From 609d7fa9565c754428d2520cac2accc9052e1245 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 2 Oct 2006 02:17:15 -0700 Subject: [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fcntl.c | 77 +++++++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 49 insertions(+), 28 deletions(-) (limited to 'fs/fcntl.c') diff --git a/fs/fcntl.c b/fs/fcntl.c index d35cbc6bc11..e7c66a1bf83 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -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); -- cgit v1.2.3