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Commit 609d7fa9 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
Browse files

[PATCH] file: modify struct fown_struct to use a struct pid 



File handles can be requested to send sigio and sigurg to processes.  By
tracking the destination processes using struct pid instead of pid_t we make
the interface safe from all potential pid wrap around problems.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent bde0d2c9

drivers/net/tun.c

+1 −1
Original line number Diff line number Diff line
@@ -697,7 +697,7 @@ static int tun_chr_fasync(int fd, struct file *file, int on) 
		return ret;



	if (on) {

		ret = f_setown(file, current->pid, 0);

		ret = __f_setown(file, task_pid(current), PIDTYPE_PID, 0);

		if (ret)

			return ret;

		tun->flags |= TUN_FASYNC;

fs/dnotify.c

+1 −1
Original line number Diff line number Diff line
@@ -92,7 +92,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) 
		prev = &odn->dn_next;

	}



	error = f_setown(filp, current->pid, 0);

	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);

	if (error)

		goto out_free;

fs/fcntl.c

+49 −28
Original line number Diff line number Diff line
@@ -250,19 +250,22 @@ static int setfl(int fd, struct file * filp, unsigned long arg) 
	return error;

}



static void f_modown(struct file *filp, unsigned long pid,

static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,

                     uid_t uid, uid_t euid, int force)

{

	write_lock_irq(&filp->f_owner.lock);

	if (force || !filp->f_owner.pid) {

		filp->f_owner.pid = pid;

		put_pid(filp->f_owner.pid);

		filp->f_owner.pid = get_pid(pid);

		filp->f_owner.pid_type = type;

		filp->f_owner.uid = uid;

		filp->f_owner.euid = euid;

	}

	write_unlock_irq(&filp->f_owner.lock);

}



int f_setown(struct file *filp, unsigned long arg, int force)

int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,

		int force)

{

	int err;
@@ -270,15 +273,42 @@ int f_setown(struct file *filp, unsigned long arg, int force) 
	if (err)

		return err;



	f_modown(filp, arg, current->uid, current->euid, force);

	f_modown(filp, pid, type, current->uid, current->euid, force);

	return 0;

}

EXPORT_SYMBOL(__f_setown);



int f_setown(struct file *filp, unsigned long arg, int force)

{

	enum pid_type type;

	struct pid *pid;

	int who = arg;

	int result;

	type = PIDTYPE_PID;

	if (who < 0) {

		type = PIDTYPE_PGID;

		who = -who;

	}

	rcu_read_lock();

	pid = find_pid(who);

	result = __f_setown(filp, pid, type, force);

	rcu_read_unlock();

	return result;

}

EXPORT_SYMBOL(f_setown);



void f_delown(struct file *filp)

{

	f_modown(filp, 0, 0, 0, 1);

	f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1);

}



pid_t f_getown(struct file *filp)

{

	pid_t pid;

	pid = pid_nr(filp->f_owner.pid);

	if (filp->f_owner.pid_type == PIDTYPE_PGID)

		pid = -pid;

	return pid;

}



static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
@@ -319,7 +349,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 
		 * current syscall conventions, the only way

		 * to fix this will be in libc.

		 */

		err = filp->f_owner.pid;

		err = f_getown(filp);

		force_successful_syscall_return();

		break;

	case F_SETOWN:
@@ -470,24 +500,19 @@ static void send_sigio_to_task(struct task_struct *p, 
void send_sigio(struct fown_struct *fown, int fd, int band)

{

	struct task_struct *p;

	int pid;

	enum pid_type type;

	struct pid *pid;

	

	read_lock(&fown->lock);

	type = fown->pid_type;

	pid = fown->pid;

	if (!pid)

		goto out_unlock_fown;

	

	read_lock(&tasklist_lock);

	if (pid > 0) {

		p = find_task_by_pid(pid);

		if (p) {

	do_each_pid_task(pid, type, p) {

		send_sigio_to_task(p, fown, fd, band);

		}

	} else {

		do_each_task_pid(-pid, PIDTYPE_PGID, p) {

			send_sigio_to_task(p, fown, fd, band);

		} while_each_task_pid(-pid, PIDTYPE_PGID, p);

	}

	} while_each_pid_task(pid, type, p);

	read_unlock(&tasklist_lock);

 out_unlock_fown:

	read_unlock(&fown->lock);
@@ -503,9 +528,12 @@ static void send_sigurg_to_task(struct task_struct *p, 
int send_sigurg(struct fown_struct *fown)

{

	struct task_struct *p;

	int pid, ret = 0;

	enum pid_type type;

	struct pid *pid;

	int ret = 0;

	

	read_lock(&fown->lock);

	type = fown->pid_type;

	pid = fown->pid;

	if (!pid)

		goto out_unlock_fown;
@@ -513,16 +541,9 @@ int send_sigurg(struct fown_struct *fown) 
	ret = 1;

	

	read_lock(&tasklist_lock);

	if (pid > 0) {

		p = find_task_by_pid(pid);

		if (p) {

	do_each_pid_task(pid, type, p) {

		send_sigurg_to_task(p, fown);

		}

	} else {

		do_each_task_pid(-pid, PIDTYPE_PGID, p) {

			send_sigurg_to_task(p, fown);

		} while_each_task_pid(-pid, PIDTYPE_PGID, p);

	}

	} while_each_pid_task(pid, type, p);

	read_unlock(&tasklist_lock);

 out_unlock_fown:

	read_unlock(&fown->lock);

fs/file_table.c

+1 −0
Original line number Diff line number Diff line
@@ -174,6 +174,7 @@ void fastcall __fput(struct file *file) 
	fops_put(file->f_op);

	if (file->f_mode & FMODE_WRITE)

		put_write_access(inode);

	put_pid(file->f_owner.pid);

	file_kill(file);

	file->f_dentry = NULL;

	file->f_vfsmnt = NULL;

fs/locks.c

+1 −1
Original line number Diff line number Diff line
@@ -1514,7 +1514,7 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) 
		goto out_unlock;

	}



	error = f_setown(filp, current->pid, 0);

	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);

out_unlock:

	unlock_kernel();

	return error;