graphene/LibOS/shim/src/fs/proc/thread.c

/* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
/* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */

#include <shim_internal.h>
#include <shim_table.h>
#include <shim_thread.h>
#include <shim_handle.h>
#include <shim_fs.h>
#include <shim_utils.h>

#include <pal.h>
#include <pal_error.h>

#include <asm/mman.h>
#include <asm/unistd.h>
#include <asm/prctl.h>
#include <errno.h>

static int parse_thread_name (const char * name,
                              const char ** next, int * next_len,
                              const char ** nextnext)
{
    const char * p = name;
    int pid = 0;

    if (*p == '/')
        p++;

    if (!memcmp(p, "self", 4) && (!*(p + 4) || *(p + 4) == '/')) {
        p += 4;
        pid = get_cur_tid();
    } else {
        for ( ; *p && *p != '/' ; p++) {
            if (*p < '0' || *p > '9')
                return -ENOENT;

            pid = pid * 10 + *p - '0';
        }
    }

    if (next) {
        if (*(p++) == '/' && *p) {
            *next = p;

            if (next_len || nextnext)
                for ( ; *p && *p != '/' ; p++);

            if (next_len)
                *next_len = p - *next;

            if (nextnext)
                *nextnext = (*(p++) == '/' && *p) ? p : NULL;
        } else {
            *next = NULL;
        }
    }

    return pid;
}

static int find_thread_link (const char * name, struct shim_qstr * link,
                             struct shim_dentry ** dentptr,
                             struct shim_thread ** threadptr)
{
    const char * next, * nextnext;
    int next_len;
    int pid = parse_thread_name(name, &next, &next_len, &nextnext);
    if (pid < 0)
        return pid;

    struct shim_thread * thread = lookup_thread(pid);
    struct shim_dentry * dent = NULL;
    int ret = 0;

    if (!thread)
        return -ENOENT;

    if (!thread->in_vm) {
        ret = -ENOENT;
        goto out;
    }

    lock(thread->lock);

    if (next_len == 4 && !memcmp(next, "root", next_len)) {
        dent = thread->root;
        get_dentry(dent);
    }

    if (next_len == 3 && !memcmp(next, "cwd", next_len)) {
        dent = thread->cwd;
        get_dentry(dent);
    }

    if (next_len == 3 && !memcmp(next, "exe", next_len)) {
        struct shim_handle * exec = thread->exec;
        if (!exec->dentry) {
            unlock(thread->lock);
            ret = -ENOENT;
            goto out;
        }

        dent = exec->dentry;
        get_dentry(dent);
    }

    unlock(thread->lock);

    if (nextnext) {
        struct shim_dentry * next_dent = NULL;

        ret = path_lookupat(dent, nextnext, 0, &next_dent);
        if (ret < 0)
            goto out;

        put_dentry(dent);
        dent = next_dent;
    }

    if (link) {
        int size;
        char * path = dentry_get_path(dent, true, &size);
        qstrsetstr(link, path, size);
    }

    if (dentptr) {
        get_dentry(dent);
        *dentptr = dent;
    }

    if (threadptr) {
        get_thread(thread);
        *threadptr = thread;
    }

    ret = 0;
out:
    if (dent)
        put_dentry(dent);
    if (thread)
        put_thread(thread);
    return ret;
}

static int proc_thread_link_open (struct shim_handle * hdl,
                                  const char * name, int flags)
{
    struct shim_dentry * dent;

    int ret = find_thread_link(name, NULL, &dent, NULL);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->open) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->open(hdl, dent, flags);
out:
    put_dentry(dent);
    return 0;
}

static int proc_thread_link_mode (const char * name, mode_t * mode)
{
    struct shim_dentry * dent;

    int ret = find_thread_link(name, NULL, &dent, NULL);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->mode) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->mode(dent, mode, true);
out:
    put_dentry(dent);
    return ret;
}

static int proc_thread_link_stat (const char * name, struct stat * buf)
{
    struct shim_dentry * dent;

    int ret = find_thread_link(name, NULL, &dent, NULL);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->stat) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->stat(dent, buf);
out:
    put_dentry(dent);
    return ret;
}

static int proc_thread_link_follow_link (const char * name,
                                         struct shim_qstr * link)
{
    return find_thread_link(name, link, NULL, NULL);
}

static const struct proc_fs_ops fs_thread_link = {
            .open           = &proc_thread_link_open,
            .mode           = &proc_thread_link_mode,
            .stat           = &proc_thread_link_stat,
            .follow_link    = &proc_thread_link_follow_link,
        };

static int parse_thread_fd (const char * name, const char ** rest,
                            struct shim_handle ** phdl)
{
    const char * next, * nextnext;
    int next_len;

    int pid = parse_thread_name(name, &next, &next_len, &nextnext);

    if (!pid)
        return pid;

    if (!next || !nextnext || memcmp(next, "fd", next_len))
        return -EINVAL;

    const char * p = nextnext;
    int fd = 0;

    for ( ; *p && *p != '/' ; p++) {
        if (*p < '0' || *p > '9')
            return -ENOENT;
        fd = fd * 10 + *p - '0';
        if (fd >= MAX_FDS)
            return -ENOENT;
    }

    struct shim_thread * thread = lookup_thread(pid);

    if (!thread)
        return -ENOENT;

    struct shim_handle_map * handle_map = get_cur_handle_map(thread);

    lock(handle_map->lock);

    if (fd >= handle_map->fd_top ||
        handle_map->map[fd] == NULL ||
        handle_map->map[fd]->handle == NULL) {
        unlock(handle_map->lock);
        return -ENOENT;
    }

    if (phdl)
        *phdl = handle_map->map[fd]->handle;

    unlock(handle_map->lock);

    if (rest)
        *rest = *p ? p + 1 : NULL;

    return 0;
}

static int proc_match_thread_each_fd (const char * name)
{
    return parse_thread_fd(name, NULL, NULL) == 0 ? 1 : 0;
}

static int proc_list_thread_each_fd (const char * name,
                                     struct shim_dirent ** buf, int count)
{
    const char * next;
    int next_len;
    int pid = parse_thread_name(name, &next, &next_len, NULL);

    if (!pid)
        return pid;

    if (!next || memcmp(next, "fd", next_len))
        return -EINVAL;

    struct shim_thread * thread = lookup_thread(pid);
    if (!thread)
        return -ENOENT;

    struct shim_handle_map * handle_map = get_cur_handle_map(thread);
    int err = 0, bytes = 0;
    struct shim_dirent * dirent = *buf, ** last = NULL;

    lock(handle_map->lock);

    for (int i = 0 ; i < handle_map->fd_size ; i++, dirent = dirent->next)
        if (handle_map->map[i] &&
            handle_map->map[i]->handle) {
            int d = i, l = 0;
            for ( ; d ; d /= 10, l++);
            l = l ? : 1;

            bytes += sizeof(struct shim_dirent) + l + 1;
            if (bytes > count) {
                err = -ENOMEM;
                break;
            }

            dirent->next = (void *) (dirent + 1) + l + 1;
            dirent->ino = 1;
            dirent->type = LINUX_DT_LNK;
            dirent->name[0] = '0';
            dirent->name[l--] = 0;
            for (d = i ; d ; d /= 10)
                dirent->name[l--] = '0' + d % 10;
            last = &dirent->next;
        }

    unlock(handle_map->lock);
    put_thread(thread);

    if (last)
        *last = NULL;

    *buf = dirent;
    return err;
}

static const struct proc_nm_ops nm_thread_each_fd = {
            .match_name = &proc_match_thread_each_fd,
            .list_name  = &proc_list_thread_each_fd,
        };

static int find_thread_each_fd (const char * name, struct shim_qstr * link,
                                struct shim_dentry ** dentptr)
{
    const char * rest;
    struct shim_handle * handle;
    struct shim_dentry * dent = NULL;
    int ret;

    if ((ret = parse_thread_fd(name, &rest, &handle)) < 0)
        return ret;

    lock(handle->lock);

    if (handle->dentry) {
        dent = handle->dentry;
        get_dentry(dent);
    }

    unlock(handle->lock);

    if (!dent) {
        ret = -ENOENT;
        goto out;
    }

    if (rest) {
        struct shim_dentry * next_dent = NULL;

        ret = path_lookupat(dent, rest, 0, &next_dent);
        if (ret < 0)
            goto out;

        put_dentry(dent);
        dent = next_dent;
    }

    if (link) {
        int size;
        char * path = dentry_get_path(dent, true, &size);
        qstrsetstr(link, path, size);
    }

    if (dentptr) {
        get_dentry(dent);
        *dentptr = dent;
    }

out:
    if (dent)
        put_dentry(dent);

    put_handle(handle);
    return ret;
}

static int proc_thread_each_fd_open (struct shim_handle * hdl,
                                     const char * name, int flags)
{
    struct shim_dentry * dent;

    int ret = find_thread_each_fd(name, NULL, &dent);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->open) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->open(hdl, dent, flags);
out:
    put_dentry(dent);
    return 0;
}

static int proc_thread_each_fd_mode (const char * name, mode_t * mode)
{
    struct shim_dentry * dent;

    int ret = find_thread_each_fd(name, NULL, &dent);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->mode) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->mode(dent, mode, true);
out:
    put_dentry(dent);
    return 0;
}

static int proc_thread_each_fd_stat (const char * name, struct stat * buf)
{
    struct shim_dentry * dent;

    int ret = find_thread_each_fd(name, NULL, &dent);
    if (ret < 0)
        return ret;

    if (!dent->fs || !dent->fs->d_ops || !dent->fs->d_ops->stat) {
        ret = -EACCES;
        goto out;
    }

    ret = dent->fs->d_ops->stat(dent, buf);
out:
    put_dentry(dent);
    return 0;
}

static int proc_thread_each_fd_follow_link (const char * name,
                                            struct shim_qstr * link)
{
    return find_thread_each_fd(name, link, NULL);
}

static const struct proc_fs_ops fs_thread_each_fd = {
            .open           = &proc_thread_each_fd_open,
            .mode           = &proc_thread_each_fd_mode,
            .stat           = &proc_thread_each_fd_stat,
            .follow_link    = &proc_thread_each_fd_follow_link,
        };

static const struct proc_dir dir_fd = { .size = 1, .ent = { {
            .nm_ops = &nm_thread_each_fd, .fs_ops = &fs_thread_each_fd,
        }, }, };

static int proc_thread_dir_mode (const char * name, mode_t * mode)
{
    const char * next;
    int next_len;
    int pid = parse_thread_name(name, &next, &next_len, NULL);

    if (pid < 0)
        return pid;

    *mode = 0500;
    return 0;
}

static int proc_thread_dir_stat (const char * name, struct stat * buf)
{
    const char * next;
    int next_len;
    int pid = parse_thread_name(name, &next, &next_len, NULL);

    if (pid < 0)
        return pid;

    struct shim_thread * thread = lookup_thread(pid);

    if (!thread)
        return -ENOENT;

    memset(buf, 0, sizeof(struct stat));
    buf->st_dev = buf->st_ino = 1;
    buf->st_mode = 0500|S_IFDIR;
    lock(thread->lock);
    buf->st_uid = thread->uid;
    buf->st_gid = thread->gid;
    unlock(thread->lock);
    buf->st_size = 4096;
    return 0;
}

static const struct proc_fs_ops fs_thread_fd = {
            .mode       = &proc_thread_dir_mode,
            .stat       = &proc_thread_dir_stat,
        };

static int proc_match_thread (const char * name)
{
    int pid = parse_thread_name(name, NULL, NULL, NULL);

    if (pid < 0)
        return 0;

    struct shim_thread * thread = lookup_thread(pid);

    return thread ? 1 : 0;
}

static int proc_list_thread (const char * name, struct shim_dirent ** buf,
                             int len)
{
    struct walk_thread_arg {
        struct shim_dirent * buf, * buf_end;
    } args = {
        .buf = *buf, .buf_end = (void *) *buf + len,
    };

    int walk_cb (struct shim_thread * thread, void * arg, bool * unlocked) {
        struct walk_thread_arg * args = (struct walk_thread_arg *) arg;
        IDTYPE pid = thread->tid;
        int p = pid, l = 0;
        for ( ; p ; p /= 10, l++);

        if ((void *) (args->buf + 1) + l + 1 > (void *) args->buf_end)
            return -ENOBUFS;

        struct shim_dirent * buf = args->buf;

        buf->next = (void *) (buf + 1) + l + 1;
        buf->ino = 1;
        buf->type = LINUX_DT_DIR;
        buf->name[l--] = 0;
        for (p = pid ; p ; p /= 10)
            buf->name[l--] = p % 10 + '0';

        args->buf = buf->next;
        return 1;
    }

    int ret = walk_thread_list(&walk_cb, &args, false);
    if (ret < 0)
        return ret;

    *buf = args.buf;
    return 0;
}

const struct proc_nm_ops nm_thread = {
            .match_name = &proc_match_thread,
            .list_name  = &proc_list_thread,
        };

const struct proc_fs_ops fs_thread = {
            .mode   = &proc_thread_dir_mode,
            .stat   = &proc_thread_dir_stat,
        };

const struct proc_dir dir_thread = { .size = 5, .ent = {
        { .name = "cwd", .fs_ops = &fs_thread_link, },
        { .name = "exe", .fs_ops = &fs_thread_link, },
        { .name = "root", .fs_ops = &fs_thread_link, },
        { .name = "fd", .dir = &dir_fd, .fs_ops = &fs_thread_fd, },
    }, };