From 1654a04cd702fd19c297c36300a6ab834cf8c072 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Sat, 4 Jan 2014 07:18:03 -0500 Subject: sunrpc: don't wait for write before allowing reads from use-gss-proxy file It doesn't make much sense to make reads from this procfile hang. As far as I can tell, only gssproxy itself will open this file and it never reads from it. Change it to just give the present setting of sn->use_gss_proxy without waiting for anything. Note that we do not want to call use_gss_proxy() in this codepath since an inopportune read of this file could cause it to be disabled prematurely. Cc: stable@vger.kernel.org Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/svcauth_gss.c | 33 ++------------------------------- 1 file changed, 2 insertions(+), 31 deletions(-) (limited to 'net/sunrpc/auth_gss/svcauth_gss.c') diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 008cdade5aae..1b94a9c8a242 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1295,34 +1295,9 @@ static int set_gss_proxy(struct net *net, int type) else ret = -EBUSY; spin_unlock(&use_gssp_lock); - wake_up(&sn->gssp_wq); return ret; } -static inline bool gssp_ready(struct sunrpc_net *sn) -{ - switch (sn->use_gss_proxy) { - case -1: - return false; - case 0: - return true; - case 1: - return sn->gssp_clnt; - } - WARN_ON_ONCE(1); - return false; -} - -static int wait_for_gss_proxy(struct net *net, struct file *file) -{ - struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); - - if (file->f_flags & O_NONBLOCK && !gssp_ready(sn)) - return -EAGAIN; - return wait_event_interruptible(sn->gssp_wq, gssp_ready(sn)); -} - - static ssize_t write_gssp(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { @@ -1355,16 +1330,12 @@ static ssize_t read_gssp(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct net *net = PDE_DATA(file_inode(file)); + struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); unsigned long p = *ppos; char tbuf[10]; size_t len; - int ret; - - ret = wait_for_gss_proxy(net, file); - if (ret) - return ret; - snprintf(tbuf, sizeof(tbuf), "%d\n", use_gss_proxy(net)); + snprintf(tbuf, sizeof(tbuf), "%d\n", sn->use_gss_proxy); len = strlen(tbuf); if (p >= len) return 0; -- cgit v1.2.3 From a92e5eb1103341e985a575e48e26f87fbb9b1679 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Sat, 4 Jan 2014 07:18:04 -0500 Subject: sunrpc: fix potential race between setting use_gss_proxy and the upcall rpc_clnt An nfsd thread can call use_gss_proxy and find it set to '1' but find gssp_clnt still NULL, so that when it attempts the upcall the result will be an unnecessary -EIO. So, ensure that gssp_clnt is created first, and set the use_gss_proxy variable only if that succeeds. Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/svcauth_gss.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/sunrpc/auth_gss/svcauth_gss.c') diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 1b94a9c8a242..60dc3700b2cb 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1317,10 +1317,10 @@ static ssize_t write_gssp(struct file *file, const char __user *buf, return res; if (i != 1) return -EINVAL; - res = set_gss_proxy(net, 1); + res = set_gssp_clnt(net); if (res) return res; - res = set_gssp_clnt(net); + res = set_gss_proxy(net, 1); if (res) return res; return count; -- cgit v1.2.3 From 0fdc26785d0a5bb33d9adb572307fd2d7a406734 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Sat, 4 Jan 2014 07:18:05 -0500 Subject: sunrpc: get rid of use_gssp_lock We can achieve the same result with a cmpxchg(). This also fixes a potential race in use_gss_proxy(). The value of sn->use_gss_proxy could go from -1 to 1 just after we check it in use_gss_proxy() but before we acquire the spinlock. The procfile write would end up returning success but the value would flip to 0 soon afterward. With this method we not only avoid locking but the first "setter" always wins. Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/svcauth_gss.c | 42 +++++++++++++++++---------------------- 1 file changed, 18 insertions(+), 24 deletions(-) (limited to 'net/sunrpc/auth_gss/svcauth_gss.c') diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 60dc3700b2cb..2a935404047f 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1263,41 +1263,35 @@ out: return ret; } -DEFINE_SPINLOCK(use_gssp_lock); - -static bool use_gss_proxy(struct net *net) +/* + * Try to set the sn->use_gss_proxy variable to a new value. We only allow + * it to be changed if it's currently undefined (-1). If it's any other value + * then return -EBUSY unless the type wouldn't have changed anyway. + */ +static int set_gss_proxy(struct net *net, int type) { struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); + int ret; - if (sn->use_gss_proxy != -1) - return sn->use_gss_proxy; - spin_lock(&use_gssp_lock); - /* - * If you wanted gss-proxy, you should have said so before - * starting to accept requests: - */ - sn->use_gss_proxy = 0; - spin_unlock(&use_gssp_lock); + WARN_ON_ONCE(type != 0 && type != 1); + ret = cmpxchg(&sn->use_gss_proxy, -1, type); + if (ret != -1 && ret != type) + return -EBUSY; return 0; } -#ifdef CONFIG_PROC_FS - -static int set_gss_proxy(struct net *net, int type) +static bool use_gss_proxy(struct net *net) { struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); - int ret = 0; - WARN_ON_ONCE(type != 0 && type != 1); - spin_lock(&use_gssp_lock); - if (sn->use_gss_proxy == -1 || sn->use_gss_proxy == type) - sn->use_gss_proxy = type; - else - ret = -EBUSY; - spin_unlock(&use_gssp_lock); - return ret; + /* If use_gss_proxy is still undefined, then try to disable it */ + if (sn->use_gss_proxy == -1) + set_gss_proxy(net, 0); + return sn->use_gss_proxy; } +#ifdef CONFIG_PROC_FS + static ssize_t write_gssp(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { -- cgit v1.2.3 From bba0f88bf7c4ad467eeb3a17443de1f9cd0437e0 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Fri, 18 Jan 2013 11:33:08 -0500 Subject: minor svcauth_gss.c cleanup --- net/sunrpc/auth_gss/svcauth_gss.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'net/sunrpc/auth_gss/svcauth_gss.c') diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 2a935404047f..0f73f4507746 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1591,8 +1591,7 @@ svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp) BUG_ON(integ_len % 4); *p++ = htonl(integ_len); *p++ = htonl(gc->gc_seq); - if (xdr_buf_subsegment(resbuf, &integ_buf, integ_offset, - integ_len)) + if (xdr_buf_subsegment(resbuf, &integ_buf, integ_offset, integ_len)) BUG(); if (resbuf->tail[0].iov_base == NULL) { if (resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE > PAGE_SIZE) @@ -1600,10 +1599,8 @@ svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp) resbuf->tail[0].iov_base = resbuf->head[0].iov_base + resbuf->head[0].iov_len; resbuf->tail[0].iov_len = 0; - resv = &resbuf->tail[0]; - } else { - resv = &resbuf->tail[0]; } + resv = &resbuf->tail[0]; mic.data = (u8 *)resv->iov_base + resv->iov_len + 4; if (gss_get_mic(gsd->rsci->mechctx, &integ_buf, &mic)) goto out_err; -- cgit v1.2.3