1 files changed, 67 insertions, 57 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 4530fc654455..e73759783dc8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -41,6 +41,8 @@
 
 static struct kmem_cache *sigqueue_cachep;
 
+DEFINE_TRACE(sched_signal_send);
+
 static void __user *sig_handler(struct task_struct *t, int sig)
 {
         return t->sighand->action[sig - 1].sa.sa_handler;
@@ -177,6 +179,11 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
         return sig;
 }
 
+/*
+ * allocate a new signal queue record
+ * - this may be called without locks if and only if t == current, otherwise an
+ *   appopriate lock must be held to stop the target task from exiting
+ */
 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
                                          int override_rlimit)
 {
@@ -184,11 +191,12 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
         struct user_struct *user;
 
         /*
-         * In order to avoid problems with "switch_user()", we want to make
-         * sure that the compiler doesn't re-load "t->user"
+         * We won't get problems with the target's UID changing under us
+         * because changing it requires RCU be used, and if t != current, the
+         * caller must be holding the RCU readlock (by way of a spinlock) and
+         * we use RCU protection here
          */
-        user = t->user;
-        barrier();
+        user = get_uid(__task_cred(t)->user);
         atomic_inc(&user->sigpending);
         if (override_rlimit ||
             atomic_read(&user->sigpending) <=
@@ -196,12 +204,14 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
                 q = kmem_cache_alloc(sigqueue_cachep, flags);
         if (unlikely(q == NULL)) {
                 atomic_dec(&user->sigpending);
+                free_uid(user);
         } else {
                 INIT_LIST_HEAD(&q->list);
                 q->flags = 0;
-                q->user = get_uid(user);
+                q->user = user;
         }
-        return(q);
+
+        return q;
 }
 
 static void __sigqueue_free(struct sigqueue *q)
@@ -562,10 +572,12 @@ static int rm_from_queue(unsigned long mask, struct sigpending *s)
 
 /*
  * Bad permissions for sending the signal
+ * - the caller must hold at least the RCU read lock
  */
 static int check_kill_permission(int sig, struct siginfo *info,
                                  struct task_struct *t)
 {
+        const struct cred *cred = current_cred(), *tcred;
         struct pid *sid;
         int error;
 
@@ -579,8 +591,11 @@ static int check_kill_permission(int sig, struct siginfo *info,
         if (error)
                 return error;
 
-        if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
-            (current->uid  ^ t->suid) && (current->uid  ^ t->uid) &&
+        tcred = __task_cred(t);
+        if ((cred->euid ^ tcred->suid) &&
+            (cred->euid ^ tcred->uid) &&
+            (cred->uid  ^ tcred->suid) &&
+            (cred->uid  ^ tcred->uid) &&
             !capable(CAP_KILL)) {
                 switch (sig) {
                 case SIGCONT:
@@ -843,8 +858,9 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
                         q->info.si_signo = sig;
                         q->info.si_errno = 0;
                         q->info.si_code = SI_USER;
-                        q->info.si_pid = task_pid_vnr(current);
-                        q->info.si_uid = current->uid;
+                        q->info.si_pid = task_tgid_nr_ns(current,
+                                                        task_active_pid_ns(t));
+                        q->info.si_uid = current_uid();
                         break;
                 case (unsigned long) SEND_SIG_PRIV:
                         q->info.si_signo = sig;
@@ -1008,6 +1024,10 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long
         return sighand;
 }
 
+/*
+ * send signal info to all the members of a group
+ * - the caller must hold the RCU read lock at least
+ */
 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
         unsigned long flags;
@@ -1029,8 +1049,8 @@ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 /*
  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
  * control characters do (^C, ^Z etc)
+ * - the caller must hold at least a readlock on tasklist_lock
  */
-
 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
 {
         struct task_struct *p = NULL;
@@ -1086,6 +1106,7 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
 {
         int ret = -EINVAL;
         struct task_struct *p;
+        const struct cred *pcred;
 
         if (!valid_signal(sig))
                 return ret;
@@ -1096,9 +1117,11 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
                 ret = -ESRCH;
                 goto out_unlock;
         }
-        if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
-            && (euid != p->suid) && (euid != p->uid)
-            && (uid != p->suid) && (uid != p->uid)) {
+        pcred = __task_cred(p);
+        if ((info == SEND_SIG_NOINFO ||
+             (!is_si_special(info) && SI_FROMUSER(info))) &&
+            euid != pcred->suid && euid != pcred->uid &&
+            uid  != pcred->suid && uid  != pcred->uid) {
                 ret = -EPERM;
                 goto out_unlock;
         }
@@ -1369,10 +1392,9 @@ int do_notify_parent(struct task_struct *tsk, int sig)
          */
         rcu_read_lock();
         info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+        info.si_uid = __task_cred(tsk)->uid;
         rcu_read_unlock();
 
-        info.si_uid = tsk->uid;
-
         thread_group_cputime(tsk, &cputime);
         info.si_utime = cputime_to_jiffies(cputime.utime);
         info.si_stime = cputime_to_jiffies(cputime.stime);
@@ -1440,10 +1462,9 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
          */
         rcu_read_lock();
         info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+        info.si_uid = __task_cred(tsk)->uid;
         rcu_read_unlock();
 
-        info.si_uid = tsk->uid;
-
         info.si_utime = cputime_to_clock_t(tsk->utime);
         info.si_stime = cputime_to_clock_t(tsk->stime);
 
@@ -1598,7 +1619,7 @@ void ptrace_notify(int exit_code)
         info.si_signo = SIGTRAP;
         info.si_code = exit_code;
         info.si_pid = task_pid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         /* Let the debugger run.  */
         spin_lock_irq(&current->sighand->siglock);
@@ -1710,7 +1731,7 @@ static int ptrace_signal(int signr, siginfo_t *info,
                 info->si_errno = 0;
                 info->si_code = SI_USER;
                 info->si_pid = task_pid_vnr(current->parent);
-                info->si_uid = current->parent->uid;
+                info->si_uid = task_uid(current->parent);
         }
 
         /* If the (new) signal is now blocked, requeue it.  */
@@ -1940,7 +1961,7 @@ EXPORT_SYMBOL(unblock_all_signals);
  * System call entry points.
  */
 
-asmlinkage long sys_restart_syscall(void)
+SYSCALL_DEFINE0(restart_syscall)
 {
         struct restart_block *restart = &current_thread_info()->restart_block;
         return restart->fn(restart);
@@ -1993,8 +2014,8 @@ int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
         return error;
 }
 
-asmlinkage long
-sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
+SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, set,
+                sigset_t __user *, oset, size_t, sigsetsize)
 {
         int error = -EINVAL;
         sigset_t old_set, new_set;
@@ -2053,8 +2074,7 @@ out:
         return error;
 }       
 
-asmlinkage long
-sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
+SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
 {
         return do_sigpending(set, sigsetsize);
 }
@@ -2125,11 +2145,9 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
 
 #endif
 
-asmlinkage long
-sys_rt_sigtimedwait(const sigset_t __user *uthese,
-                    siginfo_t __user *uinfo,
-                    const struct timespec __user *uts,
-                    size_t sigsetsize)
+SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
+                siginfo_t __user *, uinfo, const struct timespec __user *, uts,
+                size_t, sigsetsize)
 {
         int ret, sig;
         sigset_t these;
@@ -2202,8 +2220,7 @@ sys_rt_sigtimedwait(const sigset_t __user *uthese,
         return ret;
 }
 
-asmlinkage long
-sys_kill(pid_t pid, int sig)
+SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
 {
         struct siginfo info;
 
@@ -2211,7 +2228,7 @@ sys_kill(pid_t pid, int sig)
         info.si_errno = 0;
         info.si_code = SI_USER;
         info.si_pid = task_tgid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         return kill_something_info(sig, &info, pid);
 }
@@ -2228,7 +2245,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
         info.si_errno = 0;
         info.si_code = SI_TKILL;
         info.si_pid = task_tgid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         rcu_read_lock();
         p = find_task_by_vpid(pid);
@@ -2262,7 +2279,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
  *  exists but it's not belonging to the target process anymore. This
  *  method solves the problem of threads exiting and PIDs getting reused.
  */
-asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
+SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
 {
         /* This is only valid for single tasks */
         if (pid <= 0 || tgid <= 0)
@@ -2274,8 +2291,7 @@ asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
 /*
  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
  */
-asmlinkage long
-sys_tkill(pid_t pid, int sig)
+SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
 {
         /* This is only valid for single tasks */
         if (pid <= 0)
@@ -2284,8 +2300,8 @@ sys_tkill(pid_t pid, int sig)
         return do_tkill(0, pid, sig);
 }
 
-asmlinkage long
-sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
+SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
+                siginfo_t __user *, uinfo)
 {
         siginfo_t info;
 
@@ -2413,8 +2429,7 @@ out:
 
 #ifdef __ARCH_WANT_SYS_SIGPENDING
 
-asmlinkage long
-sys_sigpending(old_sigset_t __user *set)
+SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
 {
         return do_sigpending(set, sizeof(*set));
 }
@@ -2425,8 +2440,8 @@ sys_sigpending(old_sigset_t __user *set)
 /* Some platforms have their own version with special arguments others
    support only sys_rt_sigprocmask.  */
 
-asmlinkage long
-sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
+SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set,
+                old_sigset_t __user *, oset)
 {
         int error;
         old_sigset_t old_set, new_set;
@@ -2476,11 +2491,10 @@ out:
 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
 
 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
-asmlinkage long
-sys_rt_sigaction(int sig,
-                 const struct sigaction __user *act,
-                 struct sigaction __user *oact,
-                 size_t sigsetsize)
+SYSCALL_DEFINE4(rt_sigaction, int, sig,
+                const struct sigaction __user *, act,
+                struct sigaction __user *, oact,
+                size_t, sigsetsize)
 {
         struct k_sigaction new_sa, old_sa;
         int ret = -EINVAL;
@@ -2510,15 +2524,13 @@ out:
 /*
  * For backwards compatibility.  Functionality superseded by sigprocmask.
  */
-asmlinkage long
-sys_sgetmask(void)
+SYSCALL_DEFINE0(sgetmask)
 {
         /* SMP safe */
         return current->blocked.sig[0];
 }
 
-asmlinkage long
-sys_ssetmask(int newmask)
+SYSCALL_DEFINE1(ssetmask, int, newmask)
 {
         int old;
 
@@ -2538,8 +2550,7 @@ sys_ssetmask(int newmask)
 /*
  * For backwards compatibility.  Functionality superseded by sigaction.
  */
-asmlinkage unsigned long
-sys_signal(int sig, __sighandler_t handler)
+SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
 {
         struct k_sigaction new_sa, old_sa;
         int ret;
@@ -2556,8 +2567,7 @@ sys_signal(int sig, __sighandler_t handler)
 
 #ifdef __ARCH_WANT_SYS_PAUSE
 
-asmlinkage long
-sys_pause(void)
+SYSCALL_DEFINE0(pause)
 {
         current->state = TASK_INTERRUPTIBLE;
         schedule();
@@ -2567,7 +2577,7 @@ sys_pause(void)
 #endif
 
 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
-asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
+SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
 {
         sigset_t newset;