/*
 *  linux/kernel/sys.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/times.h>
#include <linux/utsname.h>
#include <linux/param.h>
#include <linux/resource.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/stat.h>
#include <linux/mman.h>
#include <linux/mm.h>

#include <asm/segment.h>
#include <asm/io.h>

/*
 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
 */
static int C_A_D = 1;

extern void adjust_clock(void);

#define PZERO   15

asmlinkage int sys_ni_syscall(void)
{
        return -ENOSYS;
}

static int proc_sel(struct task_struct *p, int which, int who)
{
        switch (which) {
                case PRIO_PROCESS:
                        if (!who && p == current)
                                return 1;
                        return(p->pid == who);
                case PRIO_PGRP:
                        if (!who)
                                who = current->pgrp;
                        return(p->pgrp == who);
                case PRIO_USER:
                        if (!who)
                                who = current->uid;
                        return(p->uid == who);
        }
        return 0;
}

asmlinkage int sys_setpriority(int which, int who, int niceval)
{
        struct task_struct **p;
        int error = ESRCH;
        int priority;

        if (which > 2 || which < 0)
                return -EINVAL;

        if ((priority = PZERO - niceval) <= 0)
                priority = 1;

        for(p = &LAST_TASK; p > &FIRST_TASK; --p) {
                if (!*p || !proc_sel(*p, which, who))
                        continue;
                if ((*p)->uid != current->euid &&
                        (*p)->uid != current->uid && !suser()) {
                        error = EPERM;
                        continue;
                }
                if (error == ESRCH)
                        error = 0;
                if (priority > (*p)->priority && !suser())
                        error = EACCES;
                else
                        (*p)->priority = priority;
        }
        return -error;
}

asmlinkage int sys_getpriority(int which, int who)
{
        struct task_struct **p;
        int max_prio = 0;

        if (which > 2 || which < 0)
                return -EINVAL;

        for(p = &LAST_TASK; p > &FIRST_TASK; --p) {
                if (!*p || !proc_sel(*p, which, who))
                        continue;
                if ((*p)->priority > max_prio)
                        max_prio = (*p)->priority;
        }
        return(max_prio ? max_prio : -ESRCH);
}

asmlinkage int sys_profil(void)
{
        return -ENOSYS;
}

asmlinkage int sys_ftime(void)
{
        return -ENOSYS;
}

asmlinkage int sys_break(void)
{
        return -ENOSYS;
}

asmlinkage int sys_stty(void)
{
        return -ENOSYS;
}

asmlinkage int sys_gtty(void)
{
        return -ENOSYS;
}

asmlinkage int sys_prof(void)
{
        return -ENOSYS;
}

extern void hard_reset_now(void);
extern asmlinkage sys_kill(int, int);

/*
 * Reboot system call: for obvious reasons only root may call it,
 * and even root needs to set up some magic numbers in the registers
 * so that some mistake won't make this reboot the whole machine.
 * You can also set the meaning of the ctrl-alt-del-key here.
 *
 * reboot doesn't sync: do that yourself before calling this.
 */
asmlinkage int sys_reboot(int magic, int magic_too, int flag)
{
        if (!suser())
                return -EPERM;
        if (magic != 0xfee1dead || magic_too != 672274793)
                return -EINVAL;
        if (flag == 0x01234567)
                hard_reset_now();
        else if (flag == 0x89ABCDEF)
                C_A_D = 1;
        else if (!flag)
                C_A_D = 0;
        else if (flag == 0xCDEF0123) {
                printk(KERN_EMERG "System halted\n");
                sys_kill(-1, SIGKILL);
                do_exit(0);
        } else
                return -EINVAL;
        return (0);
}

/*
 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 * As it's called within an interrupt, it may NOT sync: the only choice
 * is whether to reboot at once, or just ignore the ctrl-alt-del.
 */
void ctrl_alt_del(void)
{
        if (C_A_D)
                hard_reset_now();
        else
                send_sig(SIGINT,task[1],1);
}
        

/*
 * Unprivileged users may change the real gid to the effective gid
 * or vice versa.  (BSD-style)
 *
 * If you set the real gid at all, or set the effective gid to a value not
 * equal to the real gid, then the saved gid is set to the new effective gid.
 *
 * This makes it possible for a setgid program to completely drop its
 * privileges, which is often a useful assertion to make when you are doing
 * a security audit over a program.
 *
 * The general idea is that a program which uses just setregid() will be
 * 100% compatible with BSD.  A program which uses just setgid() will be
 * 100% compatible with POSIX w/ Saved ID's. 
 */
asmlinkage int sys_setregid(gid_t rgid, gid_t egid)
{
        int old_rgid = current->gid;
        int old_egid = current->egid;

        if (rgid != (gid_t) -1) {
                if ((old_rgid == rgid) ||
                    (current->egid==rgid) ||
                    suser())
                        current->gid = rgid;
                else
                        return(-EPERM);
        }
        if (egid != (gid_t) -1) {
                if ((old_rgid == egid) ||
                    (current->egid == egid) ||
                    (current->sgid == egid) ||
                    suser())
                        current->egid = egid;
                else {
                        current->gid = old_rgid;
                        return(-EPERM);
                }
        }
        if (rgid != (gid_t) -1 ||
            (egid != (gid_t) -1 && egid != old_rgid))
                current->sgid = current->egid;
        current->fsgid = current->egid;
        if (current->egid != old_egid)
                current->dumpable = 0;
        return 0;
}

/*
 * setgid() is implemented like SysV w/ SAVED_IDS 
 */
asmlinkage int sys_setgid(gid_t gid)
{
        int old_egid = current->egid;

        if (suser())
                current->gid = current->egid = current->sgid = current->fsgid = gid;
        else if ((gid == current->gid) || (gid == current->sgid))
                current->egid = current->fsgid = gid;
        else
                return -EPERM;
        if (current->egid != old_egid)
                current->dumpable = 0;
        return 0;
}

asmlinkage int sys_acct(void)
{
        return -ENOSYS;
}

asmlinkage int sys_phys(void)
{
        return -ENOSYS;
}

asmlinkage int sys_lock(void)
{
        return -ENOSYS;
}

asmlinkage int sys_mpx(void)
{
        return -ENOSYS;
}

asmlinkage int sys_ulimit(void)
{
        return -ENOSYS;
}

asmlinkage int sys_old_syscall(void)
{
        return -ENOSYS;
}

/*
 * Unprivileged users may change the real uid to the effective uid
 * or vice versa.  (BSD-style)
 *
 * If you set the real uid at all, or set the effective uid to a value not
 * equal to the real uid, then the saved uid is set to the new effective uid.
 *
 * This makes it possible for a setuid program to completely drop its
 * privileges, which is often a useful assertion to make when you are doing
 * a security audit over a program.
 *
 * The general idea is that a program which uses just setreuid() will be
 * 100% compatible with BSD.  A program which uses just setuid() will be
 * 100% compatible with POSIX w/ Saved ID's. 
 */
asmlinkage int sys_setreuid(uid_t ruid, uid_t euid)
{
        int old_ruid = current->uid;
        int old_euid = current->euid;

        if (ruid != (uid_t) -1) {
                if ((old_ruid == ruid) || 
                    (current->euid==ruid) ||
                    suser())
                        current->uid = ruid;
                else
                        return(-EPERM);
        }
        if (euid != (uid_t) -1) {
                if ((old_ruid == euid) ||
                    (current->euid == euid) ||
                    (current->suid == euid) ||
                    suser())
                        current->euid = euid;
                else {
                        current->uid = old_ruid;
                        return(-EPERM);
                }
        }
        if (ruid != (uid_t) -1 ||
            (euid != (uid_t) -1 && euid != old_ruid))
                current->suid = current->euid;
        current->fsuid = current->euid;
        if (current->euid != old_euid)
                current->dumpable = 0;
        return 0;
}

/*
 * setuid() is implemented like SysV w/ SAVED_IDS 
 * 
 * Note that SAVED_ID's is deficient in that a setuid root program
 * like sendmail, for example, cannot set its uid to be a normal 
 * user and then switch back, because if you're root, setuid() sets
 * the saved uid too.  If you don't like this, blame the bright people
 * in the POSIX committee and/or USG.  Note that the BSD-style setreuid()
 * will allow a root program to temporarily drop privileges and be able to
 * regain them by swapping the real and effective uid.  
 */
asmlinkage int sys_setuid(uid_t uid)
{
        int old_euid = current->euid;

        if (suser())
                current->uid = current->euid = current->suid = current->fsuid = uid;
        else if ((uid == current->uid) || (uid == current->suid))
                current->fsuid = current->euid = uid;
        else
                return -EPERM;
        if (current->euid != old_euid)
                current->dumpable = 0;
        return(0);
}

/*
 * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
 * is used for "access()" and for the NFS daemon (letting nfsd stay at
 * whatever uid it wants to). It normally shadows "euid", except when
 * explicitly set by setfsuid() or for access..
 */
asmlinkage int sys_setfsuid(uid_t uid)
{
        int old_fsuid = current->fsuid;

        if (uid == current->uid || uid == current->euid ||
            uid == current->suid || uid == current->fsuid || suser())
                current->fsuid = uid;
        if (current->fsuid != old_fsuid)
                current->dumpable = 0;
        return old_fsuid;
}

/*
 * Samma på svenska..
 */
asmlinkage int sys_setfsgid(gid_t gid)
{
        int old_fsgid = current->fsgid;

        if (gid == current->gid || gid == current->egid ||
            gid == current->sgid || gid == current->fsgid || suser())
                current->fsgid = gid;
        if (current->fsgid != old_fsgid)
                current->dumpable = 0;
        return old_fsgid;
}

asmlinkage int sys_times(struct tms * tbuf)
{
        if (tbuf) {
                int error = verify_area(VERIFY_WRITE,tbuf,sizeof *tbuf);
                if (error)
                        return error;
                put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
                put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
                put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
                put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
        }
        return jiffies;
}

asmlinkage int sys_brk(unsigned long brk)
{
        int freepages;
        unsigned long rlim;
        unsigned long newbrk, oldbrk;

        if (brk < current->mm->end_code)
                return current->mm->brk;
        newbrk = PAGE_ALIGN(brk);
        oldbrk = PAGE_ALIGN(current->mm->brk);
        if (oldbrk == newbrk)
                return current->mm->brk = brk;

        /*
         * Always allow shrinking brk
         */
        if (brk <= current->mm->brk) {
                current->mm->brk = brk;
                do_munmap(newbrk, oldbrk-newbrk);
                return brk;
        }
        /*
         * Check against rlimit and stack..
         */
        rlim = current->rlim[RLIMIT_DATA].rlim_cur;
        if (rlim >= RLIM_INFINITY)
                rlim = ~0;
        if (brk - current->mm->end_code > rlim ||
            brk >= current->mm->start_stack - 16384)
                return current->mm->brk;
        /*
         * Check against existing mmap mappings.
         */
        if (find_vma_intersection(current, oldbrk, newbrk))
                return current->mm->brk;
        /*
         * stupid algorithm to decide if we have enough memory: while
         * simple, it hopefully works in most obvious cases.. Easy to
         * fool it, but this should catch most mistakes.
         */
        freepages = buffermem >> 12;
        freepages += nr_free_pages;
        freepages += nr_swap_pages;
        freepages -= (high_memory - 0x100000) >> 16;
        freepages -= (newbrk-oldbrk) >> 12;
        if (freepages < 0)
                return current->mm->brk;
#if 0
        freepages += current->mm->rss;
        freepages -= oldbrk >> 12;
        if (freepages < 0)
                return current->mm->brk;
#endif
        /*
         * Ok, we have probably got enough memory - let it rip.
         */
        current->mm->brk = brk;
        do_mmap(NULL, oldbrk, newbrk-oldbrk,
                PROT_READ|PROT_WRITE|PROT_EXEC,
                MAP_FIXED|MAP_PRIVATE, 0);
        return brk;
}

/*
 * This needs some heave checking ...
 * I just haven't get the stomach for it. I also don't fully
 * understand sessions/pgrp etc. Let somebody who does explain it.
 *
 * OK, I think I have the protection semantics right.... this is really
 * only important on a multi-user system anyway, to make sure one user
 * can't send a signal to a process owned by another.  -TYT, 12/12/91
 *
 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
 * LBT 04.03.94
 */
asmlinkage int sys_setpgid(pid_t pid, pid_t pgid)
{
        struct task_struct * p;

        if (!pid)
                pid = current->pid;
        if (!pgid)
                pgid = pid;
        if (pgid < 0)
                return -EINVAL;
        for_each_task(p) {
                if (p->pid == pid)
                        goto found_task;
        }
        return -ESRCH;

found_task:
        if (p->p_pptr == current || p->p_opptr == current) {
                if (p->session != current->session)
                        return -EPERM;
                if (p->did_exec)
                        return -EACCES;
        } else if (p != current)
                return -ESRCH;
        if (p->leader)
                return -EPERM;
        if (pgid != pid) {
                struct task_struct * tmp;
                for_each_task (tmp) {
                        if (tmp->pgrp == pgid &&
                         tmp->session == current->session)
                                goto ok_pgid;
                }
                return -EPERM;
        }

ok_pgid:
        p->pgrp = pgid;
        return 0;
}

asmlinkage int sys_getpgid(pid_t pid)
{
        struct task_struct * p;

        if (!pid)
                return current->pgrp;
        for_each_task(p) {
                if (p->pid == pid)
                        return p->pgrp;
        }
        return -ESRCH;
}

asmlinkage int sys_getpgrp(void)
{
        return current->pgrp;
}

asmlinkage int sys_setsid(void)
{
        if (current->leader)
                return -EPERM;
        current->leader = 1;
        current->session = current->pgrp = current->pid;
        current->tty = NULL;
        current->tty_old_pgrp = 0;
        return current->pgrp;
}

/*
 * Supplementary group ID's
 */
asmlinkage int sys_getgroups(int gidsetsize, gid_t *grouplist)
{
        int i;

        if (gidsetsize) {
                i = verify_area(VERIFY_WRITE, grouplist, sizeof(gid_t) * gidsetsize);
                if (i)
                        return i;
        }
        for (i = 0 ; (i < NGROUPS) && (current->groups[i] != NOGROUP) ; i++) {
                if (!gidsetsize)
                        continue;
                if (i >= gidsetsize)
                        break;
                put_fs_word(current->groups[i], (short *) grouplist);
                grouplist++;
        }
        return(i);
}

asmlinkage int sys_setgroups(int gidsetsize, gid_t *grouplist)
{
        int     i;

        if (!suser())
                return -EPERM;
        if (gidsetsize > NGROUPS)
                return -EINVAL;
        for (i = 0; i < gidsetsize; i++, grouplist++) {
                current->groups[i] = get_fs_word((unsigned short *) grouplist);
        }
        if (i < NGROUPS)
                current->groups[i] = NOGROUP;
        return 0;
}

int in_group_p(gid_t grp)
{
        int     i;

        if (grp == current->fsgid)
                return 1;

        for (i = 0; i < NGROUPS; i++) {
                if (current->groups[i] == NOGROUP)
                        break;
                if (current->groups[i] == grp)
                        return 1;
        }
        return 0;
}

asmlinkage int sys_newuname(struct new_utsname * name)
{
        int error;

        if (!name)
                return -EFAULT;
        error = verify_area(VERIFY_WRITE, name, sizeof *name);
        if (!error)
                memcpy_tofs(name,&system_utsname,sizeof *name);
        return error;
}

asmlinkage int sys_uname(struct old_utsname * name)
{
        int error;
        if (!name)
                return -EFAULT;
        error = verify_area(VERIFY_WRITE, name,sizeof *name);
        if (error)
                return error;
        memcpy_tofs(&name->sysname,&system_utsname.sysname,
                sizeof (system_utsname.sysname));
        memcpy_tofs(&name->nodename,&system_utsname.nodename,
                sizeof (system_utsname.nodename));
        memcpy_tofs(&name->release,&system_utsname.release,
                sizeof (system_utsname.release));
        memcpy_tofs(&name->version,&system_utsname.version,
                sizeof (system_utsname.version));
        memcpy_tofs(&name->machine,&system_utsname.machine,
                sizeof (system_utsname.machine));
        return 0;
}

asmlinkage int sys_olduname(struct oldold_utsname * name)
{
        int error;
        if (!name)
                return -EFAULT;
        error = verify_area(VERIFY_WRITE, name,sizeof *name);
        if (error)
                return error;
        memcpy_tofs(&name->sysname,&system_utsname.sysname,__OLD_UTS_LEN);
        put_fs_byte(0,name->sysname+__OLD_UTS_LEN);
        memcpy_tofs(&name->nodename,&system_utsname.nodename,__OLD_UTS_LEN);
        put_fs_byte(0,name->nodename+__OLD_UTS_LEN);
        memcpy_tofs(&name->release,&system_utsname.release,__OLD_UTS_LEN);
        put_fs_byte(0,name->release+__OLD_UTS_LEN);
        memcpy_tofs(&name->version,&system_utsname.version,__OLD_UTS_LEN);
        put_fs_byte(0,name->version+__OLD_UTS_LEN);
        memcpy_tofs(&name->machine,&system_utsname.machine,__OLD_UTS_LEN);
        put_fs_byte(0,name->machine+__OLD_UTS_LEN);
        return 0;
}

/*
 * Only sethostname; gethostname can be implemented by calling uname()
 */
asmlinkage int sys_sethostname(char *name, int len)
{
        int     i;
        
        if (!suser())
                return -EPERM;
        if (len > __NEW_UTS_LEN)
                return -EINVAL;
        for (i=0; i < len; i++) {
                if ((system_utsname.nodename[i] = get_fs_byte(name+i)) == 0)
                        return 0;
        }
        system_utsname.nodename[i] = 0;
        return 0;
}

/*
 * Only setdomainname; getdomainname can be implemented by calling
 * uname()
 */
asmlinkage int sys_setdomainname(char *name, int len)
{
        int     i;
        
        if (!suser())
                return -EPERM;
        if (len > __NEW_UTS_LEN)
                return -EINVAL;
        for (i=0; i < len; i++) {
                if ((system_utsname.domainname[i] = get_fs_byte(name+i)) == 0)
                        return 0;
        }
        system_utsname.domainname[i] = 0;
        return 0;
}

asmlinkage int sys_getrlimit(unsigned int resource, struct rlimit *rlim)
{
        int error;

        if (resource >= RLIM_NLIMITS)
                return -EINVAL;
        error = verify_area(VERIFY_WRITE,rlim,sizeof *rlim);
        if (error)
                return error;
        put_fs_long(current->rlim[resource].rlim_cur, 
                    (unsigned long *) rlim);
        put_fs_long(current->rlim[resource].rlim_max, 
                    ((unsigned long *) rlim)+1);
        return 0;       
}

asmlinkage int sys_setrlimit(unsigned int resource, struct rlimit *rlim)
{
        struct rlimit new_rlim, *old_rlim;
        int err;

        if (resource >= RLIM_NLIMITS)
                return -EINVAL;
        err = verify_area(VERIFY_READ, rlim, sizeof(*rlim));
        if (err)
                return err;
        memcpy_fromfs(&new_rlim, rlim, sizeof(*rlim));
        old_rlim = current->rlim + resource;
        if (((new_rlim.rlim_cur > old_rlim->rlim_max) ||
             (new_rlim.rlim_max > old_rlim->rlim_max)) &&
            !suser())
                return -EPERM;
        if (resource == RLIMIT_NOFILE) {
                if (new_rlim.rlim_cur > NR_OPEN || new_rlim.rlim_max > NR_OPEN)
                        return -EPERM;
        }
        *old_rlim = new_rlim;
        return 0;
}

/*
 * It would make sense to put struct rusage in the task_struct,
 * except that would make the task_struct be *really big*.  After
 * task_struct gets moved into malloc'ed memory, it would
 * make sense to do this.  It will make moving the rest of the information
 * a lot simpler!  (Which we're not doing right now because we're not
 * measuring them yet).
 */
int getrusage(struct task_struct *p, int who, struct rusage *ru)
{
        int error;
        struct rusage r;

        error = verify_area(VERIFY_WRITE, ru, sizeof *ru);
        if (error)
                return error;
        memset((char *) &r, 0, sizeof(r));
        switch (who) {
                case RUSAGE_SELF:
                        r.ru_utime.tv_sec = CT_TO_SECS(p->utime);
                        r.ru_utime.tv_usec = CT_TO_USECS(p->utime);
                        r.ru_stime.tv_sec = CT_TO_SECS(p->stime);
                        r.ru_stime.tv_usec = CT_TO_USECS(p->stime);
                        r.ru_minflt = p->mm->min_flt;
                        r.ru_majflt = p->mm->maj_flt;
                        break;
                case RUSAGE_CHILDREN:
                        r.ru_utime.tv_sec = CT_TO_SECS(p->cutime);
                        r.ru_utime.tv_usec = CT_TO_USECS(p->cutime);
                        r.ru_stime.tv_sec = CT_TO_SECS(p->cstime);
                        r.ru_stime.tv_usec = CT_TO_USECS(p->cstime);
                        r.ru_minflt = p->mm->cmin_flt;
                        r.ru_majflt = p->mm->cmaj_flt;
                        break;
                default:
                        r.ru_utime.tv_sec = CT_TO_SECS(p->utime + p->cutime);
                        r.ru_utime.tv_usec = CT_TO_USECS(p->utime + p->cutime);
                        r.ru_stime.tv_sec = CT_TO_SECS(p->stime + p->cstime);
                        r.ru_stime.tv_usec = CT_TO_USECS(p->stime + p->cstime);
                        r.ru_minflt = p->mm->min_flt + p->mm->cmin_flt;
                        r.ru_majflt = p->mm->maj_flt + p->mm->cmaj_flt;
                        break;
        }
        memcpy_tofs(ru, &r, sizeof(r));
        return 0;
}

asmlinkage int sys_getrusage(int who, struct rusage *ru)
{
        if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
                return -EINVAL;
        return getrusage(current, who, ru);
}

asmlinkage int sys_umask(int mask)
{
        int old = current->fs->umask;

        current->fs->umask = mask & S_IRWXUGO;
        return (old);
}