[PATCHv4 06/28] timerfd/timens: Take into account ns clock offsets
From: Dmitry Safonov <hidden>
Date: 2019-06-12 19:28:34
Also in:
lkml
Subsystem:
filesystems (vfs and infrastructure), posix clocks and timers, the rest · Maintainers:
Alexander Viro, Christian Brauner, Anna-Maria Behnsen, Frederic Weisbecker, Thomas Gleixner, Linus Torvalds
From: Andrei Vagin <redacted> Make timerfd respect timens offsets. Provide a helper timens_ktime_to_host() that is useful to wire up timens to different kernel subsystems. Signed-off-by: Andrei Vagin <redacted> Co-developed-by: Dmitry Safonov <redacted> Signed-off-by: Dmitry Safonov <redacted> --- fs/timerfd.c | 3 +++ include/linux/time_namespace.h | 18 ++++++++++++++++++ kernel/time_namespace.c | 27 +++++++++++++++++++++++++++ 3 files changed, 48 insertions(+)
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 6a6fc8aa1de7..9b0c2f65e7e8 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c@@ -26,6 +26,7 @@ #include <linux/syscalls.h> #include <linux/compat.h> #include <linux/rcupdate.h> +#include <linux/time_namespace.h> struct timerfd_ctx { union {
@@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags, } if (texp != 0) { + if (flags & TFD_TIMER_ABSTIME) + texp = timens_ktime_to_host(clockid, texp); if (isalarm(ctx)) { if (flags & TFD_TIMER_ABSTIME) alarm_start(&ctx->t.alarm, texp);
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 1dda8af6b9fe..d32b55fad953 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h@@ -56,6 +56,19 @@ static inline void timens_add_boottime(struct timespec64 *ts) *ts = timespec64_add(*ts, ns_offsets->boottime); } +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim, + struct timens_offsets *offsets); +static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim) +{ + struct timens_offsets *offsets = current->nsproxy->time_ns->offsets; + + if (!offsets) /* fast-path for the root time namespace */ + return tim; + + return do_timens_ktime_to_host(clockid, tim, offsets); +} + + #else static inline struct time_namespace *get_time_ns(struct time_namespace *ns) {
@@ -82,6 +95,11 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts static inline void timens_add_monotonic(struct timespec64 *ts) {} static inline void timens_add_boottime(struct timespec64 *ts) {} + +static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim) +{ + return tim; +} #endif #endif /* _LINUX_TIMENS_H */
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index 4828447721ec..b3cffdf2635c 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c@@ -15,6 +15,33 @@ #include <linux/sched/task.h> #include <linux/mm.h> +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim, struct timens_offsets *ns_offsets) +{ + ktime_t koff; + + switch (clockid) { + case CLOCK_MONOTONIC: + koff = timespec64_to_ktime(ns_offsets->monotonic); + break; + case CLOCK_BOOTTIME: + case CLOCK_BOOTTIME_ALARM: + koff = timespec64_to_ktime(ns_offsets->boottime); + break; + default: + return tim; + } + + /* tim - off has to be in [0, KTIME_MAX) */ + if (tim < koff) + tim = 0; + else if (KTIME_MAX - tim < -koff) + tim = KTIME_MAX; + else + tim = ktime_sub(tim, koff); + + return tim; +} + static struct ucounts *inc_time_namespaces(struct user_namespace *ns) { return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
--
2.22.0