User space applications watch for timestamp changes on character device
files in order to determine idle time of a given terminal session. For
example, "w" program uses this information to populate the IDLE column
of its output [1]. Similarly, systemd-logind has optional feature where
it uses atime of the tty character device to determine if there was
activity on the terminal associated with the logind's session object. If
there was no activity for a configured period of time then logind will
terminate such session [2].
Now, usually (e.g. bash running on the terminal) the use of the terminal
will update timestamps (atime and mtime) on the corresponding terminal
character device. However, if access to the terminal, e.g. /dev/pts/0,
is performed through magic character device /dev/tty then such access
obviously changes the state of the terminal, however timestamps on the
device that correspond to the terminal (/dev/pts/0) are not updated.
This patch makes sure that we update timestamps on *all* character
devices that correspond to the given tty, because outside observers (w,
systemd-logind) are maybe checking these timestamps. Obviously, they can
not check timestamps on /dev/tty as that has per-process meaning.
[1] https://gitlab.com/procps-ng/procps/-/blob/v4.0.0/w.c#L286
[2] https://github.com/systemd/systemd/blob/v252/NEWS#L477
Signed-off-by: Michal Sekletar <msekleta(a)redhat.com>
---
drivers/tty/tty_io.c | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 36fb945fdad4..48e0148b0f3e 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -101,6 +101,7 @@
#include <linux/compat.h>
#include <linux/uaccess.h>
#include <linux/termios_internal.h>
+#include <linux/fs.h>
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
@@ -811,18 +812,27 @@ void start_tty(struct tty_struct *tty)
}
EXPORT_SYMBOL(start_tty);
-static void tty_update_time(struct timespec64 *time)
+static void tty_update_time(struct tty_struct *tty, int tstamp)
{
+ struct tty_file_private *priv;
time64_t sec = ktime_get_real_seconds();
- /*
- * We only care if the two values differ in anything other than the
- * lower three bits (i.e every 8 seconds). If so, then we can update
- * the time of the tty device, otherwise it could be construded as a
- * security leak to let userspace know the exact timing of the tty.
- */
- if ((sec ^ time->tv_sec) & ~7)
- time->tv_sec = sec;
+ spin_lock(&tty->files_lock);
+ list_for_each_entry(priv, &tty->tty_files, list) {
+ struct file *filp = priv->file;
+ struct inode *inode = file_inode(filp);
+ struct timespec64 *time = tstamp == S_MTIME ? &inode->i_mtime : &inode->i_atime;
+
+ /*
+ * We only care if the two values differ in anything other than the
+ * lower three bits (i.e every 8 seconds). If so, then we can update
+ * the time of the tty device, otherwise it could be construded as a
+ * security leak to let userspace know the exact timing of the tty.
+ */
+ if ((sec ^ time->tv_sec) & ~7)
+ time->tv_sec = sec;
+ }
+ spin_unlock(&tty->files_lock);
}
/*
@@ -928,7 +938,7 @@ static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
tty_ldisc_deref(ld);
if (i > 0)
- tty_update_time(&inode->i_atime);
+ tty_update_time(tty, S_ATIME);
return i;
}
@@ -1036,7 +1046,7 @@ static inline ssize_t do_tty_write(
cond_resched();
}
if (written) {
- tty_update_time(&file_inode(file)->i_mtime);
+ tty_update_time(tty, S_MTIME);
ret = written;
}
out:
--
2.39.2
Hi,
Commit cb2c7d1a1776 ("landlock: Support filesystem access-control")
introduced a new ARCH_EPHEMERAL_INODES configuration, only enabled for
User-Mode Linux. The reason was that UML's hostfs managed inodes in an
ephemeral way: from the kernel point of view, the same inode struct
could be created several times while being used by user space because
the kernel didn't hold references to inodes. Because Landlock (and
probably other subsystems) ties properties (i.e. access rights) to inode
objects, it wasn't possible to create rules that match inodes and then
allow specific accesses.
This patch series fixes the way UML manages inodes according to the
underlying filesystem. They are now properly handles as for other
filesystems, which enables to support Landlock (and probably other
features).
Backporting these patches requires some selftest harness patches
backports too.
Regards,
Mickaël Salaün (5):
hostfs: Fix ephemeral inodes
selftests/landlock: Don't create useless file layouts
selftests/landlock: Add supports_filesystem() helper
selftests/landlock: Make mounts configurable
selftests/landlock: Add tests for pseudo filesystems
arch/Kconfig | 7 -
arch/um/Kconfig | 1 -
fs/hostfs/hostfs.h | 1 +
fs/hostfs/hostfs_kern.c | 213 ++++++------
fs/hostfs/hostfs_user.c | 1 +
security/landlock/Kconfig | 2 +-
tools/testing/selftests/landlock/config | 8 +-
tools/testing/selftests/landlock/fs_test.c | 381 +++++++++++++++++++--
8 files changed, 472 insertions(+), 142 deletions(-)
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
--
2.39.2
Hi,
This follows the discussion here:
https://lore.kernel.org/linux-kselftest/20230324123157.bbwvfq4gsxnlnfwb@hou…
This shows a couple of inconsistencies with regard to how device-managed
resources are cleaned up. Basically, devm resources will only be cleaned up
if the device is attached to a bus and bound to a driver. Failing any of
these cases, a call to device_unregister will not end up in the devm
resources being released.
We had to work around it in DRM to provide helpers to create a device for
kunit tests, but the current discussion around creating similar, generic,
helpers for kunit resumed interest in fixing this.
This can be tested using the command:
./tools/testing/kunit/kunit.py run --kunitconfig=drivers/base/test/
Let me know what you think,
Maxime
Signed-off-by: Maxime Ripard <maxime(a)cerno.tech>
---
Maxime Ripard (2):
drivers: base: Add basic devm tests for root devices
drivers: base: Add basic devm tests for platform devices
drivers/base/test/.kunitconfig | 2 +
drivers/base/test/Kconfig | 4 +
drivers/base/test/Makefile | 3 +
drivers/base/test/platform-device-test.c | 278 +++++++++++++++++++++++++++++++
drivers/base/test/root-device-test.c | 120 +++++++++++++
5 files changed, 407 insertions(+)
---
base-commit: a6faf7ea9fcb7267d06116d4188947f26e00e57e
change-id: 20230329-kunit-devm-inconsistencies-test-5e5a7d01e60d
Best regards,
--
Maxime Ripard <maxime(a)cerno.tech>
This is the v7 of this series which tries to implement the fd-based KVM
guest private memory. The patches are based on latest kvm/queue branch
commit:
b9b71f43683a (kvm/queue) KVM: x86/mmu: Buffer nested MMU
split_desc_cache only by default capacity
Introduction
------------
In general this patch series introduce fd-based memslot which provides
guest memory through memory file descriptor fd[offset,size] instead of
hva/size. The fd can be created from a supported memory filesystem
like tmpfs/hugetlbfs etc. which we refer as memory backing store. KVM
and the the memory backing store exchange callbacks when such memslot
gets created. At runtime KVM will call into callbacks provided by the
backing store to get the pfn with the fd+offset. Memory backing store
will also call into KVM callbacks when userspace punch hole on the fd
to notify KVM to unmap secondary MMU page table entries.
Comparing to existing hva-based memslot, this new type of memslot allows
guest memory unmapped from host userspace like QEMU and even the kernel
itself, therefore reduce attack surface and prevent bugs.
Based on this fd-based memslot, we can build guest private memory that
is going to be used in confidential computing environments such as Intel
TDX and AMD SEV. When supported, the memory backing store can provide
more enforcement on the fd and KVM can use a single memslot to hold both
the private and shared part of the guest memory.
mm extension
---------------------
Introduces new MFD_INACCESSIBLE flag for memfd_create(), the file
created with these flags cannot read(), write() or mmap() etc via normal
MMU operations. The file content can only be used with the newly
introduced memfile_notifier extension.
The memfile_notifier extension provides two sets of callbacks for KVM to
interact with the memory backing store:
- memfile_notifier_ops: callbacks for memory backing store to notify
KVM when memory gets invalidated.
- backing store callbacks: callbacks for KVM to call into memory
backing store to request memory pages for guest private memory.
The memfile_notifier extension also provides APIs for memory backing
store to register/unregister itself and to trigger the notifier when the
bookmarked memory gets invalidated.
The patchset also introduces a new memfd seal F_SEAL_AUTO_ALLOCATE to
prevent double allocation caused by unintentional guest when we only
have a single side of the shared/private memfds effective.
memslot extension
-----------------
Add the private fd and the fd offset to existing 'shared' memslot so
that both private/shared guest memory can live in one single memslot.
A page in the memslot is either private or shared. Whether a guest page
is private or shared is maintained through reusing existing SEV ioctls
KVM_MEMORY_ENCRYPT_{UN,}REG_REGION.
Test
----
To test the new functionalities of this patch TDX patchset is needed.
Since TDX patchset has not been merged so I did two kinds of test:
- Regresion test on kvm/queue (this patchset)
Most new code are not covered. Code also in below repo:
https://github.com/chao-p/linux/tree/privmem-v7
- New Funational test on latest TDX code
The patch is rebased to latest TDX code and tested the new
funcationalities. See below repos:
Linux: https://github.com/chao-p/linux/tree/privmem-v7-tdx
QEMU: https://github.com/chao-p/qemu/tree/privmem-v7
An example QEMU command line for TDX test:
-object tdx-guest,id=tdx,debug=off,sept-ve-disable=off \
-machine confidential-guest-support=tdx \
-object memory-backend-memfd-private,id=ram1,size=${mem} \
-machine memory-backend=ram1
Changelog
----------
v7:
- Move the private/shared info from backing store to KVM.
- Introduce F_SEAL_AUTO_ALLOCATE to avoid double allocation.
- Rework on the sync mechanism between zap/page fault paths.
- Addressed other comments in v6.
v6:
- Re-organzied patch for both mm/KVM parts.
- Added flags for memfile_notifier so its consumers can state their
features and memory backing store can check against these flags.
- Put a backing store reference in the memfile_notifier and move pfn_ops
into backing store.
- Only support boot time backing store register.
- Overall KVM part improvement suggested by Sean and some others.
v5:
- Removed userspace visible F_SEAL_INACCESSIBLE, instead using an
in-kernel flag (SHM_F_INACCESSIBLE for shmem). Private fd can only
be created by MFD_INACCESSIBLE.
- Introduced new APIs for backing store to register itself to
memfile_notifier instead of direct function call.
- Added the accounting and restriction for MFD_INACCESSIBLE memory.
- Added KVM API doc for new memslot extensions and man page for the new
MFD_INACCESSIBLE flag.
- Removed the overlap check for mapping the same file+offset into
multiple gfns due to perf consideration, warned in document.
- Addressed other comments in v4.
v4:
- Decoupled the callbacks between KVM/mm from memfd and use new
name 'memfile_notifier'.
- Supported register multiple memslots to the same backing store.
- Added per-memslot pfn_ops instead of per-system.
- Reworked the invalidation part.
- Improved new KVM uAPIs (private memslot extension and memory
error) per Sean's suggestions.
- Addressed many other minor fixes for comments from v3.
v3:
- Added locking protection when calling
invalidate_page_range/fallocate callbacks.
- Changed memslot structure to keep use useraddr for shared memory.
- Re-organized F_SEAL_INACCESSIBLE and MEMFD_OPS.
- Added MFD_INACCESSIBLE flag to force F_SEAL_INACCESSIBLE.
- Commit message improvement.
- Many small fixes for comments from the last version.
Links to previous discussions
-----------------------------
[1] Original design proposal:
https://lkml.kernel.org/kvm/20210824005248.200037-1-seanjc@google.com/
[2] Updated proposal and RFC patch v1:
https://lkml.kernel.org/linux-fsdevel/20211111141352.26311-1-chao.p.peng@li…
[3] Patch v5: https://lkml.org/lkml/2022/5/19/861
Chao Peng (12):
mm: Add F_SEAL_AUTO_ALLOCATE seal to memfd
selftests/memfd: Add tests for F_SEAL_AUTO_ALLOCATE
mm: Introduce memfile_notifier
mm/memfd: Introduce MFD_INACCESSIBLE flag
KVM: Rename KVM_PRIVATE_MEM_SLOTS to KVM_INTERNAL_MEM_SLOTS
KVM: Use gfn instead of hva for mmu_notifier_retry
KVM: Rename mmu_notifier_*
KVM: Extend the memslot to support fd-based private memory
KVM: Add KVM_EXIT_MEMORY_FAULT exit
KVM: Register/unregister the guest private memory regions
KVM: Handle page fault for private memory
KVM: Enable and expose KVM_MEM_PRIVATE
Kirill A. Shutemov (1):
mm/shmem: Support memfile_notifier
Documentation/virt/kvm/api.rst | 77 +++++-
arch/arm64/kvm/mmu.c | 8 +-
arch/mips/include/asm/kvm_host.h | 2 +-
arch/mips/kvm/mmu.c | 10 +-
arch/powerpc/include/asm/kvm_book3s_64.h | 2 +-
arch/powerpc/kvm/book3s_64_mmu_host.c | 4 +-
arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 +-
arch/powerpc/kvm/book3s_64_mmu_radix.c | 6 +-
arch/powerpc/kvm/book3s_hv_nested.c | 2 +-
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 8 +-
arch/powerpc/kvm/e500_mmu_host.c | 4 +-
arch/riscv/kvm/mmu.c | 4 +-
arch/x86/include/asm/kvm_host.h | 3 +-
arch/x86/kvm/Kconfig | 3 +
arch/x86/kvm/mmu.h | 2 -
arch/x86/kvm/mmu/mmu.c | 74 +++++-
arch/x86/kvm/mmu/mmu_internal.h | 18 ++
arch/x86/kvm/mmu/mmutrace.h | 1 +
arch/x86/kvm/mmu/paging_tmpl.h | 4 +-
arch/x86/kvm/x86.c | 2 +-
include/linux/kvm_host.h | 105 +++++---
include/linux/memfile_notifier.h | 91 +++++++
include/linux/shmem_fs.h | 2 +
include/uapi/linux/fcntl.h | 1 +
include/uapi/linux/kvm.h | 37 +++
include/uapi/linux/memfd.h | 1 +
mm/Kconfig | 4 +
mm/Makefile | 1 +
mm/memfd.c | 18 +-
mm/memfile_notifier.c | 123 ++++++++++
mm/shmem.c | 125 +++++++++-
tools/testing/selftests/memfd/memfd_test.c | 166 +++++++++++++
virt/kvm/Kconfig | 3 +
virt/kvm/kvm_main.c | 272 ++++++++++++++++++---
virt/kvm/pfncache.c | 14 +-
35 files changed, 1074 insertions(+), 127 deletions(-)
create mode 100644 include/linux/memfile_notifier.h
create mode 100644 mm/memfile_notifier.c
--
2.25.1
v2:
---
* swap order of patches (thanks Claudio)
* add r-b
* add comment why memslots are zeroed
Add a new selftest for CMMA migration. Also fix a small issue found during
development of the test.
Nico Boehr (2):
KVM: s390: fix KVM_S390_GET_CMMA_BITS for GFNs in memslot holes
KVM: s390: selftests: add selftest for CMMA migration
arch/s390/kvm/kvm-s390.c | 4 +
tools/testing/selftests/kvm/Makefile | 1 +
tools/testing/selftests/kvm/s390x/cmma_test.c | 680 ++++++++++++++++++
3 files changed, 685 insertions(+)
create mode 100644 tools/testing/selftests/kvm/s390x/cmma_test.c
--
2.39.1
The default timeout for kselftests is 45 seconds, but pcm-test can take
longer than that to run depending on the number of PCMs present on a
device.
As a data point, running pcm-test on mt8192-asurada-spherion takes about
1m15s.
Set the timeout to 10 minutes, which should give enough slack to run the
test even on devices with many PCMs.
Signed-off-by: Nícolas F. R. A. Prado <nfraprado(a)collabora.com>
---
tools/testing/selftests/alsa/settings | 1 +
1 file changed, 1 insertion(+)
create mode 100644 tools/testing/selftests/alsa/settings
diff --git a/tools/testing/selftests/alsa/settings b/tools/testing/selftests/alsa/settings
new file mode 100644
index 000000000000..a62d2fa1275c
--- /dev/null
+++ b/tools/testing/selftests/alsa/settings
@@ -0,0 +1 @@
+timeout=600
--
2.39.0
Hi all,
following bug is trying to workaround an error on ppc64le, where
zram01.sh LTP test (there is also kernel selftest
tools/testing/selftests/zram/zram01.sh, but LTP test got further
updates) has often mem_used_total 0 although zram is already filled.
Patch tries to repeatedly read /sys/block/zram*/mm_stat for 1 sec,
waiting for mem_used_total > 0. The question if this is expected and
should be workarounded or a bug which should be fixed.
REPRODUCE THE ISSUE
Quickest way to install only zram tests and their dependencies:
make autotools && ./configure && for i in testcases/lib/ testcases/kernel/device-drivers/zram/; do cd $i && make -j$(getconf _NPROCESSORS_ONLN) && make install && cd -; done
Run the test (only on vfat)
PATH="/opt/ltp/testcases/bin:$PATH" LTP_SINGLE_FS_TYPE=vfat zram01.sh
Petr Vorel (1):
zram01.sh: Workaround division by 0 on vfat on ppc64le
.../kernel/device-drivers/zram/zram01.sh | 27 +++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
--
2.38.0