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SubjectRe: capable open_port() check wrong for kmem

On 10 Dec 2002 05:45:09 GMT, David Wagner wrote:

>carbonated beverage wrote:

>> I found that I can't open /dev/kmem O_RDONLY. The open_mem
>>and open_kmem calls (open_port()) in drivers/char/mem.c checks for
>>CAP_SYS_RAWIO.

>> Is there a possibility of splitting that off into a read and
>>write pair, i.e. CAP_SYS_RAWIO_WRITE, CAP_SYS_RAWIO_READ?

>Read-only access to /dev/kmem is probably enough to get root access
>(maybe you can snoop root's password, for instance). This would make
>the power of the two capabilities roughly equivalent, so if this is true,
>I'm not sure I understand the point of splitting them in two this way.

Many capabilities can be leveraged into root access with sufficient
cleverness. If this were considered a sufficient argument for merging
capabilities, we'd have far fewer of them.

DS


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