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[Qemu-devel] [PATCH RFC 20/36] 9pfs: local: readlink: don't follow symli
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH RFC 20/36] 9pfs: local: readlink: don't follow symlinks |
Date: |
Mon, 30 Jan 2017 13:12:08 +0100 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
This fixes CVE-2016-9602 for all security models.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/9pfs/9p-local.c | 37 +++++++++++++++++++++++++++----------
1 file changed, 27 insertions(+), 10 deletions(-)
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index a1fff04c3219..1f9239de07e5 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -346,31 +346,48 @@ err:
return -1;
}
+static int readlink_nofollow(FsContext *fs_ctx, const char *path, char *buf,
+ size_t bufsz)
+{
+ char *dirpath = local_dirname(path);
+ char *name = local_basename(path);
+ int dirfd, ret = -1;
+
+ dirfd = local_opendir_nofollow(fs_ctx, dirpath);
+ if (dirfd == -1) {
+ goto out;
+ }
+
+ ret = readlinkat(dirfd, name, buf, bufsz);
+ close_preserve_errno(dirfd);
+out:
+ g_free(name);
+ g_free(dirpath);
+ return ret;
+}
+
static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
char *buf, size_t bufsz)
{
- ssize_t tsize = -1;
- char *buffer;
- char *path = fs_path->data;
+ ssize_t tsize;
if ((fs_ctx->export_flags & V9FS_SM_MAPPED) ||
(fs_ctx->export_flags & V9FS_SM_MAPPED_FILE)) {
int fd;
- buffer = rpath(fs_ctx, path);
- fd = open(buffer, O_RDONLY | O_NOFOLLOW);
- g_free(buffer);
+
+ fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
if (fd == -1) {
return -1;
}
do {
tsize = read(fd, (void *)buf, bufsz);
} while (tsize == -1 && errno == EINTR);
- close(fd);
+ close_preserve_errno(fd);
} else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
(fs_ctx->export_flags & V9FS_SM_NONE)) {
- buffer = rpath(fs_ctx, path);
- tsize = readlink(buffer, buf, bufsz);
- g_free(buffer);
+ tsize = readlink_nofollow(fs_ctx, fs_path->data, buf, bufsz);
+ } else {
+ g_assert_not_reached();
}
return tsize;
}
- [Qemu-devel] [PATCH RFC 11/36] 9pfs: local: post rename operation for mapped-file security, (continued)
- [Qemu-devel] [PATCH RFC 11/36] 9pfs: local: post rename operation for mapped-file security, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 12/36] 9pfs: local: pre remove operation for mapped-file security, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 06/36] 9pfs: local: split symlink operation per security model, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 13/36] 9pfs: local: pre unlikat operation for mapped-file security, Greg Kurz, 2017/01/30
- [Qemu-devel] [PATCH RFC 14/36] 9pfs: remove side-effects in local_init(), Greg Kurz, 2017/01/30
- [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 <=
- [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, 2017/01/30
- [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