commit 34951f3c28bdf6481d949a20413b2ce7693687b2 upstream.
Describe the code and data of the decompressor binary using separate
.text and .data PE/COFF sections, so that we will be able to map them
using restricted permissions once we increase the section and file
alignment sufficiently. This avoids the need for memory mappings that
are writable and executable at the same time, which is something that
is best avoided for security reasons.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-17-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit efa089e63b56bdc5eca754b995cb039dd7a5457e upstream.
Now that the size of the setup block is visible to the assembler, it is
possible to populate the PE/COFF header fields from the asm code
directly, instead of poking the values into the binary using the build
tool. This will make it easier to reorganize the section layout without
having to tweak the build tool in lockstep.
This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-15-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit aeb92067f6ae994b541d7f9752fe54ed3d108bcc upstream.
Tweak the linker script so that the value of _edata represents the
decompressor binary's file size rounded up to the appropriate alignment.
This removes the need to calculate it in the build tool, and will make
it easier to refer to the file size from the header directly in
subsequent changes to the PE header layout.
While adding _edata to the sed regex that parses the compressed
vmlinux's symbol list, tweak the regex a bit for conciseness.
This change has no impact on the resulting bzImage binary when
configured with CONFIG_EFI_STUB=y.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-14-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 093ab258e3fb1d1d3afdfd4a69403d44ce90e360 upstream.
The setup block contains the real mode startup code that is used when
booting from a legacy BIOS, along with the boot_params/setup_data that
is used by legacy x86 bootloaders to pass the command line and initial
ramdisk parameters, among other things.
The setup block also contains the PE/COFF header of the entire combined
image, which includes the compressed kernel image, the decompressor and
the EFI stub.
This PE header describes the layout of the executable image in memory,
and currently, the fact that the setup block precedes it makes it rather
fiddly to get the right values into the right place in the final image.
Let's make things a bit easier by defining the setup_size in the linker
script so it can be referenced from the asm code directly, rather than
having to rely on the build tool to calculate it. For the time being,
add 64 bytes of fixed padding for the .reloc and .compat sections - this
will be removed in a subsequent patch after the PE/COFF header has been
reorganized.
This change has no impact on the resulting bzImage binary when
configured with CONFIG_EFI_MIXED=y.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-13-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit eac956345f99dda3d68f4ae6cf7b494105e54780 upstream.
The offsets of the EFI handover entrypoints are available to the
assembler when constructing the header, so there is no need to set them
from the build tool afterwards.
This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-12-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 2e765c02dcbfc2a8a4527c621a84b9502f6b9bd2 upstream.
Instead of parsing zoffset.h and poking the kernel_info offset value
into the header from the build tool, just grab the value directly in the
asm file that describes this header.
This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-11-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b618d31f112bea3d2daea19190d63e567f32a4db upstream.
The x86 boot image generation tool assign a default value to startup_64
and subsequently parses the actual value from zoffset.h but it never
actually uses the value anywhere. So remove this code.
This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230912090051.4014114-25-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 7448e8e5d15a3c4df649bf6d6d460f78396f7e1e upstream.
The root device defaults to 0,0 and is no longer configurable at build
time [0], so there is no need for the build tool to ever write to this
field.
[0] 079f85e624 ("x86, build: Do not set the root_dev field in bzImage")
This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230912090051.4014114-23-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8eace5b3555606e684739bef5bcdfcfe68235257 upstream.
Now that the EFI stub decompresses the kernel and hands over to the
decompressed image directly, there is no longer a need to provide a
decompression buffer as part of the .BSS allocation of the PE/COFF
image. It also means the PE/COFF image can be loaded anywhere in memory,
and setting the preferred image base is unnecessary. So drop the
handling of this from the header and from the build tool.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230912090051.4014114-22-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 768171d7ebbce005210e1cf8456f043304805c15 upstream.
Ancient (pre-2003) x86 kernels could boot from a floppy disk straight from
the BIOS, using a small real mode boot stub at the start of the image
where the BIOS would expect the boot record (or boot block) to appear.
Due to its limitations (kernel size < 1 MiB, no support for IDE, USB or
El Torito floppy emulation), this support was dropped, and a Linux aware
bootloader is now always required to boot the kernel from a legacy BIOS.
To smoothen this transition, the boot stub was not removed entirely, but
replaced with one that just prints an error message telling the user to
install a bootloader.
As it is unlikely that anyone doing direct floppy boot with such an
ancient kernel is going to upgrade to v6.5+ and expect that this boot
method still works, printing this message is kind of pointless, and so
it should be possible to remove the logic that emits it.
Let's free up this space so it can be used to expand the PE header in a
subsequent patch.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: https://lore.kernel.org/r/20230912090051.4014114-21-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 7e50262229faad0c7b8c54477cd1c883f31cc4a7 upstream.
The native EFI entrypoint does not take a struct boot_params from the
loader, but instead, it constructs one from scratch, using the setup
header data placed at the start of the image.
This setup header is placed in a way that permits legacy loaders to
manipulate the contents (i.e., to pass the kernel command line or the
address and size of an initial ramdisk), but EFI boot does not use it in
that way - it only copies the contents that were placed there at build
time, but EFI loaders will not (and should not) manipulate the setup
header to configure the boot. (Commit 63bf28ceb3 "efi: x86: Wipe
setup_data on pure EFI boot" deals with some of the fallout of using
setup_data in a way that breaks EFI boot.)
Given that none of the non-zero values that are copied from the setup
header into the EFI stub's struct boot_params are relevant to the boot
now that the EFI stub no longer enters via the legacy decompressor, the
copy can be omitted altogether.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230912090051.4014114-19-ardb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5ea9a7c5fe4149f165f0e3b624fe08df02b6c301 upstream.
A recent change to check_for_locks() changed it to take ->flc_lock while
holding ->fi_lock. This creates a lock inversion (reported by lockdep)
because there is a case where ->fi_lock is taken while holding
->flc_lock.
->flc_lock is held across ->fl_lmops callbacks, and
nfsd_break_deleg_cb() is one of those and does take ->fi_lock. However
it doesn't need to.
Prior to v4.17-rc1~110^2~22 ("nfsd: create a separate lease for each
delegation") nfsd_break_deleg_cb() would walk the ->fi_delegations list
and so needed the lock. Since then it doesn't walk the list and doesn't
need the lock.
Two actions are performed under the lock. One is to call
nfsd_break_one_deleg which calls nfsd4_run_cb(). These doesn't act on
the nfs4_file at all, so don't need the lock.
The other is to set ->fi_had_conflict which is in the nfs4_file.
This field is only ever set here (except when initialised to false)
so there is no possible problem will multiple threads racing when
setting it.
The field is tested twice in nfs4_set_delegation(). The first test does
not hold a lock and is documented as an opportunistic optimisation, so
it doesn't impose any need to hold ->fi_lock while setting
->fi_had_conflict.
The second test in nfs4_set_delegation() *is* make under ->fi_lock, so
removing the locking when ->fi_had_conflict is set could make a change.
The change could only be interesting if ->fi_had_conflict tested as
false even though nfsd_break_one_deleg() ran before ->fi_lock was
unlocked. i.e. while hash_delegation_locked() was running.
As hash_delegation_lock() doesn't interact in any way with nfs4_run_cb()
there can be no importance to this interaction.
So this patch removes the locking from nfsd_break_one_deleg() and moves
the final test on ->fi_had_conflict out of the locked region to make it
clear that locking isn't important to the test. It is still tested
*after* vfs_setlease() has succeeded. This might be significant and as
vfs_setlease() takes ->flc_lock, and nfsd_break_one_deleg() is called
under ->flc_lock this "after" is a true ordering provided by a spinlock.
Fixes: edcf9725150e ("nfsd: fix RELEASE_LOCKOWNER")
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 43aa6f97c2d03a52c1ddb86768575fc84344bdbb upstream.
The eventfs inode had pointers to dentries (and child dentries) without
actually holding a refcount on said pointer. That is fundamentally
broken, and while eventfs tried to then maintain coherence with dentries
going away by hooking into the '.d_iput' callback, that doesn't actually
work since it's not ordered wrt lookups.
There were two reasonms why eventfs tried to keep a pointer to a dentry:
- the creation of a 'events' directory would actually have a stable
dentry pointer that it created with tracefs_start_creating().
And it needed that dentry when tearing it all down again in
eventfs_remove_events_dir().
This use is actually ok, because the special top-level events
directory dentries are actually stable, not just a temporary cache of
the eventfs data structures.
- the 'eventfs_inode' (aka ei) needs to stay around as long as there
are dentries that refer to it.
It then used these dentry pointers as a replacement for doing
reference counting: it would try to make sure that there was only
ever one dentry associated with an event_inode, and keep a child
dentry array around to see which dentries might still refer to the
parent ei.
This gets rid of the invalid dentry pointer use, and renames the one
valid case to a different name to make it clear that it's not just any
random dentry.
The magic child dentry array that is kind of a "reverse reference list"
is simply replaced by having child dentries take a ref to the ei. As
does the directory dentries. That makes the broken use case go away.
Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240131185513.280463000@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: c1504e5102 ("eventfs: Implement eventfs dir creation functions")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8dce06e98c70a7fcbb4bca7d90faf40522e65c58 upstream.
In order for the dentries to stay up-to-date with the eventfs changes,
just add a 'd_revalidate' function that checks the 'is_freed' bit.
Also, clean up the dentry release to actually use d_release() rather
than the slightly odd d_iput() function. We don't care about the inode,
all we want to do is to get rid of the refcount to the eventfs data
added by dentry->d_fsdata.
It would probably be cleaner to make eventfs its own filesystem, or at
least set its own dentry ops when looking up eventfs files. But as it
is, only eventfs dentries use d_fsdata, so we don't really need to split
these things up by use.
Another thing that might be worth doing is to make all eventfs lookups
mark their dentries as not worth caching. We could do that with
d_delete(), but the DCACHE_DONTCACHE flag would likely be even better.
As it is, the dentries are all freeable, but they only tend to get freed
at memory pressure rather than more proactively. But that's a separate
issue.
Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240131185513.124644253@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: c1504e5102 ("eventfs: Implement eventfs dir creation functions")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 99c001cb617df409dac275a059d6c3f187a2da7a upstream.
The eventfs_find_events() code tries to walk up the tree to find the
event directory that a dentry belongs to, in order to then find the
eventfs inode that is associated with that event directory.
However, it uses an odd combination of walking the dentry parent,
looking up the eventfs inode associated with that, and then looking up
the dentry from there. Repeat.
But the code shouldn't have back-pointers to dentries in the first
place, and it should just walk the dentry parenthood chain directly.
Similarly, 'set_top_events_ownership()' looks up the dentry from the
eventfs inode, but the only reason it wants a dentry is to look up the
superblock in order to look up the root dentry.
But it already has the real filesystem inode, which has that same
superblock pointer. So just pass in the superblock pointer using the
information that's already there, instead of looking up extraneous data
that is irrelevant.
Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240131185512.638645365@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: c1504e5102 ("eventfs: Implement eventfs dir creation functions")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 834bf76add3e6168038150f162cbccf1fd492a67 upstream.
The eventfs inodes and directories are allocated when referenced. But this
leaves the issue of keeping consistent inode numbers and the number is
only saved in the inode structure itself. When the inode is no longer
referenced, it can be freed. When the file that the inode was representing
is referenced again, the inode is once again created, but the inode number
needs to be the same as it was before.
Just making the inode numbers the same for all files is fine, but that
does not work with directories. The find command will check for loops via
the inode number and having the same inode number for directories triggers:
# find /sys/kernel/tracing
find: File system loop detected;
'/sys/kernel/debug/tracing/events/initcall/initcall_finish' is part of the same file system loop as
'/sys/kernel/debug/tracing/events/initcall'.
[..]
Linus pointed out that the eventfs_inode structure ends with a single
32bit int, and on 64 bit machines, there's likely a 4 byte hole due to
alignment. We can use this hole to store the inode number for the
eventfs_inode. All directories in eventfs are represented by an
eventfs_inode and that data structure can hold its inode number.
That last int was also purposely placed at the end of the structure to
prevent holes from within. Now that there's a 4 byte number to hold the
inode, both the inode number and the last integer can be moved up in the
structure for better cache locality, where the llist and rcu fields can be
moved to the end as they are only used when the eventfs_inode is being
deleted.
Link: https://lore.kernel.org/all/CAMuHMdXKiorg-jiuKoZpfZyDJ3Ynrfb8=X+c7x0Eewxn-YRdCA@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240122152748.46897388@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 53c41052ba31 ("eventfs: Have the inodes all for files and directories all be the same")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 852e46e239ee6db3cd220614cf8bce96e79227c2 upstream.
The original eventfs code added a wrapper around the dcache_readdir open
callback and created all the dentries and inodes at open, and increment
their ref count. A wrapper was added around the dcache_readdir release
function to decrement all the ref counts of those created inodes and
dentries. But this proved to be buggy[1] for when a kprobe was created
during a dir read, it would create a dentry between the open and the
release, and because the release would decrement all ref counts of all
files and directories, that would include the kprobe directory that was
not there to have its ref count incremented in open. This would cause the
ref count to go to negative and later crash the kernel.
To solve this, the dentries and inodes that were created and had their ref
count upped in open needed to be saved. That list needed to be passed from
the open to the release, so that the release would only decrement the ref
counts of the entries that were incremented in the open.
Unfortunately, the dcache_readdir logic was already using the
file->private_data, which is the only field that can be used to pass
information from the open to the release. What was done was the eventfs
created another descriptor that had a void pointer to save the
dcache_readdir pointer, and it wrapped all the callbacks, so that it could
save the list of entries that had their ref counts incremented in the
open, and pass it to the release. The wrapped callbacks would just put
back the dcache_readdir pointer and call the functions it used so it could
still use its data[2].
But Linus had an issue with the "hijacking" of the file->private_data
(unfortunately this discussion was on a security list, so no public link).
Which we finally agreed on doing everything within the iterate_shared
callback and leave the dcache_readdir out of it[3]. All the information
needed for the getents() could be created then.
But this ended up being buggy too[4]. The iterate_shared callback was not
the right place to create the dentries and inodes. Even Christian Brauner
had issues with that[5].
An attempt was to go back to creating the inodes and dentries at
the open, create an array to store the information in the
file->private_data, and pass that information to the other callbacks.[6]
The difference between that and the original method, is that it does not
use dcache_readdir. It also does not up the ref counts of the dentries and
pass them. Instead, it creates an array of a structure that saves the
dentry's name and inode number. That information is used in the
iterate_shared callback, and the array is freed in the dir release. The
dentries and inodes created in the open are not used for the iterate_share
or release callbacks. Just their names and inode numbers.
Linus did not like that either[7] and just wanted to remove the dentries
being created in iterate_shared and use the hard coded inode numbers.
[ All this while Linus enjoyed an unexpected vacation during the merge
window due to lack of power. ]
[1] https://lore.kernel.org/linux-trace-kernel/20230919211804.230edf1e@gandalf.local.home/
[2] https://lore.kernel.org/linux-trace-kernel/20230922163446.1431d4fa@gandalf.local.home/
[3] https://lore.kernel.org/linux-trace-kernel/20240104015435.682218477@goodmis.org/
[4] https://lore.kernel.org/all/202401152142.bfc28861-oliver.sang@intel.com/
[5] https://lore.kernel.org/all/20240111-unzahl-gefegt-433acb8a841d@brauner/
[6] https://lore.kernel.org/all/20240116114711.7e8637be@gandalf.local.home/
[7] https://lore.kernel.org/all/20240116170154.5bf0a250@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20240116211353.573784051@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Fixes: 493ec81a8fb8 ("eventfs: Stop using dcache_readdir() for getdents()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401152142.bfc28861-oliver.sang@intel.com
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1e4624eb5a0ecaae0d2c4e3019bece119725bb98 upstream.
The ctx->pos was only updated when it added an entry, but the "skip to
current pos" check (c--) happened for every loop regardless of if the
entry was added or not. This inconsistency caused readdir to be incorrect.
It was due to:
for (i = 0; i < ei->nr_entries; i++) {
if (c > 0) {
c--;
continue;
}
mutex_lock(&eventfs_mutex);
/* If ei->is_freed then just bail here, nothing more to do */
if (ei->is_freed) {
mutex_unlock(&eventfs_mutex);
goto out;
}
r = entry->callback(name, &mode, &cdata, &fops);
mutex_unlock(&eventfs_mutex);
[..]
ctx->pos++;
}
But this can cause the iterator to return a file that was already read.
That's because of the way the callback() works. Some events may not have
all files, and the callback can return 0 to tell eventfs to skip the file
for this directory.
for instance, we have:
# ls /sys/kernel/tracing/events/ftrace/function
format hist hist_debug id inject
and
# ls /sys/kernel/tracing/events/sched/sched_switch/
enable filter format hist hist_debug id inject trigger
Where the function directory is missing "enable", "filter" and
"trigger". That's because the callback() for events has:
static int event_callback(const char *name, umode_t *mode, void **data,
const struct file_operations **fops)
{
struct trace_event_file *file = *data;
struct trace_event_call *call = file->event_call;
[..]
/*
* Only event directories that can be enabled should have
* triggers or filters, with the exception of the "print"
* event that can have a "trigger" file.
*/
if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) {
if (call->class->reg && strcmp(name, "enable") == 0) {
*mode = TRACE_MODE_WRITE;
*fops = &ftrace_enable_fops;
return 1;
}
if (strcmp(name, "filter") == 0) {
*mode = TRACE_MODE_WRITE;
*fops = &ftrace_event_filter_fops;
return 1;
}
}
if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||
strcmp(trace_event_name(call), "print") == 0) {
if (strcmp(name, "trigger") == 0) {
*mode = TRACE_MODE_WRITE;
*fops = &event_trigger_fops;
return 1;
}
}
[..]
return 0;
}
Where the function event has the TRACE_EVENT_FL_IGNORE_ENABLE set.
This means that the entries array elements for "enable", "filter" and
"trigger" when called on the function event will have the callback return
0 and not 1, to tell eventfs to skip these files for it.
Because the "skip to current ctx->pos" check happened for all entries, but
the ctx->pos++ only happened to entries that exist, it would confuse the
reading of a directory. Which would cause:
# ls /sys/kernel/tracing/events/ftrace/function/
format hist hist hist_debug hist_debug id inject inject
The missing "enable", "filter" and "trigger" caused ls to show "hist",
"hist_debug" and "inject" twice.
Update the ctx->pos for every iteration to keep its update and the "skip"
update consistent. This also means that on error, the ctx->pos needs to be
decremented if it was incremented without adding something.
Link: https://lore.kernel.org/all/20240104150500.38b15a62@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20240104220048.172295263@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: 493ec81a8fb8e ("eventfs: Stop using dcache_readdir() for getdents()")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8186fff7ab649085e2c60d032d9a20a85af1d87c upstream.
Instead of walking the dentries on mount/remount to update the gid values of
all the dentries if a gid option is specified on mount, just update the root
inode. Add .getattr, .setattr, and .permissions on the tracefs inode
operations to update the permissions of the files and directories.
For all files and directories in the top level instance:
/sys/kernel/tracing/*
It will use the root inode as the default permissions. The inode that
represents: /sys/kernel/tracing (or wherever it is mounted).
When an instance is created:
mkdir /sys/kernel/tracing/instance/foo
The directory "foo" and all its files and directories underneath will use
the default of what foo is when it was created. A remount of tracefs will
not affect it.
If a user were to modify the permissions of any file or directory in
tracefs, it will also no longer be modified by a change in ownership of a
remount.
The events directory, if it is in the top level instance, will use the
tracefs root inode as the default ownership for itself and all the files and
directories below it.
For the events directory in an instance ("foo"), it will keep the ownership
of what it was when it was created, and that will be used as the default
ownership for the files and directories beneath it.
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wjVdGkjDXBbvLn2wbZnqP4UsH46E3gqJ9m7UG6DpX2+WA@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240103215016.1e0c9811@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ad579864637af46447208254719943179b69d41a upstream.
If a getdents() is called on the tracefs directory but does not get all
the files, it can leave a "cursor" dentry in the d_subdirs list of tracefs
dentry. This cursor dentry does not have a d_inode for it. Before
referencing tracefs_inode from the dentry, the d_inode must first be
checked if it has content. If not, then it's not a tracefs_inode and can
be ignored.
The following caused a crash:
#define getdents64(fd, dirp, count) syscall(SYS_getdents64, fd, dirp, count)
#define BUF_SIZE 256
#define TDIR "/tmp/file0"
int main(void)
{
char buf[BUF_SIZE];
int fd;
int n;
mkdir(TDIR, 0777);
mount(NULL, TDIR, "tracefs", 0, NULL);
fd = openat(AT_FDCWD, TDIR, O_RDONLY);
n = getdents64(fd, buf, BUF_SIZE);
ret = mount(NULL, TDIR, NULL, MS_NOSUID|MS_REMOUNT|MS_RELATIME|MS_LAZYTIME,
"gid=1000");
return 0;
}
That's because the 256 BUF_SIZE was not big enough to read all the
dentries of the tracefs file system and it left a "cursor" dentry in the
subdirs of the tracefs root inode. Then on remounting with "gid=1000",
it would cause an iteration of all dentries which hit:
ti = get_tracefs(dentry->d_inode);
if (ti && (ti->flags & TRACEFS_EVENT_INODE))
eventfs_update_gid(dentry, gid);
Which crashed because of the dereference of the cursor dentry which had a NULL
d_inode.
In the subdir loop of the dentry lookup of set_gid(), if a child has a
NULL d_inode, simply skip it.
Link: https://lore.kernel.org/all/20240102135637.3a21fb10@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20240102151249.05da244d@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 7e8358edf503e ("eventfs: Fix file and directory uid and gid ownership")
Reported-by: "Ubisectech Sirius" <bugreport@ubisectech.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 7e8358edf503e87236c8d07f69ef0ed846dd5112 upstream.
It was reported that when mounting the tracefs file system with a gid
other than root, the ownership did not carry down to the eventfs directory
due to the dynamic nature of it.
A fix was done to solve this, but it had two issues.
(a) if the attr passed into update_inode_attr() was NULL, it didn't do
anything. This is true for files that have not had a chown or chgrp
done to itself or any of its sibling files, as the attr is allocated
for all children when any one needs it.
# umount /sys/kernel/tracing
# mount -o rw,seclabel,relatime,gid=1000 -t tracefs nodev /mnt
# ls -ld /mnt/events/sched
drwxr-xr-x 28 root rostedt 0 Dec 21 13:12 /mnt/events/sched/
# ls -ld /mnt/events/sched/sched_switch
drwxr-xr-x 2 root rostedt 0 Dec 21 13:12 /mnt/events/sched/sched_switch/
But when checking the files:
# ls -l /mnt/events/sched/sched_switch
total 0
-rw-r----- 1 root root 0 Dec 21 13:12 enable
-rw-r----- 1 root root 0 Dec 21 13:12 filter
-r--r----- 1 root root 0 Dec 21 13:12 format
-r--r----- 1 root root 0 Dec 21 13:12 hist
-r--r----- 1 root root 0 Dec 21 13:12 id
-rw-r----- 1 root root 0 Dec 21 13:12 trigger
(b) When the attr does not denote the UID or GID, it defaulted to using
the parent uid or gid. This is incorrect as changing the parent
uid or gid will automatically change all its children.
# chgrp tracing /mnt/events/timer
# ls -ld /mnt/events/timer
drwxr-xr-x 2 root tracing 0 Dec 21 14:34 /mnt/events/timer
# ls -l /mnt/events/timer
total 0
-rw-r----- 1 root root 0 Dec 21 14:35 enable
-rw-r----- 1 root root 0 Dec 21 14:35 filter
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 hrtimer_cancel
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 hrtimer_expire_entry
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 hrtimer_expire_exit
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 hrtimer_init
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 hrtimer_start
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 itimer_expire
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 itimer_state
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 tick_stop
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 timer_cancel
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 timer_expire_entry
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 timer_expire_exit
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 timer_init
drwxr-xr-x 2 root tracing 0 Dec 21 14:35 timer_start
At first it was thought that this could be easily fixed by just making the
default ownership of the superblock when it was mounted. But this does not
handle the case of:
# chgrp tracing instances
# mkdir instances/foo
If the superblock was used, then the group ownership would be that of what
it was when it was mounted, when it should instead be "tracing".
Instead, set a flag for the top level eventfs directory ("events") to flag
which eventfs_inode belongs to it.
Since the "events" directory's dentry and inode are never freed, it does
not need to use its attr field to restore its mode and ownership. Use the
this eventfs_inode's attr as the default ownership for all the files and
directories underneath it.
When the events eventfs_inode is created, it sets its ownership to its
parent uid and gid. As the events directory is created at boot up before
it gets mounted, this will always be uid=0 and gid=0. If it's created via
an instance, then it will take the ownership of the instance directory.
When the file system is mounted, it will update all the gids if one is
specified. This will have a callback to update the events evenfs_inode's
default entries.
When a file or directory is created under the events directory, it will
walk the ei->dentry parents until it finds the evenfs_inode that belongs
to the events directory to retrieve the default uid and gid values.
Link: https://lore.kernel.org/all/CAHk-=wiwQtUHvzwyZucDq8=Gtw+AnwScyLhpFswrQ84PjhoGsg@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231221190757.7eddbca9@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Dongliang Cui <cuidongliang390@gmail.com>
Cc: Hongyu Jin <hongyu.jin@unisoc.com>
Fixes: 0dfc852b6fe3 ("eventfs: Have event files and directories default to parent uid and gid")
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0dfc852b6fe3cbecbea67332a0dce2bebeba540d upstream.
Dongliang reported:
I found that in the latest version, the nodes of tracefs have been
changed to dynamically created.
This has caused me to encounter a problem where the gid I specified in
the mounting parameters cannot apply to all files, as in the following
situation:
/data/tmp/events # mount | grep tracefs
tracefs on /data/tmp type tracefs (rw,seclabel,relatime,gid=3012)
gid 3012 = readtracefs
/data/tmp # ls -lh
total 0
-r--r----- 1 root readtracefs 0 1970-01-01 08:00 README
-r--r----- 1 root readtracefs 0 1970-01-01 08:00 available_events
ums9621_1h10:/data/tmp/events # ls -lh
total 0
drwxr-xr-x 2 root root 0 2023-12-19 00:56 alarmtimer
drwxr-xr-x 2 root root 0 2023-12-19 00:56 asoc
It will prevent certain applications from accessing tracefs properly, I
try to avoid this issue by making the following modifications.
To fix this, have the files created default to taking the ownership of
the parent dentry unless the ownership was previously set by the user.
Link: https://lore.kernel.org/linux-trace-kernel/1703063706-30539-1-git-send-email-dongliang.cui@unisoc.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231220105017.1489d790@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Hongyu Jin <hongyu.jin@unisoc.com>
Fixes: 28e12c09f5aa0 ("eventfs: Save ownership and mode")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Dongliang Cui <cuidongliang390@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bcae32c5632fc0a0dbce46fa731cd23403117e66 upstream.
The both create_file_dentry() and create_dir_dentry() takes a boolean
parameter "lookup", as on lookup the inode_lock should already be taken,
but for dcache_dir_open_wrapper() it is not taken.
There's no reason that the dcache_dir_open_wrapper() can't take the
inode_lock before calling these functions. In fact, it's better if it
does, as the lock can be held throughout both directory and file
creations.
This also simplifies the code, and possibly prevents unexpected race
conditions when the lock is released.
Link: https://lkml.kernel.org/r/20231121231112.528544825@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4763d635c907baed212664dc579dde1663bb2676 upstream.
If memory reclaim happens, it can reclaim file system pages. The file
system pages from eventfs may take the eventfs_mutex on reclaim. This
means that allocation while holding the eventfs_mutex must not call into
filesystem reclaim. A lockdep splat uncovered this.
Link: https://lkml.kernel.org/r/20231121231112.373501894@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 28e12c09f5aa0 ("eventfs: Save ownership and mode")
Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 88903daecacf03b1e5636e1b5f18bda5b07030fc upstream.
The logic to free the eventfs_inode (ei) use to set is_freed and clear the
"dentry" field under the eventfs_mutex. But that changed when a race was
found where the ei->dentry needed to be cleared when the last dput() was
called on it. But there was still logic that checked if ei->dentry was not
NULL and is_freed is set, and would warn if it was.
But since that situation was changed and the ei->dentry isn't cleared
until the last dput() is called on it while the ei->is_freed is set, do
not test for that condition anymore, and change the comments to reflect
that.
Link: https://lkml.kernel.org/r/20231120235154.265826243@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 020010fbfa20 ("eventfs: Delete eventfs_inode when the last dentry is freed")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 407c6726ca71b33330d2d6345d9ea7ebc02575e9 upstream.
Looking at how dentry is removed via the tracefs system, I found that
eventfs does not do everything that it did under tracefs. The tracefs
removal of a dentry calls simple_recursive_removal() that does a lot more
than a simple d_invalidate().
As it should be a requirement that any eventfs_inode that has a dentry, so
does its parent. When removing a eventfs_inode, if it has a dentry, a call
to simple_recursive_removal() on that dentry should clean up all the
dentries underneath it.
Add WARN_ON_ONCE() to check for the parent having a dentry if any children
do.
Link: https://lore.kernel.org/all/20231101022553.GE1957730@ZenIV/
Link: https://lkml.kernel.org/r/20231101172650.552471568@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 5bdcd5f533 ("eventfs: Implement removal of meta data from eventfs")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
