ACK/Cmnt: [SRU][F][G][PATCH 1/1] net/smc: tolerate future SMCD versions
Frank Heimes
frank.heimes at canonical.com
Mon Jul 13 09:25:22 UTC 2020
While testing the old code, IBM identified the issue and came up with that
patch, that they are now bringing upstream.
The patch was already tested by IBM, but
I provided a patched kernel based on Ubuntu (focal) master-next on top for
further testing:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1882088/comments/12
and I'm expecting some feedback from the initial reporter (IBM) on that,
too.
Thx, Frank
On Mon, Jul 13, 2020 at 9:20 AM Stefan Bader <stefan.bader at canonical.com>
wrote:
> On 10.07.20 21:21, frank.heimes at canonical.com wrote:
> > From: Ursula Braun <ubraun at linux.ibm.com>
> >
> > BugLink: https://bugs.launchpad.net/bugs/1882088
> >
> > CLC proposal messages of future SMCD versions could be larger than SMCD
> > V1 CLC proposal messages.
> > To enable toleration in SMC V1 the receival of CLC proposal messages
> > is adapted:
> > * accept larger length values in CLC proposal
> > * check trailing eye catcher for incoming CLC proposal with V1 length
> only
> > * receive the whole CLC proposal even in cases it does not fit into the
> > V1 buffer
> >
> > Fixes: e7b7a64a8493d ("smc: support variable CLC proposal messages")
> > Signed-off-by: Ursula Braun <ubraun at linux.ibm.com>
> > Signed-off-by: Karsten Graul <kgraul at linux.ibm.com>
> > Signed-off-by: David S. Miller <davem at davemloft.net>
> > (cherry picked from commit fb4f79264c0fc6fd5a68ffe3e31bfff97311e1f1i
> linux-next)
> > Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> Acked-by: Stefan Bader <stefan.bader at canonical.com>
> > ---
>
> I am a bit torn here. Though not extremely large, I find it hard to decide
> about
> risk based on the delta. And it is common code that is changed. On the
> positive
> side it is queued upstream, but that not necessarily means it is without
> flaws.
> Have been (or will there be) tests of the new code using the old version
> (if
> that is possible), old and new, and both new?
>
> -Stefan
>
> > net/smc/smc_clc.c | 45 ++++++++++++++++++++++++w ++++++++-------------
> > net/smc/smc_clc.h | 4 ++++
> > 2 files changed, 36 insertions(+), 13 deletions(-)
> >
> > diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
> > index aee9ccfa99c2..640cce262015 100644
> > --- a/net/smc/smc_clc.c
> > +++ b/net/smc/smc_clc.c
> > @@ -27,6 +27,7 @@
> >
> > #define SMCR_CLC_ACCEPT_CONFIRM_LEN 68
> > #define SMCD_CLC_ACCEPT_CONFIRM_LEN 48
> > +#define SMC_CLC_RECV_BUF_LEN 100
> >
> > /* eye catcher "SMCR" EBCDIC for CLC messages */
> > static const char SMC_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xd9'};
> > @@ -36,7 +37,7 @@ static const char SMCD_EYECATCHER[4] = {'\xe2',
> '\xd4', '\xc3', '\xc4'};
> > /* check if received message has a correct header length and contains
> valid
> > * heading and trailing eyecatchers
> > */
> > -static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
> > +static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm, bool
> check_trl)
> > {
> > struct smc_clc_msg_proposal_prefix *pclc_prfx;
> > struct smc_clc_msg_accept_confirm *clc;
> > @@ -49,12 +50,9 @@ static bool smc_clc_msg_hdr_valid(struct
> smc_clc_msg_hdr *clcm)
> > return false;
> > switch (clcm->type) {
> > case SMC_CLC_PROPOSAL:
> > - if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
> > - clcm->path != SMC_TYPE_B)
> > - return false;
> > pclc = (struct smc_clc_msg_proposal *)clcm;
> > pclc_prfx = smc_clc_proposal_get_prefix(pclc);
> > - if (ntohs(pclc->hdr.length) !=
> > + if (ntohs(pclc->hdr.length) <
> > sizeof(*pclc) + ntohs(pclc->iparea_offset) +
> > sizeof(*pclc_prfx) +
> > pclc_prfx->ipv6_prefixes_cnt *
> > @@ -86,7 +84,8 @@ static bool smc_clc_msg_hdr_valid(struct
> smc_clc_msg_hdr *clcm)
> > default:
> > return false;
> > }
> > - if (memcmp(trl->eyecatcher, SMC_EYECATCHER,
> sizeof(SMC_EYECATCHER)) &&
> > + if (check_trl &&
> > + memcmp(trl->eyecatcher, SMC_EYECATCHER,
> sizeof(SMC_EYECATCHER)) &&
> > memcmp(trl->eyecatcher, SMCD_EYECATCHER,
> sizeof(SMCD_EYECATCHER)))
> > return false;
> > return true;
> > @@ -276,7 +275,8 @@ int smc_clc_wait_msg(struct smc_sock *smc, void
> *buf, int buflen,
> > struct msghdr msg = {NULL, 0};
> > int reason_code = 0;
> > struct kvec vec = {buf, buflen};
> > - int len, datlen;
> > + int len, datlen, recvlen;
> > + bool check_trl = true;
> > int krflags;
> >
> > /* peek the first few bytes to determine length of data to receive
> > @@ -320,10 +320,7 @@ int smc_clc_wait_msg(struct smc_sock *smc, void
> *buf, int buflen,
> > }
> > datlen = ntohs(clcm->length);
> > if ((len < sizeof(struct smc_clc_msg_hdr)) ||
> > - (datlen > buflen) ||
> > - (clcm->version != SMC_CLC_V1) ||
> > - (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
> > - clcm->path != SMC_TYPE_B) ||
> > + (clcm->version < SMC_CLC_V1) ||
> > ((clcm->type != SMC_CLC_DECLINE) &&
> > (clcm->type != expected_type))) {
> > smc->sk.sk_err = EPROTO;
> > @@ -331,16 +328,38 @@ int smc_clc_wait_msg(struct smc_sock *smc, void
> *buf, int buflen,
> > goto out;
> > }
> >
> > + if (clcm->type == SMC_CLC_PROPOSAL && clcm->path == SMC_TYPE_N)
> > + reason_code = SMC_CLC_DECL_VERSMISMAT; /* just V2 offered
> */
> > +
> > /* receive the complete CLC message */
> > memset(&msg, 0, sizeof(struct msghdr));
> > - iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, datlen);
> > + if (datlen > buflen) {
> > + check_trl = false;
> > + recvlen = buflen;
> > + } else {
> > + recvlen = datlen;
> > + }
> > + iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
> > krflags = MSG_WAITALL;
> > len = sock_recvmsg(smc->clcsock, &msg, krflags);
> > - if (len < datlen || !smc_clc_msg_hdr_valid(clcm)) {
> > + if (len < recvlen || !smc_clc_msg_hdr_valid(clcm, check_trl)) {
> > smc->sk.sk_err = EPROTO;
> > reason_code = -EPROTO;
> > goto out;
> > }
> > + datlen -= len;
> > + while (datlen) {
> > + u8 tmp[SMC_CLC_RECV_BUF_LEN];
> > +
> > + vec.iov_base = &tmp;
> > + vec.iov_len = SMC_CLC_RECV_BUF_LEN;
> > + /* receive remaining proposal message */
> > + recvlen = datlen > SMC_CLC_RECV_BUF_LEN ?
> > + SMC_CLC_RECV_BUF_LEN :
> datlen;
> > + iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
> > + len = sock_recvmsg(smc->clcsock, &msg, krflags);
> > + datlen -= len;
> > + }
> > if (clcm->type == SMC_CLC_DECLINE) {
> > struct smc_clc_msg_decline *dclc;
> >
> > diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
> > index ca209272e5fa..76c2b150d040 100644
> > --- a/net/smc/smc_clc.h
> > +++ b/net/smc/smc_clc.h
> > @@ -25,6 +25,7 @@
> > #define SMC_CLC_V1 0x1 /* SMC version
> */
> > #define SMC_TYPE_R 0 /* SMC-R only
> */
> > #define SMC_TYPE_D 1 /* SMC-D only
> */
> > +#define SMC_TYPE_N 2 /* neither SMC-R nor
> SMC-D */
> > #define SMC_TYPE_B 3 /* SMC-R and SMC-D
> */
> > #define CLC_WAIT_TIME (6 * HZ) /* max. wait time
> on clcsock */
> > #define CLC_WAIT_TIME_SHORT HZ /* short wait time on
> clcsock */
> > @@ -44,6 +45,9 @@
> > #define SMC_CLC_DECL_DIFFPREFIX 0x03070000 /* IP prefix / subnet
> mismatch */
> > #define SMC_CLC_DECL_GETVLANERR 0x03080000 /* err to get vlan id
> of ip device*/
> > #define SMC_CLC_DECL_ISMVLANERR 0x03090000 /* err to reg vlan id
> on ism dev */
> > +#define SMC_CLC_DECL_NOACTLINK 0x030a0000 /* no active smc-r
> link in lgr */
> > +#define SMC_CLC_DECL_NOSRVLINK 0x030b0000 /* SMC-R link from srv
> not found */
> > +#define SMC_CLC_DECL_VERSMISMAT 0x030c0000 /* SMC version
> mismatch */
> > #define SMC_CLC_DECL_SYNCERR 0x04000000 /* synchronization error
> */
> > #define SMC_CLC_DECL_PEERDECL 0x05000000 /* peer declined
> during handshake */
> > #define SMC_CLC_DECL_INTERR 0x09990000 /* internal error
> */
> >
>
>
>
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