From: Andrei Vagin <[email protected]> API to set time namespace offsets for children processes, i.e.: echo "clockid off_ses off_nsec" > /proc/self/timens_offsets
Signed-off-by: Andrei Vagin <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> --- fs/proc/base.c | 101 +++++++++++++++++++++++++++++++++ include/linux/time_namespace.h | 10 ++++ kernel/time_namespace.c | 71 +++++++++++++++++++++++ 3 files changed, 182 insertions(+) diff --git a/fs/proc/base.c b/fs/proc/base.c index 633a63462573..1ba31050dcb5 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -94,6 +94,7 @@ #include <linux/sched/stat.h> #include <linux/flex_array.h> #include <linux/posix-timers.h> +#include <linux/time_namespace.h> #include <trace/events/oom.h> #include "internal.h" #include "fd.h" @@ -1520,6 +1521,103 @@ static const struct file_operations proc_pid_sched_autogroup_operations = { #endif /* CONFIG_SCHED_AUTOGROUP */ +#ifdef CONFIG_TIME_NS +static int timens_offsets_show(struct seq_file *m, void *v) +{ + struct inode *inode = m->private; + struct task_struct *p; + + p = get_proc_task(inode); + if (!p) + return -ESRCH; + proc_timens_show_offsets(p, m); + + put_task_struct(p); + + return 0; +} + +static ssize_t +timens_offsets_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct inode *inode = file_inode(file); + struct proc_timens_offset offsets[2]; + char *kbuf = NULL, *pos, *next_line; + struct task_struct *p; + int ret, noffsets; + + /* Only allow < page size writes at the beginning of the file */ + if ((*ppos != 0) || (count >= PAGE_SIZE)) + return -EINVAL; + + /* Slurp in the user data */ + kbuf = memdup_user_nul(buf, count); + if (IS_ERR(kbuf)) + return PTR_ERR(kbuf); + + /* Parse the user data */ + ret = -EINVAL; + noffsets = 0; + pos = kbuf; + for (; pos; pos = next_line) { + struct proc_timens_offset *off = &offsets[noffsets]; + int err; + + /* Find the end of line and ensure I don't look past it */ + next_line = strchr(pos, '\n'); + if (next_line) { + *next_line = '\0'; + next_line++; + if (*next_line == '\0') + next_line = NULL; + } + + err = sscanf(pos, "%u %lld %lu", &off->clockid, + &off->val.tv_sec, &off->val.tv_nsec); + if (err != 3 || off->val.tv_nsec >= NSEC_PER_SEC) + goto out; + if (noffsets++ == ARRAY_SIZE(offsets)) + break; + } + + ret = -ESRCH; + p = get_proc_task(inode); + if (!p) + goto out; + ret = proc_timens_set_offset(p, offsets, noffsets); + put_task_struct(p); + if (ret) + goto out; + + ret = count; +out: + kfree(kbuf); + return ret; +} + +static int timens_offsets_open(struct inode *inode, struct file *filp) +{ + int ret; + + ret = single_open(filp, timens_offsets_show, NULL); + if (!ret) { + struct seq_file *m = filp->private_data; + + m->private = inode; + } + return ret; +} + +static const struct file_operations proc_timens_offsets_operations = { + .open = timens_offsets_open, + .read = seq_read, + .write = timens_offsets_write, + .llseek = seq_lseek, + .release = single_release, +}; +#endif /* CONFIG_TIME_NS */ + static ssize_t comm_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) { @@ -2953,6 +3051,9 @@ static const struct pid_entry tgid_base_stuff[] = { #endif #ifdef CONFIG_SCHED_AUTOGROUP REG("autogroup", S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations), +#endif +#ifdef CONFIG_TIME_NS + REG("timens_offsets", S_IRUGO|S_IWUSR, proc_timens_offsets_operations), #endif REG("comm", S_IRUGO|S_IWUSR, proc_pid_set_comm_operations), #ifdef CONFIG_HAVE_ARCH_TRACEHOOK diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h index f1807d7f524d..c9ba7366b3d6 100644 --- a/include/linux/time_namespace.h +++ b/include/linux/time_namespace.h @@ -41,6 +41,16 @@ static inline void put_time_ns(struct time_namespace *ns) } +extern void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m); + +struct proc_timens_offset { + int clockid; + struct timespec64 val; +}; + +extern int proc_timens_set_offset(struct task_struct *p, + struct proc_timens_offset *offsets, int n); + extern void timens_clock_to_host(int clockid, struct timespec64 *val); extern void timens_clock_from_host(int clockid, struct timespec64 *val); diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c index 1d1d1c023ec1..6e2e6629e1ba 100644 --- a/kernel/time_namespace.c +++ b/kernel/time_namespace.c @@ -13,6 +13,7 @@ #include <linux/user_namespace.h> #include <linux/proc_ns.h> #include <linux/sched/task.h> +#include <linux/seq_file.h> #include <linux/mm.h> #include <asm/vdso.h> @@ -202,6 +203,76 @@ static struct user_namespace *timens_owner(struct ns_common *ns) return to_time_ns(ns)->user_ns; } +static void show_offset(struct seq_file *m, int clockid, struct timespec64 *ts) +{ + seq_printf(m, "%d %lld %ld\n", clockid, ts->tv_sec, ts->tv_nsec); +} + +void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m) +{ + struct ns_common *ns; + struct time_namespace *time_ns; + struct timens_offsets *ns_offsets; + + ns = timens_for_children_get(p); + if (!ns) + return; + time_ns = to_time_ns(ns); + + if (!time_ns->offsets) { + put_time_ns(time_ns); + return; + } + ns_offsets = time_ns->offsets; + + show_offset(m, CLOCK_MONOTONIC, &ns_offsets->monotonic_time_offset); + show_offset(m, CLOCK_BOOTTIME, &ns_offsets->monotonic_boottime_offset); + put_time_ns(time_ns); +} + +int proc_timens_set_offset(struct task_struct *p, + struct proc_timens_offset *offsets, int noffsets) +{ + struct ns_common *ns; + struct time_namespace *time_ns; + struct timens_offsets *ns_offsets; + int i, err; + + ns = timens_for_children_get(p); + if (!ns) + return -ESRCH; + time_ns = to_time_ns(ns); + + if (!time_ns->offsets || time_ns->initialized || + !ns_capable(time_ns->user_ns, CAP_SYS_TIME)) { + put_time_ns(time_ns); + return -EPERM; + } + ns_offsets = time_ns->offsets; + + err = -EINVAL; + for (i = 0; i < noffsets; i++) { + struct proc_timens_offset *off = &offsets[i]; + + switch (off->clockid) { + case CLOCK_MONOTONIC: + ns_offsets->monotonic_time_offset = off->val; + break; + case CLOCK_BOOTTIME: + ns_offsets->monotonic_boottime_offset = off->val; + break; + default: + goto out; + } + } + + err = 0; +out: + put_time_ns(time_ns); + + return err; +} + static void clock_timens_fixup(int clockid, struct timespec64 *val, bool to_ns) { struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets; -- 2.20.1
