[RFC PATCH v3] net/memif: change socket listener owner uid/gid

[Junxiao Shi <git@mail1.yoursunny.com>]

This allows a DPDK application running with root privilege to create a
memif socket listener with non-root owner uid and gid, which can be
connected from client applications running without root privilege.

Signed-off-by: Junxiao Shi <git@mail1.yoursunny.com>
---
 doc/guides/nics/memif.rst         |  2 ++
 drivers/net/memif/memif_socket.c  | 13 +++++++--
 drivers/net/memif/rte_eth_memif.c | 48 +++++++++++++++++++++++++++++--
 drivers/net/memif/rte_eth_memif.h |  2 ++
 4 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/doc/guides/nics/memif.rst b/doc/guides/nics/memif.rst
index aca843640b..8a8141aa72 100644
--- a/doc/guides/nics/memif.rst
+++ b/doc/guides/nics/memif.rst
@@ -44,6 +44,8 @@ client.
    "rsize=11", "Log2 of ring size. If rsize is 10, actual ring size is 1024", "10", "1-14"
    "socket=/tmp/memif.sock", "Socket filename", "/tmp/memif.sock", "string len 108"
    "socket-abstract=no", "Set usage of abstract socket address", "yes", "yes|no"
+   "uid=1000", "Set socket listener owner uid. Only relevant to server with socket-abstract=no", "unchanged", "uid_t"
+   "gid=1000", "Set socket listener owner gid. Only relevant to server with socket-abstract=no", "unchanged", "gid_t"
    "mac=01:23:45:ab:cd:ef", "Mac address", "01:ab:23:cd:45:ef", ""
    "secret=abc123", "Secret is an optional security option, which if specified, must be matched by peer", "", "string len 24"
    "zero-copy=yes", "Enable/disable zero-copy client mode. Only relevant to client, requires '--single-file-segments' eal argument", "no", "yes|no"
diff --git a/drivers/net/memif/memif_socket.c b/drivers/net/memif/memif_socket.c
index 7886644412..c2b038d01a 100644
--- a/drivers/net/memif/memif_socket.c
+++ b/drivers/net/memif/memif_socket.c
@@ -889,7 +889,7 @@ memif_listener_handler(void *arg)
 }
 
 static struct memif_socket *
-memif_socket_create(char *key, uint8_t listener, bool is_abstract)
+memif_socket_create(char *key, uint8_t listener, bool is_abstract, uid_t owner_uid, gid_t owner_gid)
 {
 	struct memif_socket *sock;
 	struct sockaddr_un un = { 0 };
@@ -941,6 +941,14 @@ memif_socket_create(char *key, uint8_t listener, bool is_abstract)
 
 		MIF_LOG(DEBUG, "Memif listener socket %s created.", sock->filename);
 
+		if (!is_abstract && (owner_uid != (uid_t)-1 || owner_gid != (gid_t)-1)) {
+			ret = chown(sock->filename, owner_uid, owner_gid);
+			if (ret < 0) {
+				MIF_LOG(ERR, "Failed to change listener socket owner %d", errno);
+				goto error;
+			}
+		}
+
 		/* Allocate interrupt instance */
 		sock->intr_handle =
 			rte_intr_instance_alloc(RTE_INTR_INSTANCE_F_SHARED);
@@ -1017,7 +1025,8 @@ memif_socket_init(struct rte_eth_dev *dev, const char *socket_filename)
 	if (ret < 0) {
 		socket = memif_socket_create(key,
 			(pmd->role == MEMIF_ROLE_CLIENT) ? 0 : 1,
-			pmd->flags & ETH_MEMIF_FLAG_SOCKET_ABSTRACT);
+			pmd->flags & ETH_MEMIF_FLAG_SOCKET_ABSTRACT,
+			pmd->owner_uid, pmd->owner_gid);
 		if (socket == NULL)
 			return -1;
 		ret = rte_hash_add_key_data(hash, key, socket);
diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c
index dd951b8296..092f1cbc92 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -37,6 +37,8 @@
 #define ETH_MEMIF_RING_SIZE_ARG		"rsize"
 #define ETH_MEMIF_SOCKET_ARG		"socket"
 #define ETH_MEMIF_SOCKET_ABSTRACT_ARG	"socket-abstract"
+#define ETH_MEMIF_OWNER_UID_ARG		"owner-uid"
+#define ETH_MEMIF_OWNER_GID_ARG		"owner-gid"
 #define ETH_MEMIF_MAC_ARG		"mac"
 #define ETH_MEMIF_ZC_ARG		"zero-copy"
 #define ETH_MEMIF_SECRET_ARG		"secret"
@@ -48,6 +50,8 @@ static const char * const valid_arguments[] = {
 	ETH_MEMIF_RING_SIZE_ARG,
 	ETH_MEMIF_SOCKET_ARG,
 	ETH_MEMIF_SOCKET_ABSTRACT_ARG,
+	ETH_MEMIF_OWNER_UID_ARG,
+	ETH_MEMIF_OWNER_GID_ARG,
 	ETH_MEMIF_MAC_ARG,
 	ETH_MEMIF_ZC_ARG,
 	ETH_MEMIF_SECRET_ARG,
@@ -1515,7 +1519,7 @@ static const struct eth_dev_ops ops = {
 static int
 memif_create(struct rte_vdev_device *vdev, enum memif_role_t role,
 	     memif_interface_id_t id, uint32_t flags,
-	     const char *socket_filename,
+	     const char *socket_filename, uid_t owner_uid, gid_t owner_gid,
 	     memif_log2_ring_size_t log2_ring_size,
 	     uint16_t pkt_buffer_size, const char *secret,
 	     struct rte_ether_addr *ether_addr)
@@ -1554,6 +1558,8 @@ memif_create(struct rte_vdev_device *vdev, enum memif_role_t role,
 	/* Zero-copy flag irelevant to server. */
 	if (pmd->role == MEMIF_ROLE_SERVER)
 		pmd->flags &= ~ETH_MEMIF_FLAG_ZERO_COPY;
+	pmd->owner_uid = owner_uid;
+	pmd->owner_gid = owner_gid;
 
 	ret = memif_socket_init(eth_dev, socket_filename);
 	if (ret < 0)
@@ -1740,6 +1746,30 @@ memif_set_is_socket_abstract(const char *key __rte_unused, const char *value, vo
 	return 0;
 }
 
+static int
+memif_set_owner(const char *key, const char *value, void *extra_args)
+{
+	RTE_ASSERT(sizeof(uid_t) == sizeof(uint32_t));
+	RTE_ASSERT(sizeof(gid_t) == sizeof(uint32_t));
+
+	unsigned long val;
+	char *end = NULL;
+	uint32_t *id = (uint32_t *)extra_args;
+
+	val = strtoul(value, &end, 10);
+	if (*value == '\0' || *end != '\0') {
+		MIF_LOG(ERR, "Failed to parse %s: %s.", key, value);
+		return -EINVAL;
+	}
+	if (val >= UINT32_MAX) {
+		MIF_LOG(ERR, "Invalid %s: %s.", key, value);
+		return -ERANGE;
+	}
+
+	*id = val;
+	return 0;
+}
+
 static int
 memif_set_mac(const char *key __rte_unused, const char *value, void *extra_args)
 {
@@ -1772,6 +1802,8 @@ rte_pmd_memif_probe(struct rte_vdev_device *vdev)
 	uint16_t pkt_buffer_size = ETH_MEMIF_DEFAULT_PKT_BUFFER_SIZE;
 	memif_log2_ring_size_t log2_ring_size = ETH_MEMIF_DEFAULT_RING_SIZE;
 	const char *socket_filename = ETH_MEMIF_DEFAULT_SOCKET_FILENAME;
+	uid_t owner_uid = -1;
+	gid_t owner_gid = -1;
 	uint32_t flags = 0;
 	const char *secret = NULL;
 	struct rte_ether_addr *ether_addr = rte_zmalloc("",
@@ -1855,6 +1887,14 @@ rte_pmd_memif_probe(struct rte_vdev_device *vdev)
 					 &memif_set_is_socket_abstract, &flags);
 		if (ret < 0)
 			goto exit;
+		ret = rte_kvargs_process(kvlist, ETH_MEMIF_OWNER_UID_ARG,
+					 &memif_set_owner, &owner_uid);
+		if (ret < 0)
+			goto exit;
+		ret = rte_kvargs_process(kvlist, ETH_MEMIF_OWNER_GID_ARG,
+					 &memif_set_owner, &owner_gid);
+		if (ret < 0)
+			goto exit;
 		ret = rte_kvargs_process(kvlist, ETH_MEMIF_MAC_ARG,
 					 &memif_set_mac, ether_addr);
 		if (ret < 0)
@@ -1876,7 +1916,7 @@ rte_pmd_memif_probe(struct rte_vdev_device *vdev)
 	}
 
 	/* create interface */
-	ret = memif_create(vdev, role, id, flags, socket_filename,
+	ret = memif_create(vdev, role, id, flags, socket_filename, owner_uid, owner_gid,
 			   log2_ring_size, pkt_buffer_size, secret, ether_addr);
 
 exit:
@@ -1909,7 +1949,9 @@ RTE_PMD_REGISTER_PARAM_STRING(net_memif,
 			      ETH_MEMIF_PKT_BUFFER_SIZE_ARG "=<int>"
 			      ETH_MEMIF_RING_SIZE_ARG "=<int>"
 			      ETH_MEMIF_SOCKET_ARG "=<string>"
-				  ETH_MEMIF_SOCKET_ABSTRACT_ARG "=yes|no"
+			      ETH_MEMIF_SOCKET_ABSTRACT_ARG "=yes|no"
+			      ETH_MEMIF_OWNER_UID_ARG "=<int>"
+			      ETH_MEMIF_OWNER_GID_ARG "=<int>"
 			      ETH_MEMIF_MAC_ARG "=xx:xx:xx:xx:xx:xx"
 			      ETH_MEMIF_ZC_ARG "=yes|no"
 			      ETH_MEMIF_SECRET_ARG "=<string>");
diff --git a/drivers/net/memif/rte_eth_memif.h b/drivers/net/memif/rte_eth_memif.h
index 81e7dceae0..b43895a55f 100644
--- a/drivers/net/memif/rte_eth_memif.h
+++ b/drivers/net/memif/rte_eth_memif.h
@@ -89,6 +89,8 @@ struct pmd_internals {
 /**< use abstract socket address */
 
 	char *socket_filename;			/**< pointer to socket filename */
+	uid_t owner_uid;			/**< socket owner uid */
+	gid_t owner_gid;			/**< socket owner gid */
 	char secret[ETH_MEMIF_SECRET_SIZE]; /**< secret (optional security parameter) */
 
 	struct memif_control_channel *cc;	/**< control channel */
-- 
2.17.1