// SPDX-License-Identifier: GPL-2.0
+#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/magic.h>
#include <linux/mount.h>
#include <linux/pid.h>
+#include <linux/pidfs.h>
#include <linux/pid_namespace.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
static int pidfd_release(struct inode *inode, struct file *file)
{
+#ifndef CONFIG_FS_PID
struct pid *pid = file->private_data;
file->private_data = NULL;
put_pid(pid);
+#endif
return 0;
}
*/
static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
{
- struct pid *pid = f->private_data;
+ struct pid *pid = pidfd_pid(f);
struct pid_namespace *ns;
pid_t nr = -1;
*/
static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
{
- struct pid *pid = file->private_data;
+ struct pid *pid = pidfd_pid(file);
bool thread = file->f_flags & PIDFD_THREAD;
struct task_struct *task;
__poll_t poll_flags = 0;
return poll_flags;
}
-const struct file_operations pidfd_fops = {
+static const struct file_operations pidfs_file_operations = {
.release = pidfd_release,
.poll = pidfd_poll,
#ifdef CONFIG_PROC_FS
.show_fdinfo = pidfd_show_fdinfo,
#endif
};
+
+struct pid *pidfd_pid(const struct file *file)
+{
+ if (file->f_op != &pidfs_file_operations)
+ return ERR_PTR(-EBADF);
+#ifdef CONFIG_FS_PID
+ return file_inode(file)->i_private;
+#else
+ return file->private_data;
+#endif
+}
+
+#ifdef CONFIG_FS_PID
+static struct vfsmount *pidfs_mnt __ro_after_init;
+static struct super_block *pidfs_sb __ro_after_init;
+
+/*
+ * The vfs falls back to simple_setattr() if i_op->setattr() isn't
+ * implemented. Let's reject it completely until we have a clean
+ * permission concept for pidfds.
+ */
+static int pidfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+ struct iattr *attr)
+{
+ return -EOPNOTSUPP;
+}
+
+static int pidfs_getattr(struct mnt_idmap *idmap, const struct path *path,
+ struct kstat *stat, u32 request_mask,
+ unsigned int query_flags)
+{
+ struct inode *inode = d_inode(path->dentry);
+
+ generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
+ return 0;
+}
+
+static const struct inode_operations pidfs_inode_operations = {
+ .getattr = pidfs_getattr,
+ .setattr = pidfs_setattr,
+};
+
+static void pidfs_evict_inode(struct inode *inode)
+{
+ struct pid *pid = inode->i_private;
+
+ clear_inode(inode);
+ put_pid(pid);
+}
+
+static const struct super_operations pidfs_sops = {
+ .drop_inode = generic_delete_inode,
+ .evict_inode = pidfs_evict_inode,
+ .statfs = simple_statfs,
+};
+
+static char *pidfs_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+ return dynamic_dname(buffer, buflen, "pidfd:[%lu]",
+ d_inode(dentry)->i_ino);
+}
+
+static const struct dentry_operations pidfs_dentry_operations = {
+ .d_delete = always_delete_dentry,
+ .d_dname = pidfs_dname,
+};
+
+static int pidfs_init_fs_context(struct fs_context *fc)
+{
+ struct pseudo_fs_context *ctx;
+
+ ctx = init_pseudo(fc, PID_FS_MAGIC);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->ops = &pidfs_sops;
+ ctx->dops = &pidfs_dentry_operations;
+ return 0;
+}
+
+static struct file_system_type pidfs_type = {
+ .name = "pidfs",
+ .init_fs_context = pidfs_init_fs_context,
+ .kill_sb = kill_anon_super,
+};
+
+struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags)
+{
+
+ struct inode *inode;
+ struct file *pidfd_file;
+
+ inode = iget_locked(pidfs_sb, pid->ino);
+ if (!inode)
+ return ERR_PTR(-ENOMEM);
+
+ if (inode->i_state & I_NEW) {
+ /*
+ * Inode numbering for pidfs start at RESERVED_PIDS + 1.
+ * This avoids collisions with the root inode which is 1
+ * for pseudo filesystems.
+ */
+ inode->i_ino = pid->ino;
+ inode->i_mode = S_IFREG | S_IRUGO;
+ inode->i_op = &pidfs_inode_operations;
+ inode->i_fop = &pidfs_file_operations;
+ inode->i_flags |= S_IMMUTABLE;
+ inode->i_private = get_pid(pid);
+ simple_inode_init_ts(inode);
+ unlock_new_inode(inode);
+ }
+
+ pidfd_file = alloc_file_pseudo(inode, pidfs_mnt, "", flags,
+ &pidfs_file_operations);
+ if (IS_ERR(pidfd_file))
+ iput(inode);
+
+ return pidfd_file;
+}
+
+void __init pidfs_init(void)
+{
+ pidfs_mnt = kern_mount(&pidfs_type);
+ if (IS_ERR(pidfs_mnt))
+ panic("Failed to mount pidfs pseudo filesystem");
+
+ pidfs_sb = pidfs_mnt->mnt_sb;
+}
+
+#else /* !CONFIG_FS_PID */
+
+struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags)
+{
+ struct file *pidfd_file;
+
+ pidfd_file = anon_inode_getfile("[pidfd]", &pidfs_file_operations, pid,
+ flags | O_RDWR);
+ if (IS_ERR(pidfd_file))
+ return pidfd_file;
+
+ get_pid(pid);
+ return pidfd_file;
+}
+
+void __init pidfs_init(void) { }
+#endif
projects / thirdparty / linux.git / commitdiff
