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mcexec: copy a pathname string of open(2) safely

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When a open system call request is delegated, mcexec will check whether
a path name is known one such as "/proc/meminfo" and "/proc/cpuinfo".
During this check, if mcexec causes a SIGSEGV or SIGBUS signal,
mcexec will begin a loop, because mcexec has a signal handler which
returns simply.
This commit is contained in:
NAKAMURA Gou
2014-03-28 13:19:36 +09:00
parent 583c9355cd
commit da81cd2d1d
1 changed files with 11 additions and 4 deletions
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15
executer/user/mcexec.c
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@ -959,7 +959,6 @@ kill_thread(unsigned long cpu)
}
}
#if 0
static long do_strncpy_from_user(int fd, void *dest, void *src, unsigned long n)
{
struct strncpy_from_user_desc desc;
@ -978,7 +977,6 @@ static long do_strncpy_from_user(int fd, void *dest, void *src, unsigned long n)
return desc.result;
}
#endif
#define SET_ERR(ret) if (ret == -1) ret = -errno
@ -990,6 +988,7 @@ int main_loop(int fd, int cpu, pthread_mutex_t *lock)
int sig;
int term;
struct timeval tv;
char pathbuf[PATH_MAX];
w.cpu = cpu;
w.pid = getpid();
@ -1008,9 +1007,17 @@ int main_loop(int fd, int cpu, pthread_mutex_t *lock)
switch (w.sr.number) {
case __NR_open:
__dprintf("open: %s\n", (char *)w.sr.args[0]);
ret = do_strncpy_from_user(fd, pathbuf, (void *)w.sr.args[0], PATH_MAX);
if (ret >= PATH_MAX) {
ret = -ENAMETOOLONG;
}
if (ret < 0) {
do_syscall_return(fd, cpu, ret, 0, 0, 0, 0);
break;
}
__dprintf("open: %s\n", pathbuf);
fn = (char *)w.sr.args[0];
fn = pathbuf;
if(!strcmp(fn, "/proc/meminfo")){
fn = "/admin/fs/attached/files/proc/meminfo";
}