Commit 03cfd8fa authored by Laurent Vivier's avatar Laurent Vivier Committed by Riku Voipio
Browse files

linux-user: add support of binfmt_misc 'O' flag 



The binfmt_misc module can calculate the credentials and security
token according to the binary instead of to the interpreter if the
'C' flag is enabled.

To be able to execute non-readable binaries, this flag implies 'O'
flag. When 'O' flag is enabled, bintfmt_misc opens the file for
reading and pass the file descriptor to the interpreter.

References:
linux/Documentation/binfmt_misc.txt          ['O' and 'C' description]
linux/fs/binfmt_misc.c linux/fs/binfmt_elf.c [ AT_EXECFD usage ]

Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
Signed-off-by: default avatarRiku Voipio <riku.voipio@linaro.org>
parent 0d78b3b5

linux-user/linuxload.c

+2 −6
Original line number Diff line number Diff line
@@ -131,7 +131,7 @@ abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp, 
    return sp;

}



int loader_exec(const char * filename, char ** argv, char ** envp,

int loader_exec(int fdexec, const char *filename, char **argv, char **envp,

             struct target_pt_regs * regs, struct image_info *infop,

             struct linux_binprm *bprm)

{
@@ -140,11 +140,7 @@ int loader_exec(const char * filename, char ** argv, char ** envp, 


    bprm->p = TARGET_PAGE_SIZE*MAX_ARG_PAGES-sizeof(unsigned int);

    memset(bprm->page, 0, sizeof(bprm->page));

    retval = open(filename, O_RDONLY);

    if (retval < 0) {

        return -errno;

    }

    bprm->fd = retval;

    bprm->fd = fdexec;

    bprm->filename = (char *)filename;

    bprm->argc = count(argv);

    bprm->argv = argv;

linux-user/main.c

+31 −1
Original line number Diff line number Diff line
@@ -3618,6 +3618,26 @@ static int parse_args(int argc, char **argv) 
    return optind;

}



static int get_execfd(char **envp)

{

    typedef struct {

        long a_type;

        long a_val;

    } auxv_t;

    auxv_t *auxv;



    while (*envp++ != NULL) {

        ;

    }



    for (auxv = (auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {

        if (auxv->a_type == AT_EXECFD) {

            return auxv->a_val;

        }

    }

    return -1;

}



int main(int argc, char **argv, char **envp)

{

    struct target_pt_regs regs1, *regs = &regs1;
@@ -3632,6 +3652,7 @@ int main(int argc, char **argv, char **envp) 
    int target_argc;

    int i;

    int ret;

    int execfd;



    module_call_init(MODULE_INIT_QOM);
@@ -3809,7 +3830,16 @@ int main(int argc, char **argv, char **envp) 
    env->opaque = ts;

    task_settid(ts);



    ret = loader_exec(filename, target_argv, target_environ, regs,

    execfd = get_execfd(envp);

    if (execfd < 0) {

        execfd = open(filename, O_RDONLY);

    }

    if (execfd < 0) {

        printf("Error while loading %s: %s\n", filename, strerror(-execfd));

        _exit(1);

    }



    ret = loader_exec(execfd, filename, target_argv, target_environ, regs,

        info, &bprm);

    if (ret != 0) {

        printf("Error while loading %s: %s\n", filename, strerror(-ret));

linux-user/qemu.h

+1 −1
Original line number Diff line number Diff line
@@ -174,7 +174,7 @@ struct linux_binprm { 
void do_init_thread(struct target_pt_regs *regs, struct image_info *infop);

abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,

                              abi_ulong stringp, int push_ptr);

int loader_exec(const char * filename, char ** argv, char ** envp,

int loader_exec(int fdexec, const char *filename, char **argv, char **envp,

             struct target_pt_regs * regs, struct image_info *infop,

             struct linux_binprm *);