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Commit 51e06618 authored by Nick Kralevich's avatar Nick Kralevich
Browse files

init: make system properties more secure. 

Currently, system properties are passed via the environment
variable ANDROID_PROPERTY_WORKSPACE and a file descriptor passed
from parent to child. This is insecure for setuid executables,
as the environment variable can be changed by the caller.

Modify system property handling so that we get the properties
from a root owned properties file, rather than using an
environment variable.

Related to bug: 8029617

Change-Id: I18610128e11c4037ed6f4dec6eba20f69fa647eb
parent d984497a

init/init.c

+0 −5
Original line number Diff line number Diff line
@@ -233,11 +233,6 @@ void service_start(struct service *svc, const char *dynamic_args) 
        int fd, sz;



        umask(077);

        if (properties_inited()) {

            get_property_workspace(&fd, &sz);

            sprintf(tmp, "%d,%d", dup(fd), sz);

            add_environment("ANDROID_PROPERTY_WORKSPACE", tmp);

        }



        for (ei = svc->envvars; ei; ei = ei->next)

            add_environment(ei->name, ei->value);

init/property_service.c

+4 −20
Original line number Diff line number Diff line
@@ -112,7 +112,6 @@ struct { 
typedef struct {

    void *data;

    size_t size;

    int fd;

} workspace;



static int init_workspace(workspace *w, size_t size)
@@ -123,7 +122,7 @@ static int init_workspace(workspace *w, size_t size) 
    /* dev is a tmpfs that we can use to carve a shared workspace

     * out of, so let's do that...

     */

    fd = open("/dev/__properties__", O_RDWR | O_CREAT | O_NOFOLLOW, 0600);

    fd = open(PROP_FILENAME, O_RDWR | O_CREAT | O_NOFOLLOW, 0644);

    if (fd < 0)

        return -1;
@@ -136,15 +135,8 @@ static int init_workspace(workspace *w, size_t size) 


    close(fd);



    fd = open("/dev/__properties__", O_RDONLY | O_NOFOLLOW);

    if (fd < 0)

        return -1;



    unlink("/dev/__properties__");



    w->data = data;

    w->size = size;

    w->fd = fd;

    return 0;



out:
@@ -174,8 +166,6 @@ static int init_property_area(void) 
    if(init_workspace(&pa_workspace, PA_SIZE))

        return -1;



    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);



    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);



    pa = pa_workspace.data;
@@ -463,12 +453,6 @@ void handle_property_set_fd() 
    }

}



void get_property_workspace(int *fd, int *sz)

{

    *fd = pa_workspace.fd;

    *sz = pa_workspace.size;

}



static void load_properties(char *data)

{

    char *key, *value, *eol, *sol, *tmp;

init/property_service.h

+0 −1
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ extern void property_init(void); 
extern void property_load_boot_defaults(void);

extern void load_persist_props(void);

extern void start_property_service(void);

void get_property_workspace(int *fd, int *sz);

extern const char* property_get(const char *name);

extern int property_set(const char *name, const char *value);

extern int properties_inited();