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twx-linux/kernel
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Christian Brauner 9698d5a483
pidfs: rework inode number allocation 
Recently we received a patchset that aims to enable file handle encoding
and decoding via name_to_handle_at(2) and open_by_handle_at(2).

A crucical step in the patch series is how to go from inode number to
struct pid without leaking information into unprivileged contexts. The
issue is that in order to find a struct pid the pid number in the
initial pid namespace must be encoded into the file handle via
name_to_handle_at(2). This can be used by containers using a separate
pid namespace to learn what the pid number of a given process in the
initial pid namespace is. While this is a weak information leak it could
be used in various exploits and in general is an ugly wart in the design.

To solve this problem a new way is needed to lookup a struct pid based
on the inode number allocated for that struct pid. The other part is to
remove the custom inode number allocation on 32bit systems that is also
an ugly wart that should go away.

So, a new scheme is used that I was discusssing with Tejun some time
back. A cyclic ida is used for the lower 32 bits and a the high 32 bits
are used for the generation number. This gives a 64 bit inode number
that is unique on both 32 bit and 64 bit. The lower 32 bit number is
recycled slowly and can be used to lookup struct pids.

Link: https://lore.kernel.org/r/20241129-work-pidfs-v2-1-61043d66fbce@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-12-14 12:40:31 +01:00
..
bpf Summary 2024-11-22 20:36:11 -08:00
cgroup cgroup: Changes for v6.13 2024-11-20 09:54:49 -08:00
configs configs/debug: make sure PROVE_RCU_LIST=y takes effect 2024-10-28 10:21:09 -07:00
debug kdb: fix ctrl+e/a/f/b/d/p/n broken in keyboard mode 2024-11-18 15:20:22 +00:00
dma dma-debug: fix physical address calculation for struct dma_debug_entry 2024-11-28 10:19:16 +01:00
entry sched: Add TIF_NEED_RESCHED_LAZY infrastructure 2024-11-05 12:55:37 +01:00
events - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
futex futex: improve user space accesses 2024-11-25 12:11:55 -08:00
gcov gcov: add support for GCC 14 2024-06-15 10:43:06 -07:00
irq A set of updates for the interrupt subsystem: 2024-11-19 15:54:19 -08:00
kcsan kcsan: Remove redundant call of kallsyms_lookup_name() 2024-10-14 16:44:56 +02:00
livepatch livepatch: Replace snprintf() with sysfs_emit() 2024-07-02 16:56:18 +02:00
locking Scheduler changes for v6.13: 2024-11-19 14:16:06 -08:00
module Modules changes for v6.13-rc1 2024-11-27 10:20:50 -08:00
power The biggest change here is eliminating the awful idea that KVM had, of 2024-11-23 16:00:50 -08:00
printk printk changes for 6.13 2024-11-20 09:21:11 -08:00
rcu A set of updates for the interrupt subsystem: 2024-11-19 15:54:19 -08:00
sched sched_ext: Change for v6.13 2024-11-20 10:08:00 -08:00
time ntp: Remove invalid cast in time offset math 2024-11-28 12:02:38 +01:00
trace tracing: Record task flag NEED_RESCHED_LAZY. 2024-11-22 17:49:39 -05:00
.gitignore
acct.c kernel misc: Remove the now superfluous sentinel elements from ctl_table array 2024-04-24 09:43:53 +02:00
async.c async: Use a dedicated unbound workqueue with raised min_active 2024-02-09 11:13:59 -10:00
audit_fsnotify.c
audit_tree.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit_watch.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit.c lsm/stable-6.13 PR 20241112 2024-11-18 17:34:05 -08:00
audit.h audit: change context data from secid to lsm_prop 2024-10-11 14:34:16 -04:00
auditfilter.c audit: change context data from secid to lsm_prop 2024-10-11 14:34:16 -04:00
auditsc.c - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
backtracetest.c backtracetest: add MODULE_DESCRIPTION() 2024-06-24 22:24:55 -07:00
bounds.c bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS 2024-04-29 08:29:29 -07:00
capability.c
cfi.c
compat.c
configs.c
context_tracking.c context_tracking, rcu: Rename rcu_dyntick trace event into rcu_watching 2024-08-15 21:30:43 +05:30
cpu_pm.c
cpu.c Driver core changes for 6.13-rc1 2024-11-29 11:43:29 -08:00
crash_core.c kexec/crash: no crash update when kexec in progress 2024-11-05 17:12:27 -08:00
crash_reserve.c crash: fix crash memory reserve exceed system memory bug 2024-09-01 20:43:30 -07:00
cred.c cred: Add a light version of override/revert_creds() 2024-11-11 10:45:04 +01:00
delayacct.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
dma.c
elfcorehdr.c crash: remove dependency of FA_DUMP on CRASH_DUMP 2024-02-23 17:48:22 -08:00
exec_domain.c
exit.c remove pointless includes of <linux/fdtable.h> 2024-10-07 13:34:41 -04:00
exit.h
extable.c
fail_function.c
fork.c Revert "fs: don't block i_writecount during exec" 2024-11-27 12:51:30 +01:00
freezer.c sched/fair: Fix external p->on_rq users 2024-10-14 09:14:35 +02:00
gen_kheaders.sh kheaders: use command -v to test for existence of cpio 2024-05-30 01:13:20 +09:00
groups.c groups: Convert group_info.usage to refcount_t 2023-09-29 11:28:39 -07:00
hung_task.c hung_task: add detect count for hung tasks 2024-11-11 17:17:03 -08:00
iomem.c
irq_work.c
jump_label.c jump_label: Fix static_key_slow_dec() yet again 2024-09-10 11:57:27 +02:00
kallsyms_internal.h kallsyms: get rid of code for absolute kallsyms 2024-07-20 16:33:21 +09:00
kallsyms_selftest.c kallsyms: Match symbols exactly with CONFIG_LTO_CLANG 2024-08-15 09:33:35 -07:00
kallsyms_selftest.h
kallsyms.c kallsyms: Match symbols exactly with CONFIG_LTO_CLANG 2024-08-15 09:33:35 -07:00
kcmp.c get rid of ...lookup...fdget_rcu() family 2024-10-07 13:34:41 -04:00
Kconfig.freezer
Kconfig.hz
Kconfig.kexec crash, powerpc: default to CRASH_DUMP=n on PPC_BOOK3S_32 2024-11-14 22:43:48 -08:00
Kconfig.locks
Kconfig.preempt sched: No PREEMPT_RT=y for all{yes,mod}config 2024-11-07 15:25:05 +01:00
kcov.c Updates for KCOV instrumentation on x86: 2024-09-17 12:40:34 +02:00
kexec_core.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kexec_elf.c
kexec_file.c kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y 2024-09-01 17:59:01 -07:00
kexec_internal.h kexec: use atomic_try_cmpxchg_acquire() in kexec_trylock() 2024-09-01 20:43:23 -07:00
kexec.c crash: add a new kexec flag for hotplug support 2024-04-23 14:59:01 +10:00
kheaders.c
kprobes.c kprobes: Use struct_size() in __get_insn_slot() 2024-10-31 11:00:58 +09:00
ksyms_common.c
ksysfs.c profiling: remove prof_cpu_mask 2024-07-29 10:45:54 -07:00
kthread.c get rid of __get_task_comm() 2024-11-05 17:12:28 -08:00
latencytop.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
Makefile mm: move kernel/numa.c to mm/ 2024-09-03 21:15:26 -07:00
module_signature.c
notifier.c reboot: move reboot_notifier_list to kernel/reboot.c 2024-11-05 17:12:31 -08:00
nsproxy.c fdget(), trivial conversions 2024-11-03 01:28:06 -05:00
padata.c padata: Clean up in padata_do_multithreaded() 2024-11-10 11:50:54 +08:00
panic.c drm next for 6.12-rc1 2024-09-19 10:18:15 +02:00
params.c params: Fix multi-line comment style 2023-12-01 09:51:44 -08:00
pid_namespace.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
pid_sysctl.h sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
pid.c pidfs: rework inode number allocation 2024-12-14 12:40:31 +01:00
profile.c profiling: remove profile=sleep support 2024-08-04 13:36:28 -07:00
ptrace.c ptrace_attach: shift send(SIGSTOP) into ptrace_set_stopped() 2024-02-22 15:38:52 -08:00
range.c
reboot.c kernel/reboot: replace sprintf() with sysfs_emit() 2024-11-11 17:17:05 -08:00
regset.c regset: use kvzalloc() for regset_get_alloc() 2024-04-25 21:07:03 -07:00
relay.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
resource_kunit.c resource, kunit: fix user-after-free in resource_test_region_intersects() 2024-10-09 12:47:19 -07:00
resource.c - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
rseq.c
scftorture.c scftorture: Handle NULL argument passed to scf_add_to_free_list(). 2024-11-14 16:09:51 -08:00
scs.c
seccomp.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
signal.c posix-timers: Target group sigqueue to current task only if not exiting 2024-11-29 13:19:09 +01:00
smp.c locking/csd-lock: Switch from sched_clock() to ktime_get_mono_fast_ns() 2024-10-11 09:31:21 -07:00
smpboot.c kthread: add kthread_stop_put 2023-10-04 10:41:57 -07:00
smpboot.h
softirq.c A set of updates for the interrupt subsystem: 2024-11-19 15:54:19 -08:00
stackleak.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
stacktrace.c stacktrace: fix kernel-doc typo 2023-12-29 12:22:29 -08:00
static_call_inline.c static_call: Replace pointless WARN_ON() in static_call_module_notify() 2024-09-06 16:29:22 +02:00
static_call.c
stop_machine.c rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs() 2024-08-15 21:30:42 +05:30
sys_ni.c Probes updates for v6.11: 2024-07-18 12:19:20 -07:00
sys.c arm64 updates for 6.13: 2024-11-18 18:10:37 -08:00
sysctl-test.c sysctl: Add module description to sysctl-testing 2024-06-03 15:20:37 +02:00
sysctl.c sysctl: Reorganize kerneldoc parameter names 2024-10-23 15:28:40 +02:00
task_work.c sched/core: Disable page allocation in task_tick_mm_cid() 2024-10-11 10:49:32 +02:00
taskstats.c fdget(), more trivial conversions 2024-11-03 01:28:06 -05:00
torture.c torture: Add MODULE_DESCRIPTION() 2024-05-30 15:31:38 -07:00
tracepoint.c tracing: Fix syscall tracepoint use-after-free 2024-11-01 14:37:31 -04:00
tsacct.c tsacct: replace strncpy() with strscpy() 2024-07-12 16:39:53 -07:00
ucount.c Summary 2024-11-22 20:36:11 -08:00
uid16.c
uid16.h
umh.c remove pointless includes of <linux/fdtable.h> 2024-10-07 13:34:41 -04:00
up.c
user_namespace.c user_namespace: use kmemdup_array() instead of kmemdup() for multiple allocation 2024-09-09 16:47:42 -07:00
user-return-notifier.c
user.c uidgid: make sure we fit into one cacheline 2024-09-12 12:16:09 +02:00
usermode_driver.c
utsname_sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
utsname.c
vhost_task.c vhost_task: Handle SIGKILL by flushing work and exiting 2024-05-22 08:31:15 -04:00
vmcore_info.c mm: support only one page_type per page 2024-09-03 21:15:43 -07:00
watch_queue.c fdget(), trivial conversions 2024-11-03 01:28:06 -05:00
watchdog_buddy.c
watchdog_perf.c watchdog/perf: properly initialize the turbo mode timestamp and rearm counter 2024-07-17 21:11:34 -07:00
watchdog.c - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
workqueue_internal.h
workqueue.c workqueue: Reduce expensive locks for unbound workqueue 2024-11-15 06:43:39 -10:00