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faccessat: Specify AT_SYMLINK_NOFOLLOW only when necessary.

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- Specify AT_SYMLINK_NOFOLLOW in faccessat only when
   the symbolic-link is analyzed by overlay_path().

Change-Id: Ie3b1f7fedef7441fd4b39c5c8b2ef0f73cba770e
Refs: #1370
This commit is contained in:
Shiratori, Takehiro
2020-03-09 11:05:54 +09:00
committed by Masamichi Takagi
parent 4946fbdd82
commit d82ac31bc6
4 changed files with 360 additions and 14 deletions
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43
executer/user/mcexec.c
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@ -3169,7 +3169,7 @@ int overlay_blacklist(const char *path)
* returns path to use *with dirfd* if it was provided.
*/
const char *
overlay_path(int dirfd, const char *in, char *buf)
overlay_path(int dirfd, const char *in, char *buf, int *resolvelinks)
{
const char *path = in;
char *linkpath, *tmppath;
@ -3179,6 +3179,10 @@ overlay_path(int dirfd, const char *in, char *buf)
ssize_t n;
int rc;
if (resolvelinks) {
*resolvelinks = 0;
}
__dprintf("considering fd %d path %s\n", dirfd, in);
if (dirfd != AT_FDCWD && in[0] != '/') {
@ -3316,6 +3320,10 @@ checkexist_resolvelinks:
if (n >= PATH_MAX)
return in;
}
if (resolvelinks) {
*resolvelinks = 1;
}
}
linkpath[0] = '/';
linkpath++;
@ -3864,7 +3872,8 @@ int main_loop(struct thread_data_s *my_thread)
__dprintf("openat: %d, %s,tid=%d\n", (int)w.sr.args[0],
pathbuf, my_thread->remote_tid);
fn = overlay_path((int)w.sr.args[0], pathbuf, tmpbuf);
fn = overlay_path((int)w.sr.args[0],
pathbuf, tmpbuf, NULL);
ret = openat(w.sr.args[0], fn, w.sr.args[2],
w.sr.args[3]);
@ -4474,7 +4483,8 @@ return_execve2:
pathbuf[ret] = 0;
__dprintf("readlinkat: %d, %s\n", (int)w.sr.args[0], pathbuf);
fn = overlay_path((int)w.sr.args[0], pathbuf, tmpbuf);
fn = overlay_path((int)w.sr.args[0],
pathbuf, tmpbuf, NULL);
ret = readlinkat(w.sr.args[0], fn, (char *)w.sr.args[2],
w.sr.args[3]);
@ -4494,7 +4504,7 @@ return_execve2:
break;
}
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = readlink(fn, (char *)w.sr.args[1], w.sr.args[2]);
SET_ERR(ret);
@ -4515,7 +4525,8 @@ return_execve2:
}
pathbuf[ret] = 0;
fn = overlay_path((int)w.sr.args[0], pathbuf, tmpbuf);
fn = overlay_path((int)w.sr.args[0],
pathbuf, tmpbuf, NULL);
ret = fstatat((int)w.sr.args[0],
fn,
@ -4539,7 +4550,7 @@ return_execve2:
break;
}
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = stat(fn, (struct stat *)w.sr.args[1]);
SET_ERR(ret);
@ -4548,7 +4559,9 @@ return_execve2:
break;
#endif /* __NR_stat */
case __NR_faccessat:
case __NR_faccessat: {
int resolvelinks = 0;
ret = do_strncpy_from_user(fd, pathbuf,
(void *)w.sr.args[1], PATH_MAX);
if (ret >= PATH_MAX) {
@ -4560,14 +4573,16 @@ return_execve2:
}
pathbuf[ret] = 0;
fn = overlay_path((int)w.sr.args[0], pathbuf, tmpbuf);
fn = overlay_path((int)w.sr.args[0],
pathbuf, tmpbuf, &resolvelinks);
/* the syscall doesn't take flags argument, link
* resolution happened first so don't do it again
*/
ret = faccessat((int)w.sr.args[0], fn,
(int)w.sr.args[2],
AT_SYMLINK_NOFOLLOW);
resolvelinks == 0 ?
0 : AT_SYMLINK_NOFOLLOW);
SET_ERR(ret);
__dprintf("faccessat: dirfd=%d, pathname=%s, mode=%d, ret=%ld\n",
(int)w.sr.args[0], fn, (int)w.sr.args[2],
@ -4575,7 +4590,7 @@ return_execve2:
do_syscall_return(fd, cpu, ret, 0, 0, 0, 0);
break;
}
#ifdef __NR_access
case __NR_access:
ret = do_strncpy_from_user(fd, pathbuf,
@ -4588,7 +4603,7 @@ return_execve2:
break;
}
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = access(fn, (int)w.sr.args[1]);
SET_ERR(ret);
@ -4607,7 +4622,7 @@ return_execve2:
break;
}
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = getxattr(fn, (char *)w.sr.args[1],
(void *)w.sr.args[2],
@ -4628,7 +4643,7 @@ return_execve2:
break;
}
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = lgetxattr(fn, (char *)w.sr.args[1],
(void *)w.sr.args[2],
@ -4862,7 +4877,7 @@ return_linux_spawn:
}
__dprintf("open: %s\n", pathbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf);
fn = overlay_path(AT_FDCWD, pathbuf, tmpbuf, NULL);
ret = open(fn, w.sr.args[1], w.sr.args[2]);
SET_ERR(ret);