From 8632729060bf840560215c91c8611bd6769deff9 Mon Sep 17 00:00:00 2001 From: Stacey Son Date: Mon, 25 Sep 2023 21:24:17 +0300 Subject: [PATCH] bsd-user: Implement freebsd_exec_common, used in implementing execve/fexecve. Signed-off-by: Stacey Son Signed-off-by: Karim Taha Reviewed-by: Warner Losh Message-Id: <20230925182425.3163-21-kariem.taha2.7@gmail.com> --- bsd-user/freebsd/os-proc.c | 181 ++++++++++++++++++++++++++++++++++++- bsd-user/main.c | 2 +- bsd-user/qemu.h | 1 + 3 files changed, 180 insertions(+), 4 deletions(-) diff --git a/bsd-user/freebsd/os-proc.c b/bsd-user/freebsd/os-proc.c index 2603c5c653..12d78b7fc9 100644 --- a/bsd-user/freebsd/os-proc.c +++ b/bsd-user/freebsd/os-proc.c @@ -30,9 +30,7 @@ struct kinfo_proc; * Get the filename for the given file descriptor. * Note that this may return NULL (fail) if no longer cached in the kernel. */ -char * -get_filename_from_fd(pid_t pid, int fd, char *filename, size_t len); -char * +static char * get_filename_from_fd(pid_t pid, int fd, char *filename, size_t len) { char *ret = NULL; @@ -80,3 +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. + */ + 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; +} + 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 41c7bd31d3..6047805ae3 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; /* -- 2.39.2