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[Qemu-devel] [PATCH RFC 25/36] 9pfs: local: symlink: don't follow symlin
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH RFC 25/36] 9pfs: local: symlink: don't follow symlinks |
Date: |
Mon, 30 Jan 2017 13:12:48 +0100 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
This fixes CVE-2016-9602 for the "passthrough" security model.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/9pfs/9p-local.c | 26 ++++++++++----------------
1 file changed, 10 insertions(+), 16 deletions(-)
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 9dfa3e306245..bbc08184564f 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -1100,29 +1100,25 @@ static int local_symlink_passthrough(FsContext *fs_ctx,
const char *oldpath,
V9fsPath *dir_path, const char *name,
FsCred *credp)
{
- int err = -1;
- int serrno = 0;
- char *newpath;
- V9fsString fullname;
- char *buffer = NULL;
+ int dirfd, err;
- v9fs_string_init(&fullname);
- v9fs_string_sprintf(&fullname, "%s/%s", dir_path->data, name);
- newpath = fullname.data;
+ dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
+ if (dirfd == -1) {
+ return -1;
+ }
- buffer = rpath(fs_ctx, newpath);
- err = symlink(oldpath, buffer);
+ err = symlinkat(oldpath, dirfd, name);
if (err) {
goto out;
}
- err = lchown(buffer, credp->fc_uid, credp->fc_gid);
+ err = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
+ AT_SYMLINK_NOFOLLOW);
if (err == -1) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
- serrno = errno;
goto err_end;
} else {
err = 0;
@@ -1131,11 +1127,9 @@ static int local_symlink_passthrough(FsContext *fs_ctx,
const char *oldpath,
goto out;
err_end:
- remove(buffer);
- errno = serrno;
+ unlinkat_preserve_errno(dirfd, name, 0);
out:
- g_free(buffer);
- v9fs_string_free(&fullname);
+ close_preserve_errno(dirfd);
return err;
}
- [Qemu-devel] [PATCH RFC 15/36] 9pfs: remove side-effects in local_open() and local_opendir(), (continued)
- [Qemu-devel] [PATCH RFC 15/36] 9pfs: remove side-effects in local_open() and local_opendir(), Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 16/36] 9pfs: introduce openat_nofollow() helper, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 17/36] 9pfs: local: keep a file descriptor on the shared folder, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 18/36] 9pfs: local: open/opendir: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 19/36] 9pfs: local: utimensat: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 20/36] 9pfs: local: readlink: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 21/36] 9pfs: local: truncate: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 22/36] 9pfs: local: statfs: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 23/36] 9pfs: local: mknod/mkdir/open2: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 24/36] 9pfs: local: chmod: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 25/36] 9pfs: local: symlink: don't follow symlinks,
Greg Kurz <=
- [Qemu-devel] [PATCH RFC 26/36] 9pfs: local: chown: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 27/36] 9pfs: local: link: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 28/36] 9pfs: local: rename: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 29/36] 9pfs: local: remove: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 30/36] 9pfs: local: unlinkat: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 32/36] 9pfs: local: lstat: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 33/36] 9pfs: local: lgetxattr: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 35/36] 9pfs: local: lsetxattr: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 36/36] 9pfs: local: lremovexattr: don't follow symlinks, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 34/36] 9pfs: local: llistxattr: don't follow symlinks, Greg Kurz, 2017/01/30