qemu/bsd-user/freebsd/os-proc.c

/*
 *  FreeBSD process related emulation code
 *
 *  Copyright (c) 2013-15 Stacey D. Son
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
#include "qemu/osdep.h"

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
struct kinfo_proc;
#include <libprocstat.h>

#include "qemu.h"

/*
 * Get the filename for the given file descriptor.
 * Note that this may return NULL (fail) if no longer cached in the kernel.
 */
static char *
get_filename_from_fd(pid_t pid, int fd, char *filename, size_t len)
{
    char *ret = NULL;
    unsigned int cnt;
    struct procstat *procstat = NULL;
    struct kinfo_proc *kp = NULL;
    struct filestat_list *head = NULL;
    struct filestat *fst;

    procstat = procstat_open_sysctl();
    if (procstat == NULL) {
        goto out;
    }

    kp = procstat_getprocs(procstat, KERN_PROC_PID, pid, &cnt);
    if (kp == NULL) {
        goto out;
    }

    head = procstat_getfiles(procstat, kp, 0);
    if (head == NULL) {
        goto out;
    }

    STAILQ_FOREACH(fst, head, next) {
        if (fd == fst->fs_fd) {
            if (fst->fs_path != NULL) {
                (void)strlcpy(filename, fst->fs_path, len);
                ret = filename;
            }
            break;
        }
    }

out:
    if (head != NULL) {
        procstat_freefiles(procstat, head);
    }
    if (kp != NULL) {
        procstat_freeprocs(procstat, kp);
    }
    if (procstat != NULL) {
        procstat_close(procstat);
    }
    return ret;
}

/*
 * execve/fexecve
 */
abi_long freebsd_exec_common(abi_ulong path_or_fd, abi_ulong guest_argp,
        abi_ulong guest_envp, int do_fexec)
{
    char **argp, **envp, **qargp, **qarg1, **qarg0, **qargend;
    int argc, envc;
    abi_ulong gp;
    abi_ulong addr;
    char **q;
    int total_size = 0;
    void *p;
    abi_long ret;

    argc = 0;
    for (gp = guest_argp; gp; gp += sizeof(abi_ulong)) {
        if (get_user_ual(addr, gp)) {
            return -TARGET_EFAULT;
        }
        if (!addr) {
            break;
        }
        argc++;
    }
    envc = 0;
    for (gp = guest_envp; gp; gp += sizeof(abi_ulong)) {
        if (get_user_ual(addr, gp)) {
            return -TARGET_EFAULT;
        }
        if (!addr) {
            break;
        }
        envc++;
    }

    qarg0 = argp = g_new0(char *, argc + 9);
    /* save the first agrument for the emulator */
    *argp++ = (char *)getprogname();
    qargp = argp;
    *argp++ = (char *)getprogname();
    qarg1 = argp;
    envp = g_new0(char *, envc + 1);
    for (gp = guest_argp, q = argp; gp; gp += sizeof(abi_ulong), q++) {
        if (get_user_ual(addr, gp)) {
            ret = -TARGET_EFAULT;
            goto execve_end;
        }
        if (!addr) {
            break;
        }
        *q = lock_user_string(addr);
        if (*q == NULL) {
            ret = -TARGET_EFAULT;
            goto execve_end;
        }
        total_size += strlen(*q) + 1;
    }
    *q++ = NULL;
    qargend = q;

    for (gp = guest_envp, q = envp; gp; gp += sizeof(abi_ulong), q++) {
        if (get_user_ual(addr, gp)) {
            ret = -TARGET_EFAULT;
            goto execve_end;
        }
        if (!addr) {
            break;
        }
        *q = lock_user_string(addr);
        if (*q == NULL) {
            ret = -TARGET_EFAULT;
            goto execve_end;
        }
        total_size += strlen(*q) + 1;
    }
    *q = NULL;

    /*
     * This case will not be caught by the host's execve() if its
     * page size is bigger than the target's.
     */
    if (total_size > MAX_ARG_PAGES * TARGET_PAGE_SIZE) {
        ret = -TARGET_E2BIG;
        goto execve_end;
    }

    if (do_fexec) {
        if (((int)path_or_fd > 0 &&
            is_target_elf_binary((int)path_or_fd)) == 1) {
            char execpath[PATH_MAX];

            /*
             * The executable is an elf binary for the target
             * arch.  execve() it using the emulator if we can
             * determine the filename path from the fd.
             */
            if (get_filename_from_fd(getpid(), (int)path_or_fd, execpath,
                        sizeof(execpath)) != NULL) {
                memmove(qarg1 + 2, qarg1, (qargend - qarg1) * sizeof(*qarg1));
                qarg1[1] = qarg1[0];
                qarg1[0] = (char *)"-0";
                qarg1 += 2;
                qargend += 2;
                *qarg1 = execpath;
#ifndef DONT_INHERIT_INTERP_PREFIX
                memmove(qarg1 + 2, qarg1, (qargend - qarg1) * sizeof(*qarg1));
                *qarg1++ = (char *)"-L";
                *qarg1++ = (char *)interp_prefix;
#endif
                ret = get_errno(execve(qemu_proc_pathname, qargp, envp));
            } else {
                /* Getting the filename path failed. */
                ret = -TARGET_EBADF;
                goto execve_end;
            }
        } else {
            ret = get_errno(fexecve((int)path_or_fd, argp, envp));
        }
    } else {
        int fd;

        p = lock_user_string(path_or_fd);
        if (p == NULL) {
            ret = -TARGET_EFAULT;
            goto execve_end;
        }

        /*
         * Check the header and see if it a target elf binary.  If so
         * then execute using qemu user mode emulator.
         */
        fd = open(p, O_RDONLY | O_CLOEXEC);
        if (fd > 0 && is_target_elf_binary(fd) == 1) {
            close(fd);
            /* execve() as a target binary using emulator. */
            memmove(qarg1 + 2, qarg1, (qargend - qarg1) * sizeof(*qarg1));
            qarg1[1] = qarg1[0];
            qarg1[0] = (char *)"-0";
            qarg1 += 2;
            qargend += 2;
            *qarg1 = (char *)p;
#ifndef DONT_INHERIT_INTERP_PREFIX
            memmove(qarg1 + 2, qarg1, (qargend - qarg1) * sizeof(*qarg1));
            *qarg1++ = (char *)"-L";
            *qarg1++ = (char *)interp_prefix;
#endif
            ret = get_errno(execve(qemu_proc_pathname, qargp, envp));
        } else {
            close(fd);
            /* Execve() as a host native binary. */
            ret = get_errno(execve(p, argp, envp));
        }
        unlock_user(p, path_or_fd, 0);
    }

execve_end:
    for (gp = guest_argp, q = argp; *q; gp += sizeof(abi_ulong), q++) {
        if (get_user_ual(addr, gp) || !addr) {
            break;
        }
        unlock_user(*q, addr, 0);
    }

    for (gp = guest_envp, q = envp; *q; gp += sizeof(abi_ulong), q++) {
        if (get_user_ual(addr, gp) || !addr) {
            break;
        }
        unlock_user(*q, addr, 0);
    }

    g_free(qarg0);
    g_free(envp);

    return ret;
}