diff options
Diffstat (limited to 'kernel/acct.c')
| -rw-r--r-- | kernel/acct.c | 676 |
1 files changed, 676 insertions, 0 deletions
diff --git a/kernel/acct.c b/kernel/acct.c new file mode 100644 index 0000000..8afbb31 --- /dev/null +++ b/kernel/acct.c @@ -0,0 +1,676 @@ +/* + * 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 <asm/uaccess.h> +#include <asm/div64.h> +#include <linux/blkdev.h> /* sector_div */ +#include <linux/pid_namespace.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. + */ +static void do_acct_process(struct bsd_acct_struct *acct, + struct pid_namespace *ns, struct file *); + +/* + * This structure is used so that all the data protected by lock + * can be placed in the same cache line as the lock. This primes + * the cache line to have the data after getting the lock. + */ +struct bsd_acct_struct { + volatile int active; + volatile int needcheck; + struct file *file; + struct pid_namespace *ns; + struct timer_list timer; + struct list_head list; +}; + +static DEFINE_SPINLOCK(acct_lock); +static LIST_HEAD(acct_list); + +/* + * Called whenever the timer says to check the free space. + */ +static void acct_timeout(unsigned long x) +{ + struct bsd_acct_struct *acct = (struct bsd_acct_struct *)x; + acct->needcheck = 1; +} + +/* + * Check the amount of free space and suspend/resume accordingly. + */ +static int check_free_space(struct bsd_acct_struct *acct, struct file *file) +{ + struct kstatfs sbuf; + int res; + int act; + sector_t resume; + sector_t suspend; + + spin_lock(&acct_lock); + res = acct->active; + if (!file || !acct->needcheck) + goto out; + spin_unlock(&acct_lock); + + /* May block */ + if (vfs_statfs(file->f_path.dentry, &sbuf)) + return res; + suspend = sbuf.f_blocks * SUSPEND; + resume = sbuf.f_blocks * RESUME; + + sector_div(suspend, 100); + sector_div(resume, 100); + + if (sbuf.f_bavail <= suspend) + act = -1; + else if (sbuf.f_bavail >= resume) + act = 1; + else + act = 0; + + /* + * If some joker switched acct->file under us we'ld better be + * silent and _not_ touch anything. + */ + spin_lock(&acct_lock); + if (file != acct->file) { + if (act) + res = act>0; + goto out; + } + + if (acct->active) { + if (act < 0) { + acct->active = 0; + printk(KERN_INFO "Process accounting paused\n"); + } + } else { + if (act > 0) { + acct->active = 1; + printk(KERN_INFO "Process accounting resumed\n"); + } + } + + del_timer(&acct->timer); + acct->needcheck = 0; + acct->timer.expires = jiffies + ACCT_TIMEOUT*HZ; + add_timer(&acct->timer); + res = acct->active; +out: + spin_unlock(&acct_lock); + return res; +} + +/* + * Close the old accounting file (if currently open) and then replace + * it with file (if non-NULL). + * + * NOTE: acct_lock MUST be held on entry and exit. + */ +static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file, + struct pid_namespace *ns) +{ + struct file *old_acct = NULL; + struct pid_namespace *old_ns = NULL; + + if (acct->file) { + old_acct = acct->file; + old_ns = acct->ns; + del_timer(&acct->timer); + acct->active = 0; + acct->needcheck = 0; + acct->file = NULL; + acct->ns = NULL; + list_del(&acct->list); + } + if (file) { + acct->file = file; + acct->ns = ns; + acct->needcheck = 0; + acct->active = 1; + list_add(&acct->list, &acct_list); + /* It's been deleted if it was used before so this is safe */ + setup_timer(&acct->timer, acct_timeout, (unsigned long)acct); + acct->timer.expires = jiffies + ACCT_TIMEOUT*HZ; + add_timer(&acct->timer); + } + if (old_acct) { + mnt_unpin(old_acct->f_path.mnt); + spin_unlock(&acct_lock); + do_acct_process(acct, old_ns, old_acct); + filp_close(old_acct, NULL); + spin_lock(&acct_lock); + } +} + +static int acct_on(char *name) +{ + struct file *file; + int error; + struct pid_namespace *ns; + struct bsd_acct_struct *acct = NULL; + + /* Difference from BSD - they don't do O_APPEND */ + file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0); + if (IS_ERR(file)) + return PTR_ERR(file); + + if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) { + filp_close(file, NULL); + return -EACCES; + } + + if (!file->f_op->write) { + filp_close(file, NULL); + return -EIO; + } + + ns = task_active_pid_ns(current); + if (ns->bacct == NULL) { + acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL); + if (acct == NULL) { + filp_close(file, NULL); + return -ENOMEM; + } + } + + error = security_acct(file); + if (error) { + kfree(acct); + filp_close(file, NULL); + return error; + } + + spin_lock(&acct_lock); + if (ns->bacct == NULL) { + ns->bacct = acct; + acct = NULL; + } + + mnt_pin(file->f_path.mnt); + acct_file_reopen(ns->bacct, file, ns); + spin_unlock(&acct_lock); + + mntput(file->f_path.mnt); /* it's pinned, now give up active reference */ + kfree(acct); + + return 0; +} + +/** + * 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; + + if (!capable(CAP_SYS_PACCT)) + return -EPERM; + + if (name) { + char *tmp = getname(name); + if (IS_ERR(tmp)) + return (PTR_ERR(tmp)); + error = acct_on(tmp); + putname(tmp); + } else { + struct bsd_acct_struct *acct; + + acct = task_active_pid_ns(current)->bacct; + if (acct == NULL) + return 0; + + error = security_acct(NULL); + if (!error) { + spin_lock(&acct_lock); + acct_file_reopen(acct, NULL, NULL); + spin_unlock(&acct_lock); + } + } + return error; +} + +/** + * acct_auto_close - turn off a filesystem's accounting if it is on + * @m: vfsmount being shut down + * + * If the accounting is turned on for a file in the subtree pointed to + * to by m, turn accounting off. Done when m is about to die. + */ +void acct_auto_close_mnt(struct vfsmount *m) +{ + struct bsd_acct_struct *acct; + + spin_lock(&acct_lock); +restart: + list_for_each_entry(acct, &acct_list, list) + if (acct->file && acct->file->f_path.mnt == m) { + acct_file_reopen(acct, NULL, NULL); + goto restart; + } + spin_unlock(&acct_lock); +} + +/** + * acct_auto_close - turn off a filesystem's accounting if it is on + * @sb: super block for the filesystem + * + * If the accounting is turned on for a file in the filesystem pointed + * to by sb, turn accounting off. + */ +void acct_auto_close(struct super_block *sb) +{ + struct bsd_acct_struct *acct; + + spin_lock(&acct_lock); +restart: + list_for_each_entry(acct, &acct_list, list) + if (acct->file && acct->file->f_path.mnt->mnt_sb == sb) { + acct_file_reopen(acct, NULL, NULL); + goto restart; + } + spin_unlock(&acct_lock); +} + +void acct_exit_ns(struct pid_namespace *ns) +{ + struct bsd_acct_struct *acct; + + spin_lock(&acct_lock); + acct = ns->bacct; + if (acct != NULL) { + if (acct->file != NULL) + acct_file_reopen(acct, NULL, NULL); + + kfree(acct); + } + spin_unlock(&acct_lock); +} + +/* + * 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. + */ + +/* + * do_acct_process does all actual work. Caller holds the reference to file. + */ +static void do_acct_process(struct bsd_acct_struct *acct, + struct pid_namespace *ns, struct file *file) +{ + struct pacct_struct *pacct = ¤t->signal->pacct; + acct_t ac; + mm_segment_t fs; + unsigned long flim; + u64 elapsed; + u64 run_time; + struct timespec uptime; + struct tty_struct *tty; + + /* + * First check to see if there is enough free_space to continue + * the process accounting system. + */ + if (!check_free_space(acct, file)) + return; + + /* + * Fill the accounting struct with the needed info as recorded + * by the different kernel functions. + */ + memset((caddr_t)&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*/ + do_posix_clock_monotonic_gettime(&uptime); + run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec; + run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC + + current->group_leader->start_time.tv_nsec; + /* 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; + /* we really need to bite the bullet and change layout */ + ac.ac_uid = current->uid; + ac.ac_gid = current->gid; +#if ACCT_VERSION==2 + ac.ac_ahz = AHZ; +#endif +#if ACCT_VERSION==1 || ACCT_VERSION==2 + /* backward-compatible 16 bit fields */ + ac.ac_uid16 = current->uid; + ac.ac_gid16 = current->gid; +#endif +#if ACCT_VERSION==3 + 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 + + spin_lock_irq(¤t->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(¤t->sighand->siglock); + ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */ + ac.ac_rw = encode_comp_t(ac.ac_io / 1024); + ac.ac_swaps = encode_comp_t(0); + + /* + * Kernel segment override to datasegment and write it + * to the accounting file. + */ + fs = get_fs(); + set_fs(KERNEL_DS); + /* + * 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; + file->f_op->write(file, (char *)&ac, + sizeof(acct_t), &file->f_pos); + current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim; + set_fs(fs); +} + +/** + * acct_init_pacct - initialize a new pacct_struct + * @pacct: per-process accounting info struct to initialize + */ +void acct_init_pacct(struct pacct_struct *pacct) +{ + memset(pacct, 0, sizeof(struct pacct_struct)); + pacct->ac_utime = pacct->ac_stime = cputime_zero; +} + +/** + * 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 = ¤t->signal->pacct; + unsigned long vsize = 0; + + if (group_dead && current->mm) { + struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); + vma = current->mm->mmap; + while (vma) { + vsize += vma->vm_end - vma->vm_start; + vma = vma->vm_next; + } + up_read(¤t->mm->mmap_sem); + } + + spin_lock_irq(¤t->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; + pacct->ac_utime = cputime_add(pacct->ac_utime, current->utime); + pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime); + pacct->ac_minflt += current->min_flt; + pacct->ac_majflt += current->maj_flt; + spin_unlock_irq(¤t->sighand->siglock); +} + +static void acct_process_in_ns(struct pid_namespace *ns) +{ + struct file *file = NULL; + struct bsd_acct_struct *acct; + + acct = ns->bacct; + /* + * accelerate the common fastpath: + */ + if (!acct || !acct->file) + return; + + spin_lock(&acct_lock); + file = acct->file; + if (unlikely(!file)) { + spin_unlock(&acct_lock); + return; + } + get_file(file); + spin_unlock(&acct_lock); + + do_acct_process(acct, ns, file); + fput(file); +} + +/** + * acct_process - now just a wrapper around acct_process_in_ns, + * which in turn is a wrapper around do_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) + acct_process_in_ns(ns); +} |
