From 73243284463a761e04d69d22c7516b2be7de096c Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Sun, 6 May 2007 14:50:20 -0700 Subject: [PATCH] Return EPERM not ECHILD on security_task_wait failure wait* syscalls return -ECHILD even when an individual PID of a live child was requested explicitly, when security_task_wait denies the operation. This means that something like a broken SELinux policy can produce an unexpected failure that looks just like a bug with wait or ptrace or something. This patch makes do_wait return -EACCES (or other appropriate error returned from security_task_wait() instead of -ECHILD if some children were ruled out solely because security_task_wait failed. [jmorris@namei.org: switch error code to EACCES] Signed-off-by: Roland McGrath Acked-by: Stephen Smalley Cc: Chris Wright Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index b55ed4cc9104..92369240d91d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1033,6 +1033,8 @@ asmlinkage void sys_exit_group(int error_code) static int eligible_child(pid_t pid, int options, struct task_struct *p) { + int err; + if (pid > 0) { if (p->pid != pid) return 0; @@ -1066,8 +1068,9 @@ static int eligible_child(pid_t pid, int options, struct task_struct *p) if (delay_group_leader(p)) return 2; - if (security_task_wait(p)) - return 0; + err = security_task_wait(p); + if (err) + return err; return 1; } @@ -1449,6 +1452,7 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, DECLARE_WAITQUEUE(wait, current); struct task_struct *tsk; int flag, retval; + int allowed, denied; add_wait_queue(¤t->signal->wait_chldexit,&wait); repeat: @@ -1457,6 +1461,7 @@ repeat: * match our criteria, even if we are not able to reap it yet. */ flag = 0; + allowed = denied = 0; current->state = TASK_INTERRUPTIBLE; read_lock(&tasklist_lock); tsk = current; @@ -1472,6 +1477,12 @@ repeat: if (!ret) continue; + if (unlikely(ret < 0)) { + denied = ret; + continue; + } + allowed = 1; + switch (p->state) { case TASK_TRACED: /* @@ -1570,6 +1581,8 @@ check_continued: goto repeat; } retval = -ECHILD; + if (unlikely(denied) && !allowed) + retval = denied; end: current->state = TASK_RUNNING; remove_wait_queue(¤t->signal->wait_chldexit,&wait); -- 2.20.1