[PATCH] Isolate some explicit usage of task->tgid

From: Pavel Emelyanov
Date: Fri Aug 17 2007 - 10:19:01 EST

With pid namespaces this field is now dangerous to use explicitly, so hide it behind the helpers.

Also the pid and pgrp fields o task_struct and signal_struct are to be deprecated. Unfortunately this patch cannot be sent right now as this leads to tons of warnings, so start isolating them, and deprecate later.

Actually the p->tgid == pid has to be changed to has_group_leader_pid(), but Oleg pointed out that this is the same and thread_group_leader() is more preferable.

Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>

---

fs/exec.c | 4 ++--
fs/proc/base.c | 4 ++--
include/linux/sched.h | 6 ++++++
kernel/posix-cpu-timers.c | 12 ++++++------
kernel/posix-timers.c | 4 ++--
kernel/ptrace.c | 2 +-
kernel/signal.c | 2 +-
mm/oom_kill.c | 2 +-
8 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f8cebf8..24b669d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1691,6 +1691,12 @@ static inline int has_group_leader_pid(s
return p->pid == p->tgid;
}

+static inline
+int same_thread_group(struct task_struct *p1, struct task_struct *p2)
+{
+ return p1->tgid == p2->tgid;
+}
+
static inline struct task_struct *next_thread(const struct task_struct *p)
{
return list_entry(rcu_dereference(p->thread_group.next),
diff --git a/fs/exec.c b/fs/exec.c
index 35013f2..415cefb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -865,8 +865,8 @@ static int de_thread(struct task_struct

write_lock_irq(&tasklist_lock);

- BUG_ON(leader->tgid != tsk->tgid);
- BUG_ON(tsk->pid == tsk->tgid);
+ BUG_ON(!same_thread_group(leader, tsk));
+ BUG_ON(thread_group_leader(tsk));
/*
* An exec() starts a new thread group with the
* TGID of the previous thread group. Rehash the
diff --git a/fs/proc/base.c b/fs/proc/base.c
index e3009ab..31e7dfe 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2288,7 +2288,7 @@ retry:
* found doesn't happen to be a thread group leader.
* As we don't care in the case of readdir.
*/
- if (!task || !has_group_leader_pid(task))
+ if (!task || !thread_group_leader(task))
goto retry;
get_task_struct(task);
}
@@ -2474,7 +2474,7 @@ static struct dentry *proc_task_lookup(s
rcu_read_unlock();
if (!task)
goto out;
- if (leader->tgid != task->tgid)
+ if (!same_thread_group(leader, task))
goto out_drop_task;

result = proc_task_instantiate(dir, dentry, task, NULL);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b53c8fc..68c9637 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -21,8 +21,8 @@ static int check_clock(const clockid_t w

read_lock(&tasklist_lock);
p = find_task_by_pid(pid);
- if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
- p->tgid != current->tgid : p->tgid != pid)) {
+ if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
+ same_thread_group(p, current) : thread_group_leader(p))) {
error = -EINVAL;
}
read_unlock(&tasklist_lock);
@@ -308,13 +308,13 @@ int posix_cpu_clock_get(const clockid_t p = find_task_by_pid(pid);
if (p) {
if (CPUCLOCK_PERTHREAD(which_clock)) {
- if (p->tgid == current->tgid) {
+ if (same_thread_group(p, current)) {
error = cpu_clock_sample(which_clock,
p, &rtn);
}
} else {
read_lock(&tasklist_lock);
- if (p->tgid == pid && p->signal) {
+ if (thread_group_leader(p) && p->signal) {
error =
cpu_clock_sample_group(which_clock,
p, &rtn);
@@ -355,7 +355,7 @@ int posix_cpu_timer_create(struct k_itim
p = current;
} else {
p = find_task_by_pid(pid);
- if (p && p->tgid != current->tgid)
+ if (p && !same_thread_group(p, current))
p = NULL;
}
} else {
@@ -363,7 +363,7 @@ int posix_cpu_timer_create(struct k_itim
p = current->group_leader;
} else {
p = find_task_by_pid(pid);
- if (p && p->tgid != pid)
+ if (p && !thread_group_leader(p))
p = NULL;
}
}
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 8d2cb05..bc77ba8 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -404,7 +404,7 @@ static struct task_struct * good_sigeven

if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
(!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
- rtn->tgid != current->tgid ||
+ !same_thread_group(rtn, current) ||
(event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
return NULL;

@@ -609,7 +609,7 @@ static struct k_itimer * lock_timer(time
spin_unlock(&idr_lock);

if ((timr->it_id != timer_id) || !(timr->it_process) ||
- timr->it_process->tgid != current->tgid) {
+ !same_thread_group(timr->it_process, current)) {
unlock_timer(timr, *flags);
timr = NULL;
}
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 0d7fd07..f90207a 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -169,7 +169,7 @@ int ptrace_attach(struct task_struct *ta
retval = -EPERM;
if (task->pid <= 1)
goto out;
- if (task->tgid == current->tgid)
+ if (same_thread_group(task, current))
goto out;

repeat:
diff --git a/kernel/signal.c b/kernel/signal.c
index d6ca591..df785a7 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1145,7 +1145,7 @@ static int kill_something_info(int sig,

read_lock(&tasklist_lock);
for_each_process(p) {
- if (p->pid > 1 && p->tgid != current->tgid) {
+ if (p->pid > 1 && !same_thread_group(p, current)) {
int err = group_send_sig_info(sig, info, p);
++count;
if (err != -EPERM)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index e276a3c..1a2f687 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -330,7 +330,7 @@ static int oom_kill_task(struct task_str
* to memory reserves though, otherwise we might deplete all memory.
*/
do_each_thread(g, q) {
- if (q->mm == mm && q->tgid != p->tgid)
+ if (q->mm == mm && !same_thread_group(q, p))
force_sig(SIGKILL, q);
} while_each_thread(g, q);

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