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

#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 <errno.h>

#include <linux/stat.h>
#include <linux/fcntl.h>

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

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

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

    if (strpartcmp_static(p, "self")) {
        p += static_strlen("self");
        if (*p && *p != '/')
            return -ENOENT;
        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;
        }
    }

    if (pidptr) *pidptr = pid;
    return 0;
}

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

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

    if (!thread)
        return -ENOENT;

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

    lock(&thread->lock);

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

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

    if (next_len == static_strlen("exe") && !memcmp(next, "exe", next_len)) {
        struct shim_handle * exec = thread->exec;
        if (!exec->dentry) {
            unlock(&thread->lock);
            ret = -EINVAL;
            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, dent->fs);
        if (ret < 0)
            goto out;

        put_dentry(dent);
        dent = next_dent;
    }

    if (link) {
        size_t 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);
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,
        };

/* If *phdl is returned on success, the ref count is incremented */
static int parse_thread_fd (const char * name, const char ** rest,
                            struct shim_handle ** phdl)
{
    const char * next, * nextnext;
    size_t next_len;
    IDTYPE pid;
    int ret = parse_thread_name(name, &pid, &next, &next_len, &nextnext);
    if (ret < 0)
        return ret;

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

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

    for ( ; *p && *p != '/' ; p++) {
        if (*p < '0' || *p > '9')
            return -ENOENT;
        fd = fd * 10 + *p - '0';
        if (fd >= __rlim[RLIMIT_NOFILE].rlim_cur)
            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;
        get_handle(*phdl);
    }

    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;
    size_t next_len;
    IDTYPE pid;
    int ret = parse_thread_name(name, &pid, &next, &next_len, NULL);
    if (ret < 0)
        return ret;

    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++)
        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;
            dirent = 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, dent->fs);
        if (ret < 0)
            goto out;

        put_dentry(dent);
        dent = next_dent;
    }

    if (link) {
        size_t 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);
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_maps_open (struct shim_handle * hdl,
                                  const char * name, int flags)
{
    if (flags & (O_WRONLY|O_RDWR))
        return -EACCES;

    const char * next;
    size_t next_len;
    IDTYPE pid;
    int ret = parse_thread_name(name, &pid, &next, &next_len, NULL);
    if (ret < 0)
        return ret;

    struct shim_thread * thread = lookup_thread(pid);

    if (!thread)
        return -ENOENT;

    size_t count = DEFAULT_VMA_COUNT;
    struct shim_vma_val * vmas = malloc(sizeof(struct shim_vma_val) * count);

    if (!vmas) {
        ret = -ENOMEM;
        goto out;
    }

retry_dump_vmas:
    ret = dump_all_vmas(vmas, count);

    if (ret == -EOVERFLOW) {
        struct shim_vma_val * new_vmas
                = malloc(sizeof(struct shim_vma_val) * count * 2);
        if (!new_vmas) {
            ret = -ENOMEM;
            goto err;
        }
        free(vmas);
        vmas = new_vmas;
        count *= 2;
        goto retry_dump_vmas;
    }

    if (ret < 0)
        goto err;

#define DEFAULT_VMA_BUFFER_SIZE     256

    count = ret;
    size_t buffer_size = DEFAULT_VMA_BUFFER_SIZE, offset = 0;
    char * buffer = malloc(buffer_size);
    if (!buffer) {
        ret = -ENOMEM;
        goto err;
    }

    for (struct shim_vma_val * vma = vmas ; vma < vmas + count ; vma++) {
        size_t old_offset = offset;
        uintptr_t start = (uintptr_t) vma->addr;
        uintptr_t end   = (uintptr_t) vma->addr + vma->length;
        char pt[3] = {
            (vma->prot & PROT_READ)  ? 'r' : '-',
            (vma->prot & PROT_WRITE) ? 'w' : '-',
            (vma->prot & PROT_EXEC)  ? 'x' : '-',
        };
        char pr = (vma->flags & MAP_PRIVATE) ? 'p' : 's';

#define ADDR_FMT(addr) ((addr) > 0xffffffff ? "%lx" : "%08lx")
#define EMIT(fmt ...)                                                   \
        do {                                                            \
            offset += snprintf(buffer + offset, buffer_size - offset,   \
                               fmt);                                    \
        } while (0)

retry_emit_vma:
        if (vma->file) {
            int dev_major = 0, dev_minor = 0;
            unsigned long ino = vma->file->dentry ? vma->file->dentry->ino : 0;
            const char * name = "[unknown]";

            if (!qstrempty(&vma->file->path))
                name = qstrgetstr(&vma->file->path);

            EMIT(ADDR_FMT(start), start);
            EMIT("-");
            EMIT(ADDR_FMT(end),   end);
            EMIT(" %c%c%c%c %08lx %02d:%02d %lu %s\n", pt[0], pt[1], pt[2], pr,
                 vma->offset, dev_major, dev_minor, ino, name);
        } else {
            EMIT(ADDR_FMT(start), start);
            EMIT("-");
            EMIT(ADDR_FMT(end),   end);
            if (vma->comment[0])
                EMIT(" %c%c%c%c 00000000 00:00 0 %s\n", pt[0], pt[1], pt[2], pr,
                     vma->comment);
            else
                EMIT(" %c%c%c%c 00000000 00:00 0\n", pt[0], pt[1], pt[2], pr);
        }

        if (offset >= buffer_size) {
            char * new_buffer = malloc(buffer_size * 2);
            if (!new_buffer) {
                ret = -ENOMEM;
                goto err;
            }

            offset = old_offset;
            memcpy(new_buffer, buffer, old_offset);
            free(buffer);
            buffer = new_buffer;
            buffer_size *= 2;
            goto retry_emit_vma;
        }
    }

    struct shim_str_data * data = calloc(1, sizeof(struct shim_str_data));
    if (!data) {
        ret = -ENOMEM;
        goto err;
    }

    data->str  = buffer;
    data->len  = offset;
    hdl->type  = TYPE_STR;
    hdl->flags = flags & ~O_RDONLY;
    hdl->acc_mode = MAY_READ;
    hdl->info.str.data = data;
    ret = 0;
out:
    put_thread(thread);
    if (vmas)
        free_vma_val_array(vmas, count);
    return ret;

err:
    if (buffer)
        free(buffer);
    goto out;
}

static int proc_thread_maps_mode (const char * name, mode_t * mode)
{
    // Only used by one file
    __UNUSED(name);
    *mode = 0400;
    return 0;
}

static int proc_thread_maps_stat (const char * name, struct stat * buf)
{
    // Only used by one file
    __UNUSED(name);
    memset(buf, 0, sizeof(struct stat));

    buf->st_dev = buf->st_ino = 1;
    buf->st_mode = 0400|S_IFREG;
    buf->st_uid = 0;
    buf->st_gid = 0;
    buf->st_size = 0;

    return 0;
}

static const struct proc_fs_ops fs_thread_maps = {
            .open           = &proc_thread_maps_open,
            .mode           = &proc_thread_maps_mode,
            .stat           = &proc_thread_maps_stat,
        };

static int proc_thread_dir_open (struct shim_handle * hdl,
                                 const char * name, int flags)
{
    __UNUSED(hdl);
    __UNUSED(name);

    if (flags & (O_WRONLY|O_RDWR))
        return -EISDIR;

    // Don't really need to do any work here, but keeping as a placeholder,
    // just in case.

    return 0;

}

static int proc_thread_dir_mode (const char * name, mode_t * mode)
{
    const char * next;
    size_t next_len;
    IDTYPE pid;
    int ret = parse_thread_name(name, &pid, &next, &next_len, NULL);
    if (ret < 0)
        return ret;

    *mode = 0500;
    return 0;
}

static int proc_thread_dir_stat (const char * name, struct stat * buf)
{
    const char * next;
    size_t next_len;
    IDTYPE pid;
    int ret = parse_thread_name(name, &pid, &next, &next_len, NULL);
    if (ret < 0)
        return ret;

    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)
{
    IDTYPE pid;
    if (parse_thread_name(name, &pid, NULL, NULL, NULL) < 0)
        return 0;

    struct shim_thread * thread = lookup_thread(pid);

    return thread ? 1 : 0;
}

struct walk_thread_arg {
    struct shim_dirent * buf, * buf_end;
};

static int walk_cb (struct shim_thread * thread, void * arg, bool * unlocked)
{
    // unlocked needed for kill
    __UNUSED(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;
}

static int proc_list_thread (const char * name, struct shim_dirent ** buf,
                             int len)
{
    __UNUSED(name); // We know this is for "/proc/self"
    struct walk_thread_arg args =
        { .buf = *buf, .buf_end = (void *) *buf + len, };

    int ret = walk_thread_list(&walk_cb, &args);
    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 = {
            .open   = &proc_thread_dir_open,
            .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, },
        { .name = "maps", .fs_ops = &fs_thread_maps, },
    }, };