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Commit 883ca833 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
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dccp: Initialisation and type-checking of feature sysctls 



This patch takes care of initialising and type-checking sysctls
related to feature negotiation. Type checking is important since some
of the sysctls now directly impact the feature-negotiation process.

The sysctls are initialised with the known default values for each
feature.  For the type-checking the value constraints from RFC 4340
are used:

 * Sequence Window uses the specified Wmin=32, the maximum is ulong (4 bytes),
   tested and confirmed that it works up to 4294967295 - for Gbps speed;
 * Ack Ratio is between 0 .. 0xffff (2-byte unsigned integer);
 * CCIDs are between 0 .. 255;
 * request_retries, retries1, retries2 also between 0..255 for good measure;
 * tx_qlen is checked to be non-negative;
 * sync_ratelimit remains as before.

Notes:
------
 1. Die s@sysctl_dccp_feat@sysctl_dccp@g since the sysctls are now in feat.c.
 2. As pointed out by Arnaldo, the pattern of type-checking repeats itself in
    other places, sometimes with exactly the same kind of definitions (e.g.
    "static int zero;"). It may be a good idea (kernel janitors?) to consolidate
    type checking. For the sake of keeping the changeset small and in order not
    to affect other subsystems, I have not strived to generalise here.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 792b4878

include/linux/dccp.h

+0 −8
Original line number Diff line number Diff line
@@ -355,14 +355,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb) 
	return __dccp_hdr_len(dccp_hdr(skb));

}





/* initial values for each feature */

#define DCCPF_INITIAL_SEQUENCE_WINDOW		100

#define DCCPF_INITIAL_ACK_RATIO			2

#define DCCPF_INITIAL_CCID			DCCPC_CCID2

/* FIXME: for now we're default to 1 but it should really be 0 */

#define DCCPF_INITIAL_SEND_NDP_COUNT		1



/**

 * struct dccp_request_sock  -  represent DCCP-specific connection request

 * @dreq_inet_rsk: structure inherited from

net/dccp/dccp.h

+0 −3
Original line number Diff line number Diff line
@@ -95,9 +95,6 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo); 
extern int  sysctl_dccp_request_retries;

extern int  sysctl_dccp_retries1;

extern int  sysctl_dccp_retries2;

extern int  sysctl_dccp_feat_sequence_window;

extern int  sysctl_dccp_feat_rx_ccid;

extern int  sysctl_dccp_feat_tx_ccid;

extern int  sysctl_dccp_tx_qlen;

extern int  sysctl_dccp_sync_ratelimit;

net/dccp/feat.c

+8 −3
Original line number Diff line number Diff line
@@ -25,6 +25,11 @@ 
#include "ccid.h"

#include "feat.h"



/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */

unsigned long	sysctl_dccp_sequence_window __read_mostly = 100;

int		sysctl_dccp_rx_ccid	    __read_mostly = 2,

		sysctl_dccp_tx_ccid	    __read_mostly = 2;



/*

 * Feature activation handlers.

 *
@@ -1146,7 +1151,7 @@ int dccp_feat_init(struct sock *sk) 


	/* Non-negotiable (NN) features */

	rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,

				    sysctl_dccp_feat_sequence_window);

				    sysctl_dccp_sequence_window);

	if (rc)

		return rc;
@@ -1172,8 +1177,8 @@ int dccp_feat_init(struct sock *sk) 
	    ccid_get_builtin_ccids(&rx.val, &rx.len))

		return -ENOBUFS;



	if (!dccp_feat_prefer(sysctl_dccp_feat_tx_ccid, tx.val, tx.len) ||

	    !dccp_feat_prefer(sysctl_dccp_feat_rx_ccid, rx.val, rx.len))

	if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||

	    !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))

		goto free_ccid_lists;



	rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);

net/dccp/feat.h

+8 −0
Original line number Diff line number Diff line
@@ -100,6 +100,13 @@ struct ccid_dependency { 
	u8	val;

};



/*

 * Sysctls to seed defaults for feature negotiation

 */

extern unsigned long sysctl_dccp_sequence_window;

extern int	     sysctl_dccp_rx_ccid;

extern int	     sysctl_dccp_tx_ccid;



#ifdef CONFIG_IP_DCCP_DEBUG

extern const char *dccp_feat_typename(const u8 type);

extern const char *dccp_feat_name(const u8 feat);
@@ -114,6 +121,7 @@ static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val) 
#endif /* CONFIG_IP_DCCP_DEBUG */



extern int  dccp_feat_init(struct sock *sk);

extern void dccp_feat_initialise_sysctls(void);

extern int  dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,

				  u8 const *list, u8 len);

extern int  dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);

net/dccp/options.c

+0 −4
Original line number Diff line number Diff line
@@ -23,10 +23,6 @@ 
#include "dccp.h"

#include "feat.h"



int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;

int sysctl_dccp_feat_rx_ccid	      = DCCPF_INITIAL_CCID;

int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;



u64 dccp_decode_value_var(const u8 *bf, const u8 len)

{

	u64 value = 0;