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// psneuter.c, written by scotty2.
// neuter the android property service.
// ashmem allows us to restrict permissions for a page further, but not relax them.
// adb relies on the ability to read ro.secure to know whether to drop its privileges or not;
// if it can't read the ro.secure property (because perhaps it couldn't map the ashmem page... :)
// then it will come up as root under the assumption that ro.secure is off.
// this will have the unfortunate side effect of rendering any of the bionic userspace that relies on the property
// service and things like dns broken.
// thus, we will want to use this, see if we can fix the misc partition, and downgrade the firmware as a whole to something more root friendly.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <linux/ioctl.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdint.h>
#define ASHMEM_NAME_LEN 256
#define __ASHMEMIOC 0x77
#define ASHMEM_SET_NAME _IOW(__ASHMEMIOC, 1, char[ASHMEM_NAME_LEN])
#define ASHMEM_GET_NAME _IOR(__ASHMEMIOC, 2, char[ASHMEM_NAME_LEN])
#define ASHMEM_SET_SIZE _IOW(__ASHMEMIOC, 3, size_t)
#define ASHMEM_GET_SIZE _IO(__ASHMEMIOC, 4)
#define ASHMEM_SET_PROT_MASK _IOW(__ASHMEMIOC, 5, unsigned long)
#define ASHMEM_GET_PROT_MASK _IO(__ASHMEMIOC, 6)
#define ASHMEM_PIN _IOW(__ASHMEMIOC, 7, struct ashmem_pin)
#define ASHMEM_UNPIN _IOW(__ASHMEMIOC, 8, struct ashmem_pin)
#define ASHMEM_GET_PIN_STATUS _IO(__ASHMEMIOC, 9)
#define ASHMEM_PURGE_ALL_CACHES _IO(__ASHMEMIOC, 10)
int main(int argc, char **argv, char **envp)
{
char *workspace;
char *fdStr;
char *szStr;
char *ppage;
int fd;
long sz;
DIR *dir;
struct dirent *dent;
char cmdlinefile[PATH_MAX];
char cmdline[PATH_MAX];
pid_t adbdpid = 0;
setvbuf(stdout, 0, _IONBF, 0);
setvbuf(stderr, 0, _IONBF, 0);
workspace = getenv("ANDROID_PROPERTY_WORKSPACE");
if(!workspace)
{
fprintf(stderr, "Couldn't get workspace.\n");
exit(1);
}
fdStr = workspace;
if(strstr(workspace, ","))
*(strstr(workspace, ",")) = 0;
else
{
fprintf(stderr, "Incorrect format of ANDROID_PROPERTY_WORKSPACE environment variable?\n");
exit(1);
}
szStr = fdStr + strlen(fdStr) + 1;
fd = atoi(fdStr);
sz = atol(szStr);
if((ppage = mmap(0, sz, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED)
{
fprintf(stderr, "mmap() failed. %s\n", strerror(errno));
exit(1);
}
if(ioctl(fd, ASHMEM_SET_PROT_MASK, 0))
{
fprintf(stderr, "Failed to set prot mask (%s)\n", strerror(errno));
exit(1);
}
printf("property service neutered.\n");
printf("killing adbd. (should restart in a second or two)\n");
// now kill adbd.
dir = opendir("/proc");
if(!dir)
{
fprintf(stderr, "Failed to open /proc? kill adbd manually... somehow\n");
exit(1);
}
while((dent = readdir(dir)))
{
if(strspn(dent->d_name, "0123456789") == strlen(dent->d_name))
{
// pid dir
strcpy(cmdlinefile, "/proc/");
strcat(cmdlinefile, dent->d_name);
strcat(cmdlinefile, "/cmdline");
if((fd = open(cmdlinefile, O_RDONLY)) < 0)
{
fprintf(stderr, "Failed to open cmdline for pid %s\n", dent->d_name);
continue;
}
if(read(fd, cmdline, PATH_MAX) < 0)
{
fprintf(stderr, "Failed to read cmdline for pid %s\n", dent->d_name);
close(fd);
continue;
}
close(fd);
// printf("cmdline: %s\n", cmdline);
if(!strcmp(cmdline, "/sbin/adbd"))
{
// we got it.
adbdpid = atoi(dent->d_name);
break;
}
}
}
if(!adbdpid)
{
fprintf(stderr, "Failed to find adbd pid :(\n");
exit(1);
}
if(kill(adbdpid, SIGTERM))
{
fprintf(stderr, "Failed to kill adbd (%s)\n", strerror(errno));
exit(1);
}
return 0;
}
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