Re: [PATCH v2] scsi: require CAP_SYS_ADMIN to write to procfs interface

[Randy Dunlap]

On 11/04/2017 01:26 PM, 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: 
> Cc: "Eric W. Biederman" 
> Signed-off-by: Aleksa Sarai 

There should be an
#include 
somewhere... even if some other header file is dragging it in (which
it must be), the preferred style is to always explicitly #include
header files that are used.

> ---
>  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..8c891ab16b11 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;
>  
> 


-- 
~Randy

[PATCH v2] scsi: require CAP_SYS_ADMIN to write to procfs interface

[Aleksa Sarai]

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: 
Cc: "Eric W. Biederman" 
Signed-off-by: Aleksa Sarai 
---
 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..8c891ab16b11 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;
 
-- 
2.14.3