access permissions can be changed. The mkzonefs tool is used to format zoned block devices for use with zonefs. This tool is available on Github at: git@github.com:damien-lemoal/zonefs-tools.git. zonefs-tools also includes a test suite which can be run against any zoned block device, including null_blk block device created with zoned mode. Example: the following formats a 15TB host-managed SMR HDD with 256 MB zones with the conventional zones aggregation feature enabled. $ sudo mkzonefs -o aggr_cnv /dev/sdX $ sudo mount -t zonefs /dev/sdX /mnt $ ls -l /mnt/ total 0 dr-xr-xr-x 2 root root 1 Nov 25 13:23 cnv dr-xr-xr-x 2 root root 55356 Nov 25 13:23 seq The size of the zone files sub-directories indicate the number of files existing for each type of zones. In this example, there is only one conventional zone file (all conventional zones are aggregated under a single file). $ ls -l /mnt/cnv total 137101312 -rw-r----- 1 root root 140391743488 Nov 25 13:23 0 This aggregated conventional zone file can be used as a regular file. $ sudo mkfs.ext4 /mnt/cnv/0 $ sudo mount -o loop /mnt/cnv/0 /data The "seq" sub-directory grouping files for sequential write zones has in this example 55356 zones. $ ls -lv /mnt/seq total 14511243264 -rw-r----- 1 root root 0 Nov 25 13:23 0 -rw-r----- 1 root root 0 Nov 25 13:23 1 -rw-r----- 1 root root 0 Nov 25 13:23 2 ... -rw-r----- 1 root root 0 Nov 25 13:23 55354 -rw-r----- 1 root root 0 Nov 25 13:23 55355 For sequential write zone files, the file size changes as data is appended at the end of the file, similarly to any regular file system. $ dd if=/dev/zero of=/mnt/seq/0 bs=4K count=1 conv=notrunc oflag=direct 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.000452219 s, 9.1 MB/s $ ls -l /mnt/seq/0 -rw-r----- 1 root root 4096 Nov 25 13:23 /mnt/seq/0 The written file can be truncated to the zone size, preventing any further write operation. $ truncate -s 268435456 /mnt/seq/0 $ ls -l /mnt/seq/0 -rw-r----- 1 root root 268435456 Nov 25 13:49 /mnt/seq/0 Truncation to 0 size allows freeing the file zone storage space and restart append-writes to the file. $ truncate -s 0 /mnt/seq/0 $ ls -l /mnt/seq/0 -rw-r----- 1 root root 0 Nov 25 13:49 /mnt/seq/0 Since files are statically mapped to zones on the disk, the number of blocks of a file as reported by stat() and fstat() indicates the size of the file zone. $ stat /mnt/seq/0 File: /mnt/seq/0 Size: 0 Blocks: 524288 IO Block: 4096 regular empty file Device: 870h/2160d Inode: 50431 Links: 1 Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2019-11-25 13:23:57.048971997 +0900 Modify: 2019-11-25 13:52:25.553805765 +0900 Change: 2019-11-25 13:52:25.553805765 +0900 Birth: - The number of blocks of the file ("Blocks") in units of 512B blocks gives the maximum file size of 524288 * 512 B = 256 MB, corresponding to the device zone size in this example. Of note is that the "IO block" field always indicates the minimum IO size for writes and corresponds to the device physical sector size. This code contains contributions from: * Johannes Thumshirn , * Darrick J. Wong , * Christoph Hellwig , * Chaitanya Kulkarni and * Ting Yao . Signed-off-by: Damien Le Moal Reviewed-by: Dave Chinner