Re: genetlink misinterprets NEW as GET

On 07/01/11 10:38, Jan Engelhardt wrote:

On Friday 2011-01-07 02:31, Pablo Neira Ayuso wrote:

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	/* Modifiers to GET request */
	#define NLM_F_ROOT      0x100
	#define NLM_F_MATCH     0x200
	#define NLM_F_ATOMIC    0x400
	#define NLM_F_DUMP      (NLM_F_ROOT|NLM_F_MATCH)

[...]

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[N.B.: I am also wondering whether
	(nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP
may have been desired, because NLM_F_DUMP is composed of two bits.]

Someone may include NLM_F_ATOMIC to a dump operation, in that case the
checking that you propose is not valid.

Are you saying that NLM_F_MATCH and NLM_F_ATOMIC are mutually
exclusive, and that NLM_F_ROOT|NLM_F_ATOMIC would also signal a
dump operation?  Otherwise the test that Jan proposes looks valid
to me.

Indeed, Jan's test is fine to fix this. Please, send a patch to Davem asap.

But that would still mean that a user sending a
NLM_F_REQUEST|NLM_F_REPLACE|NLM_F_EXCL message would be misinterpreted
as NLM_F_DUMP.

That flag combination does not make sense to me. Valid combinations are:

NLM_F_REQUEST|NLM_F_CREATE : if it does not exist, create it, if it
exists, update it.
NLM_F_REQUEST|NLM_F_CREATE|NLM_F_EXCL: if it does not exist, create it,
if it exists, return -EEXIST.
NLM_F_REQUEST|NLM_F_REPLACE: if it does not exist, return -ENOENT, if it
exists, replace it.