Prevent races in accesses of the software crypto session array.
swcr_newsession can change the pointer for swcr_sessions which races with swcr_process which is looking up entries in this array. Add a rwlock that protects changes to the array pointer so that swcr_newsession and swcr_process no longer race. Original patch by: Steve O'Hara-Smith <Steve.OHaraSmith@isilon.com> Reviewed by: jmg Sponsored by: EMC / Isilon Storage Division
This commit is contained in:
Benno Rice
parent
d7d8b00bec
commit
109919c67a
@ -35,6 +35,8 @@ __FBSDID("$FreeBSD$");
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#include <sys/random.h>
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#include <sys/kernel.h>
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#include <sys/uio.h>
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#include <sys/lock.h>
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#include <sys/rwlock.h>
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#include <crypto/blowfish/blowfish.h>
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#include <crypto/sha1.h>
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@ -54,6 +56,8 @@ __FBSDID("$FreeBSD$");
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static int32_t swcr_id;
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static struct swcr_data **swcr_sessions = NULL;
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static u_int32_t swcr_sesnum;
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/* Protects swcr_sessions pointer, not data. */
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static struct rwlock swcr_sessions_lock;
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u_int8_t hmac_ipad_buffer[HMAC_MAX_BLOCK_LEN];
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u_int8_t hmac_opad_buffer[HMAC_MAX_BLOCK_LEN];
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@ -62,6 +66,7 @@ static int swcr_encdec(struct cryptodesc *, struct swcr_data *, caddr_t, int);
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static int swcr_authcompute(struct cryptodesc *, struct swcr_data *, caddr_t, int);
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static int swcr_compdec(struct cryptodesc *, struct swcr_data *, caddr_t, int);
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static int swcr_freesession(device_t dev, u_int64_t tid);
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static int swcr_freesession_locked(device_t dev, u_int64_t tid);
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/*
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* Apply a symmetric encryption/decryption algorithm.
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@ -670,6 +675,7 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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if (sid == NULL || cri == NULL)
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return EINVAL;
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rw_wlock(&swcr_sessions_lock);
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if (swcr_sessions) {
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for (i = 1; i < swcr_sesnum; i++)
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if (swcr_sessions[i] == NULL)
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@ -692,6 +698,7 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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swcr_sesnum = 0;
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else
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swcr_sesnum /= 2;
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rw_wunlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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@ -705,6 +712,7 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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swcr_sessions = swd;
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}
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rw_downgrade(&swcr_sessions_lock);
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swd = &swcr_sessions[i];
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*sid = i;
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@ -712,7 +720,8 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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*swd = malloc(sizeof(struct swcr_data),
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M_CRYPTO_DATA, M_NOWAIT|M_ZERO);
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if (*swd == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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@ -749,7 +758,8 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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error = txf->setkey(&((*swd)->sw_kschedule),
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cri->cri_key, cri->cri_klen / 8);
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if (error) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return error;
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}
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}
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@ -780,14 +790,16 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
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M_NOWAIT);
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if ((*swd)->sw_ictx == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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(*swd)->sw_octx = malloc(axf->ctxsize, M_CRYPTO_DATA,
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M_NOWAIT);
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if ((*swd)->sw_octx == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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@ -810,14 +822,16 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
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M_NOWAIT);
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if ((*swd)->sw_ictx == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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(*swd)->sw_octx = malloc(cri->cri_klen / 8,
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M_CRYPTO_DATA, M_NOWAIT);
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if ((*swd)->sw_octx == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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@ -841,7 +855,8 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
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M_NOWAIT);
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if ((*swd)->sw_ictx == NULL) {
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return ENOBUFS;
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}
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@ -855,7 +870,8 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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(*swd)->sw_cxf = cxf;
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break;
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default:
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swcr_freesession(dev, i);
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swcr_freesession_locked(dev, i);
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rw_runlock(&swcr_sessions_lock);
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return EINVAL;
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}
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@ -863,14 +879,26 @@ swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
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cri = cri->cri_next;
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swd = &((*swd)->sw_next);
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}
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rw_runlock(&swcr_sessions_lock);
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return 0;
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}
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static int
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swcr_freesession(device_t dev, u_int64_t tid)
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{
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int error;
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rw_rlock(&swcr_sessions_lock);
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error = swcr_freesession_locked(dev, tid);
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rw_runlock(&swcr_sessions_lock);
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return error;
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}
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/*
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* Free a session.
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*/
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static int
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swcr_freesession(device_t dev, u_int64_t tid)
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swcr_freesession_locked(device_t dev, u_int64_t tid)
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{
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struct swcr_data *swd;
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struct enc_xform *txf;
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@ -976,10 +1004,14 @@ swcr_process(device_t dev, struct cryptop *crp, int hint)
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}
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lid = crp->crp_sid & 0xffffffff;
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if (lid >= swcr_sesnum || lid == 0 || swcr_sessions[lid] == NULL) {
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rw_rlock(&swcr_sessions_lock);
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if (swcr_sessions == NULL || lid >= swcr_sesnum || lid == 0 ||
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swcr_sessions[lid] == NULL) {
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rw_runlock(&swcr_sessions_lock);
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crp->crp_etype = ENOENT;
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goto done;
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}
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rw_runlock(&swcr_sessions_lock);
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/* Go through crypto descriptors, processing as we go */
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for (crd = crp->crp_desc; crd; crd = crd->crd_next) {
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@ -993,10 +1025,17 @@ swcr_process(device_t dev, struct cryptop *crp, int hint)
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* XXX between the various instances of an algorithm (so we can
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* XXX locate the correct crypto context).
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*/
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rw_rlock(&swcr_sessions_lock);
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if (swcr_sessions == NULL) {
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rw_runlock(&swcr_sessions_lock);
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crp->crp_etype = ENOENT;
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goto done;
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}
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for (sw = swcr_sessions[lid];
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sw && sw->sw_alg != crd->crd_alg;
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sw = sw->sw_next)
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;
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rw_runlock(&swcr_sessions_lock);
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/* No such context ? */
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if (sw == NULL) {
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@ -1074,6 +1113,7 @@ swcr_probe(device_t dev)
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static int
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swcr_attach(device_t dev)
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{
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rw_init(&swcr_sessions_lock, "swcr_sessions_lock");
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memset(hmac_ipad_buffer, HMAC_IPAD_VAL, HMAC_MAX_BLOCK_LEN);
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memset(hmac_opad_buffer, HMAC_OPAD_VAL, HMAC_MAX_BLOCK_LEN);
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@ -1115,8 +1155,11 @@ static int
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swcr_detach(device_t dev)
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{
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crypto_unregister_all(swcr_id);
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if (swcr_sessions != NULL)
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free(swcr_sessions, M_CRYPTO_DATA);
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rw_wlock(&swcr_sessions_lock);
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free(swcr_sessions, M_CRYPTO_DATA);
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swcr_sessions = NULL;
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rw_wunlock(&swcr_sessions_lock);
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rw_destroy(&swcr_sessions_lock);
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return 0;
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}
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