From 67d7ddded322db99f451a7959d56ed6c70a6c4aa Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 14 May 2017 20:53:13 -0400 Subject: [PATCH] waitid(2): leave copyout of siginfo to syscall itself have kernel_waitid() collect the information needed for siginfo into a small structure (waitid_info) passed to it; deal with copyout in sys_waitid()/compat_sys_waitid(). Signed-off-by: Al Viro --- kernel/exit.c | 168 ++++++++++++++++++++++------------------------------------ 1 file changed, 64 insertions(+), 104 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 94cdccf8e7e7..42f26480b3cc 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -996,12 +996,19 @@ SYSCALL_DEFINE1(exit_group, int, error_code) return 0; } +struct waitid_info { + pid_t pid; + uid_t uid; + int status; + int cause; +}; + struct wait_opts { enum pid_type wo_type; int wo_flags; struct pid *wo_pid; - struct siginfo __user *wo_info; + struct waitid_info *wo_info; int wo_stat; struct rusage *wo_rusage; @@ -1053,8 +1060,7 @@ eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, pid_t pid, uid_t uid, int why, int status) { - struct siginfo __user *infop; - int retval = 0; + struct waitid_info *infop; if (wo->wo_rusage) getrusage(p, RUSAGE_BOTH, wo->wo_rusage); @@ -1062,22 +1068,12 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, put_task_struct(p); infop = wo->wo_info; if (infop) { - if (!retval) - retval = put_user(SIGCHLD, &infop->si_signo); - if (!retval) - retval = put_user(0, &infop->si_errno); - if (!retval) - retval = put_user((short)why, &infop->si_code); - if (!retval) - retval = put_user(pid, &infop->si_pid); - if (!retval) - retval = put_user(uid, &infop->si_uid); - if (!retval) - retval = put_user(status, &infop->si_status); + infop->cause = why; + infop->pid = pid; + infop->uid = uid; + infop->status = status; } - if (!retval) - retval = pid; - return retval; + return pid; } /* @@ -1088,10 +1084,10 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, */ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) { - int state, retval, status; + int state, status; pid_t pid = task_pid_vnr(p); uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); - struct siginfo __user *infop; + struct waitid_info *infop; if (!likely(wo->wo_flags & WEXITED)) return 0; @@ -1186,36 +1182,22 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) if (wo->wo_rusage) getrusage(p, RUSAGE_BOTH, wo->wo_rusage); - retval = 0; status = (p->signal->flags & SIGNAL_GROUP_EXIT) ? p->signal->group_exit_code : p->exit_code; wo->wo_stat = status; infop = wo->wo_info; - if (!retval && infop) - retval = put_user(SIGCHLD, &infop->si_signo); - if (!retval && infop) - retval = put_user(0, &infop->si_errno); - if (!retval && infop) { - int why; - + if (infop) { if ((status & 0x7f) == 0) { - why = CLD_EXITED; - status >>= 8; + infop->cause = CLD_EXITED; + infop->status = status >> 8; } else { - why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; - status &= 0x7f; + infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; + infop->status = status & 0x7f; } - retval = put_user((short)why, &infop->si_code); - if (!retval) - retval = put_user(status, &infop->si_status); + infop->pid = pid; + infop->uid = uid; } - if (!retval && infop) - retval = put_user(pid, &infop->si_pid); - if (!retval && infop) - retval = put_user(uid, &infop->si_uid); - if (!retval) - retval = pid; if (state == EXIT_TRACE) { write_lock_irq(&tasklist_lock); @@ -1232,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) if (state == EXIT_DEAD) release_task(p); - return retval; + return pid; } static int *task_stopped_code(struct task_struct *p, bool ptrace) @@ -1268,8 +1250,8 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace) static int wait_task_stopped(struct wait_opts *wo, int ptrace, struct task_struct *p) { - struct siginfo __user *infop; - int retval, exit_code, *p_code, why; + struct waitid_info *infop; + int exit_code, *p_code, why; uid_t uid = 0; /* unneeded, required by compiler */ pid_t pid; @@ -1320,28 +1302,19 @@ unlock_sig: if (wo->wo_rusage) getrusage(p, RUSAGE_BOTH, wo->wo_rusage); - retval = 0; wo->wo_stat = (exit_code << 8) | 0x7f; infop = wo->wo_info; - if (!retval && infop) - retval = put_user(SIGCHLD, &infop->si_signo); - if (!retval && infop) - retval = put_user(0, &infop->si_errno); - if (!retval && infop) - retval = put_user((short)why, &infop->si_code); - if (!retval && infop) - retval = put_user(exit_code, &infop->si_status); - if (!retval && infop) - retval = put_user(pid, &infop->si_pid); - if (!retval && infop) - retval = put_user(uid, &infop->si_uid); - if (!retval) - retval = pid; + if (infop) { + infop->cause = why; + infop->status = exit_code; + infop->pid = pid; + infop->uid = uid; + } put_task_struct(p); - BUG_ON(!retval); - return retval; + BUG_ON(!pid); + return pid; } /* @@ -1618,7 +1591,7 @@ end: return retval; } -static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop, +static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, int options, struct rusage *ru) { struct wait_opts wo; @@ -1660,27 +1633,8 @@ static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop, wo.wo_rusage = ru; ret = do_wait(&wo); - if (ret > 0) { + if (ret > 0) ret = 0; - } else if (infop) { - /* - * For a WNOHANG return, clear out all the fields - * we would set so the user can easily tell the - * difference. - */ - if (!ret) - ret = put_user(0, &infop->si_signo); - if (!ret) - ret = put_user(0, &infop->si_errno); - if (!ret) - ret = put_user(0, &infop->si_code); - if (!ret) - ret = put_user(0, &infop->si_pid); - if (!ret) - ret = put_user(0, &infop->si_uid); - if (!ret) - ret = put_user(0, &infop->si_status); - } put_pid(pid); return ret; @@ -1690,12 +1644,24 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, infop, int, options, struct rusage __user *, ru) { struct rusage r; - long err = kernel_waitid(which, upid, infop, options, ru ? &r : NULL); + struct waitid_info info = {.status = 0}; + long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); if (!err) { if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) return -EFAULT; } + if (!infop) + return err; + + if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) || + put_user(0, &infop->si_errno) || + put_user((short)info.cause, &infop->si_code) || + put_user(info.pid, &infop->si_pid) || + put_user(info.uid, &infop->si_uid) || + put_user(info.status, &infop->si_status)) + err = -EFAULT; + return err; } @@ -1785,33 +1751,27 @@ COMPAT_SYSCALL_DEFINE5(waitid, struct compat_siginfo __user *, infop, int, options, struct compat_rusage __user *, uru) { - siginfo_t info; struct rusage ru; - long ret; - mm_segment_t old_fs = get_fs(); - - memset(&info, 0, sizeof(info)); + struct waitid_info info = {.status = 0}; + long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); - set_fs(KERNEL_DS); - ret = kernel_waitid(which, pid, (siginfo_t __user *)&info, options, - uru ? &ru : NULL); - set_fs(old_fs); - - if ((ret < 0) || (info.si_signo == 0)) - return ret; - - if (uru) { - /* sys_waitid() overwrites everything in ru */ + if (!err && uru) { + /* kernel_waitid() overwrites everything in ru */ if (COMPAT_USE_64BIT_TIME) - ret = copy_to_user(uru, &ru, sizeof(ru)); + err = copy_to_user(uru, &ru, sizeof(ru)); else - ret = put_compat_rusage(&ru, uru); - if (ret) + err = put_compat_rusage(&ru, uru); + if (err) return -EFAULT; } - BUG_ON(info.si_code & __SI_MASK); - info.si_code |= __SI_CHLD; - return copy_siginfo_to_user32(infop, &info); + if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) || + put_user(0, &infop->si_errno) || + put_user((short)info.cause, &infop->si_code) || + put_user(info.pid, &infop->si_pid) || + put_user(info.uid, &infop->si_uid) || + put_user(info.status, &infop->si_status)) + err = -EFAULT; + return err; } #endif -- 2.11.0