kernel/linux.git/drivers/ptp, branch v6.1.168

ptp: Add PHC file mode checks. Allow RO adjtime() without FMODE_WRITE.

2026-02-06T15:44:03+00:00

[ Upstream commit b4e53b15c04e3852949003752f48f7a14ae39e86 ] Many devices implement highly accurate clocks, which the kernel manages as PTP Hardware Clocks (PHCs). Userspace applications rely on these clocks to timestamp events, trace workload execution, correlate timescales across devices, and keep various clocks in sync. The kernel’s current implementation of PTP clocks does not enforce file permissions checks for most device operations except for POSIX clock operations, where file mode is verified in the POSIX layer before forwarding the call to the PTP subsystem. Consequently, it is common practice to not give unprivileged userspace applications any access to PTP clocks whatsoever by giving the PTP chardevs 600 permissions. An example of users running into this limitation is documented in [1]. Additionally, POSIX layer requires WRITE permission even for readonly adjtime() calls which are used in PTP layer to return current frequency offset applied to the PHC. Add permission checks for functions that modify the state of a PTP device. Continue enforcing permission checks for POSIX clock operations (settime, adjtime) in the POSIX layer. Only require WRITE access for dynamic clocks adjtime() if any flags are set in the modes field. [1] https://lists.nwtime.org/sympa/arc/linuxptp-users/2024-01/msg00036.html Changes in v4: - Require FMODE_WRITE in ajtime() only for calls modifying the clock in any way. Acked-by: Richard Cochran Reviewed-by: Vadim Fedorenko Signed-off-by: Wojtek Wasko Reviewed-by: Thomas Gleixner Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

posix-clock: introduce posix_clock_context concept

2026-02-06T15:44:02+00:00

[ Upstream commit 60c6946675fc06dd2fd2b7a4b6fd1c1f046f1056 ] Add the necessary structure to support custom private-data per posix-clock user. The previous implementation of posix-clock assumed all file open instances need access to the same clock structure on private_data. The need for individual data structures per file open instance has been identified when developing support for multiple timestamp event queue users for ptp_clock. Signed-off-by: Xabier Marquiegui Suggested-by: Richard Cochran Suggested-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Stable-dep-of: e859d375d169 ("posix-clock: Store file pointer in struct posix_clock_context") Signed-off-by: Sasha Levin

ptp: Limit time setting of PTP clocks

2025-12-06T21:12:21+00:00

[ Upstream commit 5a8c02a6bf52b1cf9cfb7868a8330f7c3c6aebe9 ] Networking drivers implementing PTP clocks and kernel socket code handling hardware timestamps use the 64-bit signed ktime_t type counting nanoseconds. When a PTP clock reaches the maximum value in year 2262, the timestamps returned to applications will overflow into year 1667. The same thing happens when injecting a large offset with clock_adjtime(ADJ_SETOFFSET). The commit 7a8e61f84786 ("timekeeping: Force upper bound for setting CLOCK_REALTIME") limited the maximum accepted value setting the system clock to 30 years before the maximum representable value (i.e. year 2232) to avoid the overflow, assuming the system will not run for more than 30 years. Enforce the same limit for PTP clocks. Don't allow negative values and values closer than 30 years to the maximum value. Drivers may implement an even lower limit if the hardware registers cannot represent the whole interval between years 1970 and 2262 in the required resolution. Signed-off-by: Miroslav Lichvar Cc: Richard Cochran Cc: Thomas Gleixner Cc: John Stultz Cc: Arnd Bergmann Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20250828103300.1387025-1-mlichvar@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ptp: Use ratelimite for freerun error message

2025-08-28T14:25:58+00:00

[ Upstream commit e9a7795e75b78b56997fb0070c18d6e1057b6462 ] Replace pr_err() with pr_err_ratelimited() in ptp_clock_settime() to prevent log flooding when the physical clock is free running, which happens on some of my hosts. This ensures error messages are rate-limited and improves kernel log readability. Signed-off-by: Breno Leitao Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250613-ptp-v1-1-ee44260ce9e2@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ptp: allow reading of currently dialed frequency to succeed on free-running clocks

2025-06-27T10:07:39+00:00

[ Upstream commit aa112cbc5f0ac6f3b44d829005bf34005d9fe9bb ] There is a bug in ptp_clock_adjtime() which makes it refuse the operation even if we just want to read the current clock dialed frequency, not modify anything (tx->modes == 0). That should be possible even if the clock is free-running. For context, the kernel UAPI is the same for getting and setting the frequency of a POSIX clock. For example, ptp4l errors out at clock_create() -> clockadj_get_freq() -> clock_adjtime() time, when it should logically only have failed on actual adjustments to the clock, aka if the clock was configured as slave. But in master mode it should work. This was discovered when examining the issue described in the previous commit, where ptp_clock_freerun() returned true despite n_vclocks being zero. Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion") Signed-off-by: Vladimir Oltean Link: https://patch.msgid.link/20250613174749.406826-3-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ptp: fix breakage after ptp_vclock_in_use() rework

2025-06-27T10:07:39+00:00

[ Upstream commit 5ab73b010cad294851e558f1d4714a85c6f206c7 ] What is broken -------------- ptp4l, and any other application which calls clock_adjtime() on a physical clock, is greeted with error -EBUSY after commit 87f7ce260a3c ("ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()"). Explanation for the breakage ---------------------------- The blamed commit was based on the false assumption that ptp_vclock_in_use() callers already test for n_vclocks prior to calling this function. This is notably incorrect for the code path below, in which there is, in fact, no n_vclocks test: ptp_clock_adjtime() -> ptp_clock_freerun() -> ptp_vclock_in_use() The result is that any clock adjustment on any physical clock is now impossible. This is _despite_ there not being any vclock over this physical clock. $ ptp4l -i eno0 -2 -P -m ptp4l[58.425]: selected /dev/ptp0 as PTP clock [ 58.429749] ptp: physical clock is free running ptp4l[58.431]: Failed to open /dev/ptp0: Device or resource busy failed to create a clock $ cat /sys/class/ptp/ptp0/n_vclocks 0 The patch makes the ptp_vclock_in_use() function say "if it's not a virtual clock, then this physical clock does have virtual clocks on top". Then ptp_clock_freerun() uses this information to say "this physical clock has virtual clocks on top, so it must stay free-running". Then ptp_clock_adjtime() uses this information to say "well, if this physical clock has to be free-running, I can't do it, return -EBUSY". Simply put, ptp_vclock_in_use() cannot be simplified so as to remove the test whether vclocks are in use. What did the blamed commit intend to fix ---------------------------------------- The blamed commit presents a lockdep warning stating "possible recursive locking detected", with the n_vclocks_store() and ptp_clock_unregister() functions involved. The recursive locking seems this: n_vclocks_store() -> mutex_lock_interruptible(&ptp->n_vclocks_mux) // 1 -> device_for_each_child_reverse(..., unregister_vclock) -> unregister_vclock() -> ptp_vclock_unregister() -> ptp_clock_unregister() -> ptp_vclock_in_use() -> mutex_lock_interruptible(&ptp->n_vclocks_mux) // 2 The issue can be triggered by creating and then deleting vclocks: $ echo 2 > /sys/class/ptp/ptp0/n_vclocks $ echo 0 > /sys/class/ptp/ptp0/n_vclocks But note that in the original stack trace, the address of the first lock is different from the address of the second lock. This is because at step 1 marked above, &ptp->n_vclocks_mux is the lock of the parent (physical) PTP clock, and at step 2, the lock is of the child (virtual) PTP clock. They are different locks of different devices. In this situation there is no real deadlock, the lockdep warning is caused by the fact that the mutexes have the same lock class on both the parent and the child. Functionally it is fine. Proposed alternative solution ----------------------------- We must reintroduce the body of ptp_vclock_in_use() mostly as it was structured prior to the blamed commit, but avoid the lockdep warning. Based on the fact that vclocks cannot be nested on top of one another (ptp_is_attribute_visible() hides n_vclocks for virtual clocks), we already know that ptp->n_vclocks is zero for a virtual clock. And ptp->is_virtual_clock is a runtime invariant, established at ptp_clock_register() time and never changed. There is no need to serialize on any mutex in order to read ptp->is_virtual_clock, and we take advantage of that by moving it outside the lock. Thus, virtual clocks do not need to acquire &ptp->n_vclocks_mux at all, and step 2 in the code walkthrough above can simply go away. We can simply return false to the question "ptp_vclock_in_use(a virtual clock)". Other notes ----------- Releasing &ptp->n_vclocks_mux before ptp_vclock_in_use() returns execution seems racy, because the returned value can become stale as soon as the function returns and before the return value is used (i.e. n_vclocks_store() can run any time). The locking requirement should somehow be transferred to the caller, to ensure a longer life time for the returned value, but this seems out of scope for this severe bug fix. Because we are also fixing up the logic from the original commit, there is another Fixes: tag for that. Fixes: 87f7ce260a3c ("ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()") Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion") Signed-off-by: Vladimir Oltean Link: https://patch.msgid.link/20250613174749.406826-2-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()

2025-06-27T10:07:21+00:00

[ Upstream commit 87f7ce260a3c838b49e1dc1ceedf1006795157a2 ] There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use. However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store(). ============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted -------------------------------------------- syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415 but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** .... ============================================ The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use(). The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and all functions are already written this way. And in the function that uses ptp->n_vclocks, we already get ptp->n_vclocks_mux before unregistering vclocks. Therefore, we need to remove the redundant check for ptp->n_vclocks in ptp_vclock_in_use() to prevent recursive locking. Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion") Signed-off-by: Jeongjun Park Acked-by: Richard Cochran Link: https://patch.msgid.link/20250520160717.7350-1-aha310510@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ptp: ocp: fix start time alignment in ptp_ocp_signal_set

2025-04-25T08:43:51+00:00

[ Upstream commit 2a5970d5aaff8f3e33ce3bfaa403ae88c40de40d ] In ptp_ocp_signal_set, the start time for periodic signals is not aligned to the next period boundary. The current code rounds up the start time and divides by the period but fails to multiply back by the period, causing misaligned signal starts. Fix this by multiplying the rounded-up value by the period to ensure the start time is the closest next period. Fixes: 4bd46bb037f8e ("ptp: ocp: Use DIV64_U64_ROUND_UP for rounding.") Signed-off-by: Sagi Maimon Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20250415053131.129413-1-maimon.sagi@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

pps: Fix a use-after-free

2025-02-21T12:49:55+00:00

commit c79a39dc8d060b9e64e8b0fa9d245d44befeefbe upstream. On a board running ntpd and gpsd, I'm seeing a consistent use-after-free in sys_exit() from gpsd when rebooting: pps pps1: removed ------------[ cut here ]------------ kobject: '(null)' (00000000db4bec24): is not initialized, yet kobject_put() is being called. WARNING: CPU: 2 PID: 440 at lib/kobject.c:734 kobject_put+0x120/0x150 CPU: 2 UID: 299 PID: 440 Comm: gpsd Not tainted 6.11.0-rc6-00308-gb31c44928842 #1 Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : kobject_put+0x120/0x150 lr : kobject_put+0x120/0x150 sp : ffffffc0803d3ae0 x29: ffffffc0803d3ae0 x28: ffffff8042dc9738 x27: 0000000000000001 x26: 0000000000000000 x25: ffffff8042dc9040 x24: ffffff8042dc9440 x23: ffffff80402a4620 x22: ffffff8042ef4bd0 x21: ffffff80405cb600 x20: 000000000008001b x19: ffffff8040b3b6e0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 696e6920746f6e20 x14: 7369203a29343263 x13: 205d303434542020 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000 Call trace: kobject_put+0x120/0x150 cdev_put+0x20/0x3c __fput+0x2c4/0x2d8 ____fput+0x1c/0x38 task_work_run+0x70/0xfc do_exit+0x2a0/0x924 do_group_exit+0x34/0x90 get_signal+0x7fc/0x8c0 do_signal+0x128/0x13b4 do_notify_resume+0xdc/0x160 el0_svc+0xd4/0xf8 el0t_64_sync_handler+0x140/0x14c el0t_64_sync+0x190/0x194 ---[ end trace 0000000000000000 ]--- ...followed by more symptoms of corruption, with similar stacks: refcount_t: underflow; use-after-free. kernel BUG at lib/list_debug.c:62! Kernel panic - not syncing: Oops - BUG: Fatal exception This happens because pps_device_destruct() frees the pps_device with the embedded cdev immediately after calling cdev_del(), but, as the comment above cdev_del() notes, fops for previously opened cdevs are still callable even after cdev_del() returns. I think this bug has always been there: I can't explain why it suddenly started happening every time I reboot this particular board. In commit d953e0e837e6 ("pps: Fix a use-after free bug when unregistering a source."), George Spelvin suggested removing the embedded cdev. That seems like the simplest way to fix this, so I've implemented his suggestion, using __register_chrdev() with pps_idr becoming the source of truth for which minor corresponds to which device. But now that pps_idr defines userspace visibility instead of cdev_add(), we need to be sure the pps->dev refcount can't reach zero while userspace can still find it again. So, the idr_remove() call moves to pps_unregister_cdev(), and pps_idr now holds a reference to pps->dev. pps_core: source serial1 got cdev (251:1) <...> pps pps1: removed pps_core: unregistering pps1 pps_core: deallocating pps1 Fixes: d953e0e837e6 ("pps: Fix a use-after free bug when unregistering a source.") Cc: stable@vger.kernel.org Signed-off-by: Calvin Owens Reviewed-by: Michal Schmidt Link: https://lore.kernel.org/r/a17975fd5ae99385791929e563f72564edbcf28f.1731383727.git.calvin@wbinvd.org Signed-off-by: Calvin Owens Signed-off-by: Greg Kroah-Hartman

ptp: Ensure info->enable callback is always set

2025-02-21T12:49:53+00:00

commit fd53aa40e65f518453115b6f56183b0c201db26b upstream. The ioctl and sysfs handlers unconditionally call the ->enable callback. Not all drivers implement that callback, leading to NULL dereferences. Example of affected drivers: ptp_s390.c, ptp_vclock.c and ptp_mock.c. Instead use a dummy callback if no better was specified by the driver. Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh Acked-by: Richard Cochran Reviewed-by: Michal Swiatkowski Link: https://patch.msgid.link/20250123-ptp-enable-v1-1-b015834d3a47@weissschuh.net Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman