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signal: Use PIDTYPE_TGID to clearly store where file signals will be sent 

When f_setown is called a pid and a pid type are stored.  Replace the use
of PIDTYPE_PID with PIDTYPE_TGID as PIDTYPE_TGID goes to the entire thread
group.  Replace the use of PIDTYPE_MAX with PIDTYPE_PID as PIDTYPE_PID now
is only for a thread.

Update the users of __f_setown to use PIDTYPE_TGID instead of
PIDTYPE_PID.

For now the code continues to capture task_pid (when task_tgid would
really be appropriate), and iterate on PIDTYPE_PID (even when type ==
PIDTYPE_TGID) out of an abundance of caution to preserve existing
behavior.

Oleg Nesterov suggested using the test to ensure we use PIDTYPE_PID
for tgid lookup also be used to avoid taking the tasklist lock.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2017-07-16 22:05:57 -05:00
parent 6883f81aac
commit 019191342f
5 changed files with 37 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/tun.c
View File

@ -3216,7 +3216,7 @@ static int tun_chr_fasync(int fd, struct file *file, int on)
goto out;
if (on) {
__f_setown(file, task_pid(current), PIDTYPE_PID, 0);
__f_setown(file, task_pid(current), PIDTYPE_TGID, 0);
tfile->flags |= TUN_FASYNC;
} else
tfile->flags &= ~TUN_FASYNC;

2
drivers/tty/tty_io.c
View File

@ -2122,7 +2122,7 @@ static int __tty_fasync(int fd, struct file *filp, int on)
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_PID;
type = PIDTYPE_TGID;
}
get_pid(pid);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);

34
fs/fcntl.c
View File

@ -116,7 +116,7 @@ int f_setown(struct file *filp, unsigned long arg, int force)
struct pid *pid = NULL;
int who = arg, ret = 0;
type = PIDTYPE_PID;
type = PIDTYPE_TGID;
if (who < 0) {
/* avoid overflow below */
if (who == INT_MIN)
@ -143,7 +143,7 @@ EXPORT_SYMBOL(f_setown);
void f_delown(struct file *filp)
{
f_modown(filp, NULL, PIDTYPE_PID, 1);
f_modown(filp, NULL, PIDTYPE_TGID, 1);
}
pid_t f_getown(struct file *filp)
@ -171,11 +171,11 @@ static int f_setown_ex(struct file *filp, unsigned long arg)
switch (owner.type) {
case F_OWNER_TID:
type = PIDTYPE_MAX;
type = PIDTYPE_PID;
break;
case F_OWNER_PID:
type = PIDTYPE_PID;
type = PIDTYPE_TGID;
break;
case F_OWNER_PGRP:
@ -206,11 +206,11 @@ static int f_getown_ex(struct file *filp, unsigned long arg)
read_lock(&filp->f_owner.lock);
owner.pid = pid_vnr(filp->f_owner.pid);
switch (filp->f_owner.pid_type) {
case PIDTYPE_MAX:
case PIDTYPE_PID:
owner.type = F_OWNER_TID;
break;
case PIDTYPE_PID:
case PIDTYPE_TGID:
owner.type = F_OWNER_PID;
break;
@ -785,20 +785,25 @@ void send_sigio(struct fown_struct *fown, int fd, int band)
read_lock(&fown->lock);
type = fown->pid_type;
if (type == PIDTYPE_MAX) {
if (type == PIDTYPE_PID)
group = 0;
type = PIDTYPE_PID;
}
pid = fown->pid;
if (!pid)
goto out_unlock_fown;
if (type <= PIDTYPE_TGID) {
rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
send_sigio_to_task(p, fown, fd, band, group);
rcu_read_unlock();
} else {
read_lock(&tasklist_lock);
do_each_pid_task(pid, type, p) {
send_sigio_to_task(p, fown, fd, band, group);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
}
out_unlock_fown:
read_unlock(&fown->lock);
}
@ -821,10 +826,8 @@ int send_sigurg(struct fown_struct *fown)
read_lock(&fown->lock);
type = fown->pid_type;
if (type == PIDTYPE_MAX) {
if (type == PIDTYPE_PID)
group = 0;
type = PIDTYPE_PID;
}
pid = fown->pid;
if (!pid)
@ -832,11 +835,18 @@ int send_sigurg(struct fown_struct *fown)
ret = 1;
if (type <= PIDTYPE_TGID) {
rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
send_sigurg_to_task(p, fown, group);
rcu_read_unlock();
} else {
read_lock(&tasklist_lock);
do_each_pid_task(pid, type, p) {
send_sigurg_to_task(p, fown, group);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
}
out_unlock_fown:
read_unlock(&fown->lock);
return ret;

2
fs/locks.c
View File

@ -546,7 +546,7 @@ lease_setup(struct file_lock *fl, void **priv)
if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
*priv = NULL;
__f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
}
static const struct lock_manager_operations lease_manager_ops = {

3
fs/notify/dnotify/dnotify.c
View File

@ -19,6 +19,7 @@
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/dnotify.h>
#include <linux/init.h>
#include <linux/spinlock.h>
@ -353,7 +354,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
goto out;
}
__f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
error = attach_dn(dn, dn_mark, id, fd, filp, mask);
/* !error means that we attached the dn to the dn_mark, so don't free it */