FreeBSD/Linux Kernel Cross Reference
sys/kernel/sys.c

     /*
      *  linux/kernel/sys.c
      *
      *  Copyright (C) 1991, 1992  Linus Torvalds
      */
     
     #include <linux/module.h>
     #include <linux/mm.h>
     #include <linux/utsname.h>
    #include <linux/mman.h>
    #include <linux/smp_lock.h>
    #include <linux/notifier.h>
    #include <linux/reboot.h>
    #include <linux/prctl.h>
    #include <linux/init.h>
    #include <linux/highuid.h>
    
    #include <asm/uaccess.h>
    #include <asm/io.h>
    
    #ifndef SET_UNALIGN_CTL
    # define SET_UNALIGN_CTL(a,b)   (-EINVAL)
    #endif
    #ifndef GET_UNALIGN_CTL
    # define GET_UNALIGN_CTL(a,b)   (-EINVAL)
    #endif
    #ifndef SET_FPEMU_CTL
    # define SET_FPEMU_CTL(a,b)     (-EINVAL)
    #endif
    #ifndef GET_FPEMU_CTL
    # define GET_FPEMU_CTL(a,b)     (-EINVAL)
    #endif
    #ifndef SET_FPEXC_CTL
    # define SET_FPEXC_CTL(a,b)     (-EINVAL)
    #endif
    #ifndef GET_FPEXC_CTL
    # define GET_FPEXC_CTL(a,b)     (-EINVAL)
    #endif
    
    /*
     * this is where the system-wide overflow UID and GID are defined, for
     * architectures that now have 32-bit UID/GID but didn't in the past
     */
    
    int overflowuid = DEFAULT_OVERFLOWUID;
    int overflowgid = DEFAULT_OVERFLOWGID;
    
    /*
     * the same as above, but for filesystems which can only store a 16-bit
     * UID and GID. as such, this is needed on all architectures
     */
    
    int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
    int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
    
    /*
     * this indicates whether you can reboot with ctrl-alt-del: the default is yes
     */
    
    int C_A_D = 1;
    int cad_pid = 1;
    
    
    /*
     *      Notifier list for kernel code which wants to be called
     *      at shutdown. This is used to stop any idling DMA operations
     *      and the like. 
     */
    
    static struct notifier_block *reboot_notifier_list;
    rwlock_t notifier_lock = RW_LOCK_UNLOCKED;
    
    /**
     *      notifier_chain_register - Add notifier to a notifier chain
     *      @list: Pointer to root list pointer
     *      @n: New entry in notifier chain
     *
     *      Adds a notifier to a notifier chain.
     *
     *      Currently always returns zero.
     */
     
    int notifier_chain_register(struct notifier_block **list, struct notifier_block *n)
    {
            write_lock(&notifier_lock);
            while(*list)
            {
                    if(n->priority > (*list)->priority)
                            break;
                    list= &((*list)->next);
            }
            n->next = *list;
            *list=n;
            write_unlock(&notifier_lock);
            return 0;
    }
    
    /**
     *      notifier_chain_unregister - Remove notifier from a notifier chain
    *      @nl: Pointer to root list pointer
    *      @n: New entry in notifier chain
    *
    *      Removes a notifier from a notifier chain.
    *
    *      Returns zero on success, or %-ENOENT on failure.
    */
    
   int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
   {
           write_lock(&notifier_lock);
           while((*nl)!=NULL)
           {
                   if((*nl)==n)
                   {
                           *nl=n->next;
                           write_unlock(&notifier_lock);
                           return 0;
                   }
                   nl=&((*nl)->next);
           }
           write_unlock(&notifier_lock);
           return -ENOENT;
   }
   
   /**
    *      notifier_call_chain - Call functions in a notifier chain
    *      @n: Pointer to root pointer of notifier chain
    *      @val: Value passed unmodified to notifier function
    *      @v: Pointer passed unmodified to notifier function
    *
    *      Calls each function in a notifier chain in turn.
    *
    *      If the return value of the notifier can be and'd
    *      with %NOTIFY_STOP_MASK, then notifier_call_chain
    *      will return immediately, with the return value of
    *      the notifier function which halted execution.
    *      Otherwise, the return value is the return value
    *      of the last notifier function called.
    */
    
   int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v)
   {
           int ret=NOTIFY_DONE;
           struct notifier_block *nb = *n;
   
           while(nb)
           {
                   ret=nb->notifier_call(nb,val,v);
                   if(ret&NOTIFY_STOP_MASK)
                   {
                           return ret;
                   }
                   nb=nb->next;
           }
           return ret;
   }
   
   /**
    *      register_reboot_notifier - Register function to be called at reboot time
    *      @nb: Info about notifier function to be called
    *
    *      Registers a function with the list of functions
    *      to be called at reboot time.
    *
    *      Currently always returns zero, as notifier_chain_register
    *      always returns zero.
    */
    
   int register_reboot_notifier(struct notifier_block * nb)
   {
           return notifier_chain_register(&reboot_notifier_list, nb);
   }
   
   /**
    *      unregister_reboot_notifier - Unregister previously registered reboot notifier
    *      @nb: Hook to be unregistered
    *
    *      Unregisters a previously registered reboot
    *      notifier function.
    *
    *      Returns zero on success, or %-ENOENT on failure.
    */
    
   int unregister_reboot_notifier(struct notifier_block * nb)
   {
           return notifier_chain_unregister(&reboot_notifier_list, nb);
   }
   
   asmlinkage long sys_ni_syscall(void)
   {
           return -ENOSYS;
   }
   
   static int proc_sel(struct task_struct *p, int which, int who)
   {
           if(p->pid)
           {
                   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 long sys_setpriority(int which, int who, int niceval)
   {
           struct task_struct *p;
           int error;
   
           if (which > 2 || which < 0)
                   return -EINVAL;
   
           /* normalize: avoid signed division (rounding problems) */
           error = -ESRCH;
           if (niceval < -20)
                   niceval = -20;
           if (niceval > 19)
                   niceval = 19;
   
           read_lock(&tasklist_lock);
           for_each_task(p) {
                   if (!proc_sel(p, which, who))
                           continue;
                   if (p->uid != current->euid &&
                           p->uid != current->uid && !capable(CAP_SYS_NICE)) {
                           error = -EPERM;
                           continue;
                   }
                   if (error == -ESRCH)
                           error = 0;
                   if (niceval < p->nice && !capable(CAP_SYS_NICE))
                           error = -EACCES;
                   else
                           p->nice = niceval;
           }
           read_unlock(&tasklist_lock);
   
           return error;
   }
   
   /*
    * Ugh. To avoid negative return values, "getpriority()" will
    * not return the normal nice-value, but a negated value that
    * has been offset by 20 (ie it returns 40..1 instead of -20..19)
    * to stay compatible.
    */
   asmlinkage long sys_getpriority(int which, int who)
   {
           struct task_struct *p;
           long retval = -ESRCH;
   
           if (which > 2 || which < 0)
                   return -EINVAL;
   
           read_lock(&tasklist_lock);
           for_each_task (p) {
                   long niceval;
                   if (!proc_sel(p, which, who))
                           continue;
                   niceval = 20 - p->nice;
                   if (niceval > retval)
                           retval = niceval;
           }
           read_unlock(&tasklist_lock);
   
           return retval;
   }
   
   
   /*
    * 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 long sys_reboot(int magic1, int magic2, unsigned int cmd, void * arg)
   {
           char buffer[256];
   
           /* We only trust the superuser with rebooting the system. */
           if (!capable(CAP_SYS_BOOT))
                   return -EPERM;
   
           /* For safety, we require "magic" arguments. */
           if (magic1 != LINUX_REBOOT_MAGIC1 ||
               (magic2 != LINUX_REBOOT_MAGIC2 && magic2 != LINUX_REBOOT_MAGIC2A &&
                           magic2 != LINUX_REBOOT_MAGIC2B))
                   return -EINVAL;
   
           lock_kernel();
           switch (cmd) {
           case LINUX_REBOOT_CMD_RESTART:
                   notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
                   printk(KERN_EMERG "Restarting system.\n");
                   machine_restart(NULL);
                   break;
   
           case LINUX_REBOOT_CMD_CAD_ON:
                   C_A_D = 1;
                   break;
   
           case LINUX_REBOOT_CMD_CAD_OFF:
                   C_A_D = 0;
                   break;
   
           case LINUX_REBOOT_CMD_HALT:
                   notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL);
                   printk(KERN_EMERG "System halted.\n");
                   machine_halt();
                   do_exit(0);
                   break;
   
           case LINUX_REBOOT_CMD_POWER_OFF:
                   notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL);
                   printk(KERN_EMERG "Power down.\n");
                   machine_power_off();
                   do_exit(0);
                   break;
   
           case LINUX_REBOOT_CMD_RESTART2:
                   if (strncpy_from_user(&buffer[0], (char *)arg, sizeof(buffer) - 1) < 0) {
                           unlock_kernel();
                           return -EFAULT;
                   }
                   buffer[sizeof(buffer) - 1] = '\0';
   
                   notifier_call_chain(&reboot_notifier_list, SYS_RESTART, buffer);
                   printk(KERN_EMERG "Restarting system with command '%s'.\n", buffer);
                   machine_restart(buffer);
                   break;
   
           default:
                   unlock_kernel();
                   return -EINVAL;
           }
           unlock_kernel();
           return 0;
   }
   
   static void deferred_cad(void *dummy)
   {
           notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
           machine_restart(NULL);
   }
   
   /*
    * 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)
   {
           static struct tq_struct cad_tq = {
                   routine: deferred_cad,
           };
   
           if (C_A_D)
                   schedule_task(&cad_tq);
           else
                   kill_proc(cad_pid, SIGINT, 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 with saved IDs. 
    *
    * SMP: There are not races, the GIDs are checked only by filesystem
    *      operations (as far as semantic preservation is concerned).
    */
   asmlinkage long sys_setregid(gid_t rgid, gid_t egid)
   {
           int old_rgid = current->gid;
           int old_egid = current->egid;
           int new_rgid = old_rgid;
           int new_egid = old_egid;
   
           if (rgid != (gid_t) -1) {
                   if ((old_rgid == rgid) ||
                       (current->egid==rgid) ||
                       capable(CAP_SETGID))
                           new_rgid = rgid;
                   else
                           return -EPERM;
           }
           if (egid != (gid_t) -1) {
                   if ((old_rgid == egid) ||
                       (current->egid == egid) ||
                       (current->sgid == egid) ||
                       capable(CAP_SETGID))
                           new_egid = egid;
                   else {
                           return -EPERM;
                   }
           }
           if (new_egid != old_egid)
           {
                   current->mm->dumpable = 0;
                   wmb();
           }
           if (rgid != (gid_t) -1 ||
               (egid != (gid_t) -1 && egid != old_rgid))
                   current->sgid = new_egid;
           current->fsgid = new_egid;
           current->egid = new_egid;
           current->gid = new_rgid;
           return 0;
   }
   
   /*
    * setgid() is implemented like SysV w/ SAVED_IDS 
    *
    * SMP: Same implicit races as above.
    */
   asmlinkage long sys_setgid(gid_t gid)
   {
           int old_egid = current->egid;
   
           if (capable(CAP_SETGID))
           {
                   if(old_egid != gid)
                   {
                           current->mm->dumpable=0;
                           wmb();
                   }
                   current->gid = current->egid = current->sgid = current->fsgid = gid;
           }
           else if ((gid == current->gid) || (gid == current->sgid))
           {
                   if(old_egid != gid)
                   {
                           current->mm->dumpable=0;
                           wmb();
                   }
                   current->egid = current->fsgid = gid;
           }
           else
                   return -EPERM;
           return 0;
   }
     
   /* 
    * cap_emulate_setxuid() fixes the effective / permitted capabilities of
    * a process after a call to setuid, setreuid, or setresuid.
    *
    *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
    *  {r,e,s}uid != 0, the permitted and effective capabilities are
    *  cleared.
    *
    *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
    *  capabilities of the process are cleared.
    *
    *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
    *  capabilities are set to the permitted capabilities.
    *
    *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 
    *  never happen.
    *
    *  -astor 
    *
    * cevans - New behaviour, Oct '99
    * A process may, via prctl(), elect to keep its capabilities when it
    * calls setuid() and switches away from uid==0. Both permitted and
    * effective sets will be retained.
    * Without this change, it was impossible for a daemon to drop only some
    * of its privilege. The call to setuid(!=0) would drop all privileges!
    * Keeping uid 0 is not an option because uid 0 owns too many vital
    * files..
    * Thanks to Olaf Kirch and Peter Benie for spotting this.
    */
   static inline void cap_emulate_setxuid(int old_ruid, int old_euid, 
                                          int old_suid)
   {
           if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
               (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
               !current->keep_capabilities) {
                   cap_clear(current->cap_permitted);
                   cap_clear(current->cap_effective);
           }
           if (old_euid == 0 && current->euid != 0) {
                   cap_clear(current->cap_effective);
           }
           if (old_euid != 0 && current->euid == 0) {
                   current->cap_effective = current->cap_permitted;
           }
   }
   
   static int set_user(uid_t new_ruid, int dumpclear)
   {
           struct user_struct *new_user, *old_user;
   
           /* What if a process setreuid()'s and this brings the
            * new uid over his NPROC rlimit?  We can check this now
            * cheaply with the new uid cache, so if it matters
            * we should be checking for it.  -DaveM
            */
           new_user = alloc_uid(new_ruid);
           if (!new_user)
                   return -EAGAIN;
           old_user = current->user;
           atomic_dec(&old_user->processes);
           atomic_inc(&new_user->processes);
   
           if(dumpclear)
           {
                   current->mm->dumpable = 0;
                   wmb();
           }
           current->uid = new_ruid;
           current->user = new_user;
           free_uid(old_user);
           return 0;
   }
   
   /*
    * 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 with saved IDs. 
    */
   asmlinkage long sys_setreuid(uid_t ruid, uid_t euid)
   {
           int old_ruid, old_euid, old_suid, new_ruid, new_euid;
   
           new_ruid = old_ruid = current->uid;
           new_euid = old_euid = current->euid;
           old_suid = current->suid;
   
           if (ruid != (uid_t) -1) {
                   new_ruid = ruid;
                   if ((old_ruid != ruid) &&
                       (current->euid != ruid) &&
                       !capable(CAP_SETUID))
                           return -EPERM;
           }
   
           if (euid != (uid_t) -1) {
                   new_euid = euid;
                   if ((old_ruid != euid) &&
                       (current->euid != euid) &&
                       (current->suid != euid) &&
                       !capable(CAP_SETUID))
                           return -EPERM;
           }
   
           if (new_ruid != old_ruid && set_user(new_ruid, new_euid != old_euid) < 0)
                   return -EAGAIN;
   
           if (new_euid != old_euid)
           {
                   current->mm->dumpable=0;
                   wmb();
           }
           current->fsuid = current->euid = new_euid;
           if (ruid != (uid_t) -1 ||
               (euid != (uid_t) -1 && euid != old_ruid))
                   current->suid = current->euid;
           current->fsuid = current->euid;
   
           if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                   cap_emulate_setxuid(old_ruid, old_euid, old_suid);
           }
   
           return 0;
   }
   
   
                   
   /*
    * setuid() is implemented like SysV with 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 long sys_setuid(uid_t uid)
   {
           int old_euid = current->euid;
           int old_ruid, old_suid, new_ruid, new_suid;
   
           old_ruid = new_ruid = current->uid;
           old_suid = current->suid;
           new_suid = old_suid;
           
           if (capable(CAP_SETUID)) {
                   if (uid != old_ruid && set_user(uid, old_euid != uid) < 0)
                           return -EAGAIN;
                   new_suid = uid;
           } else if ((uid != current->uid) && (uid != new_suid))
                   return -EPERM;
   
           if (old_euid != uid)
           {
                   current->mm->dumpable = 0;
                   wmb();
           }
           current->fsuid = current->euid = uid;
           current->suid = new_suid;
   
           if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                   cap_emulate_setxuid(old_ruid, old_euid, old_suid);
           }
   
           return 0;
   }
   
   
   /*
    * This function implements a generic ability to update ruid, euid,
    * and suid.  This allows you to implement the 4.4 compatible seteuid().
    */
   asmlinkage long sys_setresuid(uid_t ruid, uid_t euid, uid_t suid)
   {
           int old_ruid = current->uid;
           int old_euid = current->euid;
           int old_suid = current->suid;
   
           if (!capable(CAP_SETUID)) {
                   if ((ruid != (uid_t) -1) && (ruid != current->uid) &&
                       (ruid != current->euid) && (ruid != current->suid))
                           return -EPERM;
                   if ((euid != (uid_t) -1) && (euid != current->uid) &&
                       (euid != current->euid) && (euid != current->suid))
                           return -EPERM;
                   if ((suid != (uid_t) -1) && (suid != current->uid) &&
                       (suid != current->euid) && (suid != current->suid))
                           return -EPERM;
           }
           if (ruid != (uid_t) -1) {
                   if (ruid != current->uid && set_user(ruid, euid != current->euid) < 0)
                           return -EAGAIN;
           }
           if (euid != (uid_t) -1) {
                   if (euid != current->euid)
                   {
                           current->mm->dumpable = 0;
                           wmb();
                   }
                   current->euid = euid;
           }
           current->fsuid = current->euid;
           if (suid != (uid_t) -1)
                   current->suid = suid;
   
           if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                   cap_emulate_setxuid(old_ruid, old_euid, old_suid);
           }
   
           return 0;
   }
   
   asmlinkage long sys_getresuid(uid_t *ruid, uid_t *euid, uid_t *suid)
   {
           int retval;
   
           if (!(retval = put_user(current->uid, ruid)) &&
               !(retval = put_user(current->euid, euid)))
                   retval = put_user(current->suid, suid);
   
           return retval;
   }
   
   /*
    * Same as above, but for rgid, egid, sgid.
    */
   asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
   {
           if (!capable(CAP_SETGID)) {
                   if ((rgid != (gid_t) -1) && (rgid != current->gid) &&
                       (rgid != current->egid) && (rgid != current->sgid))
                           return -EPERM;
                   if ((egid != (gid_t) -1) && (egid != current->gid) &&
                       (egid != current->egid) && (egid != current->sgid))
                           return -EPERM;
                   if ((sgid != (gid_t) -1) && (sgid != current->gid) &&
                       (sgid != current->egid) && (sgid != current->sgid))
                           return -EPERM;
           }
           if (egid != (gid_t) -1) {
                   if (egid != current->egid)
                   {
                           current->mm->dumpable = 0;
                           wmb();
                   }
                   current->egid = egid;
           }
           current->fsgid = current->egid;
           if (rgid != (gid_t) -1)
                   current->gid = rgid;
           if (sgid != (gid_t) -1)
                   current->sgid = sgid;
           return 0;
   }
   
   asmlinkage long sys_getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid)
   {
           int retval;
   
           if (!(retval = put_user(current->gid, rgid)) &&
               !(retval = put_user(current->egid, egid)))
                   retval = put_user(current->sgid, sgid);
   
           return retval;
   }
   
   
   /*
    * "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 long sys_setfsuid(uid_t uid)
   {
           int old_fsuid;
   
           old_fsuid = current->fsuid;
           if (uid == current->uid || uid == current->euid ||
               uid == current->suid || uid == current->fsuid || 
               capable(CAP_SETUID))
           {
                   if (uid != old_fsuid)
                   {
                           current->mm->dumpable = 0;
                           wmb();
                   }
                   current->fsuid = uid;
           }
   
           /* We emulate fsuid by essentially doing a scaled-down version
            * of what we did in setresuid and friends. However, we only
            * operate on the fs-specific bits of the process' effective
            * capabilities 
            *
            * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
            *          if not, we might be a bit too harsh here.
            */
           
           if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                   if (old_fsuid == 0 && current->fsuid != 0) {
                           cap_t(current->cap_effective) &= ~CAP_FS_MASK;
                   }
                   if (old_fsuid != 0 && current->fsuid == 0) {
                           cap_t(current->cap_effective) |=
                                   (cap_t(current->cap_permitted) & CAP_FS_MASK);
                   }
           }
   
           return old_fsuid;
   }
   
   /*
    * Samma på svenska..
    */
   asmlinkage long sys_setfsgid(gid_t gid)
   {
           int old_fsgid;
   
           old_fsgid = current->fsgid;
           if (gid == current->gid || gid == current->egid ||
               gid == current->sgid || gid == current->fsgid || 
               capable(CAP_SETGID))
           {
                   if (gid != old_fsgid)
                   {
                           current->mm->dumpable = 0;
                           wmb();
                   }
                   current->fsgid = gid;
           }
           return old_fsgid;
   }
   
   asmlinkage long sys_times(struct tms * tbuf)
   {
           /*
            *      In the SMP world we might just be unlucky and have one of
            *      the times increment as we use it. Since the value is an
            *      atomically safe type this is just fine. Conceptually its
            *      as if the syscall took an instant longer to occur.
            */
           if (tbuf)
                   if (copy_to_user(tbuf, &current->times, sizeof(struct tms)))
                           return -EFAULT;
           return jiffies;
   }
   
   /*
    * This needs some heavy checking ...
    * I just haven't 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 long sys_setpgid(pid_t pid, pid_t pgid)
   {
           struct task_struct * p;
           int err = -EINVAL;
   
           if (!pid)
                   pid = current->pid;
           if (!pgid)
                   pgid = pid;
           if (pgid < 0)
                   return -EINVAL;
   
           /* From this point forward we keep holding onto the tasklist lock
            * so that our parent does not change from under us. -DaveM
            */
           read_lock(&tasklist_lock);
   
           err = -ESRCH;
           p = find_task_by_pid(pid);
           if (!p)
                   goto out;
   
           if (p->p_pptr == current || p->p_opptr == current) {
                   err = -EPERM;
                   if (p->session != current->session)
                           goto out;
                   err = -EACCES;
                   if (p->did_exec)
                           goto out;
           } else if (p != current)
                   goto out;
           err = -EPERM;
           if (p->leader)
                   goto out;
           if (pgid != pid) {
                   struct task_struct * tmp;
                   for_each_task (tmp) {
                           if (tmp->pgrp == pgid &&
                               tmp->session == current->session)
                                   goto ok_pgid;
                   }
                   goto out;
           }
   
   ok_pgid:
           p->pgrp = pgid;
           err = 0;
   out:
           /* All paths lead to here, thus we are safe. -DaveM */
           read_unlock(&tasklist_lock);
           return err;
   }
   
   asmlinkage long sys_getpgid(pid_t pid)
   {
           if (!pid) {
                   return current->pgrp;
           } else {
                   int retval;
                   struct task_struct *p;
   
                   read_lock(&tasklist_lock);
                   p = find_task_by_pid(pid);
   
                   retval = -ESRCH;
                   if (p)
                           retval = p->pgrp;
                   read_unlock(&tasklist_lock);
                   return retval;
           }
   }
   
   asmlinkage long sys_getpgrp(void)
   {
           /* SMP - assuming writes are word atomic this is fine */
           return current->pgrp;
   }
   
   asmlinkage long sys_getsid(pid_t pid)
   {
           if (!pid) {
                   return current->session;
           } else {
                   int retval;
                   struct task_struct *p;
   
                   read_lock(&tasklist_lock);
                   p = find_task_by_pid(pid);
   
                   retval = -ESRCH;
                   if(p)
                           retval = p->session;
                   read_unlock(&tasklist_lock);
                   return retval;
           }
   }
   
   asmlinkage long sys_setsid(void)
   {
           struct task_struct * p;
           int err = -EPERM;
   
           read_lock(&tasklist_lock);
           for_each_task(p) {
                   if (p->pgrp == current->pid)
                           goto out;
           }
   
           current->leader = 1;
           current->session = current->pgrp = current->pid;
           current->tty = NULL;
           current->tty_old_pgrp = 0;
           err = current->pgrp;
   out:
           read_unlock(&tasklist_lock);
           return err;
   }
   
   /*
    * Supplementary group IDs
    */
   asmlinkage long sys_getgroups(int gidsetsize, gid_t *grouplist)
   {
           int i;
           
           /*
            *      SMP: Nobody else can change our grouplist. Thus we are
            *      safe.
            */
   
           if (gidsetsize < 0)
                   return -EINVAL;
           i = current->ngroups;
           if (gidsetsize) {
                   if (i > gidsetsize)
                           return -EINVAL;
                   if (copy_to_user(grouplist, current->groups, sizeof(gid_t)*i))
                           return -EFAULT;
           }
           return i;
   }
   
   /*
    *      SMP: Our groups are not shared. We can copy to/from them safely
    *      without another task interfering.
    */
    
   asmlinkage long sys_setgroups(int gidsetsize, gid_t *grouplist)
   {
           if (!capable(CAP_SETGID))
                   return -EPERM;
           if ((unsigned) gidsetsize > NGROUPS)
                   return -EINVAL;
           if(copy_from_user(current->groups, grouplist, gidsetsize * sizeof(gid_t)))
                   return -EFAULT;
           current->ngroups = gidsetsize;
           return 0;
   }
   
   static int supplemental_group_member(gid_t grp)
   {
           int i = current->ngroups;
  
          if (i) {
                  gid_t *groups = current->groups;
                  do {
                          if (*groups == grp)
                                  return 1;
                          groups++;
                          i--;
                  } while (i);
          }
          return 0;
  }
  
  /*
   * Check whether we're fsgid/egid or in the supplemental group..
   */
  int in_group_p(gid_t grp)
  {
          int retval = 1;
          if (grp != current->fsgid)
                  retval = supplemental_group_member(grp);
          return retval;
  }
  
  int in_egroup_p(gid_t grp)
  {
          int retval = 1;
          if (grp != current->egid)
                  retval = supplemental_group_member(grp);
          return retval;
  }
  
  DECLARE_RWSEM(uts_sem);
  
  asmlinkage long sys_newuname(struct new_utsname * name)
  {
          int errno = 0;
  
          down_read(&uts_sem);
          if (copy_to_user(name,&system_utsname,sizeof *name))
                  errno = -EFAULT;
          up_read(&uts_sem);
          return errno;
  }
  
  asmlinkage long sys_sethostname(char *name, int len)
  {
          int errno;
          char tmp[__NEW_UTS_LEN];
  
          if (!capable(CAP_SYS_ADMIN))
                  return -EPERM;
          if (len < 0 || len > __NEW_UTS_LEN)
                  return -EINVAL;
          down_write(&uts_sem);
          errno = -EFAULT;
          if (!copy_from_user(tmp, name, len)) {
                  memcpy(system_utsname.nodename, tmp, len);
                  system_utsname.nodename[len] = 0;
                  errno = 0;
          }
          up_write(&uts_sem);
          return errno;
  }
  
  asmlinkage long sys_gethostname(char *name, int len)
  {
          int i, errno;
  
          if (len < 0)
                  return -EINVAL;
          down_read(&uts_sem);
          i = 1 + strlen(system_utsname.nodename);
          if (i > len)
                  i = len;
          errno = 0;
          if (copy_to_user(name, system_utsname.nodename, i))
                  errno = -EFAULT;
          up_read(&uts_sem);
          return errno;
  }
  
  /*
   * Only setdomainname; getdomainname can be implemented by calling
   * uname()
   */
  asmlinkage long sys_setdomainname(char *name, int len)
  {
          int errno;
          char tmp[__NEW_UTS_LEN];
  
          if (!capable(CAP_SYS_ADMIN))
                  return -EPERM;
          if (len < 0 || len > __NEW_UTS_LEN)
                  return -EINVAL;
  
          down_write(&uts_sem);
          errno = -EFAULT;
          if (!copy_from_user(tmp, name, len)) {
                  memcpy(system_utsname.domainname, tmp, len);
                  system_utsname.domainname[len] = 0;
                  errno = 0;
          }
          up_write(&uts_sem);
          return errno;
  }
  
  asmlinkage long sys_getrlimit(unsigned int resource, struct rlimit *rlim)
  {
          if (resource >= RLIM_NLIMITS)
                  return -EINVAL;
          else
                  return copy_to_user(rlim, current->rlim + resource, sizeof(*rlim))
                          ? -EFAULT : 0;
  }
  
  #if !defined(__ia64__) 
  
  /*
   *      Back compatibility for getrlimit. Needed for some apps.
   */
   
  asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit *rlim)
  {
          struct rlimit x;
          if (resource >= RLIM_NLIMITS)
                  return -EINVAL;
  
          memcpy(&x, current->rlim + resource, sizeof(*rlim));
          if(x.rlim_cur > 0x7FFFFFFF)
                  x.rlim_cur = 0x7FFFFFFF;
          if(x.rlim_max > 0x7FFFFFFF)
                  x.rlim_max = 0x7FFFFFFF;
          return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
  }
  
  #endif
  
  asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit *rlim)
  {
          struct rlimit new_rlim, *old_rlim;
  
          if (resource >= RLIM_NLIMITS)
                  return -EINVAL;
          if(copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
                  return -EFAULT;
         if (new_rlim.rlim_cur > new_rlim.rlim_max)
                 return -EINVAL;
          old_rlim = current->rlim + resource;
          if (((new_rlim.rlim_cur > old_rlim->rlim_max) ||
               (new_rlim.rlim_max > old_rlim->rlim_max)) &&
              !capable(CAP_SYS_RESOURCE))
                  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).
   *
   * This is SMP safe.  Either we are called from sys_getrusage on ourselves
   * below (we know we aren't going to exit/disappear and only we change our
   * rusage counters), or we are called from wait4() on a process which is
   * either stopped or zombied.  In the zombied case the task won't get
   * reaped till shortly after the call to getrusage(), in both cases the
   * task being examined is in a frozen state so the counters won't change.
   *
   * FIXME! Get the fault counts properly!
   */
  int getrusage(struct task_struct *p, int who, struct rusage *ru)
  {
          struct rusage r;
  
          memset((char *) &r, 0, sizeof(r));
          switch (who) {
                  case RUSAGE_SELF:
                          r.ru_utime.tv_sec = CT_TO_SECS(p->times.tms_utime);
                          r.ru_utime.tv_usec = CT_TO_USECS(p->times.tms_utime);
                          r.ru_stime.tv_sec = CT_TO_SECS(p->times.tms_stime);
                          r.ru_stime.tv_usec = CT_TO_USECS(p->times.tms_stime);
                          r.ru_minflt = p->min_flt;
                          r.ru_majflt = p->maj_flt;
                          r.ru_nswap = p->nswap;
                          break;
                  case RUSAGE_CHILDREN:
                          r.ru_utime.tv_sec = CT_TO_SECS(p->times.tms_cutime);
                          r.ru_utime.tv_usec = CT_TO_USECS(p->times.tms_cutime);
                          r.ru_stime.tv_sec = CT_TO_SECS(p->times.tms_cstime);
                          r.ru_stime.tv_usec = CT_TO_USECS(p->times.tms_cstime);
                          r.ru_minflt = p->cmin_flt;
                          r.ru_majflt = p->cmaj_flt;
                          r.ru_nswap = p->cnswap;
                          break;
                  default:
                          r.ru_utime.tv_sec = CT_TO_SECS(p->times.tms_utime + p->times.tms_cutime);
                          r.ru_utime.tv_usec = CT_TO_USECS(p->times.tms_utime + p->times.tms_cutime);
                          r.ru_stime.tv_sec = CT_TO_SECS(p->times.tms_stime + p->times.tms_cstime);
                          r.ru_stime.tv_usec = CT_TO_USECS(p->times.tms_stime + p->times.tms_cstime);
                          r.ru_minflt = p->min_flt + p->cmin_flt;
                          r.ru_majflt = p->maj_flt + p->cmaj_flt;
                          r.ru_nswap = p->nswap + p->cnswap;
                          break;
          }
          return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
  }
  
  asmlinkage long sys_getrusage(int who, struct rusage *ru)
  {
          if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
                  return -EINVAL;
          return getrusage(current, who, ru);
  }
  
  asmlinkage long sys_umask(int mask)
  {
          mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
          return mask;
  }
      
  asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
                            unsigned long arg4, unsigned long arg5)
  {
          int error = 0;
          int sig;
  
          switch (option) {
                  case PR_SET_PDEATHSIG:
                          sig = arg2;
                          if (sig < 0 || sig > _NSIG) {
                                  error = -EINVAL;
                                  break;
                          }
                          current->pdeath_signal = sig;
                          break;
                  case PR_GET_PDEATHSIG:
                          error = put_user(current->pdeath_signal, (int *)arg2);
                          break;
                  case PR_GET_DUMPABLE:
                          if (is_dumpable(current))
                                  error = 1;
                          break;
                  case PR_SET_DUMPABLE:
                          if (arg2 != 0 && arg2 != 1) {
                                  error = -EINVAL;
                                  break;
                          }
                          current->mm->dumpable = arg2;
                          break;
  
                  case PR_SET_UNALIGN:
                          error = SET_UNALIGN_CTL(current, arg2);
                          break;
                  case PR_GET_UNALIGN:
                          error = GET_UNALIGN_CTL(current, arg2);
                          break;
                  case PR_SET_FPEMU:
                          error = SET_FPEMU_CTL(current, arg2);
                          break;
                  case PR_GET_FPEMU:
                          error = GET_FPEMU_CTL(current, arg2);
                          break;
                  case PR_SET_FPEXC:
                          error = SET_FPEXC_CTL(current, arg2);
                          break;
                  case PR_GET_FPEXC:
                          error = GET_FPEXC_CTL(current, arg2);
                          break;
  
                  case PR_GET_KEEPCAPS:
                          if (current->keep_capabilities)
                                  error = 1;
                          break;
                  case PR_SET_KEEPCAPS:
                          if (arg2 != 0 && arg2 != 1) {
                                  error = -EINVAL;
                                  break;
                          }
                          current->keep_capabilities = arg2;
                          break;
                  default:
                          error = -EINVAL;
                          break;
          }
          return error;
  }
  
  EXPORT_SYMBOL(notifier_chain_register);
  EXPORT_SYMBOL(notifier_chain_unregister);
  EXPORT_SYMBOL(notifier_call_chain);
  EXPORT_SYMBOL(register_reboot_notifier);
  EXPORT_SYMBOL(unregister_reboot_notifier);
  EXPORT_SYMBOL(in_group_p);
  EXPORT_SYMBOL(in_egroup_p);

Cache object: 2f6d585d17e56f9445bbfbba28cbab41