From: "M. Mohan Kumar" <mo...@in.ibm.com>
In passthrough security model in local fs driver, after a file creation
chown and chmod are done to set the file credentials and mode as requested
by 9p client. But if there was a request to create a file with S_ISGID
bit, doing chown on that file resets the S_ISGID bit. So first call
chown and then invoking chmod with proper mode bit retains the S_ISGID
(if present/requested)
This resulted in LTP mknod02, mknod03, mknod05, open10 test case
failures. This patch fixes this issue.
man 2 chown
When the owner or group of an executable file are changed by an unprivileged
user the S_ISUID and S_ISGID mode bits are cleared. POSIX does not specify
whether this also should happen when root does the chown(); the Linux behavior
depends on the kernel version.
Signed-off-by: M. Mohan Kumar <mo...@in.ibm.com>
---
hw/9pfs/virtio-9p-local.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 3ae6ef2..3eb481d 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -115,9 +115,6 @@ static int local_post_create_passthrough(FsContext *fs_ctx,
const char *path,
{
char buffer[PATH_MAX];
- if (chmod(rpath(fs_ctx, path, buffer), credp->fc_mode & 07777) < 0) {
- return -1;
- }
if (lchown(rpath(fs_ctx, path, buffer), credp->fc_uid,
credp->fc_gid) < 0) {
/*
@@ -128,6 +125,10 @@ static int local_post_create_passthrough(FsContext
*fs_ctx, const char *path,
return -1;
}
}
+
+ if (chmod(rpath(fs_ctx, path, buffer), credp->fc_mode & 07777) < 0) {
+ return -1;
+ }
return 0;
}
--
1.7.6
