mountd: prepend '$' to make use_ipaddr clients self-describing

From: "J. Bruce Fields" <bfields@redhat.com>

Mountd is responsible for filling three interrelated kernel caches:

	- auth_unix_ip maps an incoming ip addresses to a "domain".
	- nfsd_fh maps (domain, filehandle-fragment) pairs to paths.
	- nfsd_export maps (domain, path) pairs to export options.

Note that each export is assocated with a "client" string--the part
before the parentheses in an /etc/export line--which may be a domain
name, a netgroup, etc.

The "domain" string in the above three caches may be either:

	- in the !use_ipaddr case, a comma-separated list of client
	  strings.
	- in the use_ipaddr case, an ip address.

In the former case, mountd does the hard work of matching an ip address
to the clients when doing the auth_unix_ip mapping.  In the latter case,
it delays that until the nfsd_fh or nfsd_export upcall.

We're currently depending on being able to flush the kernel caches
completely when switching between the use_ipaddr and !use_ipaddr cases.
However, the kernel's cache-flushing doesn't really provide reliable
guarantees on return; it's still possible we could see nfsd_fh or
nfsd_export upcalls with the old domain-type after flushing.

So, instead, make the two domain types self-describing by prepending a
"$" in the use_ipaddr case.

Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mountd/auth.c b/utils/mountd/auth.c
index 688bf78411808cff236c67415e402bf12dd1d479..508040ad610bd0fd7268de26114f47f08baeda84 100644 (file)
--- a/utils/mountd/auth.c
+++ b/utils/mountd/auth.c
@@ -112,15 +112,23 @@ auth_reload()
        return counter;
 }
 
+static char *get_client_ipaddr_name(const struct sockaddr *caller)
+{
+       char buf[INET6_ADDRSTRLEN + 1];
+
+       buf[0] = '$';
+       host_ntop(caller, buf + 1, sizeof(buf) - 1);
+       return strdup(buf);
+}
+
 static char *
 get_client_hostname(const struct sockaddr *caller, struct addrinfo *ai,
                enum auth_error *error)
 {
-       char buf[INET6_ADDRSTRLEN];
        char *n;
 
        if (use_ipaddr)
-               return strdup(host_ntop(caller, buf, sizeof(buf)));
+               return get_client_ipaddr_name(caller);
        n = client_compose(ai);
        *error = unknown_host;
        if (!n)
@@ -143,7 +151,7 @@ bool namelist_client_matches(nfs_export *exp, char *dom)
 
 bool client_matches(nfs_export *exp, char *dom, struct addrinfo *ai)
 {
-       if (use_ipaddr)
+       if (is_ipaddr_client(dom))
                return ipaddr_client_matches(exp, ai);
        return namelist_client_matches(exp, dom);
 }

diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index be5198e84c830a8df418fc2e081a1a127e90af55..1ae96fe41ecca26e0ff6d7003137b520f6c1ddbc 100644 (file)
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -500,6 +500,8 @@ struct addrinfo *lookup_client_addr(char *dom)
        struct addrinfo *ret;
        struct addrinfo *tmp;
 
+       dom++; /* skip initial "$" */
+
        tmp = host_pton(dom);
        if (tmp == NULL)
                return NULL;
@@ -551,7 +553,7 @@ static void nfsd_fh(FILE *f)
 
        auth_reload();
 
-       if (use_ipaddr) {
+       if (is_ipaddr_client(dom)) {
                ai = lookup_client_addr(dom);
                if (!ai)
                        goto out;
@@ -587,7 +589,8 @@ static void nfsd_fh(FILE *f)
                                next_exp = exp->m_next;
                        }
 
-                       if (!use_ipaddr && !namelist_client_matches(exp, dom))
+                       if (!is_ipaddr_client(dom)
+                                       && !namelist_client_matches(exp, dom))
                                continue;
                        if (exp->m_export.e_mountpoint &&
                            !is_mountpoint(exp->m_export.e_mountpoint[0]?
@@ -597,7 +600,8 @@ static void nfsd_fh(FILE *f)
 
                        if (!match_fsid(&parsed, exp, path))
                                continue;
-                       if (use_ipaddr && !ipaddr_client_matches(exp, ai))
+                       if (is_ipaddr_client(dom)
+                                       && !ipaddr_client_matches(exp, ai))
                                continue;
                        if (!found || subexport(&exp->m_export, found)) {
                                found = &exp->m_export;
@@ -1071,7 +1075,7 @@ static void nfsd_export(FILE *f)
 
        auth_reload();
 
-       if (use_ipaddr) {
+       if (is_ipaddr_client(dom)) {
                ai = lookup_client_addr(dom);
                if (!ai)
                        goto out;

diff --git a/utils/mountd/mountd.h b/utils/mountd/mountd.h
index c969a27ca18e48c23625701f749a716e5a4e4d90..6d358a75d9f3cfdcafdc4380ce8223a68a93fb3b 100644 (file)
--- a/utils/mountd/mountd.h
+++ b/utils/mountd/mountd.h
@@ -60,4 +60,9 @@ bool ipaddr_client_matches(nfs_export *exp, struct addrinfo *ai);
 bool namelist_client_matches(nfs_export *exp, char *dom);
 bool client_matches(nfs_export *exp, char *dom, struct addrinfo *ai);
 
+static inline bool is_ipaddr_client(char *dom)
+{
+       return dom[0] == '$';
+}
+
 #endif /* MOUNTD_H */