On Sun, Sep 17, 2023 at 10:39 PM Karim Taha <kariem.taha...@gmail.com>
wrote:
> From: Stacey Son <s...@freebsd.org>
>
> Signed-off-by: Stacey Son <s...@freebsd.org>
> Signed-off-by: Karim Taha <kariem.taha...@gmail.com>
> ---
> bsd-user/freebsd/os-proc.c | 177 +++++++++++++++++++++++++++++++++++++
> bsd-user/main.c | 2 +-
> bsd-user/qemu.h | 1 +
> 3 files changed, 179 insertions(+), 1 deletion(-)
>
Reviewed-by: Warner Losh <i...@bsdimp.com>
But see comment below.
> diff --git a/bsd-user/freebsd/os-proc.c b/bsd-user/freebsd/os-proc.c
> index cb35f29f10..12d78b7fc9 100644
> --- a/bsd-user/freebsd/os-proc.c
> +++ b/bsd-user/freebsd/os-proc.c
> @@ -78,3 +78,180 @@ out:
> 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.
> + */
>
So we do this fd dance so we can make things like 'qemu-arm-static
/armv7/bin/sh' work.
Doug Rabson has some changes that means we can ditch this, I think, since
the
kernel will just track it and it will default to 'what is doing the current
process'
rather than the system default for the same binfmt entry.
> + 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
>
And we do this inheritance so we can pass in a non-standard library path,
maybe for testing, and have the above example also work.
Warner
> + 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);
> + }
It might be nice to unify these two if statements, but I'm thinking
we don't want to do it now since Doug's work will obsolete it if I
understand it correctly.
Warner
>
>
+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;
> +}
> +
> diff --git a/bsd-user/main.c b/bsd-user/main.c
> index f913cb55a7..a12b4be80f 100644
> --- a/bsd-user/main.c
> +++ b/bsd-user/main.c
> @@ -88,7 +88,7 @@ unsigned long reserved_va = MAX_RESERVED_VA;
> unsigned long reserved_va;
> #endif
>
> -static const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX;
> +const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX;
> const char *qemu_uname_release;
> char qemu_proc_pathname[PATH_MAX]; /* full path to exeutable */
>
> diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
> index 2cf96d9a15..1ed6024b5d 100644
> --- a/bsd-user/qemu.h
> +++ b/bsd-user/qemu.h
> @@ -111,6 +111,7 @@ typedef struct TaskState {
> } __attribute__((aligned(16))) TaskState;
>
> void stop_all_tasks(void);
> +extern const char *interp_prefix;
> extern const char *qemu_uname_release;
>
> /*
> --
> 2.42.0
>
>
