vfs: take /proc/*/mounts and friends to fs/proc_namespace.c

rationale: that stuff is far tighter bound to fs/namespace.c than to
the guts of procfs proper.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 331 insertions, 0 deletions

diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
new file mode 100644
index 000000000000..9dcd9543ca12
--- /dev/null
+++ b/fs/proc_namespace.c
@@ -0,0 +1,331 @@
+/*
+ * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
+ *
+ * In fact, that's a piece of procfs; it's *almost* isolated from
+ * the rest of fs/proc, but has rather close relationships with
+ * fs/namespace.c, thus here instead of fs/proc
+ *
+ */
+#include <linux/mnt_namespace.h>
+#include <linux/nsproxy.h>
+#include <linux/security.h>
+#include <linux/fs_struct.h>
+#include "proc/internal.h" /* only for get_proc_task() in ->open() */
+
+#include "pnode.h"
+#include "internal.h"
+
+static unsigned mounts_poll(struct file *file, poll_table *wait)
+{
+        struct proc_mounts *p = file->private_data;
+        struct mnt_namespace *ns = p->ns;
+        unsigned res = POLLIN | POLLRDNORM;
+
+        poll_wait(file, &p->ns->poll, wait);
+
+        br_read_lock(vfsmount_lock);
+        if (p->m.poll_event != ns->event) {
+                p->m.poll_event = ns->event;
+                res |= POLLERR | POLLPRI;
+        }
+        br_read_unlock(vfsmount_lock);
+
+        return res;
+}
+
+struct proc_fs_info {
+        int flag;
+        const char *str;
+};
+
+static int show_sb_opts(struct seq_file *m, struct super_block *sb)
+{
+        static const struct proc_fs_info fs_info[] = {
+                { MS_SYNCHRONOUS, ",sync" },
+                { MS_DIRSYNC, ",dirsync" },
+                { MS_MANDLOCK, ",mand" },
+                { 0, NULL }
+        };
+        const struct proc_fs_info *fs_infop;
+
+        for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
+                if (sb->s_flags & fs_infop->flag)
+                        seq_puts(m, fs_infop->str);
+        }
+
+        return security_sb_show_options(m, sb);
+}
+
+static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
+{
+        static const struct proc_fs_info mnt_info[] = {
+                { MNT_NOSUID, ",nosuid" },
+                { MNT_NODEV, ",nodev" },
+                { MNT_NOEXEC, ",noexec" },
+                { MNT_NOATIME, ",noatime" },
+                { MNT_NODIRATIME, ",nodiratime" },
+                { MNT_RELATIME, ",relatime" },
+                { 0, NULL }
+        };
+        const struct proc_fs_info *fs_infop;
+
+        for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
+                if (mnt->mnt_flags & fs_infop->flag)
+                        seq_puts(m, fs_infop->str);
+        }
+}
+
+static inline void mangle(struct seq_file *m, const char *s)
+{
+        seq_escape(m, s, " \t\n\\");
+}
+
+static void show_type(struct seq_file *m, struct super_block *sb)
+{
+        mangle(m, sb->s_type->name);
+        if (sb->s_subtype && sb->s_subtype[0]) {
+                seq_putc(m, '.');
+                mangle(m, sb->s_subtype);
+        }
+}
+
+static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
+{
+        struct mount *r = real_mount(mnt);
+        int err = 0;
+        struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+
+        if (mnt->mnt_sb->s_op->show_devname) {
+                err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+                if (err)
+                        goto out;
+        } else {
+                mangle(m, r->mnt_devname ? r->mnt_devname : "none");
+        }
+        seq_putc(m, ' ');
+        seq_path(m, &mnt_path, " \t\n\\");
+        seq_putc(m, ' ');
+        show_type(m, mnt->mnt_sb);
+        seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
+        err = show_sb_opts(m, mnt->mnt_sb);
+        if (err)
+                goto out;
+        show_mnt_opts(m, mnt);
+        if (mnt->mnt_sb->s_op->show_options)
+                err = mnt->mnt_sb->s_op->show_options(m, mnt);
+        seq_puts(m, " 0 0\n");
+out:
+        return err;
+}
+
+static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
+{
+        struct proc_mounts *p = m->private;
+        struct mount *r = real_mount(mnt);
+        struct super_block *sb = mnt->mnt_sb;
+        struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+        struct path root = p->root;
+        int err = 0;
+
+        seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
+                   MAJOR(sb->s_dev), MINOR(sb->s_dev));
+        if (sb->s_op->show_path)
+                err = sb->s_op->show_path(m, mnt);
+        else
+                seq_dentry(m, mnt->mnt_root, " \t\n\\");
+        if (err)
+                goto out;
+        seq_putc(m, ' ');
+
+        /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
+        err = seq_path_root(m, &mnt_path, &root, " \t\n\\");
+        if (err)
+                goto out;
+
+        seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
+        show_mnt_opts(m, mnt);
+
+        /* Tagged fields ("foo:X" or "bar") */
+        if (IS_MNT_SHARED(r))
+                seq_printf(m, " shared:%i", r->mnt_group_id);
+        if (IS_MNT_SLAVE(r)) {
+                int master = r->mnt_master->mnt_group_id;
+                int dom = get_dominating_id(r, &p->root);
+                seq_printf(m, " master:%i", master);
+                if (dom && dom != master)
+                        seq_printf(m, " propagate_from:%i", dom);
+        }
+        if (IS_MNT_UNBINDABLE(r))
+                seq_puts(m, " unbindable");
+
+        /* Filesystem specific data */
+        seq_puts(m, " - ");
+        show_type(m, sb);
+        seq_putc(m, ' ');
+        if (sb->s_op->show_devname)
+                err = sb->s_op->show_devname(m, mnt);
+        else
+                mangle(m, r->mnt_devname ? r->mnt_devname : "none");
+        if (err)
+                goto out;
+        seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
+        err = show_sb_opts(m, sb);
+        if (err)
+                goto out;
+        if (sb->s_op->show_options)
+                err = sb->s_op->show_options(m, mnt);
+        seq_putc(m, '\n');
+out:
+        return err;
+}
+
+static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
+{
+        struct mount *r = real_mount(mnt);
+        struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+        int err = 0;
+
+        /* device */
+        if (mnt->mnt_sb->s_op->show_devname) {
+                seq_puts(m, "device ");
+                err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+        } else {
+                if (r->mnt_devname) {
+                        seq_puts(m, "device ");
+                        mangle(m, r->mnt_devname);
+                } else
+                        seq_puts(m, "no device");
+        }
+
+        /* mount point */
+        seq_puts(m, " mounted on ");
+        seq_path(m, &mnt_path, " \t\n\\");
+        seq_putc(m, ' ');
+
+        /* file system type */
+        seq_puts(m, "with fstype ");
+        show_type(m, mnt->mnt_sb);
+
+        /* optional statistics */
+        if (mnt->mnt_sb->s_op->show_stats) {
+                seq_putc(m, ' ');
+                if (!err)
+                        err = mnt->mnt_sb->s_op->show_stats(m, mnt);
+        }
+
+        seq_putc(m, '\n');
+        return err;
+}
+
+static int mounts_open_common(struct inode *inode, struct file *file,
+                              int (*show)(struct seq_file *, struct vfsmount *))
+{
+        struct task_struct *task = get_proc_task(inode);
+        struct nsproxy *nsp;
+        struct mnt_namespace *ns = NULL;
+        struct path root;
+        struct proc_mounts *p;
+        int ret = -EINVAL;
+
+        if (!task)
+                goto err;
+
+        rcu_read_lock();
+        nsp = task_nsproxy(task);
+        if (!nsp) {
+                rcu_read_unlock();
+                put_task_struct(task);
+                goto err;
+        }
+        ns = nsp->mnt_ns;
+        if (!ns) {
+                rcu_read_unlock();
+                put_task_struct(task);
+                goto err;
+        }
+        get_mnt_ns(ns);
+        rcu_read_unlock();
+        task_lock(task);
+        if (!task->fs) {
+                task_unlock(task);
+                put_task_struct(task);
+                ret = -ENOENT;
+                goto err_put_ns;
+        }
+        get_fs_root(task->fs, &root);
+        task_unlock(task);
+        put_task_struct(task);
+
+        ret = -ENOMEM;
+        p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
+        if (!p)
+                goto err_put_path;
+
+        file->private_data = &p->m;
+        ret = seq_open(file, &mounts_op);
+        if (ret)
+                goto err_free;
+
+        p->m.private = p;
+        p->ns = ns;
+        p->root = root;
+        p->m.poll_event = ns->event;
+        p->show = show;
+
+        return 0;
+
+ err_free:
+        kfree(p);
+ err_put_path:
+        path_put(&root);
+ err_put_ns:
+        put_mnt_ns(ns);
+ err:
+        return ret;
+}
+
+static int mounts_release(struct inode *inode, struct file *file)
+{
+        struct proc_mounts *p = file->private_data;
+        path_put(&p->root);
+        put_mnt_ns(p->ns);
+        return seq_release(inode, file);
+}
+
+static int mounts_open(struct inode *inode, struct file *file)
+{
+        return mounts_open_common(inode, file, show_vfsmnt);
+}
+
+static int mountinfo_open(struct inode *inode, struct file *file)
+{
+        return mounts_open_common(inode, file, show_mountinfo);
+}
+
+static int mountstats_open(struct inode *inode, struct file *file)
+{
+        return mounts_open_common(inode, file, show_vfsstat);
+}
+
+const struct file_operations proc_mounts_operations = {
+        .open           = mounts_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = mounts_release,
+        .poll           = mounts_poll,
+};
+
+const struct file_operations proc_mountinfo_operations = {
+        .open           = mountinfo_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = mounts_release,
+        .poll           = mounts_poll,
+};
+
+const struct file_operations proc_mountstats_operations = {
+        .open           = mountstats_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = mounts_release,
+};