Commit ff5e92c1 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

net: sctp: propagate sysctl errors from proc_do* properly 



sysctl handler proc_sctp_do_hmac_alg(), proc_sctp_do_rto_min() and
proc_sctp_do_rto_max() do not properly reflect some error cases
when writing values via sysctl from internal proc functions such
as proc_dointvec() and proc_dostring().

In all these cases we pass the test for write != 0 and partially
do additional work just to notice that additional sanity checks
fail and we return with hard-coded -EINVAL while proc_do*
functions might also return different errors. So fix this up by
simply testing a successful return of proc_do* right after
calling it.

This also allows to propagate its return value onwards to the user.
While touching this, also fix up some minor style issues.

Fixes: 4f3fdf3b ("sctp: add check rto_min and rto_max in sysctl")
Fixes: 3c68198e ("sctp: Make hmac algorithm selection for cookie generation dynamic")
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d36a4f4b

net/sctp/sysctl.c

+23 −20
Original line number Diff line number Diff line
@@ -321,41 +321,40 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl, int write, 
				loff_t *ppos)

{

	struct net *net = current->nsproxy->net_ns;

	char tmp[8];

	struct ctl_table tbl;

	int ret;

	int changed = 0;

	bool changed = false;

	char *none = "none";

	char tmp[8];

	int ret;



	memset(&tbl, 0, sizeof(struct ctl_table));



	if (write) {

		tbl.data = tmp;

		tbl.maxlen = 8;

		tbl.maxlen = sizeof(tmp);

	} else {

		tbl.data = net->sctp.sctp_hmac_alg ? : none;

		tbl.maxlen = strlen(tbl.data);

	}

		ret = proc_dostring(&tbl, write, buffer, lenp, ppos);



	if (write) {

	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);

	if (write && ret == 0) {

#ifdef CONFIG_CRYPTO_MD5

		if (!strncmp(tmp, "md5", 3)) {

			net->sctp.sctp_hmac_alg = "md5";

			changed = 1;

			changed = true;

		}

#endif

#ifdef CONFIG_CRYPTO_SHA1

		if (!strncmp(tmp, "sha1", 4)) {

			net->sctp.sctp_hmac_alg = "sha1";

			changed = 1;

			changed = true;

		}

#endif

		if (!strncmp(tmp, "none", 4)) {

			net->sctp.sctp_hmac_alg = NULL;

			changed = 1;

			changed = true;

		}



		if (!changed)

			ret = -EINVAL;

	}
@@ -368,11 +367,10 @@ static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write, 
				loff_t *ppos)

{

	struct net *net = current->nsproxy->net_ns;

	int new_value;

	struct ctl_table tbl;

	unsigned int min = *(unsigned int *) ctl->extra1;

	unsigned int max = *(unsigned int *) ctl->extra2;

	int ret;

	struct ctl_table tbl;

	int ret, new_value;



	memset(&tbl, 0, sizeof(struct ctl_table));

	tbl.maxlen = sizeof(unsigned int);
@@ -381,12 +379,15 @@ static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write, 
		tbl.data = &new_value;

	else

		tbl.data = &net->sctp.rto_min;



	ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);

	if (write) {

		if (ret || new_value > max || new_value < min)

	if (write && ret == 0) {

		if (new_value > max || new_value < min)

			return -EINVAL;



		net->sctp.rto_min = new_value;

	}



	return ret;

}
@@ -395,11 +396,10 @@ static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write, 
				loff_t *ppos)

{

	struct net *net = current->nsproxy->net_ns;

	int new_value;

	struct ctl_table tbl;

	unsigned int min = *(unsigned int *) ctl->extra1;

	unsigned int max = *(unsigned int *) ctl->extra2;

	int ret;

	struct ctl_table tbl;

	int ret, new_value;



	memset(&tbl, 0, sizeof(struct ctl_table));

	tbl.maxlen = sizeof(unsigned int);
@@ -408,12 +408,15 @@ static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write, 
		tbl.data = &new_value;

	else

		tbl.data = &net->sctp.rto_max;



	ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);

	if (write) {

		if (ret || new_value > max || new_value < min)

	if (write && ret == 0) {

		if (new_value > max || new_value < min)

			return -EINVAL;



		net->sctp.rto_max = new_value;

	}



	return ret;

}

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