From 437b300c6b28040ad87e4caf042e05f2c5f13c6d Mon Sep 17 00:00:00 2001 From: Scott Mayhew Date: Tue, 16 Feb 2016 16:20:25 -0500 Subject: [PATCH] auth_gss: fix panic in gss_pipe_downcall() in fips mode On Mon, 15 Feb 2016, Trond Myklebust wrote: > Hi Scott, > > On Mon, Feb 15, 2016 at 2:28 PM, Scott Mayhew wrote: > > md5 is disabled in fips mode, and attempting to import a gss context > > using md5 while in fips mode will result in crypto_alg_mod_lookup() > > returning -ENOENT, which will make its way back up to > > gss_pipe_downcall(), where the BUG() is triggered. Handling the -ENOENT > > allows for a more graceful failure. > > > > Signed-off-by: Scott Mayhew > > --- > > net/sunrpc/auth_gss/auth_gss.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c > > index 799e65b..c30fc3b 100644 > > --- a/net/sunrpc/auth_gss/auth_gss.c > > +++ b/net/sunrpc/auth_gss/auth_gss.c > > @@ -737,6 +737,9 @@ gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen) > > case -ENOSYS: > > gss_msg->msg.errno = -EAGAIN; > > break; > > + case -ENOENT: > > + gss_msg->msg.errno = -EPROTONOSUPPORT; > > + break; > > default: > > printk(KERN_CRIT "%s: bad return from " > > "gss_fill_context: %zd\n", __func__, err); > > -- > > 2.4.3 > > > > Well debugged, but I unfortunately do have to ask if this patch is > sufficient? In addition to -ENOENT, and -ENOMEM, it looks to me as if > crypto_alg_mod_lookup() can also fail with -EINTR, -ETIMEDOUT, and > -EAGAIN. Don't we also want to handle those? You're right, I was focusing on the panic that I could easily reproduce. I'm still not sure how I could trigger those other conditions. > > In fact, peering into the rats nest that is > gss_import_sec_context_kerberos(), it looks as if that is just a tiny > subset of all the errors that we might run into. Perhaps the right > thing to do here is to get rid of the BUG() (but keep the above > printk) and just return a generic error? That sounds fine to me -- updated patch attached. -Scott >From d54c6b64a107a90a38cab97577de05f9a4625052 Mon Sep 17 00:00:00 2001 From: Scott Mayhew Date: Mon, 15 Feb 2016 15:12:19 -0500 Subject: [PATCH] auth_gss: remove the BUG() from gss_pipe_downcall() Instead return a generic error via gss_msg->msg.errno. None of the errors returned by gss_fill_context() should necessarily trigger a kernel panic. Signed-off-by: Scott Mayhew Signed-off-by: Trond Myklebust --- net/sunrpc/auth_gss/auth_gss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index 799e65b944b9..cabf586f47d7 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -740,7 +740,7 @@ gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen) default: printk(KERN_CRIT "%s: bad return from " "gss_fill_context: %zd\n", __func__, err); - BUG(); + gss_msg->msg.errno = -EIO; } goto err_release_msg; } -- 2.20.1