[PATCH 7/7] file: Modify struct fown_struct to use a struct pid.

From: Eric W. Biederman
Date: Tue Aug 15 2006 - 14:23:32 EST

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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@xxxxxxxxxxxx>
---
drivers/net/tun.c | 2 +
fs/dnotify.c | 2 +
fs/fcntl.c | 78 +++++++++++++++++++++++++++++++++-------------------
fs/file_table.c | 1 +
fs/locks.c | 2 +
include/linux/fs.h | 5 +++
kernel/futex.c | 2 +
net/socket.c | 2 +
8 files changed, 60 insertions(+), 34 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9ab8ca6..c78d79c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -697,7 +697,7 @@ static int tun_chr_fasync(int fd, struct
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;
diff --git a/fs/dnotify.c b/fs/dnotify.c
index f932591..2b0442d 100644
--- a/fs/dnotify.c
+++ b/fs/dnotify.c
@@ -92,7 +92,7 @@ int fcntl_dirnotify(int fd, struct file
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;

diff --git a/fs/fcntl.c b/fs/fcntl.c
index b43d821..55d387c 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -250,19 +250,21 @@ static int setfl(int fd, struct file * f
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 +272,44 @@ int f_setown(struct file *filp, unsigned
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 (sock->file->f_owner.pid_type == PIDTYPE_PGID)
+ pid = -pid;
+ return pid;
}

static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
@@ -319,7 +350,7 @@ static long do_fcntl(int fd, unsigned in
* 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 +501,19 @@ static void send_sigio_to_task(struct ta
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 +529,12 @@ static void send_sigurg_to_task(struct t
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 +542,9 @@ 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);
diff --git a/fs/file_table.c b/fs/file_table.c
index 2d9069c..c64764a 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -181,6 +181,7 @@ #endif
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;
diff --git a/fs/locks.c b/fs/locks.c
index d7c5339..b12e819 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1514,7 +1514,7 @@ int fcntl_setlease(unsigned int fd, stru
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;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 50e6eb2..b74d39b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -667,7 +667,8 @@ extern struct block_device *I_BDEV(struc

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 */
};
@@ -919,8 +920,10 @@ extern void kill_fasync(struct fasync_st
/* 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);

/*
diff --git a/kernel/futex.c b/kernel/futex.c
index d4633c5..d78d898 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1589,7 +1589,7 @@ static int futex_fd(u32 __user *uaddr, i
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;
}
diff --git a/net/socket.c b/net/socket.c
index 2bfc60a..a66bd4c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -825,7 +825,7 @@ #endif /* CONFIG_WIRELESS_EXT */
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:
--
1.4.2.rc3.g7e18e-dirty

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Next message: Eric W. Biederman: "[PATCH 6/7] vt: Update spawnpid to be a struct pid_t"
Previous message: Roger Heflin: "Re: What's the NFS OOM problem?"
In reply to: Dave Hansen: "Re: [Containers] [PATCH 5/7] pid: Implement pid_nr"
Next in thread: Eric W. Biederman: "[PATCH 6/7] vt: Update spawnpid to be a struct pid_t"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]