Pull clone and pidfs updates from Christian Brauner:
"Add three new clone3() flags for pidfd-based process lifecycle
management.
CLONE_AUTOREAP:
CLONE_AUTOREAP makes a child process auto-reap on exit without ever
becoming a zombie. This is a per-process property in contrast to
the existing auto-reap mechanism via SA_NOCLDWAIT or SIG_IGN for
SIGCHLD which applies to all children of a given parent.
Currently the only way to automatically reap children is to set
SA_NOCLDWAIT or SIG_IGN on SIGCHLD. This is a parent-scoped
property affecting all children which makes it unsuitable for
libraries or applications that need selective auto-reaping of
specific children while still being able to wait() on others.
CLONE_AUTOREAP stores an autoreap flag in the child's
signal_struct. When the child exits do_notify_parent() checks this
flag and causes exit_notify() to transition the task directly to
EXIT_DEAD. Since the flag lives on the child it survives
reparenting: if the original parent exits and the child is
reparented to a subreaper or init the child still auto-reaps when
it eventually exits. This is cleaner than forcing the subreaper to
get SIGCHLD and then reaping it. If the parent doesn't care the
subreaper won't care. If there's a subreaper that would care it
would be easy enough to add a prctl() that either just turns back
on SIGCHLD and turns off auto-reaping or a prctl() that just
notifies the subreaper whenever a child is reparented to it.
CLONE_AUTOREAP can be combined with CLONE_PIDFD to allow the parent
to monitor the child's exit via poll() and retrieve exit status via
PIDFD_GET_INFO. Without CLONE_PIDFD it provides a fire-and-forget
pattern. No exit signal is delivered so exit_signal must be zero.
CLONE_THREAD and CLONE_PARENT are rejected: CLONE_THREAD because
autoreap is a process-level property, and CLONE_PARENT because an
autoreap child reparented via CLONE_PARENT could become an
invisible zombie under a parent that never calls wait().
The flag is not inherited by the autoreap process's own children.
Each child that should be autoreaped must be explicitly created
with CLONE_AUTOREAP.
CLONE_NNP:
CLONE_NNP sets no_new_privs on the child at clone time. Unlike
prctl(PR_SET_NO_NEW_PRIVS) which a process sets on itself,
CLONE_NNP allows the parent to impose no_new_privs on the child at
creation without affecting the parent's own privileges.
CLONE_THREAD is rejected because threads share credentials.
CLONE_NNP is useful on its own for any spawn-and-sandbox pattern
but was specifically introduced to enable unprivileged usage of
CLONE_PIDFD_AUTOKILL.
CLONE_PIDFD_AUTOKILL:
This flag ties a child's lifetime to the pidfd returned from
clone3(). When the last reference to the struct file created by
clone3() is closed the kernel sends SIGKILL to the child. A pidfd
obtained via pidfd_open() for the same process does not keep the
child alive and does not trigger autokill - only the specific
struct file from clone3() has this property. This is useful for
container runtimes, service managers, and sandboxed subprocess
execution - any scenario where the child must die if the parent
crashes or abandons the pidfd or just wants a throwaway helper
process.
CLONE_PIDFD_AUTOKILL requires both CLONE_PIDFD and CLONE_AUTOREAP.
It requires CLONE_PIDFD because the whole point is tying the
child's lifetime to the pidfd. It requires CLONE_AUTOREAP because a
killed child with no one to reap it would become a zombie - the
primary use case is the parent crashing or abandoning the pidfd so
no one is around to call waitpid(). CLONE_THREAD is rejected
because autokill targets a process not a thread.
If CLONE_NNP is specified together with CLONE_PIDFD_AUTOKILL an
unprivileged user may spawn a process that is autokilled. The child
cannot escalate privileges via setuid/setgid exec after being
spawned. If CLONE_PIDFD_AUTOKILL is specified without CLONE_NNP the
caller must have have CAP_SYS_ADMIN in its user namespace"
* tag 'vfs-7.1-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: check pidfd_info->coredump_code correctness
pidfds: add coredump_code field to pidfd_info
kselftest/coredump: reintroduce null pointer dereference
selftests/pidfd: add CLONE_PIDFD_AUTOKILL tests
selftests/pidfd: add CLONE_NNP tests
selftests/pidfd: add CLONE_AUTOREAP tests
pidfd: add CLONE_PIDFD_AUTOKILL
clone: add CLONE_NNP
clone: add CLONE_AUTOREAP
Pull vfs xattr updates from Christian Brauner:
"This reworks the simple_xattr infrastructure and adds support for
user.* extended attributes on sockets.
The simple_xattr subsystem currently uses an rbtree protected by a
reader-writer spinlock. This series replaces the rbtree with an
rhashtable giving O(1) average-case lookup with RCU-based lockless
reads. This sped up concurrent access patterns on tmpfs quite a bit
and it's an overall easy enough conversion to do and gets rid or
rwlock_t.
The conversion is done incrementally: a new rhashtable path is added
alongside the existing rbtree, consumers are migrated one at a time
(shmem, kernfs, pidfs), and then the rbtree code is removed. All three
consumers switch from embedded structs to pointer-based lazy
allocation so the rhashtable overhead is only paid for inodes that
actually use xattrs.
With this infrastructure in place the series adds support for user.*
xattrs on sockets. Path-based AF_UNIX sockets inherit xattr support
from the underlying filesystem (e.g. tmpfs) but sockets in sockfs -
that is everything created via socket() including abstract namespace
AF_UNIX sockets - had no xattr support at all.
The xattr_permission() checks are reworked to allow user.* xattrs on
S_IFSOCK inodes. Sockfs sockets get per-inode limits of 128 xattrs and
128KB total value size matching the limits already in use for kernfs.
The practical motivation comes from several directions. systemd and
GNOME are expanding their use of Varlink as an IPC mechanism.
For D-Bus there are tools like dbus-monitor that can observe IPC
traffic across the system but this only works because D-Bus has a
central broker.
For Varlink there is no broker and there is currently no way to
identify which sockets speak Varlink. With user.* xattrs on sockets a
service can label its socket with the IPC protocol it speaks (e.g.,
user.varlink=1) and an eBPF program can then selectively capture
traffic on those sockets. Enumerating bound sockets via netlink
combined with these xattr labels gives a way to discover all Varlink
IPC entrypoints for debugging and introspection.
Similarly, systemd-journald wants to use xattrs on the /dev/log socket
for protocol negotiation to indicate whether RFC 5424 structured
syslog is supported or whether only the legacy RFC 3164 format should
be used.
In containers these labels are particularly useful as high-privilege
or more complicated solutions for socket identification aren't
available.
The series comes with comprehensive selftests covering path-based
AF_UNIX sockets, sockfs socket operations, per-inode limit
enforcement, and xattr operations across multiple address families
(AF_INET, AF_INET6, AF_NETLINK, AF_PACKET)"
* tag 'vfs-7.1-rc1.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/xattr: test xattrs on various socket families
selftests/xattr: sockfs socket xattr tests
selftests/xattr: path-based AF_UNIX socket xattr tests
xattr: support extended attributes on sockets
xattr,net: support limited amount of extended attributes on sockfs sockets
xattr: move user limits for xattrs to generic infra
xattr: switch xattr_permission() to switch statement
xattr: add xattr_permission_error()
xattr: remove rbtree-based simple_xattr infrastructure
pidfs: adapt to rhashtable-based simple_xattrs
kernfs: adapt to rhashtable-based simple_xattrs with lazy allocation
shmem: adapt to rhashtable-based simple_xattrs with lazy allocation
xattr: add rhashtable-based simple_xattr infrastructure
xattr: add rcu_head and rhash_head to struct simple_xattr
The struct pidfd_info currently exposes in a field called coredump_signal the
signal number (si_signo) that triggered the dump (for example, 11 for SIGSEGV).
However, it is also valuable to understand the reason why that signal was sent.
This additional context is provided by the signal code (si_code), such as 2 for
SEGV_ACCERR.
Add a new field to struct pidfd_info called coredump_code with the value of
si_code for the benefit of sysadmins who pipe core dumps to user-space programs
for later analysis. The following snippet illustrates a simplified C program
that consumes coredump_signal and coredump_code, and then logs core dump
signals and codes to a file:
int pidfd = (int)atoi(argv[1]);
struct pidfd_info info = {
.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP,
};
if (ioctl(pidfd, PIDFD_GET_INFO, &info) == 0)
if (info.mask & PIDFD_INFO_COREDUMP)
fprintf(f, "PID=%d, si_signo: %d si_code: %d\n",
info.pid, info.coredump_signal, info.coredump_code);
Assuming the program is installed under /usr/local/bin/core-logger, core dump
processing can be enabled by setting /proc/sys/kernel/core_pattern to
'|/usr/local/bin/dumpstuff %F'.
systemd-coredump(8) already uses pidfds to process core dumps, and it could be
extended to include the values of coredump_code too.
Signed-off-by: Emanuele Rocca <emanuele.rocca@arm.com>
Link: https://patch.msgid.link/acE52HIFivNZN3nE@NH27D9T0LF
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add a new clone3() flag CLONE_PIDFD_AUTOKILL that ties a child's
lifetime to the pidfd returned from clone3(). When the last reference to
the struct file created by clone3() is closed the kernel sends SIGKILL
to the child. A pidfd obtained via pidfd_open() for the same process
does not keep the child alive and does not trigger autokill - only the
specific struct file from clone3() has this property.
This is useful for container runtimes, service managers, and sandboxed
subprocess execution - any scenario where the child must die if the
parent crashes or abandons the pidfd.
CLONE_PIDFD_AUTOKILL requires both CLONE_PIDFD (the whole point is tying
lifetime to the pidfd file) and CLONE_AUTOREAP (a killed child with no
one to reap it would become a zombie). CLONE_THREAD is rejected because
autokill targets a process not a thread.
The clone3 pidfd is identified by the PIDFD_AUTOKILL file flag set on
the struct file at clone3() time. The pidfs .release handler checks this
flag and sends SIGKILL via do_send_sig_info(SIGKILL, SEND_SIG_PRIV, ...)
only when it is set. Files from pidfd_open() or open_by_handle_at() are
distinct struct files that do not carry this flag. dup()/fork() share the
same struct file so they extend the child's lifetime until the last
reference drops.
CLONE_PIDFD_AUTOKILL uses a privilege model based on CLONE_NNP: without
CLONE_NNP the child could escalate privileges via setuid/setgid exec
after being spawned, so the caller must have CAP_SYS_ADMIN in its user
namespace. With CLONE_NNP the child can never gain new privileges so
unprivileged usage is allowed. This is a deliberate departure from the
pdeath_signal model which is reset during secureexec and commit_creds()
rendering it useless for container runtimes that need to deprivilege
themselves.
Link: https://patch.msgid.link/20260226-work-pidfs-autoreap-v5-3-d148b984a989@kernel.org
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Adapt pidfs to use the rhashtable-based xattr path by switching from a
dedicated slab cache to simple_xattrs_alloc().
Previously pidfs used a custom kmem_cache (pidfs_xattr_cachep) that
allocated a struct containing an embedded simple_xattrs plus
simple_xattrs_init(). Replace this with simple_xattrs_alloc() which
combines kzalloc + rhashtable_init, and drop the dedicated slab cache
entirely.
Use simple_xattr_free_rcu() for replaced xattr entries to allow
concurrent RCU readers to finish.
Link: https://patch.msgid.link/20260216-work-xattr-socket-v1-5-c2efa4f74cb7@kernel.org
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull vfs fixes from Christian Brauner:
- Fix an uninitialized variable in file_getattr().
The flags_valid field wasn't initialized before calling
vfs_fileattr_get(), triggering KMSAN uninit-value reports in fuse
- Fix writeback wakeup and logging timeouts when DETECT_HUNG_TASK is
not enabled.
sysctl_hung_task_timeout_secs is 0 in that case causing spurious
"waiting for writeback completion for more than 1 seconds" warnings
- Fix a null-ptr-deref in do_statmount() when the mount is internal
- Add missing kernel-doc description for the @private parameter in
iomap_readahead()
- Fix mount namespace creation to hold namespace_sem across the mount
copy in create_new_namespace().
The previous drop-and-reacquire pattern was fragile and failed to
clean up mount propagation links if the real rootfs was a shared or
dependent mount
- Fix /proc mount iteration where m->index wasn't updated when
m->show() overflows, causing a restart to repeatedly show the same
mount entry in a rapidly expanding mount table
- Return EFSCORRUPTED instead of ENOSPC in minix_new_inode() when the
inode number is out of range
- Fix unshare(2) when CLONE_NEWNS is set and current->fs isn't shared.
copy_mnt_ns() received the live fs_struct so if a subsequent
namespace creation failed the rollback would leave pwd and root
pointing to detached mounts. Always allocate a new fs_struct when
CLONE_NEWNS is requested
- fserror bug fixes:
- Remove the unused fsnotify_sb_error() helper now that all callers
have been converted to fserror_report_metadata
- Fix a lockdep splat in fserror_report() where igrab() takes
inode::i_lock which can be held in IRQ context.
Replace igrab() with a direct i_count bump since filesystems
should not report inodes that are about to be freed or not yet
exposed
- Handle error pointer in procfs for try_lookup_noperm()
- Fix an integer overflow in ep_loop_check_proc() where recursive calls
returning INT_MAX would overflow when +1 is added, breaking the
recursion depth check
- Fix a misleading break in pidfs
* tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
pidfs: avoid misleading break
eventpoll: Fix integer overflow in ep_loop_check_proc()
proc: Fix pointer error dereference
fserror: fix lockdep complaint when igrabbing inode
fsnotify: drop unused helper
unshare: fix unshare_fs() handling
minix: Correct errno in minix_new_inode
namespace: fix proc mount iteration
mount: hold namespace_sem across copy in create_new_namespace()
iomap: Describe @private in iomap_readahead()
statmount: Fix the null-ptr-deref in do_statmount()
writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK
fs: init flags_valid before calling vfs_fileattr_get
Pull more misc vfs updates from Christian Brauner:
"Features:
- Optimize close_range() from O(range size) to O(active FDs) by using
find_next_bit() on the open_fds bitmap instead of linearly scanning
the entire requested range. This is a significant improvement for
large-range close operations on sparse file descriptor tables.
- Add FS_XFLAG_VERITY file attribute for fs-verity files, retrievable
via FS_IOC_FSGETXATTR and file_getattr(). The flag is read-only.
Add tracepoints for fs-verity enable and verify operations,
replacing the previously removed debug printk's.
- Prevent nfsd from exporting special kernel filesystems like pidfs
and nsfs. These filesystems have custom ->open() and ->permission()
export methods that are designed for open_by_handle_at(2) only and
are incompatible with nfsd. Update the exportfs documentation
accordingly.
Fixes:
- Fix KMSAN uninit-value in ovl_fill_real() where strcmp() was used
on a non-null-terminated decrypted directory entry name from
fscrypt. This triggered on encrypted lower layers when the
decrypted name buffer contained uninitialized tail data.
The fix also adds VFS-level name_is_dot(), name_is_dotdot(), and
name_is_dot_dotdot() helpers, replacing various open-coded "." and
".." checks across the tree.
- Fix read-only fsflags not being reset together with xflags in
vfs_fileattr_set(). Currently harmless since no read-only xflags
overlap with flags, but this would cause inconsistencies for any
future shared read-only flag
- Return -EREMOTE instead of -ESRCH from PIDFD_GET_INFO when the
target process is in a different pid namespace. This lets userspace
distinguish "process exited" from "process in another namespace",
matching glibc's pidfd_getpid() behavior
Cleanups:
- Use C-string literals in the Rust seq_file bindings, replacing the
kernel::c_str!() macro (available since Rust 1.77)
- Fix typo in d_walk_ret enum comment, add porting notes for the
readlink_copy() calling convention change"
* tag 'vfs-7.0-rc1.misc.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: add porting notes about readlink_copy()
pidfs: return -EREMOTE when PIDFD_GET_INFO is called on another ns
nfsd: do not allow exporting of special kernel filesystems
exportfs: clarify the documentation of open()/permission() expotrfs ops
fsverity: add tracepoints
fs: add FS_XFLAG_VERITY for fs-verity files
rust: seq_file: replace `kernel::c_str!` with C-Strings
fs: dcache: fix typo in enum d_walk_ret comment
ovl: use name_is_dot* helpers in readdir code
fs: add helpers name_is_dot{,dot,_dotdot}
ovl: Fix uninit-value in ovl_fill_real
fs: reset read-only fsflags together with xflags
fs/file: optimize close_range() complexity from O(N) to O(Sparse)
Pull pidfs updates from Christian Brauner:
- pid: introduce task_ppid_vnr() helper
- pidfs: convert rb-tree to rhashtable
Mateusz reported performance penalties during task creation because
pidfs uses pidmap_lock to add elements into the rbtree. Switch to an
rhashtable to have separate fine-grained locking and to decouple from
pidmap_lock moving all heavy manipulations outside of it
Also move inode allocation outside of pidmap_lock. With this there's
nothing happening for pidfs under pidmap_lock
- pid: reorder fields in pid_namespace to reduce false sharing
- Revert "pid: make __task_pid_nr_ns(ns => NULL) safe for zombie
callers"
- ipc: Add SPDX license id to mqueue.c
* tag 'kernel-7.0-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
pid: introduce task_ppid_vnr() helper
pidfs: implement ino allocation without the pidmap lock
Revert "pid: make __task_pid_nr_ns(ns => NULL) safe for zombie callers"
pid: reorder fields in pid_namespace to reduce false sharing
pidfs: convert rb-tree to rhashtable
ipc: Add SPDX license id to mqueue.c
Mateusz reported performance penalties [1] during task creation because
pidfs uses pidmap_lock to add elements into the rbtree. Switch to an
rhashtable to have separate fine-grained locking and to decouple from
pidmap_lock moving all heavy manipulations outside of it.
Convert the pidfs inode-to-pid mapping from an rb-tree with seqcount
protection to an rhashtable. This removes the global pidmap_lock
contention from pidfs_ino_get_pid() lookups and allows the hashtable
insert to happen outside the pidmap_lock.
pidfs_add_pid() is split. pidfs_prepare_pid() allocates inode number and
initializes pid fields and is called inside pidmap_lock. pidfs_add_pid()
inserts pid into rhashtable and is called outside pidmap_lock. Insertion
into the rhashtable can fail and memory allocation may happen so we need
to drop the spinlock.
To guard against accidently opening an already reaped task
pidfs_ino_get_pid() uses additional checks beyond pid_vnr(). If
pid->attr is PIDFS_PID_DEAD or NULL the pid either never had a pidfd or
it already went through pidfs_exit() aka the process as already reaped.
If pid->attr is valid check PIDFS_ATTR_BIT_EXIT to figure out whether
the task has exited.
This slightly changes visibility semantics: pidfd creation is denied
after pidfs_exit() runs, which is just before the pid number is removed
from the via free_pid(). That should not be an issue though.
Link: https://lore.kernel.org/20251206131955.780557-1-mjguzik@gmail.com [1]
Link: https://patch.msgid.link/20260120-work-pidfs-rhashtable-v2-1-d593c4d0f576@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
We originally protected PIDFD_GET_<ns-type>_NAMESPACE ioctls() through
ifdefs and recent rework made it possible to drop them. There was an
oversight though. When the relevant namespace is turned off ns->ops will
be NULL so even though opening a file descriptor is perfectly legitimate
it would fail during inode eviction when the file was closed.
The simple fix would be to check ns->ops for NULL and continue allow to
retrieve namespace fds from pidfds but we don't allow retrieving them
when the relevant namespace type is turned off. So keep the
simplification but add the ifdefs back in.
Link: https://lore.kernel.org/20251222214907.GA189632@quark
Link: https://patch.msgid.link/20251224-ununterbrochen-gagen-ea949b83f8f2@brauner
Fixes: a71e4f103a ("pidfs: simplify PIDFD_GET_<type>_NAMESPACE ioctls")
Tested-by: Brendan Jackman <jackmanb@kernel.org>
Tested-by: Eric Biggers <ebiggers@kernel.org>
Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull pidfd and coredump updates from Christian Brauner:
"Features:
- Expose coredump signal via pidfd
Expose the signal that caused the coredump through the pidfd
interface. The recent changes to rework coredump handling to rely
on unix sockets are in the process of being used in systemd. The
previous systemd coredump container interface requires the coredump
file descriptor and basic information including the signal number
to be sent to the container. This means the signal number needs to
be available before sending the coredump to the container.
- Add supported_mask field to pidfd
Add a new supported_mask field to struct pidfd_info that indicates
which information fields are supported by the running kernel. This
allows userspace to detect feature availability without relying on
error codes or kernel version checks.
Cleanups:
- Drop struct pidfs_exit_info and prepare to drop exit_info pointer,
simplifying the internal publication mechanism for exit and
coredump information retrievable via the pidfd ioctl
- Use guard() for task_lock in pidfs
- Reduce wait_pidfd lock scope
- Add missing PIDFD_INFO_SIZE_VER1 constant
- Add missing BUILD_BUG_ON() assert on struct pidfd_info
Fixes:
- Fix PIDFD_INFO_COREDUMP handling
Selftests:
- Split out coredump socket tests and common helpers into separate
files for better organization
- Fix userspace coredump client detection issues
- Handle edge-triggered epoll correctly
- Ignore ENOSPC errors in tests
- Add debug logging to coredump socket tests, socket protocol tests,
and test helpers
- Add tests for PIDFD_INFO_COREDUMP_SIGNAL
- Add tests for supported_mask field
- Update pidfd header for selftests"
* tag 'vfs-6.19-rc1.coredump' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits)
pidfs: reduce wait_pidfd lock scope
selftests/coredump: add second PIDFD_INFO_COREDUMP_SIGNAL test
selftests/coredump: add first PIDFD_INFO_COREDUMP_SIGNAL test
selftests/coredump: ignore ENOSPC errors
selftests/coredump: add debug logging to coredump socket protocol tests
selftests/coredump: add debug logging to coredump socket tests
selftests/coredump: add debug logging to test helpers
selftests/coredump: handle edge-triggered epoll correctly
selftests/coredump: fix userspace coredump client detection
selftests/coredump: fix userspace client detection
selftests/coredump: split out coredump socket tests
selftests/coredump: split out common helpers
selftests/pidfd: add second supported_mask test
selftests/pidfd: add first supported_mask test
selftests/pidfd: update pidfd header
pidfs: expose coredump signal
pidfs: drop struct pidfs_exit_info
pidfs: prepare to drop exit_info pointer
pidfd: add a new supported_mask field
pidfs: add missing BUILD_BUG_ON() assert on struct pidfd_info
...
There will likely be more info that we need to store in struct
pidfs_attr. We need to make sure that some of the information such as
exit info or coredump info that consists of multiple bits is either
available completely or not at all, but never partially. Currently we
use a pointer that we assign to. That doesn't scale. We can't waste a
pointer for each mulit-part information struct we want to expose. Use a
bitmask instead.
Link: https://patch.msgid.link/20251028-work-coredump-signal-v1-6-ca449b7b7aa0@kernel.org
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Some of the future fields in struct pidfd_info can be optional. If the
kernel has nothing to emit in that field, then it doesn't set the flag
in the reply. This presents a problem: There is currently no way to know
what mask flags the kernel supports since one can't always count on them
being in the reply.
Add a new PIDFD_INFO_SUPPORTED_MASK flag and field that the kernel can
set in the reply. Userspace can use this to determine if the fields it
requires from the kernel are supported. This also gives us a way to
deprecate fields in the future, if that should become necessary.
Link: https://patch.msgid.link/20251028-work-coredump-signal-v1-5-ca449b7b7aa0@kernel.org
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
When PIDFD_INFO_COREDUMP is requested we raise it unconditionally in the
returned mask even if no coredump actually did take place. This was
done because we assumed that the later check whether ->coredump_mask as
non-zero detects that it is zero and then retrieves the dumpability
settings from the task's mm. This has issues though becuase there are
tasks that might not have any mm. Also it's just not very cleanly
implemented. Fix this.
Link: https://patch.msgid.link/20251028-work-coredump-signal-v1-2-ca449b7b7aa0@kernel.org
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Linus Torvalds
Emanuele RoccaandChristian Brauner
Oleg NesterovandChristian Brauner
Mateusz GuzikandChristian Brauner
Luca BoccassiandChristian Brauner