[Qemu-devel] [PATCH] linux-user: support target-to-host SCM_CREDENTIALS

[Qemu-devel] [PATCH] linux-user: support target-to-host SCM_CREDENTIALS

[Alex Suykov]

When passing ancillary data through a unix socket, handle
credentials properly instead of doing a simple copy and
issuing a warning.

Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
---
 linux-user/syscall.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index aaac6a2..b067c5c 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1214,16 +1214,23 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
         cmsg->cmsg_type = tswap32(target_cmsg->cmsg_type);
         cmsg->cmsg_len = CMSG_LEN(len);
 
-        if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
-            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
-            memcpy(data, target_data, len);
-        } else {
+        if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
             int *fd = (int *)data;
             int *target_fd = (int *)target_data;
             int i, numfds = len / sizeof(int);
 
             for (i = 0; i < numfds; i++)
                 fd[i] = tswap32(target_fd[i]);
+        } else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS) {
+            struct ucred *cred = (struct ucred *)data;
+            struct target_ucred *target_cred = (struct target_ucred *)target_data;
+
+            __put_user(target_cred->pid, &cred->pid);
+            __put_user(target_cred->uid, &cred->uid);
+            __put_user(target_cred->gid, &cred->gid);
+        } else {
+            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
+            memcpy(data, target_data, len);
         }
 
         cmsg = CMSG_NXTHDR(msgh, cmsg);
-- 
2.0.3

Re: [Qemu-devel] [PATCH] linux-user: support target-to-host SCM_CREDENTIALS

[Fam Zheng]

On Sun, 12/21 13:02, Alex Suykov wrote:
> When passing ancillary data through a unix socket, handle
> credentials properly instead of doing a simple copy and
> issuing a warning.
> 
> Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
> ---
>  linux-user/syscall.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index aaac6a2..b067c5c 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1214,16 +1214,23 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
>          cmsg->cmsg_type = tswap32(target_cmsg->cmsg_type);
>          cmsg->cmsg_len = CMSG_LEN(len);
>  
> -        if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
> -            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
> -            memcpy(data, target_data, len);
> -        } else {
> +        if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
>              int *fd = (int *)data;
>              int *target_fd = (int *)target_data;
>              int i, numfds = len / sizeof(int);
>  
>              for (i = 0; i < numfds; i++)
>                  fd[i] = tswap32(target_fd[i]);
> +        } else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS) {
> +            struct ucred *cred = (struct ucred *)data;
> +            struct target_ucred *target_cred = (struct target_ucred *)target_data;
> +
> +            __put_user(target_cred->pid, &cred->pid);
> +            __put_user(target_cred->uid, &cred->uid);
> +            __put_user(target_cred->gid, &cred->gid);
> +        } else {
> +            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
> +            memcpy(data, target_data, len);
>          }
>  
>          cmsg = CMSG_NXTHDR(msgh, cmsg);
> -- 
> 2.0.3
> 
> 

I didn't review the code but checkpatch.pl complains about a few lines over 80
characters.

Fam

Re: [Qemu-devel] [PATCH] linux-user: support target-to-host SCM_CREDENTIALS

[Alex Suykov]

Tue, Dec 23, 2014 at 09:59:57AM +0800, Fam Zheng wrote:

> On Sun, 12/21 13:02, Alex Suykov wrote:
> > When passing ancillary data through a unix socket, handle
> > credentials properly instead of doing a simple copy and
> > issuing a warning.
> > 
> > Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
> > ---
...
> > -            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
...
> > +            gemu_log("Unsupported ancillary data: %d/%d\n", cmsg->cmsg_level, cmsg->cmsg_type);
...
> 
> I didn't review the code but checkpatch.pl complains about a few lines over 80
> characters.

The patch does not change the length of the longest line in that function,
just moves it around. So my guess was that mixing semantic changes
and reformatting is not a good idea.

Sending checkpatch-compliant v2.