On Thu, Jun 07, 2007 at 04:27:33PM -0700, Zach Brown wrote:
> On Thu, May 31, 2007 at 02:19:23PM -0400, Jeff Dike wrote:
> > cachemiss_thread should explicitly return 0 or error instead of
> > task_ret_reg(current) (which is -ENOSYS anyway) because
> > async_thread_helper is careful to put the return value in eax anyway.
>
> Here's the fix I came up with for this. Untested (my test boxes are
> busy doing some aio+syslet perf runs :)). What do you guys think?
I don't like it :-)
It's better though. With the test below (a hacked up version of
aio-read.c), I still get -ENOSYS leaking out of sys_async_exec when it
tries an async setuid.
I haven't started looking into this yet.
Jeff
--
Work email - jdike at linux dot intel dot com
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <linux/unistd.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include "sys.h"
/*
* Set up a syslet atom:
*/
static void
init_atom(struct syslet_uatom *atom, int nr,
void *arg_ptr0, void *arg_ptr1, void *arg_ptr2,
void *arg_ptr3, void *arg_ptr4, void *arg_ptr5,
void *ret_ptr, unsigned long flags, struct syslet_uatom *next)
{
atom->nr = nr;
atom->arg_ptr[0] = (u64)(unsigned long)arg_ptr0;
atom->arg_ptr[1] = (u64)(unsigned long)arg_ptr1;
atom->arg_ptr[2] = (u64)(unsigned long)arg_ptr2;
atom->arg_ptr[3] = (u64)(unsigned long)arg_ptr3;
atom->arg_ptr[4] = (u64)(unsigned long)arg_ptr4;
atom->arg_ptr[5] = (u64)(unsigned long)arg_ptr5;
atom->ret_ptr = (u64)(unsigned long)ret_ptr;
atom->flags = flags;
atom->next = (u64)(unsigned long)next;
}
#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
static int collect_status(void)
{
int n = 0;
sys_async_wait(1, async_head.user_ring_idx, &async_head);
while(completion_ring[async_head.user_ring_idx] != 0){
completion_ring[async_head.user_ring_idx++] = 0;
async_head.user_ring_idx %= ARRAY_SIZE(completion_ring);
n++;
}
return n;
}
int oneshot(struct syslet_uatom *atom, int syscall)
{
struct syslet_uatom *done;
int err = -1;
init_atom(atom, __NR_getuid, NULL, NULL, NULL, NULL, NULL, NULL,
&err, SYSLET_ASYNC, NULL);
if(async_head.new_thread_stack == 0)
async_head.new_thread_stack = thread_stack_alloc();
done = sys_async_exec(atom, &async_head);
if(done == atom)
printf("setuid was synchronous\n");
else if(done == NULL){
collect_status();
}
else {
perror("async setuid");
exit(1);
}
return err;
}
int main(int argc, char *argv[])
{
struct syslet_uatom *atoms, *done;
struct stat stbuf;
char *file, *buf;
int fd, err, npages, i, len, async, sync;
if(argc < 2){
fprintf(stderr, "Usage : aio-read file\n");
exit(1);
}
file = argv[1];
fd = open(file, O_RDONLY);
if(fd < 0){
perror("open");
exit(1);
}
err = fstat(fd, &stbuf);
if(err < 0){
perror("stat");
exit(1);
}
buf = malloc(stbuf.st_size);
if(buf == NULL){
perror("malloc");
exit(1);
}
len = getpagesize();
npages = (stbuf.st_size + len - 1) / len;
atoms = malloc(npages * sizeof(struct syslet_uatom));
if(atoms == NULL){
perror("malloc atoms");
exit(1);
}
async_head_init();
async = 0;
sync = 0;
printf("head pid = %d, uid = %d\n", getpid(), getuid());
for(i = 0; i < npages; i++){
char *ptr = &buf[i * len];
init_atom(&atoms[i], __NR_sys_read, &fd, &ptr, &len,
NULL, NULL, NULL, NULL, 0, NULL);
if(async_head.new_thread_stack == 0)
async_head.new_thread_stack = thread_stack_alloc();
done = sys_async_exec(&atoms[i], &async_head);
if(done == &atoms[i]){
sync++;
continue;
}
else if(done < 0)
perror("sys_async_exec");
async++;
printf("async = %d, pid = %ld\n", async, syscall(__NR_gettid));
if(async < ARRAY_SIZE(completion_ring))
continue;
async -= collect_status();
}
while(async)
async -= collect_status();
if(setuid(500) < 0){
perror("setuid");
exit(1);
}
err = oneshot(&atoms[0], __NR_getuid);
printf("uid1 = %d\n", err);
printf("current uid1 = %d\n", getuid());
err = oneshot(&atoms[0], __NR_getuid);
printf("uid2 = %d\n", err);
printf("current uid2 = %d\n", getuid());
err = oneshot(&atoms[0], __NR_getuid);
printf("uid3 = %d\n", err);
printf("current uid3 = %d\n", getuid());
pause();
return 0;
}
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