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[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: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Eric W. Biederman 2006-10-02 02:17:15 -07:00 committed by Linus Torvalds
parent bde0d2c98b
commit 609d7fa956
8 changed files with 59 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/tun.c
View File

@ -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;

2
fs/dnotify.c
View File

@ -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;

77
fs/fcntl.c
View File

@ -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) {
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);
}
do_each_pid_task(pid, type, p) {
send_sigio_to_task(p, fown, fd, band);
} 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) {
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);
}
do_each_pid_task(pid, type, p) {
send_sigurg_to_task(p, fown);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
out_unlock_fown:
read_unlock(&fown->lock);

1
fs/file_table.c
View File

@ -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;

2
fs/locks.c
View File

@ -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;

5
include/linux/fs.h
View File

@ -684,7 +684,8 @@ extern struct block_device *I_BDEV(struct inode *inode);
struct fown_struct {
rwlock_t lock; /* protects pid, uid, euid fields */
int pid; /* pid or -pgrp where SIGIO should be sent */
struct pid *pid; /* pid or -pgrp where SIGIO should be sent */
enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
uid_t uid, euid; /* uid/euid of process setting the owner */
int signum; /* posix.1b rt signal to be delivered on IO */
};
@ -880,8 +881,10 @@ extern void kill_fasync(struct fasync_struct **, int, int);
/* only for net: no internal synchronization */
extern void __kill_fasync(struct fasync_struct *, int, int);
extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
extern int f_setown(struct file *filp, unsigned long arg, int force);
extern void f_delown(struct file *filp);
extern pid_t f_getown(struct file *filp);
extern int send_sigurg(struct fown_struct *fown);
/*

2
kernel/futex.c
View File

@ -1527,7 +1527,7 @@ static int futex_fd(u32 __user *uaddr, int signal)
filp->f_mapping = filp->f_dentry->d_inode->i_mapping;
if (signal) {
err = f_setown(filp, current->pid, 1);
err = __f_setown(filp, task_pid(current), PIDTYPE_PID, 1);
if (err < 0) {
goto error;
}

2
net/socket.c
View File

@ -825,7 +825,7 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
break;
case FIOGETOWN:
case SIOCGPGRP:
err = put_user(sock->file->f_owner.pid,
err = put_user(f_getown(sock->file),
(int __user *)argp);
break;
case SIOCGIFBR: