/* * linux/kernel/sys.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/config.h> #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 <linux/fs.h> #include <linux/kernel.h> #include <linux/kexec.h> #include <linux/workqueue.h> #include <linux/capability.h> #include <linux/device.h> #include <linux/key.h> #include <linux/times.h> #include <linux/posix-timers.h> #include <linux/security.h> #include <linux/dcookies.h> #include <linux/suspend.h> #include <linux/tty.h> #include <linux/signal.h> #include <linux/cn_proc.h> #include <linux/compat.h> #include <linux/syscalls.h> #include <linux/kprobes.h> #include <asm/uaccess.h> #include <asm/io.h> #include <asm/unistd.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; #ifdef CONFIG_UID16 EXPORT_SYMBOL(overflowuid); EXPORT_SYMBOL(overflowgid); #endif /* * 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; EXPORT_SYMBOL(fs_overflowuid); EXPORT_SYMBOL(fs_overflowgid); /* * 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; static DEFINE_RWLOCK(notifier_lock); /** * 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(¬ifier_lock); while(*list) { if(n->priority > (*list)->priority) break; list= &((*list)->next); } n->next = *list; *list=n; write_unlock(¬ifier_lock); return 0; } EXPORT_SYMBOL(notifier_chain_register); /** * 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(¬ifier_lock); while((*nl)!=NULL) { if((*nl)==n) { *nl=n->next; write_unlock(¬ifier_lock); return 0; } nl=&((*nl)->next); } write_unlock(¬ifier_lock); return -ENOENT; } EXPORT_SYMBOL(notifier_chain_unregister); /** * 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 __kprobes 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; } EXPORT_SYMBOL(notifier_call_chain); /** * 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); } EXPORT_SYMBOL(register_reboot_notifier); /** * 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); } EXPORT_SYMBOL(unregister_reboot_notifier); static int set_one_prio(struct task_struct *p, int niceval, int error) { int no_nice; if (p->uid != current->euid && p->euid != current->euid && !capable(CAP_SYS_NICE)) { error = -EPERM; goto out; } if (niceval < task_nice(p) && !can_nice(p, niceval)) { error = -EACCES; goto out; } no_nice = security_task_setnice(p, niceval); if (no_nice) { error = no_nice; goto out; } if (error == -ESRCH) error = 0; set_user_nice(p, niceval); out: return error; } asmlinkage long sys_setpriority(int which, int who, int niceval) { struct task_struct *g, *p; struct user_struct *user; int error = -EINVAL; if (which > 2 || which < 0) goto out; /* normalize: avoid signed division (rounding problems) */ error = -ESRCH; if (niceval < -20) niceval = -20; if (niceval > 19) niceval = 19; read_lock(&tasklist_lock); switch (which) { case PRIO_PROCESS: if (!who) who = current->pid; p = find_task_by_pid(who); if (p) error = set_one_prio(p, niceval, error); break; case PRIO_PGRP: if (!who) who = process_group(current); do_each_task_pid(who, PIDTYPE_PGID, p) { error = set_one_prio(p, niceval, error); } while_each_task_pid(who, PIDTYPE_PGID, p); break; case PRIO_USER: user = current->user; if (!who) who = current->uid; else if ((who != current->uid) && !(user = find_user(who))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) if (p->uid == who) error = set_one_prio(p, niceval, error); while_each_thread(g, p); if (who != current->uid) free_uid(user); /* For find_user() */ break; } out_unlock: read_unlock(&tasklist_lock); out: 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 *g, *p; struct user_struct *user; long niceval, retval = -ESRCH; if (which > 2 || which < 0) return -EINVAL; read_lock(&tasklist_lock); switch (which) { case PRIO_PROCESS: if (!who) who = current->pid; p = find_task_by_pid(who); if (p) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } break; case PRIO_PGRP: if (!who) who = process_group(current); do_each_task_pid(who, PIDTYPE_PGID, p) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } while_each_task_pid(who, PIDTYPE_PGID, p); break; case PRIO_USER: user = current->user; if (!who) who = current->uid; else if ((who != current->uid) && !(user = find_user(who))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) if (p->uid == who) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } while_each_thread(g, p); if (who != current->uid) free_uid(user); /* for find_user() */ break; } out_unlock: read_unlock(&tasklist_lock); return retval; } /** * emergency_restart - reboot the system * * Without shutting down any hardware or taking any locks * reboot the system. This is called when we know we are in * trouble so this is our best effort to reboot. This is * safe to call in interrupt context. */ void emergency_restart(void) { machine_emergency_restart(); } EXPORT_SYMBOL_GPL(emergency_restart); void kernel_restart_prepare(char *cmd) { notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); system_state = SYSTEM_RESTART; device_shutdown(); } /** * kernel_restart - reboot the system * @cmd: pointer to buffer containing command to execute for restart * or %NULL * * Shutdown everything and perform a clean reboot. * This is not safe to call in interrupt context. */ void kernel_restart(char *cmd) { kernel_restart_prepare(cmd); if (!cmd) { printk(KERN_EMERG "Restarting system.\n"); } else { printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd); } printk(".\n"); machine_restart(cmd); } EXPORT_SYMBOL_GPL(kernel_restart); /** * kernel_kexec - reboot the system * * Move into place and start executing a preloaded standalone * executable. If nothing was preloaded return an error. */ void kernel_kexec(void) { #ifdef CONFIG_KEXEC struct kimage *image; image = xchg(&kexec_image, NULL); if (!image) { return; } kernel_restart_prepare(NULL); printk(KERN_EMERG "Starting new kernel\n"); machine_shutdown(); machine_kexec(image); #endif } EXPORT_SYMBOL_GPL(kernel_kexec); void kernel_shutdown_prepare(enum system_states state) { notifier_call_chain(&reboot_notifier_list, (state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL); system_state = state; device_shutdown(); } /** * kernel_halt - halt the system * * Shutdown everything and perform a clean system halt. */ void kernel_halt(void) { kernel_shutdown_prepare(SYSTEM_HALT); printk(KERN_EMERG "System halted.\n"); machine_halt(); } EXPORT_SYMBOL_GPL(kernel_halt); /** * kernel_power_off - power_off the system * * Shutdown everything and perform a clean system power_off. */ void kernel_power_off(void) { kernel_shutdown_prepare(SYSTEM_POWER_OFF); printk(KERN_EMERG "Power down.\n"); machine_power_off(); } EXPORT_SYMBOL_GPL(kernel_power_off); /* * 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 __user * 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 && magic2 != LINUX_REBOOT_MAGIC2C)) return -EINVAL; /* Instead of trying to make the power_off code look like * halt when pm_power_off is not set do it the easy way. */ if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off) cmd = LINUX_REBOOT_CMD_HALT; lock_kernel(); switch (cmd) { case LINUX_REBOOT_CMD_RESTART: kernel_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: kernel_halt(); unlock_kernel(); do_exit(0); break; case LINUX_REBOOT_CMD_POWER_OFF: kernel_power_off(); unlock_kernel(); do_exit(0); break; case LINUX_REBOOT_CMD_RESTART2: if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { unlock_kernel(); return -EFAULT; } buffer[sizeof(buffer) - 1] = '\0'; kernel_restart(buffer); break; case LINUX_REBOOT_CMD_KEXEC: kernel_kexec(); unlock_kernel(); return -EINVAL; #ifdef CONFIG_SOFTWARE_SUSPEND case LINUX_REBOOT_CMD_SW_SUSPEND: { int ret = software_suspend(); unlock_kernel(); return ret; } #endif default: unlock_kernel(); return -EINVAL; } unlock_kernel(); return 0; } static void deferred_cad(void *dummy) { kernel_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 DECLARE_WORK(cad_work, deferred_cad, NULL); if (C_A_D) schedule_work(&cad_work); 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; int retval; retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE); if (retval) return retval; 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 = suid_dumpable; smp_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; key_fsgid_changed(current); proc_id_connector(current, PROC_EVENT_GID); 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; int retval; retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID); if (retval) return retval; if (capable(CAP_SETGID)) { if(old_egid != gid) { current->mm->dumpable = suid_dumpable; smp_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 = suid_dumpable; smp_wmb(); } current->egid = current->fsgid = gid; } else return -EPERM; key_fsgid_changed(current); proc_id_connector(current, PROC_EVENT_GID); return 0; } static int set_user(uid_t new_ruid, int dumpclear) { struct user_struct *new_user; new_user = alloc_uid(new_ruid); if (!new_user) return -EAGAIN; if (atomic_read(&new_user->processes) >= current->signal->rlim[RLIMIT_NPROC].rlim_cur && new_user != &root_user) { free_uid(new_user); return -EAGAIN; } switch_uid(new_user); if(dumpclear) { current->mm->dumpable = suid_dumpable; smp_wmb(); } current->uid = new_ruid; 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; int retval; retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE); if (retval) return retval; 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 = suid_dumpable; smp_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; key_fsuid_changed(current); proc_id_connector(current, PROC_EVENT_UID); return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RE); } /* * 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; int retval; retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID); if (retval) return retval; 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 = suid_dumpable; smp_wmb(); } current->fsuid = current->euid = uid; current->suid = new_suid; key_fsuid_changed(current); proc_id_connector(current, PROC_EVENT_UID); return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_ID); } /* * 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; int retval; retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES); if (retval) return retval; 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 = suid_dumpable; smp_wmb(); } current->euid = euid; } current->fsuid = current->euid; if (suid != (uid_t) -1) current->suid = suid; key_fsuid_changed(current); proc_id_connector(current, PROC_EVENT_UID); return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RES); } asmlinkage long sys_getresuid(uid_t __user *ruid, uid_t __user *euid, uid_t __user *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) { int retval; retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES); if (retval) return retval; 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 = suid_dumpable; smp_wmb(); } current->egid = egid; } current->fsgid = current->egid; if (rgid != (gid_t) -1) current->gid = rgid; if (sgid != (gid_t) -1) current->sgid = sgid; key_fsgid_changed(current); proc_id_connector(current, PROC_EVENT_GID); return 0; } asmlinkage long sys_getresgid(gid_t __user *rgid, gid_t __user *egid, gid_t __user *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 (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS)) return old_fsuid; if (uid == current->uid || uid == current->euid || uid == current->suid || uid == current->fsuid || capable(CAP_SETUID)) { if (uid != old_fsuid) { current->mm->dumpable = suid_dumpable; smp_wmb(); } current->fsuid = uid; } key_fsuid_changed(current); proc_id_connector(current, PROC_EVENT_UID); security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS); return old_fsuid; } /* * Samma p� svenska.. */ asmlinkage long sys_setfsgid(gid_t gid) { int old_fsgid; old_fsgid = current->fsgid; if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS)) return old_fsgid; if (gid == current->gid || gid == current->egid || gid == current->sgid || gid == current->fsgid || capable(CAP_SETGID)) { if (gid != old_fsgid) { current->mm->dumpable = suid_dumpable; smp_wmb(); } current->fsgid = gid; key_fsgid_changed(current); proc_id_connector(current, PROC_EVENT_GID); } return old_fsgid; } asmlinkage long sys_times(struct tms __user * 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) { struct tms tmp; cputime_t utime, stime, cutime, cstime; #ifdef CONFIG_SMP if (thread_group_empty(current)) { /* * Single thread case without the use of any locks. * * We may race with release_task if two threads are * executing. However, release task first adds up the * counters (__exit_signal) before removing the task * from the process tasklist (__unhash_process). * __exit_signal also acquires and releases the * siglock which results in the proper memory ordering * so that the list modifications are always visible * after the counters have been updated. * * If the counters have been updated by the second thread * but the thread has not yet been removed from the list * then the other branch will be executing which will * block on tasklist_lock until the exit handling of the * other task is finished. * * This also implies that the sighand->siglock cannot * be held by another processor. So we can also * skip acquiring that lock. */ utime = cputime_add(current->signal->utime, current->utime); stime = cputime_add(current->signal->utime, current->stime); cutime = current->signal->cutime; cstime = current->signal->cstime; } else #endif { /* Process with multiple threads */ struct task_struct *tsk = current; struct task_struct *t; read_lock(&tasklist_lock); utime = tsk->signal->utime; stime = tsk->signal->stime; t = tsk; do { utime = cputime_add(utime, t->utime); stime = cputime_add(stime, t->stime); t = next_thread(t); } while (t != tsk); /* * While we have tasklist_lock read-locked, no dying thread * can be updating current->signal->[us]time. Instead, * we got their counts included in the live thread loop. * However, another thread can come in right now and * do a wait call that updates current->signal->c[us]time. * To make sure we always see that pair updated atomically, * we take the siglock around fetching them. */ spin_lock_irq(&tsk->sighand->siglock); cutime = tsk->signal->cutime; cstime = tsk->signal->cstime; spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); } tmp.tms_utime = cputime_to_clock_t(utime); tmp.tms_stime = cputime_to_clock_t(stime); tmp.tms_cutime = cputime_to_clock_t(cutime); tmp.tms_cstime = cputime_to_clock_t(cstime); if (copy_to_user(tbuf, &tmp, sizeof(struct tms))) return -EFAULT; } return (long) jiffies_64_to_clock_t(get_jiffies_64()); } /* * 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; struct task_struct *group_leader = current->group_leader; int err = -EINVAL; if (!pid) pid = group_leader->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 */ write_lock_irq(&tasklist_lock); err = -ESRCH; p = find_task_by_pid(pid); if (!p) goto out; err = -EINVAL; if (!thread_group_leader(p)) goto out; if (p->real_parent == group_leader) { err = -EPERM; if (p->signal->session != group_leader->signal->session) goto out; err = -EACCES; if (p->did_exec) goto out; } else { err = -ESRCH; if (p != group_leader) goto out; } err = -EPERM; if (p->signal->leader) goto out; if (pgid != pid) { struct task_struct *p; do_each_task_pid(pgid, PIDTYPE_PGID, p) { if (p->signal->session == group_leader->signal->session) goto ok_pgid; } while_each_task_pid(pgid, PIDTYPE_PGID, p); goto out; } ok_pgid: err = security_task_setpgid(p, pgid); if (err) goto out; if (process_group(p) != pgid) { detach_pid(p, PIDTYPE_PGID); p->signal->pgrp = pgid; attach_pid(p, PIDTYPE_PGID, pgid); } err = 0; out: /* All paths lead to here, thus we are safe. -DaveM */ write_unlock_irq(&tasklist_lock); return err; } asmlinkage long sys_getpgid(pid_t pid) { if (!pid) { return process_group(current); } else { int retval; struct task_struct *p; read_lock(&tasklist_lock); p = find_task_by_pid(pid); retval = -ESRCH; if (p) { retval = security_task_getpgid(p); if (!retval) retval = process_group(p); } read_unlock(&tasklist_lock); return retval; } } #ifdef __ARCH_WANT_SYS_GETPGRP asmlinkage long sys_getpgrp(void) { /* SMP - assuming writes are word atomic this is fine */ return process_group(current); } #endif asmlinkage long sys_getsid(pid_t pid) { if (!pid) { return current->signal->session; } else { int retval; struct task_struct *p; read_lock(&tasklist_lock); p = find_task_by_pid(pid); retval = -ESRCH; if(p) { retval = security_task_getsid(p); if (!retval) retval = p->signal->session; } read_unlock(&tasklist_lock); return retval; } } asmlinkage long sys_setsid(void) { struct task_struct *group_leader = current->group_leader; struct pid *pid; int err = -EPERM; mutex_lock(&tty_mutex); write_lock_irq(&tasklist_lock); pid = find_pid(PIDTYPE_PGID, group_leader->pid); if (pid) goto out; group_leader->signal->leader = 1; __set_special_pids(group_leader->pid, group_leader->pid); group_leader->signal->tty = NULL; group_leader->signal->tty_old_pgrp = 0; err = process_group(group_leader); out: write_unlock_irq(&tasklist_lock); mutex_unlock(&tty_mutex); return err; } /* * Supplementary group IDs */ /* init to 2 - one for init_task, one to ensure it is never freed */ struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; struct group_info *groups_alloc(int gidsetsize) { struct group_info *group_info; int nblocks; int i; nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; /* Make sure we always allocate at least one indirect block pointer */ nblocks = nblocks ? : 1; group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); if (!group_info) return NULL; group_info->ngroups = gidsetsize; group_info->nblocks = nblocks; atomic_set(&group_info->usage, 1); if (gidsetsize <= NGROUPS_SMALL) { group_info->blocks[0] = group_info->small_block; } else { for (i = 0; i < nblocks; i++) { gid_t *b; b = (void *)__get_free_page(GFP_USER); if (!b) goto out_undo_partial_alloc; group_info->blocks[i] = b; } } return group_info; out_undo_partial_alloc: while (--i >= 0) { free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); return NULL; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info *group_info) { if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); } EXPORT_SYMBOL(groups_free); /* export the group_info to a user-space array */ static int groups_to_user(gid_t __user *grouplist, struct group_info *group_info) { int i; int count = group_info->ngroups; for (i = 0; i < group_info->nblocks; i++) { int cp_count = min(NGROUPS_PER_BLOCK, count); int off = i * NGROUPS_PER_BLOCK; int len = cp_count * sizeof(*grouplist); if (copy_to_user(grouplist+off, group_info->blocks[i], len)) return -EFAULT; count -= cp_count; } return 0; } /* fill a group_info from a user-space array - it must be allocated already */ static int groups_from_user(struct group_info *group_info, gid_t __user *grouplist) { int i; int count = group_info->ngroups; for (i = 0; i < group_info->nblocks; i++) { int cp_count = min(NGROUPS_PER_BLOCK, count); int off = i * NGROUPS_PER_BLOCK; int len = cp_count * sizeof(*grouplist); if (copy_from_user(group_info->blocks[i], grouplist+off, len)) return -EFAULT; count -= cp_count; } return 0; } /* a simple Shell sort */ static void groups_sort(struct group_info *group_info) { int base, max, stride; int gidsetsize = group_info->ngroups; for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) ; /* nothing */ stride /= 3; while (stride) { max = gidsetsize - stride; for (base = 0; base < max; base++) { int left = base; int right = left + stride; gid_t tmp = GROUP_AT(group_info, right); while (left >= 0 && GROUP_AT(group_info, left) > tmp) { GROUP_AT(group_info, right) = GROUP_AT(group_info, left); right = left; left -= stride; } GROUP_AT(group_info, right) = tmp; } stride /= 3; } } /* a simple bsearch */ int groups_search(struct group_info *group_info, gid_t grp) { unsigned int left, right; if (!group_info) return 0; left = 0; right = group_info->ngroups; while (left < right) { unsigned int mid = (left+right)/2; int cmp = grp - GROUP_AT(group_info, mid); if (cmp > 0) left = mid + 1; else if (cmp < 0) right = mid; else return 1; } return 0; } /* validate and set current->group_info */ int set_current_groups(struct group_info *group_info) { int retval; struct group_info *old_info; retval = security_task_setgroups(group_info); if (retval) return retval; groups_sort(group_info); get_group_info(group_info); task_lock(current); old_info = current->group_info; current->group_info = group_info; task_unlock(current); put_group_info(old_info); return 0; } EXPORT_SYMBOL(set_current_groups); asmlinkage long sys_getgroups(int gidsetsize, gid_t __user *grouplist) { int i = 0; /* * SMP: Nobody else can change our grouplist. Thus we are * safe. */ if (gidsetsize < 0) return -EINVAL; /* no need to grab task_lock here; it cannot change */ i = current->group_info->ngroups; if (gidsetsize) { if (i > gidsetsize) { i = -EINVAL; goto out; } if (groups_to_user(grouplist, current->group_info)) { i = -EFAULT; goto out; } } out: return i; } /* * SMP: Our groups are copy-on-write. We can set them safely * without another task interfering. */ asmlinkage long sys_setgroups(int gidsetsize, gid_t __user *grouplist) { struct group_info *group_info; int retval; if (!capable(CAP_SETGID)) return -EPERM; if ((unsigned)gidsetsize > NGROUPS_MAX) return -EINVAL; group_info = groups_alloc(gidsetsize); if (!group_info) return -ENOMEM; retval = groups_from_user(group_info, grouplist); if (retval) { put_group_info(group_info); return retval; } retval = set_current_groups(group_info); put_group_info(group_info); return retval; } /* * 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 = groups_search(current->group_info, grp); } return retval; } EXPORT_SYMBOL(in_group_p); int in_egroup_p(gid_t grp) { int retval = 1; if (grp != current->egid) { retval = groups_search(current->group_info, grp); } return retval; } EXPORT_SYMBOL(in_egroup_p); DECLARE_RWSEM(uts_sem); EXPORT_SYMBOL(uts_sem); asmlinkage long sys_newuname(struct new_utsname __user * 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 __user *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; } #ifdef __ARCH_WANT_SYS_GETHOSTNAME asmlinkage long sys_gethostname(char __user *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; } #endif /* * Only setdomainname; getdomainname can be implemented by calling * uname() */ asmlinkage long sys_setdomainname(char __user *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 __user *rlim) { if (resource >= RLIM_NLIMITS) return -EINVAL; else { struct rlimit value; task_lock(current->group_leader); value = current->signal->rlim[resource]; task_unlock(current->group_leader); return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0; } } #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT /* * Back compatibility for getrlimit. Needed for some apps. */ asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit __user *rlim) { struct rlimit x; if (resource >= RLIM_NLIMITS) return -EINVAL; task_lock(current->group_leader); x = current->signal->rlim[resource]; task_unlock(current->group_leader); 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 __user *rlim) { struct rlimit new_rlim, *old_rlim; unsigned long it_prof_secs; int retval; 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->signal->rlim + resource; if ((new_rlim.rlim_max > old_rlim->rlim_max) && !capable(CAP_SYS_RESOURCE)) return -EPERM; if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > NR_OPEN) return -EPERM; retval = security_task_setrlimit(resource, &new_rlim); if (retval) return retval; task_lock(current->group_leader); *old_rlim = new_rlim; task_unlock(current->group_leader); if (resource != RLIMIT_CPU) goto out; /* * RLIMIT_CPU handling. Note that the kernel fails to return an error * code if it rejected the user's attempt to set RLIMIT_CPU. This is a * very long-standing error, and fixing it now risks breakage of * applications, so we live with it */ if (new_rlim.rlim_cur == RLIM_INFINITY) goto out; it_prof_secs = cputime_to_secs(current->signal->it_prof_expires); if (it_prof_secs == 0 || new_rlim.rlim_cur <= it_prof_secs) { unsigned long rlim_cur = new_rlim.rlim_cur; cputime_t cputime; if (rlim_cur == 0) { /* * The caller is asking for an immediate RLIMIT_CPU * expiry. But we use the zero value to mean "it was * never set". So let's cheat and make it one second * instead */ rlim_cur = 1; } cputime = secs_to_cputime(rlim_cur); read_lock(&tasklist_lock); spin_lock_irq(¤t->sighand->siglock); set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL); spin_unlock_irq(¤t->sighand->siglock); read_unlock(&tasklist_lock); } out: 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). * * When sampling multiple threads for RUSAGE_SELF, under SMP we might have * races with threads incrementing their own counters. But since word * reads are atomic, we either get new values or old values and we don't * care which for the sums. We always take the siglock to protect reading * the c* fields from p->signal from races with exit.c updating those * fields when reaping, so a sample either gets all the additions of a * given child after it's reaped, or none so this sample is before reaping. * * tasklist_lock locking optimisation: * If we are current and single threaded, we do not need to take the tasklist * lock or the siglock. No one else can take our signal_struct away, * no one else can reap the children to update signal->c* counters, and * no one else can race with the signal-> fields. * If we do not take the tasklist_lock, the signal-> fields could be read * out of order while another thread was just exiting. So we place a * read memory barrier when we avoid the lock. On the writer side, * write memory barrier is implied in __exit_signal as __exit_signal releases * the siglock spinlock after updating the signal-> fields. * * We don't really need the siglock when we access the non c* fields * of the signal_struct (for RUSAGE_SELF) even in multithreaded * case, since we take the tasklist lock for read and the non c* signal-> * fields are updated only in __exit_signal, which is called with * tasklist_lock taken for write, hence these two threads cannot execute * concurrently. * */ static void k_getrusage(struct task_struct *p, int who, struct rusage *r) { struct task_struct *t; unsigned long flags; cputime_t utime, stime; int need_lock = 0; memset((char *) r, 0, sizeof *r); utime = stime = cputime_zero; if (p != current || !thread_group_empty(p)) need_lock = 1; if (need_lock) { read_lock(&tasklist_lock); if (unlikely(!p->signal)) { read_unlock(&tasklist_lock); return; } } else /* See locking comments above */ smp_rmb(); switch (who) { case RUSAGE_BOTH: case RUSAGE_CHILDREN: spin_lock_irqsave(&p->sighand->siglock, flags); utime = p->signal->cutime; stime = p->signal->cstime; r->ru_nvcsw = p->signal->cnvcsw; r->ru_nivcsw = p->signal->cnivcsw; r->ru_minflt = p->signal->cmin_flt; r->ru_majflt = p->signal->cmaj_flt; spin_unlock_irqrestore(&p->sighand->siglock, flags); if (who == RUSAGE_CHILDREN) break; case RUSAGE_SELF: utime = cputime_add(utime, p->signal->utime); stime = cputime_add(stime, p->signal->stime); r->ru_nvcsw += p->signal->nvcsw; r->ru_nivcsw += p->signal->nivcsw; r->ru_minflt += p->signal->min_flt; r->ru_majflt += p->signal->maj_flt; t = p; do { utime = cputime_add(utime, t->utime); stime = cputime_add(stime, t->stime); r->ru_nvcsw += t->nvcsw; r->ru_nivcsw += t->nivcsw; r->ru_minflt += t->min_flt; r->ru_majflt += t->maj_flt; t = next_thread(t); } while (t != p); break; default: BUG(); } if (need_lock) read_unlock(&tasklist_lock); cputime_to_timeval(utime, &r->ru_utime); cputime_to_timeval(stime, &r->ru_stime); } int getrusage(struct task_struct *p, int who, struct rusage __user *ru) { struct rusage r; k_getrusage(p, who, &r); return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0; } asmlinkage long sys_getrusage(int who, struct rusage __user *ru) { if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) return -EINVAL; return getrusage(current, who, ru); } asmlinkage long sys_umask(int mask) { mask = xchg(¤t->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) { long error; error = security_task_prctl(option, arg2, arg3, arg4, arg5); if (error) return error; switch (option) { case PR_SET_PDEATHSIG: if (!valid_signal(arg2)) { error = -EINVAL; break; } current->pdeath_signal = arg2; break; case PR_GET_PDEATHSIG: error = put_user(current->pdeath_signal, (int __user *)arg2); break; case PR_GET_DUMPABLE: error = current->mm->dumpable; break; case PR_SET_DUMPABLE: if (arg2 < 0 || arg2 > 2) { 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_TIMING: error = PR_TIMING_STATISTICAL; break; case PR_SET_TIMING: if (arg2 == PR_TIMING_STATISTICAL) error = 0; else error = -EINVAL; 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; case PR_SET_NAME: { struct task_struct *me = current; unsigned char ncomm[sizeof(me->comm)]; ncomm[sizeof(me->comm)-1] = 0; if (strncpy_from_user(ncomm, (char __user *)arg2, sizeof(me->comm)-1) < 0) return -EFAULT; set_task_comm(me, ncomm); return 0; } case PR_GET_NAME: { struct task_struct *me = current; unsigned char tcomm[sizeof(me->comm)]; get_task_comm(tcomm, me); if (copy_to_user((char __user *)arg2, tcomm, sizeof(tcomm))) return -EFAULT; return 0; } default: error = -EINVAL; break; } return error; }