Initial import

1 files changed, 602 insertions, 0 deletions

diff --git a/kernel/acct.c b/kernel/acct.c
new file mode 100644
index 000000000..74963d192
--- /dev/null
+++ b/kernel/acct.c
@@ -0,0 +1,602 @@
+/*
+ *  linux/kernel/acct.c
+ *
+ *  BSD Process Accounting for Linux
+ *
+ *  Author: Marco van Wieringen <mvw@planets.elm.net>
+ *
+ *  Some code based on ideas and code from:
+ *  Thomas K. Dyas <tdyas@eden.rutgers.edu>
+ *
+ *  This file implements BSD-style process accounting. Whenever any
+ *  process exits, an accounting record of type "struct acct" is
+ *  written to the file specified with the acct() system call. It is
+ *  up to user-level programs to do useful things with the accounting
+ *  log. The kernel just provides the raw accounting information.
+ *
+ * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
+ *
+ *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if
+ *  the file happened to be read-only. 2) If the accounting was suspended
+ *  due to the lack of space it happily allowed to reopen it and completely
+ *  lost the old acct_file. 3/10/98, Al Viro.
+ *
+ *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
+ *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
+ *
+ *  Fixed a nasty interaction with with sys_umount(). If the accointing
+ *  was suspeneded we failed to stop it on umount(). Messy.
+ *  Another one: remount to readonly didn't stop accounting.
+ *	Question: what should we do if we have CAP_SYS_ADMIN but not
+ *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
+ *  unless we are messing with the root. In that case we are getting a
+ *  real mess with do_remount_sb(). 9/11/98, AV.
+ *
+ *  Fixed a bunch of races (and pair of leaks). Probably not the best way,
+ *  but this one obviously doesn't introduce deadlocks. Later. BTW, found
+ *  one race (and leak) in BSD implementation.
+ *  OK, that's better. ANOTHER race and leak in BSD variant. There always
+ *  is one more bug... 10/11/98, AV.
+ *
+ *	Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
+ * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
+ * a struct file opened for write. Fixed. 2/6/2000, AV.
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/acct.h>
+#include <linux/capability.h>
+#include <linux/file.h>
+#include <linux/tty.h>
+#include <linux/security.h>
+#include <linux/vfs.h>
+#include <linux/jiffies.h>
+#include <linux/times.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/uaccess.h>
+#include <asm/div64.h>
+#include <linux/blkdev.h> /* sector_div */
+#include <linux/pid_namespace.h>
+#include <linux/fs_pin.h>
+
+/*
+ * These constants control the amount of freespace that suspend and
+ * resume the process accounting system, and the time delay between
+ * each check.
+ * Turned into sysctl-controllable parameters. AV, 12/11/98
+ */
+
+int acct_parm[3] = {4, 2, 30};
+#define RESUME		(acct_parm[0])	/* >foo% free space - resume */
+#define SUSPEND		(acct_parm[1])	/* <foo% free space - suspend */
+#define ACCT_TIMEOUT	(acct_parm[2])	/* foo second timeout between checks */
+
+/*
+ * External references and all of the globals.
+ */
+
+struct bsd_acct_struct {
+	struct fs_pin		pin;
+	atomic_long_t		count;
+	struct rcu_head		rcu;
+	struct mutex		lock;
+	int			active;
+	unsigned long		needcheck;
+	struct file		*file;
+	struct pid_namespace	*ns;
+	struct work_struct	work;
+	struct completion	done;
+};
+
+static void do_acct_process(struct bsd_acct_struct *acct);
+
+/*
+ * Check the amount of free space and suspend/resume accordingly.
+ */
+static int check_free_space(struct bsd_acct_struct *acct)
+{
+	struct kstatfs sbuf;
+
+	if (time_is_before_jiffies(acct->needcheck))
+		goto out;
+
+	/* May block */
+	if (vfs_statfs(&acct->file->f_path, &sbuf))
+		goto out;
+
+	if (acct->active) {
+		u64 suspend = sbuf.f_blocks * SUSPEND;
+		do_div(suspend, 100);
+		if (sbuf.f_bavail <= suspend) {
+			acct->active = 0;
+			pr_info("Process accounting paused\n");
+		}
+	} else {
+		u64 resume = sbuf.f_blocks * RESUME;
+		do_div(resume, 100);
+		if (sbuf.f_bavail >= resume) {
+			acct->active = 1;
+			pr_info("Process accounting resumed\n");
+		}
+	}
+
+	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
+out:
+	return acct->active;
+}
+
+static void acct_put(struct bsd_acct_struct *p)
+{
+	if (atomic_long_dec_and_test(&p->count))
+		kfree_rcu(p, rcu);
+}
+
+static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
+{
+	return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
+}
+
+static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
+{
+	struct bsd_acct_struct *res;
+again:
+	smp_rmb();
+	rcu_read_lock();
+	res = to_acct(ACCESS_ONCE(ns->bacct));
+	if (!res) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	if (!atomic_long_inc_not_zero(&res->count)) {
+		rcu_read_unlock();
+		cpu_relax();
+		goto again;
+	}
+	rcu_read_unlock();
+	mutex_lock(&res->lock);
+	if (res != to_acct(ACCESS_ONCE(ns->bacct))) {
+		mutex_unlock(&res->lock);
+		acct_put(res);
+		goto again;
+	}
+	return res;
+}
+
+static void acct_pin_kill(struct fs_pin *pin)
+{
+	struct bsd_acct_struct *acct = to_acct(pin);
+	mutex_lock(&acct->lock);
+	do_acct_process(acct);
+	schedule_work(&acct->work);
+	wait_for_completion(&acct->done);
+	cmpxchg(&acct->ns->bacct, pin, NULL);
+	mutex_unlock(&acct->lock);
+	pin_remove(pin);
+	acct_put(acct);
+}
+
+static void close_work(struct work_struct *work)
+{
+	struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
+	struct file *file = acct->file;
+	if (file->f_op->flush)
+		file->f_op->flush(file, NULL);
+	__fput_sync(file);
+	complete(&acct->done);
+}
+
+static int acct_on(struct filename *pathname)
+{
+	struct file *file;
+	struct vfsmount *mnt, *internal;
+	struct pid_namespace *ns = task_active_pid_ns(current);
+	struct bsd_acct_struct *acct;
+	struct fs_pin *old;
+	int err;
+
+	acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
+	if (!acct)
+		return -ENOMEM;
+
+	/* Difference from BSD - they don't do O_APPEND */
+	file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
+	if (IS_ERR(file)) {
+		kfree(acct);
+		return PTR_ERR(file);
+	}
+
+	if (!S_ISREG(file_inode(file)->i_mode)) {
+		kfree(acct);
+		filp_close(file, NULL);
+		return -EACCES;
+	}
+
+	if (!(file->f_mode & FMODE_CAN_WRITE)) {
+		kfree(acct);
+		filp_close(file, NULL);
+		return -EIO;
+	}
+	internal = mnt_clone_internal(&file->f_path);
+	if (IS_ERR(internal)) {
+		kfree(acct);
+		filp_close(file, NULL);
+		return PTR_ERR(internal);
+	}
+	err = mnt_want_write(internal);
+	if (err) {
+		mntput(internal);
+		kfree(acct);
+		filp_close(file, NULL);
+		return err;
+	}
+	mnt = file->f_path.mnt;
+	file->f_path.mnt = internal;
+
+	atomic_long_set(&acct->count, 1);
+	init_fs_pin(&acct->pin, acct_pin_kill);
+	acct->file = file;
+	acct->needcheck = jiffies;
+	acct->ns = ns;
+	mutex_init(&acct->lock);
+	INIT_WORK(&acct->work, close_work);
+	init_completion(&acct->done);
+	mutex_lock_nested(&acct->lock, 1);	/* nobody has seen it yet */
+	pin_insert(&acct->pin, mnt);
+
+	rcu_read_lock();
+	old = xchg(&ns->bacct, &acct->pin);
+	mutex_unlock(&acct->lock);
+	pin_kill(old);
+	mnt_drop_write(mnt);
+	mntput(mnt);
+	return 0;
+}
+
+static DEFINE_MUTEX(acct_on_mutex);
+
+/**
+ * sys_acct - enable/disable process accounting
+ * @name: file name for accounting records or NULL to shutdown accounting
+ *
+ * Returns 0 for success or negative errno values for failure.
+ *
+ * sys_acct() is the only system call needed to implement process
+ * accounting. It takes the name of the file where accounting records
+ * should be written. If the filename is NULL, accounting will be
+ * shutdown.
+ */
+SYSCALL_DEFINE1(acct, const char __user *, name)
+{
+	int error = 0;
+
+	if (!capable(CAP_SYS_PACCT))
+		return -EPERM;
+
+	if (name) {
+		struct filename *tmp = getname(name);
+
+		if (IS_ERR(tmp))
+			return PTR_ERR(tmp);
+		mutex_lock(&acct_on_mutex);
+		error = acct_on(tmp);
+		mutex_unlock(&acct_on_mutex);
+		putname(tmp);
+	} else {
+		rcu_read_lock();
+		pin_kill(task_active_pid_ns(current)->bacct);
+	}
+
+	return error;
+}
+
+void acct_exit_ns(struct pid_namespace *ns)
+{
+	rcu_read_lock();
+	pin_kill(ns->bacct);
+}
+
+/*
+ *  encode an unsigned long into a comp_t
+ *
+ *  This routine has been adopted from the encode_comp_t() function in
+ *  the kern_acct.c file of the FreeBSD operating system. The encoding
+ *  is a 13-bit fraction with a 3-bit (base 8) exponent.
+ */
+
+#define	MANTSIZE	13			/* 13 bit mantissa. */
+#define	EXPSIZE		3			/* Base 8 (3 bit) exponent. */
+#define	MAXFRACT	((1 << MANTSIZE) - 1)	/* Maximum fractional value. */
+
+static comp_t encode_comp_t(unsigned long value)
+{
+	int exp, rnd;
+
+	exp = rnd = 0;
+	while (value > MAXFRACT) {
+		rnd = value & (1 << (EXPSIZE - 1));	/* Round up? */
+		value >>= EXPSIZE;	/* Base 8 exponent == 3 bit shift. */
+		exp++;
+	}
+
+	/*
+	 * If we need to round up, do it (and handle overflow correctly).
+	 */
+	if (rnd && (++value > MAXFRACT)) {
+		value >>= EXPSIZE;
+		exp++;
+	}
+
+	/*
+	 * Clean it up and polish it off.
+	 */
+	exp <<= MANTSIZE;		/* Shift the exponent into place */
+	exp += value;			/* and add on the mantissa. */
+	return exp;
+}
+
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+/*
+ * encode an u64 into a comp2_t (24 bits)
+ *
+ * Format: 5 bit base 2 exponent, 20 bits mantissa.
+ * The leading bit of the mantissa is not stored, but implied for
+ * non-zero exponents.
+ * Largest encodable value is 50 bits.
+ */
+
+#define MANTSIZE2       20                      /* 20 bit mantissa. */
+#define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
+#define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
+#define MAXEXP2         ((1 << EXPSIZE2) - 1)    /* Maximum exponent. */
+
+static comp2_t encode_comp2_t(u64 value)
+{
+	int exp, rnd;
+
+	exp = (value > (MAXFRACT2>>1));
+	rnd = 0;
+	while (value > MAXFRACT2) {
+		rnd = value & 1;
+		value >>= 1;
+		exp++;
+	}
+
+	/*
+	 * If we need to round up, do it (and handle overflow correctly).
+	 */
+	if (rnd && (++value > MAXFRACT2)) {
+		value >>= 1;
+		exp++;
+	}
+
+	if (exp > MAXEXP2) {
+		/* Overflow. Return largest representable number instead. */
+		return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
+	} else {
+		return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
+	}
+}
+#endif
+
+#if ACCT_VERSION == 3
+/*
+ * encode an u64 into a 32 bit IEEE float
+ */
+static u32 encode_float(u64 value)
+{
+	unsigned exp = 190;
+	unsigned u;
+
+	if (value == 0)
+		return 0;
+	while ((s64)value > 0) {
+		value <<= 1;
+		exp--;
+	}
+	u = (u32)(value >> 40) & 0x7fffffu;
+	return u | (exp << 23);
+}
+#endif
+
+/*
+ *  Write an accounting entry for an exiting process
+ *
+ *  The acct_process() call is the workhorse of the process
+ *  accounting system. The struct acct is built here and then written
+ *  into the accounting file. This function should only be called from
+ *  do_exit() or when switching to a different output file.
+ */
+
+static void fill_ac(acct_t *ac)
+{
+	struct pacct_struct *pacct = &current->signal->pacct;
+	u64 elapsed, run_time;
+	struct tty_struct *tty;
+
+	/*
+	 * Fill the accounting struct with the needed info as recorded
+	 * by the different kernel functions.
+	 */
+	memset(ac, 0, sizeof(acct_t));
+
+	ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
+	strlcpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
+
+	/* calculate run_time in nsec*/
+	run_time = ktime_get_ns();
+	run_time -= current->group_leader->start_time;
+	/* convert nsec -> AHZ */
+	elapsed = nsec_to_AHZ(run_time);
+#if ACCT_VERSION == 3
+	ac->ac_etime = encode_float(elapsed);
+#else
+	ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
+				(unsigned long) elapsed : (unsigned long) -1l);
+#endif
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+	{
+		/* new enlarged etime field */
+		comp2_t etime = encode_comp2_t(elapsed);
+
+		ac->ac_etime_hi = etime >> 16;
+		ac->ac_etime_lo = (u16) etime;
+	}
+#endif
+	do_div(elapsed, AHZ);
+	ac->ac_btime = get_seconds() - elapsed;
+#if ACCT_VERSION==2
+	ac->ac_ahz = AHZ;
+#endif
+
+	spin_lock_irq(&current->sighand->siglock);
+	tty = current->signal->tty;	/* Safe as we hold the siglock */
+	ac->ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
+	ac->ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
+	ac->ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
+	ac->ac_flag = pacct->ac_flag;
+	ac->ac_mem = encode_comp_t(pacct->ac_mem);
+	ac->ac_minflt = encode_comp_t(pacct->ac_minflt);
+	ac->ac_majflt = encode_comp_t(pacct->ac_majflt);
+	ac->ac_exitcode = pacct->ac_exitcode;
+	spin_unlock_irq(&current->sighand->siglock);
+}
+/*
+ *  do_acct_process does all actual work. Caller holds the reference to file.
+ */
+static void do_acct_process(struct bsd_acct_struct *acct)
+{
+	acct_t ac;
+	unsigned long flim;
+	const struct cred *orig_cred;
+	struct file *file = acct->file;
+
+	/*
+	 * Accounting records are not subject to resource limits.
+	 */
+	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
+	/* Perform file operations on behalf of whoever enabled accounting */
+	orig_cred = override_creds(file->f_cred);
+
+	/*
+	 * First check to see if there is enough free_space to continue
+	 * the process accounting system.
+	 */
+	if (!check_free_space(acct))
+		goto out;
+
+	fill_ac(&ac);
+	/* we really need to bite the bullet and change layout */
+	ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
+	ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+	/* backward-compatible 16 bit fields */
+	ac.ac_uid16 = ac.ac_uid;
+	ac.ac_gid16 = ac.ac_gid;
+#endif
+#if ACCT_VERSION == 3
+	{
+		struct pid_namespace *ns = acct->ns;
+
+		ac.ac_pid = task_tgid_nr_ns(current, ns);
+		rcu_read_lock();
+		ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent),
+					     ns);
+		rcu_read_unlock();
+	}
+#endif
+	/*
+	 * Get freeze protection. If the fs is frozen, just skip the write
+	 * as we could deadlock the system otherwise.
+	 */
+	if (file_start_write_trylock(file)) {
+		/* it's been opened O_APPEND, so position is irrelevant */
+		loff_t pos = 0;
+		__kernel_write(file, (char *)&ac, sizeof(acct_t), &pos);
+		file_end_write(file);
+	}
+out:
+	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
+	revert_creds(orig_cred);
+}
+
+/**
+ * acct_collect - collect accounting information into pacct_struct
+ * @exitcode: task exit code
+ * @group_dead: not 0, if this thread is the last one in the process.
+ */
+void acct_collect(long exitcode, int group_dead)
+{
+	struct pacct_struct *pacct = &current->signal->pacct;
+	cputime_t utime, stime;
+	unsigned long vsize = 0;
+
+	if (group_dead && current->mm) {
+		struct vm_area_struct *vma;
+
+		down_read(&current->mm->mmap_sem);
+		vma = current->mm->mmap;
+		while (vma) {
+			vsize += vma->vm_end - vma->vm_start;
+			vma = vma->vm_next;
+		}
+		up_read(&current->mm->mmap_sem);
+	}
+
+	spin_lock_irq(&current->sighand->siglock);
+	if (group_dead)
+		pacct->ac_mem = vsize / 1024;
+	if (thread_group_leader(current)) {
+		pacct->ac_exitcode = exitcode;
+		if (current->flags & PF_FORKNOEXEC)
+			pacct->ac_flag |= AFORK;
+	}
+	if (current->flags & PF_SUPERPRIV)
+		pacct->ac_flag |= ASU;
+	if (current->flags & PF_DUMPCORE)
+		pacct->ac_flag |= ACORE;
+	if (current->flags & PF_SIGNALED)
+		pacct->ac_flag |= AXSIG;
+	task_cputime(current, &utime, &stime);
+	pacct->ac_utime += utime;
+	pacct->ac_stime += stime;
+	pacct->ac_minflt += current->min_flt;
+	pacct->ac_majflt += current->maj_flt;
+	spin_unlock_irq(&current->sighand->siglock);
+}
+
+static void slow_acct_process(struct pid_namespace *ns)
+{
+	for ( ; ns; ns = ns->parent) {
+		struct bsd_acct_struct *acct = acct_get(ns);
+		if (acct) {
+			do_acct_process(acct);
+			mutex_unlock(&acct->lock);
+			acct_put(acct);
+		}
+	}
+}
+
+/**
+ * acct_process
+ *
+ * handles process accounting for an exiting task
+ */
+void acct_process(void)
+{
+	struct pid_namespace *ns;
+
+	/*
+	 * This loop is safe lockless, since current is still
+	 * alive and holds its namespace, which in turn holds
+	 * its parent.
+	 */
+	for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
+		if (ns->bacct)
+			break;
+	}
+	if (unlikely(ns))
+		slow_acct_process(ns);
+}