[Qemu-devel] [PATCH v2] slirp: Ensure smbd and shared directory exist when enable smb

[Qemu-devel] [PATCH v2] slirp: Ensure smbd and shared directory exist when enable smb

[Dunrong Huang]

Users may pass the following parameters to qemu:
    $ qemu-kvm -net nic -net user,smb= ...
    $ qemu-kvm -net nic -net user,smb ...
    $ qemu-kvm -net nic -net user,smb=bad_directory ...

In these cases, qemu started successfully while samba server
failed to start. Users will confuse since samba server
failed silently without any indication of what it did wrong.

To avoid it, we check whether the shared directory exist and
if users have permission to access this directory when QEMU's
"built-in" SMB server is enabled.

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
---
 net/slirp.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/net/slirp.c b/net/slirp.c
index 37b6ccf..ff36fa2 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -489,6 +489,18 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
     char smb_cmdline[128];
     FILE *f;
 
+    if (access(CONFIG_SMBD_COMMAND, F_OK)) {
+        error_report("could not find '%s', please install it",
+                     CONFIG_SMBD_COMMAND);
+        return -1;
+    }
+
+    if (access(exported_dir, R_OK | X_OK)) {
+        error_report("no such directory '%s', or you do not have permission "
+                     "to access it, please check it", exported_dir);
+        return -1;
+    }
+
     snprintf(s->smb_dir, sizeof(s->smb_dir), "/tmp/qemu-smb.%ld-%d",
              (long)getpid(), instance++);
     if (mkdir(s->smb_dir, 0700) < 0) {
-- 
1.7.8.4

Re: [Qemu-devel] [PATCH v2] slirp: Ensure smbd and shared directory exist when enable smb

[Jan Kiszka]

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On 2012-07-06 08:04, Dunrong Huang wrote:
> Users may pass the following parameters to qemu:
>     $ qemu-kvm -net nic -net user,smb= ...
>     $ qemu-kvm -net nic -net user,smb ...
>     $ qemu-kvm -net nic -net user,smb=bad_directory ...
> 
> In these cases, qemu started successfully while samba server
> failed to start. Users will confuse since samba server
> failed silently without any indication of what it did wrong.
> 
> To avoid it, we check whether the shared directory exist and
> if users have permission to access this directory when QEMU's
> "built-in" SMB server is enabled.
> 
> Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
> ---
>  net/slirp.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/net/slirp.c b/net/slirp.c
> index 37b6ccf..ff36fa2 100644
> --- a/net/slirp.c
> +++ b/net/slirp.c
> @@ -489,6 +489,18 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
>      char smb_cmdline[128];
>      FILE *f;
>  
> +    if (access(CONFIG_SMBD_COMMAND, F_OK)) {
> +        error_report("could not find '%s', please install it",
> +                     CONFIG_SMBD_COMMAND);
> +        return -1;
> +    }
> +
> +    if (access(exported_dir, R_OK | X_OK)) {
> +        error_report("no such directory '%s', or you do not have permission "
> +                     "to access it, please check it", exported_dir);
> +        return -1;
> +    }
> +
>      snprintf(s->smb_dir, sizeof(s->smb_dir), "/tmp/qemu-smb.%ld-%d",
>               (long)getpid(), instance++);
>      if (mkdir(s->smb_dir, 0700) < 0) {
> 

Thanks, applied to slirp queue.

I added a tiny patch on top that reports the exact error returned by
access():

diff --git a/net/slirp.c b/net/slirp.c
index eb80889..b82eab0 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -504,8 +504,8 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
     }
 
     if (access(exported_dir, R_OK | X_OK)) {
-        error_report("no such directory '%s', or you do not have permission "
-                     "to access it, please check it", exported_dir);
+        error_report("error accessing shared directory '%s': %s",
+                     exported_dir, strerror(errno));
         return -1;
     }
 

Jan


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