/* * 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/notifier.h> #include <linux/reboot.h> #include <linux/prctl.h> #include <linux/highuid.h> #include <linux/fs.h> #include <linux/perf_event.h> #include <linux/resource.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/getcpu.h> #include <linux/task_io_accounting_ops.h> #include <linux/seccomp.h> #include <linux/cpu.h> #include <linux/personality.h> #include <linux/ptrace.h> #include <linux/fs_struct.h> #include <linux/gfp.h> #include <linux/syscore_ops.h> #include <linux/compat.h> #include <linux/syscalls.h> #include <linux/kprobes.h> #include <linux/user_namespace.h> #include <linux/kmsg_dump.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 #ifndef GET_ENDIAN # define GET_ENDIAN(a,b) (-EINVAL) #endif #ifndef SET_ENDIAN # define SET_ENDIAN(a,b) (-EINVAL) #endif #ifndef GET_TSC_CTL # define GET_TSC_CTL(a) (-EINVAL) #endif #ifndef SET_TSC_CTL # define SET_TSC_CTL(a) (-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; struct pid *cad_pid; EXPORT_SYMBOL(cad_pid); /* * If set, this is used for preparing the system to power off. */ void (*pm_power_off_prepare)(void); /* * set the priority of a task * - the caller must hold the RCU read lock */ static int set_one_prio(struct task_struct *p, int niceval, int error) { const struct cred *cred = current_cred(), *pcred = __task_cred(p); int no_nice; if (pcred->uid != cred->euid && pcred->euid != cred->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; } SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) { struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); int error = -EINVAL; struct pid *pgrp; if (which > PRIO_USER || which < PRIO_PROCESS) goto out; /* normalize: avoid signed division (rounding problems) */ error = -ESRCH; if (niceval < -20) niceval = -20; if (niceval > 19) niceval = 19; rcu_read_lock(); read_lock(&tasklist_lock); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) error = set_one_prio(p, niceval, error); break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { error = set_one_prio(p, niceval, error); } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); break; case PRIO_USER: user = (struct user_struct *) cred->user; if (!who) who = cred->uid; else if ((who != cred->uid) && !(user = find_user(who))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) { if (__task_cred(p)->uid == who) error = set_one_prio(p, niceval, error); } while_each_thread(g, p); if (who != cred->uid) free_uid(user); /* For find_user() */ break; } out_unlock: read_unlock(&tasklist_lock); rcu_read_unlock(); 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. */ SYSCALL_DEFINE2(getpriority, int, which, int, who) { struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); long niceval, retval = -ESRCH; struct pid *pgrp; if (which > PRIO_USER || which < PRIO_PROCESS) return -EINVAL; rcu_read_lock(); read_lock(&tasklist_lock); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); break; case PRIO_USER: user = (struct user_struct *) cred->user; if (!who) who = cred->uid; else if ((who != cred->uid) && !(user = find_user(who))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) { if (__task_cred(p)->uid == who) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } } while_each_thread(g, p); if (who != cred->uid) free_uid(user); /* for find_user() */ break; } out_unlock: read_unlock(&tasklist_lock); rcu_read_unlock(); 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) { kmsg_dump(KMSG_DUMP_EMERG); machine_emergency_restart(); } EXPORT_SYMBOL_GPL(emergency_restart); void kernel_restart_prepare(char *cmd) { blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); system_state = SYSTEM_RESTART; device_shutdown(); sysdev_shutdown(); syscore_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); kmsg_dump(KMSG_DUMP_RESTART); machine_restart(cmd); } EXPORT_SYMBOL_GPL(kernel_restart); static void kernel_shutdown_prepare(enum system_states state) { blocking_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); sysdev_shutdown(); syscore_shutdown(); printk(KERN_EMERG "System halted.\n"); kmsg_dump(KMSG_DUMP_HALT); 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); if (pm_power_off_prepare) pm_power_off_prepare(); disable_nonboot_cpus(); sysdev_shutdown(); syscore_shutdown(); printk(KERN_EMERG "Power down.\n"); kmsg_dump(KMSG_DUMP_POWEROFF); machine_power_off(); } EXPORT_SYMBOL_GPL(kernel_power_off); static DEFINE_MUTEX(reboot_mutex); /* * 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. */ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, void __user *, arg) { char buffer[256]; int ret = 0; /* 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; mutex_lock(&reboot_mutex); 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(); do_exit(0); panic("cannot halt"); case LINUX_REBOOT_CMD_POWER_OFF: kernel_power_off(); do_exit(0); break; case LINUX_REBOOT_CMD_RESTART2: if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { ret = -EFAULT; break; } buffer[sizeof(buffer) - 1] = '\0'; kernel_restart(buffer); break; #ifdef CONFIG_KEXEC case LINUX_REBOOT_CMD_KEXEC: ret = kernel_kexec(); break; #endif #ifdef CONFIG_HIBERNATION case LINUX_REBOOT_CMD_SW_SUSPEND: ret = hibernate(); break; #endif default: ret = -EINVAL; break; } mutex_unlock(&reboot_mutex); return ret; } static void deferred_cad(struct work_struct *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); if (C_A_D) schedule_work(&cad_work); else kill_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). */ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (rgid != (gid_t) -1) { if (old->gid == rgid || old->egid == rgid || capable(CAP_SETGID)) new->gid = rgid; else goto error; } if (egid != (gid_t) -1) { if (old->gid == egid || old->egid == egid || old->sgid == egid || capable(CAP_SETGID)) new->egid = egid; else goto error; } if (rgid != (gid_t) -1 || (egid != (gid_t) -1 && egid != old->gid)) new->sgid = new->egid; new->fsgid = new->egid; return commit_creds(new); error: abort_creds(new); return retval; } /* * setgid() is implemented like SysV w/ SAVED_IDS * * SMP: Same implicit races as above. */ SYSCALL_DEFINE1(setgid, gid_t, gid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (capable(CAP_SETGID)) new->gid = new->egid = new->sgid = new->fsgid = gid; else if (gid == old->gid || gid == old->sgid) new->egid = new->fsgid = gid; else goto error; return commit_creds(new); error: abort_creds(new); return retval; } /* * change the user struct in a credentials set to match the new UID */ static int set_user(struct cred *new) { struct user_struct *new_user; new_user = alloc_uid(current_user_ns(), new->uid); if (!new_user) return -EAGAIN; if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) && new_user != INIT_USER) { free_uid(new_user); return -EAGAIN; } free_uid(new->user); new->user = new_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. */ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (ruid != (uid_t) -1) { new->uid = ruid; if (old->uid != ruid && old->euid != ruid && !capable(CAP_SETUID)) goto error; } if (euid != (uid_t) -1) { new->euid = euid; if (old->uid != euid && old->euid != euid && old->suid != euid && !capable(CAP_SETUID)) goto error; } if (new->uid != old->uid) { retval = set_user(new); if (retval < 0) goto error; } if (ruid != (uid_t) -1 || (euid != (uid_t) -1 && euid != old->uid)) new->suid = new->euid; new->fsuid = new->euid; retval = security_task_fix_setuid(new, old, LSM_SETID_RE); if (retval < 0) goto error; return commit_creds(new); error: abort_creds(new); return retval; } /* * 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. */ SYSCALL_DEFINE1(setuid, uid_t, uid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (capable(CAP_SETUID)) { new->suid = new->uid = uid; if (uid != old->uid) { retval = set_user(new); if (retval < 0) goto error; } } else if (uid != old->uid && uid != new->suid) { goto error; } new->fsuid = new->euid = uid; retval = security_task_fix_setuid(new, old, LSM_SETID_ID); if (retval < 0) goto error; return commit_creds(new); error: abort_creds(new); return retval; } /* * This function implements a generic ability to update ruid, euid, * and suid. This allows you to implement the 4.4 compatible seteuid(). */ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (!capable(CAP_SETUID)) { if (ruid != (uid_t) -1 && ruid != old->uid && ruid != old->euid && ruid != old->suid) goto error; if (euid != (uid_t) -1 && euid != old->uid && euid != old->euid && euid != old->suid) goto error; if (suid != (uid_t) -1 && suid != old->uid && suid != old->euid && suid != old->suid) goto error; } if (ruid != (uid_t) -1) { new->uid = ruid; if (ruid != old->uid) { retval = set_user(new); if (retval < 0) goto error; } } if (euid != (uid_t) -1) new->euid = euid; if (suid != (uid_t) -1) new->suid = suid; new->fsuid = new->euid; retval = security_task_fix_setuid(new, old, LSM_SETID_RES); if (retval < 0) goto error; return commit_creds(new); error: abort_creds(new); return retval; } SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid) { const struct cred *cred = current_cred(); int retval; if (!(retval = put_user(cred->uid, ruid)) && !(retval = put_user(cred->euid, euid))) retval = put_user(cred->suid, suid); return retval; } /* * Same as above, but for rgid, egid, sgid. */ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid) { const struct cred *old; struct cred *new; int retval; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (!capable(CAP_SETGID)) { if (rgid != (gid_t) -1 && rgid != old->gid && rgid != old->egid && rgid != old->sgid) goto error; if (egid != (gid_t) -1 && egid != old->gid && egid != old->egid && egid != old->sgid) goto error; if (sgid != (gid_t) -1 && sgid != old->gid && sgid != old->egid && sgid != old->sgid) goto error; } if (rgid != (gid_t) -1) new->gid = rgid; if (egid != (gid_t) -1) new->egid = egid; if (sgid != (gid_t) -1) new->sgid = sgid; new->fsgid = new->egid; return commit_creds(new); error: abort_creds(new); return retval; } SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid) { const struct cred *cred = current_cred(); int retval; if (!(retval = put_user(cred->gid, rgid)) && !(retval = put_user(cred->egid, egid))) retval = put_user(cred->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.. */ SYSCALL_DEFINE1(setfsuid, uid_t, uid) { const struct cred *old; struct cred *new; uid_t old_fsuid; new = prepare_creds(); if (!new) return current_fsuid(); old = current_cred(); old_fsuid = old->fsuid; if (uid == old->uid || uid == old->euid || uid == old->suid || uid == old->fsuid || capable(CAP_SETUID)) { if (uid != old_fsuid) { new->fsuid = uid; if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0) goto change_okay; } } abort_creds(new); return old_fsuid; change_okay: commit_creds(new); return old_fsuid; } /* * Samma på svenska.. */ SYSCALL_DEFINE1(setfsgid, gid_t, gid) { const struct cred *old; struct cred *new; gid_t old_fsgid; new = prepare_creds(); if (!new) return current_fsgid(); old = current_cred(); old_fsgid = old->fsgid; if (gid == old->gid || gid == old->egid || gid == old->sgid || gid == old->fsgid || capable(CAP_SETGID)) { if (gid != old_fsgid) { new->fsgid = gid; goto change_okay; } } abort_creds(new); return old_fsgid; change_okay: commit_creds(new); return old_fsgid; } void do_sys_times(struct tms *tms) { cputime_t tgutime, tgstime, cutime, cstime; spin_lock_irq(¤t->sighand->siglock); thread_group_times(current, &tgutime, &tgstime); cutime = current->signal->cutime; cstime = current->signal->cstime; spin_unlock_irq(¤t->sighand->siglock); tms->tms_utime = cputime_to_clock_t(tgutime); tms->tms_stime = cputime_to_clock_t(tgstime); tms->tms_cutime = cputime_to_clock_t(cutime); tms->tms_cstime = cputime_to_clock_t(cstime); } SYSCALL_DEFINE1(times, struct tms __user *, tbuf) { if (tbuf) { struct tms tmp; do_sys_times(&tmp); if (copy_to_user(tbuf, &tmp, sizeof(struct tms))) return -EFAULT; } force_successful_syscall_return(); 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 */ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid) { struct task_struct *p; struct task_struct *group_leader = current->group_leader; struct pid *pgrp; int err; if (!pid) pid = task_pid_vnr(group_leader); if (!pgid) pgid = pid; if (pgid < 0) return -EINVAL; rcu_read_lock(); /* 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_vpid(pid); if (!p) goto out; err = -EINVAL; if (!thread_group_leader(p)) goto out; if (same_thread_group(p->real_parent, group_leader)) { err = -EPERM; if (task_session(p) != task_session(group_leader)) 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; pgrp = task_pid(p); if (pgid != pid) { struct task_struct *g; pgrp = find_vpid(pgid); g = pid_task(pgrp, PIDTYPE_PGID); if (!g || task_session(g) != task_session(group_leader)) goto out; } err = security_task_setpgid(p, pgid); if (err) goto out; if (task_pgrp(p) != pgrp) change_pid(p, PIDTYPE_PGID, pgrp); err = 0; out: /* All paths lead to here, thus we are safe. -DaveM */ write_unlock_irq(&tasklist_lock); rcu_read_unlock(); return err; } SYSCALL_DEFINE1(getpgid, pid_t, pid) { struct task_struct *p; struct pid *grp; int retval; rcu_read_lock(); if (!pid) grp = task_pgrp(current); else { retval = -ESRCH; p = find_task_by_vpid(pid); if (!p) goto out; grp = task_pgrp(p); if (!grp) goto out; retval = security_task_getpgid(p); if (retval) goto out; } retval = pid_vnr(grp); out: rcu_read_unlock(); return retval; } #ifdef __ARCH_WANT_SYS_GETPGRP SYSCALL_DEFINE0(getpgrp) { return sys_getpgid(0); } #endif SYSCALL_DEFINE1(getsid, pid_t, pid) { struct task_struct *p; struct pid *sid; int retval; rcu_read_lock(); if (!pid) sid = task_session(current); else { retval = -ESRCH; p = find_task_by_vpid(pid); if (!p) goto out; sid = task_session(p); if (!sid) goto out; retval = security_task_getsid(p); if (retval) goto out; } retval = pid_vnr(sid); out: rcu_read_unlock(); return retval; } SYSCALL_DEFINE0(setsid) { struct task_struct *group_leader = current->group_leader; struct pid *sid = task_pid(group_leader); pid_t session = pid_vnr(sid); int err = -EPERM; write_lock_irq(&tasklist_lock); /* Fail if I am already a session leader */ if (group_leader->signal->leader) goto out; /* Fail if a process group id already exists that equals the * proposed session id. */ if (pid_task(sid, PIDTYPE_PGID)) goto out; group_leader->signal->leader = 1; __set_special_pids(sid); proc_clear_tty(group_leader); err = session; out: write_unlock_irq(&tasklist_lock); if (err > 0) { proc_sid_connector(group_leader); sched_autogroup_create_attach(group_leader); } return err; } DECLARE_RWSEM(uts_sem); #ifdef COMPAT_UTS_MACHINE #define override_architecture(name) \ (personality(current->personality) == PER_LINUX32 && \ copy_to_user(name->machine, COMPAT_UTS_MACHINE, \ sizeof(COMPAT_UTS_MACHINE))) #else #define override_architecture(name) 0 #endif SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name) { int errno = 0; down_read(&uts_sem); if (copy_to_user(name, utsname(), sizeof *name)) errno = -EFAULT; up_read(&uts_sem); if (!errno && override_architecture(name)) errno = -EFAULT; return errno; } #ifdef __ARCH_WANT_SYS_OLD_UNAME /* * Old cruft */ SYSCALL_DEFINE1(uname, struct old_utsname __user *, name) { int error = 0; if (!name) return -EFAULT; down_read(&uts_sem); if (copy_to_user(name, utsname(), sizeof(*name))) error = -EFAULT; up_read(&uts_sem); if (!error && override_architecture(name)) error = -EFAULT; return error; } SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name) { int error; if (!name) return -EFAULT; if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname))) return -EFAULT; down_read(&uts_sem); error = __copy_to_user(&name->sysname, &utsname()->sysname, __OLD_UTS_LEN); error |= __put_user(0, name->sysname + __OLD_UTS_LEN); error |= __copy_to_user(&name->nodename, &utsname()->nodename, __OLD_UTS_LEN); error |= __put_user(0, name->nodename + __OLD_UTS_LEN); error |= __copy_to_user(&name->release, &utsname()->release, __OLD_UTS_LEN); error |= __put_user(0, name->release + __OLD_UTS_LEN); error |= __copy_to_user(&name->version, &utsname()->version, __OLD_UTS_LEN); error |= __put_user(0, name->version + __OLD_UTS_LEN); error |= __copy_to_user(&name->machine, &utsname()->machine, __OLD_UTS_LEN); error |= __put_user(0, name->machine + __OLD_UTS_LEN); up_read(&uts_sem); if (!error && override_architecture(name)) error = -EFAULT; return error ? -EFAULT : 0; } #endif SYSCALL_DEFINE2(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)) { struct new_utsname *u = utsname(); memcpy(u->nodename, tmp, len); memset(u->nodename + len, 0, sizeof(u->nodename) - len); errno = 0; } up_write(&uts_sem); return errno; } #ifdef __ARCH_WANT_SYS_GETHOSTNAME SYSCALL_DEFINE2(gethostname, char __user *, name, int, len) { int i, errno; struct new_utsname *u; if (len < 0) return -EINVAL; down_read(&uts_sem); u = utsname(); i = 1 + strlen(u->nodename); if (i > len) i = len; errno = 0; if (copy_to_user(name, u->nodename, i)) errno = -EFAULT; up_read(&uts_sem); return errno; } #endif /* * Only setdomainname; getdomainname can be implemented by calling * uname() */ SYSCALL_DEFINE2(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)) { struct new_utsname *u = utsname(); memcpy(u->domainname, tmp, len); memset(u->domainname + len, 0, sizeof(u->domainname) - len); errno = 0; } up_write(&uts_sem); return errno; } SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim) { struct rlimit value; int ret; ret = do_prlimit(current, resource, NULL, &value); if (!ret) ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0; return ret; } #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT /* * Back compatibility for getrlimit. Needed for some apps. */ SYSCALL_DEFINE2(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 static inline bool rlim64_is_infinity(__u64 rlim64) { #if BITS_PER_LONG < 64 return rlim64 >= ULONG_MAX; #else return rlim64 == RLIM64_INFINITY; #endif } static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64) { if (rlim->rlim_cur == RLIM_INFINITY) rlim64->rlim_cur = RLIM64_INFINITY; else rlim64->rlim_cur = rlim->rlim_cur; if (rlim->rlim_max == RLIM_INFINITY) rlim64->rlim_max = RLIM64_INFINITY; else rlim64->rlim_max = rlim->rlim_max; } static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim) { if (rlim64_is_infinity(rlim64->rlim_cur)) rlim->rlim_cur = RLIM_INFINITY; else rlim->rlim_cur = (unsigned long)rlim64->rlim_cur; if (rlim64_is_infinity(rlim64->rlim_max)) rlim->rlim_max = RLIM_INFINITY; else rlim->rlim_max = (unsigned long)rlim64->rlim_max; } /* make sure you are allowed to change @tsk limits before calling this */ int do_prlimit(struct task_struct *tsk, unsigned int resource, struct rlimit *new_rlim, struct rlimit *old_rlim) { struct rlimit *rlim; int retval = 0; if (resource >= RLIM_NLIMITS) return -EINVAL; if (new_rlim) { if (new_rlim->rlim_cur > new_rlim->rlim_max) return -EINVAL; if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open) return -EPERM; } /* protect tsk->signal and tsk->sighand from disappearing */ read_lock(&tasklist_lock); if (!tsk->sighand) { retval = -ESRCH; goto out; } rlim = tsk->signal->rlim + resource; task_lock(tsk->group_leader); if (new_rlim) { if (new_rlim->rlim_max > rlim->rlim_max && !capable(CAP_SYS_RESOURCE)) retval = -EPERM; if (!retval) retval = security_task_setrlimit(tsk->group_leader, resource, new_rlim); if (resource == RLIMIT_CPU && new_rlim->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 */ new_rlim->rlim_cur = 1; } } if (!retval) { if (old_rlim) *old_rlim = *rlim; if (new_rlim) *rlim = *new_rlim; } task_unlock(tsk->group_leader); /* * 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 (!retval && new_rlim && resource == RLIMIT_CPU && new_rlim->rlim_cur != RLIM_INFINITY) update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: read_unlock(&tasklist_lock); return retval; } /* rcu lock must be held */ static int check_prlimit_permission(struct task_struct *task) { const struct cred *cred = current_cred(), *tcred; tcred = __task_cred(task); if (current != task && (cred->uid != tcred->euid || cred->uid != tcred->suid || cred->uid != tcred->uid || cred->gid != tcred->egid || cred->gid != tcred->sgid || cred->gid != tcred->gid) && !capable(CAP_SYS_RESOURCE)) { return -EPERM; } return 0; } SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource, const struct rlimit64 __user *, new_rlim, struct rlimit64 __user *, old_rlim) { struct rlimit64 old64, new64; struct rlimit old, new; struct task_struct *tsk; int ret; if (new_rlim) { if (copy_from_user(&new64, new_rlim, sizeof(new64))) return -EFAULT; rlim64_to_rlim(&new64, &new); } rcu_read_lock(); tsk = pid ? find_task_by_vpid(pid) : current; if (!tsk) { rcu_read_unlock(); return -ESRCH; } ret = check_prlimit_permission(tsk); if (ret) { rcu_read_unlock(); return ret; } get_task_struct(tsk); rcu_read_unlock(); ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL, old_rlim ? &old : NULL); if (!ret && old_rlim) { rlim_to_rlim64(&old, &old64); if (copy_to_user(old_rlim, &old64, sizeof(old64))) ret = -EFAULT; } put_task_struct(tsk); return ret; } SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) { struct rlimit new_rlim; if (copy_from_user(&new_rlim, rlim, sizeof(*rlim))) return -EFAULT; return do_prlimit(current, resource, &new_rlim, NULL); } /* * 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. * * Locking: * We need to take the siglock for CHILDEREN, SELF and BOTH * for the cases current multithreaded, non-current single threaded * non-current multithreaded. Thread traversal is now safe with * the siglock held. * Strictly speaking, we donot need to take the siglock if we are current and * single threaded, as 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 any lock, the * signal-> fields could be read out of order while another thread was just * exiting. So we should 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. But we don't do this yet to keep things simple. * */ static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r) { r->ru_nvcsw += t->nvcsw; r->ru_nivcsw += t->nivcsw; r->ru_minflt += t->min_flt; r->ru_majflt += t->maj_flt; r->ru_inblock += task_io_get_inblock(t); r->ru_oublock += task_io_get_oublock(t); } static void k_getrusage(struct task_struct *p, int who, struct rusage *r) { struct task_struct *t; unsigned long flags; cputime_t tgutime, tgstime, utime, stime; unsigned long maxrss = 0; memset((char *) r, 0, sizeof *r); utime = stime = cputime_zero; if (who == RUSAGE_THREAD) { task_times(current, &utime, &stime); accumulate_thread_rusage(p, r); maxrss = p->signal->maxrss; goto out; } if (!lock_task_sighand(p, &flags)) return; switch (who) { case RUSAGE_BOTH: case RUSAGE_CHILDREN: 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; r->ru_inblock = p->signal->cinblock; r->ru_oublock = p->signal->coublock; maxrss = p->signal->cmaxrss; if (who == RUSAGE_CHILDREN) break; case RUSAGE_SELF: thread_group_times(p, &tgutime, &tgstime); utime = cputime_add(utime, tgutime); stime = cputime_add(stime, tgstime); 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; r->ru_inblock += p->signal->inblock; r->ru_oublock += p->signal->oublock; if (maxrss < p->signal->maxrss) maxrss = p->signal->maxrss; t = p; do { accumulate_thread_rusage(t, r); t = next_thread(t); } while (t != p); break; default: BUG(); } unlock_task_sighand(p, &flags); out: cputime_to_timeval(utime, &r->ru_utime); cputime_to_timeval(stime, &r->ru_stime); if (who != RUSAGE_CHILDREN) { struct mm_struct *mm = get_task_mm(p); if (mm) { setmax_mm_hiwater_rss(&maxrss, mm); mmput(mm); } } r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */ } 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; } SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru) { if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN && who != RUSAGE_THREAD) return -EINVAL; return getrusage(current, who, ru); } SYSCALL_DEFINE1(umask, int, mask) { mask = xchg(¤t->fs->umask, mask & S_IRWXUGO); return mask; } SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, unsigned long, arg4, unsigned long, arg5) { struct task_struct *me = current; unsigned char comm[sizeof(me->comm)]; long error; error = security_task_prctl(option, arg2, arg3, arg4, arg5); if (error != -ENOSYS) return error; error = 0; switch (option) { case PR_SET_PDEATHSIG: if (!valid_signal(arg2)) { error = -EINVAL; break; } me->pdeath_signal = arg2; error = 0; break; case PR_GET_PDEATHSIG: error = put_user(me->pdeath_signal, (int __user *)arg2); break; case PR_GET_DUMPABLE: error = get_dumpable(me->mm); break; case PR_SET_DUMPABLE: if (arg2 < 0 || arg2 > 1) { error = -EINVAL; break; } set_dumpable(me->mm, arg2); error = 0; break; case PR_SET_UNALIGN: error = SET_UNALIGN_CTL(me, arg2); break; case PR_GET_UNALIGN: error = GET_UNALIGN_CTL(me, arg2); break; case PR_SET_FPEMU: error = SET_FPEMU_CTL(me, arg2); break; case PR_GET_FPEMU: error = GET_FPEMU_CTL(me, arg2); break; case PR_SET_FPEXC: error = SET_FPEXC_CTL(me, arg2); break; case PR_GET_FPEXC: error = GET_FPEXC_CTL(me, arg2); break; case PR_GET_TIMING: error = PR_TIMING_STATISTICAL; break; case PR_SET_TIMING: if (arg2 != PR_TIMING_STATISTICAL) error = -EINVAL; else error = 0; break; case PR_SET_NAME: comm[sizeof(me->comm)-1] = 0; if (strncpy_from_user(comm, (char __user *)arg2, sizeof(me->comm) - 1) < 0) return -EFAULT; set_task_comm(me, comm); return 0; case PR_GET_NAME: get_task_comm(comm, me); if (copy_to_user((char __user *)arg2, comm, sizeof(comm))) return -EFAULT; return 0; case PR_GET_ENDIAN: error = GET_ENDIAN(me, arg2); break; case PR_SET_ENDIAN: error = SET_ENDIAN(me, arg2); break; case PR_GET_SECCOMP: error = prctl_get_seccomp(); break; case PR_SET_SECCOMP: error = prctl_set_seccomp(arg2); break; case PR_GET_TSC: error = GET_TSC_CTL(arg2); break; case PR_SET_TSC: error = SET_TSC_CTL(arg2); break; case PR_TASK_PERF_EVENTS_DISABLE: error = perf_event_task_disable(); break; case PR_TASK_PERF_EVENTS_ENABLE: error = perf_event_task_enable(); break; case PR_GET_TIMERSLACK: error = current->timer_slack_ns; break; case PR_SET_TIMERSLACK: if (arg2 <= 0) current->timer_slack_ns = current->default_timer_slack_ns; else current->timer_slack_ns = arg2; error = 0; break; case PR_MCE_KILL: if (arg4 | arg5) return -EINVAL; switch (arg2) { case PR_MCE_KILL_CLEAR: if (arg3 != 0) return -EINVAL; current->flags &= ~PF_MCE_PROCESS; break; case PR_MCE_KILL_SET: current->flags |= PF_MCE_PROCESS; if (arg3 == PR_MCE_KILL_EARLY) current->flags |= PF_MCE_EARLY; else if (arg3 == PR_MCE_KILL_LATE) current->flags &= ~PF_MCE_EARLY; else if (arg3 == PR_MCE_KILL_DEFAULT) current->flags &= ~(PF_MCE_EARLY|PF_MCE_PROCESS); else return -EINVAL; break; default: return -EINVAL; } error = 0; break; case PR_MCE_KILL_GET: if (arg2 | arg3 | arg4 | arg5) return -EINVAL; if (current->flags & PF_MCE_PROCESS) error = (current->flags & PF_MCE_EARLY) ? PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE; else error = PR_MCE_KILL_DEFAULT; break; default: error = -EINVAL; break; } return error; } SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep, struct getcpu_cache __user *, unused) { int err = 0; int cpu = raw_smp_processor_id(); if (cpup) err |= put_user(cpu, cpup); if (nodep) err |= put_user(cpu_to_node(cpu), nodep); return err ? -EFAULT : 0; } char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; static void argv_cleanup(struct subprocess_info *info) { argv_free(info->argv); } /** * orderly_poweroff - Trigger an orderly system poweroff * @force: force poweroff if command execution fails * * This may be called from any context to trigger a system shutdown. * If the orderly shutdown fails, it will force an immediate shutdown. */ int orderly_poweroff(bool force) { int argc; char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc); static char *envp[] = { "HOME=/", "PATH=/sbin:/bin:/usr/sbin:/usr/bin", NULL }; int ret = -ENOMEM; struct subprocess_info *info; if (argv == NULL) { printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n", __func__, poweroff_cmd); goto out; } info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC); if (info == NULL) { argv_free(argv); goto out; } call_usermodehelper_setfns(info, NULL, argv_cleanup, NULL); ret = call_usermodehelper_exec(info, UMH_NO_WAIT); out: if (ret && force) { printk(KERN_WARNING "Failed to start orderly shutdown: " "forcing the issue\n"); /* I guess this should try to kick off some daemon to sync and poweroff asap. Or not even bother syncing if we're doing an emergency shutdown? */ emergency_sync(); kernel_power_off(); } return ret; } EXPORT_SYMBOL_GPL(orderly_poweroff);