scsi: require CAP_SYS_ADMIN to write to procfs interface

Submitted by Aleksa Sarai on Nov. 4, 2017, 6:59 p.m.

Details

Message ID 20171104185913.10658-1-asarai@suse.de
State New
Series "scsi: require CAP_SYS_ADMIN to write to procfs interface"
Headers show

Commit Message

Aleksa Sarai Nov. 4, 2017, 6:59 p.m.
Previously, the only capability effectively required to operate on the
/proc/scsi interface was CAP_DAC_OVERRIDE (or for some other files,
having an fsuid of GLOBAL_ROOT_UID was enough). This means that
semi-privileged processes could interfere with core components of a
system (such as causing a DoS by removing the underlying SCSI device of
the host's / mount).

Cc: <stable@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Aleksa Sarai <asarai@suse.de>
---
 drivers/scsi/scsi_proc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Patch hide | download patch | download mbox

diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
index 480a597b3877..486aedce2f05 100644
--- a/drivers/scsi/scsi_proc.c
+++ b/drivers/scsi/scsi_proc.c
@@ -51,7 +51,10 @@  static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
 	struct Scsi_Host *shost = PDE_DATA(file_inode(file));
 	ssize_t ret = -ENOMEM;
 	char *page;
-    
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM
+
 	if (count > PROC_BLOCK_SIZE)
 		return -EOVERFLOW;
 
@@ -313,6 +316,9 @@  static ssize_t proc_scsi_write(struct file *file, const char __user *buf,
 	char *buffer, *p;
 	int err;
 
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
 	if (!buf || length > PAGE_SIZE)
 		return -EINVAL;
 

Comments

Randy Dunlap Nov. 4, 2017, 8:20 p.m.
On 11/04/2017 11:59 AM, Aleksa Sarai wrote:
> Previously, the only capability effectively required to operate on the
> /proc/scsi interface was CAP_DAC_OVERRIDE (or for some other files,
> having an fsuid of GLOBAL_ROOT_UID was enough). This means that
> semi-privileged processes could interfere with core components of a
> system (such as causing a DoS by removing the underlying SCSI device of
> the host's / mount).
> 
> Cc: <stable@vger.kernel.org>
> Cc: "Eric W. Biederman" <ebiederm@xmission.com>
> Signed-off-by: Aleksa Sarai <asarai@suse.de>
> ---
>  drivers/scsi/scsi_proc.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
> index 480a597b3877..486aedce2f05 100644
> --- a/drivers/scsi/scsi_proc.c
> +++ b/drivers/scsi/scsi_proc.c
> @@ -51,7 +51,10 @@ static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
>  	struct Scsi_Host *shost = PDE_DATA(file_inode(file));
>  	ssize_t ret = -ENOMEM;
>  	char *page;
> -    
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM

did that build without a trailing ';' ?

> +
>  	if (count > PROC_BLOCK_SIZE)
>  		return -EOVERFLOW;
>  
> @@ -313,6 +316,9 @@ static ssize_t proc_scsi_write(struct file *file, const char __user *buf,
>  	char *buffer, *p;
>  	int err;
>  
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
>  	if (!buf || length > PAGE_SIZE)
>  		return -EINVAL;
>  
>
Aleksa Sarai Nov. 4, 2017, 8:26 p.m.
>> Previously, the only capability effectively required to operate on the
>> /proc/scsi interface was CAP_DAC_OVERRIDE (or for some other files,
>> having an fsuid of GLOBAL_ROOT_UID was enough). This means that
>> semi-privileged processes could interfere with core components of a
>> system (such as causing a DoS by removing the underlying SCSI device of
>> the host's / mount).
>>
>> Cc: <stable@vger.kernel.org>
>> Cc: "Eric W. Biederman" <ebiederm@xmission.com>
>> Signed-off-by: Aleksa Sarai <asarai@suse.de>
>> ---
>>   drivers/scsi/scsi_proc.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
>> index 480a597b3877..486aedce2f05 100644
>> --- a/drivers/scsi/scsi_proc.c
>> +++ b/drivers/scsi/scsi_proc.c
>> @@ -51,7 +51,10 @@ static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
>>   	struct Scsi_Host *shost = PDE_DATA(file_inode(file));
>>   	ssize_t ret = -ENOMEM;
>>   	char *page;
>> -
>> +
>> +	if (!capable(CAP_SYS_ADMIN))
>> +		return -EPERM
> 
> did that build without a trailing ';' ?

D'oh. Re-sent, thanks.