* Manage the dynamic fd arrays in the process files_struct.
*/
+#include <linux/syscalls.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
* expanded and execution may have blocked.
* The files->file_lock should be held on entry, and will be held on exit.
*/
-int expand_files(struct files_struct *files, int nr)
+static int expand_files(struct files_struct *files, int nr)
{
struct fdtable *fdt;
return expand_fdtable(files, nr);
}
+static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
+{
+ __set_bit(fd, fdt->close_on_exec);
+}
+
+static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
+{
+ __clear_bit(fd, fdt->close_on_exec);
+}
+
+static inline void __set_open_fd(int fd, struct fdtable *fdt)
+{
+ __set_bit(fd, fdt->open_fds);
+}
+
+static inline void __clear_open_fd(int fd, struct fdtable *fdt)
+{
+ __clear_bit(fd, fdt->open_fds);
+}
+
static int count_open_files(struct fdtable *fdt)
{
int size = fdt->max_fds;
.file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
};
+void daemonize_descriptors(void)
+{
+ atomic_inc(&init_files.count);
+ reset_files_struct(&init_files);
+}
+
/*
* allocate a file descriptor, mark it busy.
*/
return error;
}
-int alloc_fd(unsigned start, unsigned flags)
+static int alloc_fd(unsigned start, unsigned flags)
{
return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags);
}
}
EXPORT_SYMBOL(fd_install);
+
+/*
+ * The same warnings as for __alloc_fd()/__fd_install() apply here...
+ */
+int __close_fd(struct files_struct *files, unsigned fd)
+{
+ struct file *file;
+ struct fdtable *fdt;
+
+ spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
+ if (fd >= fdt->max_fds)
+ goto out_unlock;
+ file = fdt->fd[fd];
+ if (!file)
+ goto out_unlock;
+ rcu_assign_pointer(fdt->fd[fd], NULL);
+ __clear_close_on_exec(fd, fdt);
+ __put_unused_fd(files, fd);
+ spin_unlock(&files->file_lock);
+ return filp_close(file, files);
+
+out_unlock:
+ spin_unlock(&files->file_lock);
+ return -EBADF;
+}
+
+void do_close_on_exec(struct files_struct *files)
+{
+ unsigned i;
+ struct fdtable *fdt;
+
+ /* exec unshares first */
+ BUG_ON(atomic_read(&files->count) != 1);
+ spin_lock(&files->file_lock);
+ for (i = 0; ; i++) {
+ unsigned long set;
+ unsigned fd = i * BITS_PER_LONG;
+ fdt = files_fdtable(files);
+ if (fd >= fdt->max_fds)
+ break;
+ set = fdt->close_on_exec[i];
+ if (!set)
+ continue;
+ fdt->close_on_exec[i] = 0;
+ for ( ; set ; fd++, set >>= 1) {
+ struct file *file;
+ if (!(set & 1))
+ continue;
+ file = fdt->fd[fd];
+ if (!file)
+ continue;
+ rcu_assign_pointer(fdt->fd[fd], NULL);
+ __put_unused_fd(files, fd);
+ spin_unlock(&files->file_lock);
+ filp_close(file, files);
+ cond_resched();
+ spin_lock(&files->file_lock);
+ }
+
+ }
+ spin_unlock(&files->file_lock);
+}
+
+struct file *fget(unsigned int fd)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ /* File object ref couldn't be taken */
+ if (file->f_mode & FMODE_PATH ||
+ !atomic_long_inc_not_zero(&file->f_count))
+ file = NULL;
+ }
+ rcu_read_unlock();
+
+ return file;
+}
+
+EXPORT_SYMBOL(fget);
+
+struct file *fget_raw(unsigned int fd)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ /* File object ref couldn't be taken */
+ if (!atomic_long_inc_not_zero(&file->f_count))
+ file = NULL;
+ }
+ rcu_read_unlock();
+
+ return file;
+}
+
+EXPORT_SYMBOL(fget_raw);
+
+/*
+ * Lightweight file lookup - no refcnt increment if fd table isn't shared.
+ *
+ * You can use this instead of fget if you satisfy all of the following
+ * conditions:
+ * 1) You must call fput_light before exiting the syscall and returning control
+ * to userspace (i.e. you cannot remember the returned struct file * after
+ * returning to userspace).
+ * 2) You must not call filp_close on the returned struct file * in between
+ * calls to fget_light and fput_light.
+ * 3) You must not clone the current task in between the calls to fget_light
+ * and fput_light.
+ *
+ * The fput_needed flag returned by fget_light should be passed to the
+ * corresponding fput_light.
+ */
+struct file *fget_light(unsigned int fd, int *fput_needed)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ *fput_needed = 0;
+ if (atomic_read(&files->count) == 1) {
+ file = fcheck_files(files, fd);
+ if (file && (file->f_mode & FMODE_PATH))
+ file = NULL;
+ } else {
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ if (!(file->f_mode & FMODE_PATH) &&
+ atomic_long_inc_not_zero(&file->f_count))
+ *fput_needed = 1;
+ else
+ /* Didn't get the reference, someone's freed */
+ file = NULL;
+ }
+ rcu_read_unlock();
+ }
+
+ return file;
+}
+EXPORT_SYMBOL(fget_light);
+
+struct file *fget_raw_light(unsigned int fd, int *fput_needed)
+{
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ *fput_needed = 0;
+ if (atomic_read(&files->count) == 1) {
+ file = fcheck_files(files, fd);
+ } else {
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ if (atomic_long_inc_not_zero(&file->f_count))
+ *fput_needed = 1;
+ else
+ /* Didn't get the reference, someone's freed */
+ file = NULL;
+ }
+ rcu_read_unlock();
+ }
+
+ return file;
+}
+
+void set_close_on_exec(unsigned int fd, int flag)
+{
+ struct files_struct *files = current->files;
+ struct fdtable *fdt;
+ spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
+ if (flag)
+ __set_close_on_exec(fd, fdt);
+ else
+ __clear_close_on_exec(fd, fdt);
+ spin_unlock(&files->file_lock);
+}
+
+bool get_close_on_exec(unsigned int fd)
+{
+ struct files_struct *files = current->files;
+ struct fdtable *fdt;
+ bool res;
+ rcu_read_lock();
+ fdt = files_fdtable(files);
+ res = close_on_exec(fd, fdt);
+ rcu_read_unlock();
+ return res;
+}
+
+static int do_dup2(struct files_struct *files,
+ struct file *file, unsigned fd, unsigned flags)
+{
+ struct file *tofree;
+ struct fdtable *fdt;
+
+ /*
+ * We need to detect attempts to do dup2() over allocated but still
+ * not finished descriptor. NB: OpenBSD avoids that at the price of
+ * extra work in their equivalent of fget() - they insert struct
+ * file immediately after grabbing descriptor, mark it larval if
+ * more work (e.g. actual opening) is needed and make sure that
+ * fget() treats larval files as absent. Potentially interesting,
+ * but while extra work in fget() is trivial, locking implications
+ * and amount of surgery on open()-related paths in VFS are not.
+ * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
+ * deadlocks in rather amusing ways, AFAICS. All of that is out of
+ * scope of POSIX or SUS, since neither considers shared descriptor
+ * tables and this condition does not arise without those.
+ */
+ fdt = files_fdtable(files);
+ tofree = fdt->fd[fd];
+ if (!tofree && fd_is_open(fd, fdt))
+ goto Ebusy;
+ get_file(file);
+ rcu_assign_pointer(fdt->fd[fd], file);
+ __set_open_fd(fd, fdt);
+ if (flags & O_CLOEXEC)
+ __set_close_on_exec(fd, fdt);
+ else
+ __clear_close_on_exec(fd, fdt);
+ spin_unlock(&files->file_lock);
+
+ if (tofree)
+ filp_close(tofree, files);
+
+ return fd;
+
+Ebusy:
+ spin_unlock(&files->file_lock);
+ return -EBUSY;
+}
+
+int replace_fd(unsigned fd, struct file *file, unsigned flags)
+{
+ int err;
+ struct files_struct *files = current->files;
+
+ if (!file)
+ return __close_fd(files, fd);
+
+ if (fd >= rlimit(RLIMIT_NOFILE))
+ return -EMFILE;
+
+ spin_lock(&files->file_lock);
+ err = expand_files(files, fd);
+ if (unlikely(err < 0))
+ goto out_unlock;
+ return do_dup2(files, file, fd, flags);
+
+out_unlock:
+ spin_unlock(&files->file_lock);
+ return err;
+}
+
+SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
+{
+ int err = -EBADF;
+ struct file *file;
+ struct files_struct *files = current->files;
+
+ if ((flags & ~O_CLOEXEC) != 0)
+ return -EINVAL;
+
+ if (newfd >= rlimit(RLIMIT_NOFILE))
+ return -EMFILE;
+
+ spin_lock(&files->file_lock);
+ err = expand_files(files, newfd);
+ file = fcheck(oldfd);
+ if (unlikely(!file))
+ goto Ebadf;
+ if (unlikely(err < 0)) {
+ if (err == -EMFILE)
+ goto Ebadf;
+ goto out_unlock;
+ }
+ return do_dup2(files, file, newfd, flags);
+
+Ebadf:
+ err = -EBADF;
+out_unlock:
+ spin_unlock(&files->file_lock);
+ return err;
+}
+
+SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
+{
+ if (unlikely(newfd == oldfd)) { /* corner case */
+ struct files_struct *files = current->files;
+ int retval = oldfd;
+
+ rcu_read_lock();
+ if (!fcheck_files(files, oldfd))
+ retval = -EBADF;
+ rcu_read_unlock();
+ return retval;
+ }
+ return sys_dup3(oldfd, newfd, 0);
+}
+
+SYSCALL_DEFINE1(dup, unsigned int, fildes)
+{
+ int ret = -EBADF;
+ struct file *file = fget_raw(fildes);
+
+ if (file) {
+ ret = get_unused_fd();
+ if (ret >= 0)
+ fd_install(ret, file);
+ else
+ fput(file);
+ }
+ return ret;
+}
+
+int f_dupfd(unsigned int from, struct file *file, unsigned flags)
+{
+ int err;
+ if (from >= rlimit(RLIMIT_NOFILE))
+ return -EINVAL;
+ err = alloc_fd(from, flags);
+ if (err >= 0) {
+ get_file(file);
+ fd_install(err, file);
+ }
+ return err;
+}
+
+int iterate_fd(struct files_struct *files, unsigned n,
+ int (*f)(const void *, struct file *, unsigned),
+ const void *p)
+{
+ struct fdtable *fdt;
+ struct file *file;
+ int res = 0;
+ if (!files)
+ return 0;
+ spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
+ while (!res && n < fdt->max_fds) {
+ file = rcu_dereference_check_fdtable(files, fdt->fd[n++]);
+ if (file)
+ res = f(p, file, n);
+ }
+ spin_unlock(&files->file_lock);
+ return res;
+}
+EXPORT_SYMBOL(iterate_fd);
projects / karo-tx-linux.git / blobdiff