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From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Cc: Callum Parsey <callum@neoninteger.au>,
	me@yawnt.com, David Gibson <david@gibson.dropbear.id.au>,
	lemmi@nerd2nerd.org
Subject: [PATCH 02/10] pasta: Improve error handling on failure to join network namespace
Date: Sun, 14 May 2023 20:14:07 +0200	[thread overview]
Message-ID: <20230514181415.313420-3-sbrivio@redhat.com> (raw)
In-Reply-To: <20230514181415.313420-1-sbrivio@redhat.com>

In pasta_wait_for_ns(), open() failing with ENOENT is expected: we're
busy-looping until the network namespace appears. But any other
failure is not something we're going to recover from: return right
away if we don't get either success or ENOENT.

Now that pasta_wait_for_ns() can actually fail, handle that in
pasta_start_ns() by reporting the issue and exiting.

Looping on EPERM, when pasta doesn't actually have the permissions to
join a given namespace, isn't exactly a productive thing to do.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 pasta.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/pasta.c b/pasta.c
index 3a4d704..2fa0168 100644
--- a/pasta.c
+++ b/pasta.c
@@ -94,8 +94,11 @@ static int pasta_wait_for_ns(void *arg)
 	char ns[PATH_MAX];
 
 	snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
-	do
-		while ((c->pasta_netns_fd = open(ns, flags)) < 0);
+	while ((c->pasta_netns_fd = open(ns, flags)) < 0) {
+		if (errno != ENOENT)
+			return 0;
+	}
+
 	while (setns(c->pasta_netns_fd, CLONE_NEWNET) &&
 	       !close(c->pasta_netns_fd));
 
@@ -252,6 +255,8 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
 	}
 
 	NS_CALL(pasta_wait_for_ns, c);
+	if (c->pasta_netns_fd < 0)
+		die("Failed to join network namespace");
 }
 
 /**
-- 
@@ -94,8 +94,11 @@ static int pasta_wait_for_ns(void *arg)
 	char ns[PATH_MAX];
 
 	snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
-	do
-		while ((c->pasta_netns_fd = open(ns, flags)) < 0);
+	while ((c->pasta_netns_fd = open(ns, flags)) < 0) {
+		if (errno != ENOENT)
+			return 0;
+	}
+
 	while (setns(c->pasta_netns_fd, CLONE_NEWNET) &&
 	       !close(c->pasta_netns_fd));
 
@@ -252,6 +255,8 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
 	}
 
 	NS_CALL(pasta_wait_for_ns, c);
+	if (c->pasta_netns_fd < 0)
+		die("Failed to join network namespace");
 }
 
 /**
-- 
2.39.2


  parent reply	other threads:[~2023-05-14 18:14 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-14 18:14 [PATCH 00/10] RFC/RFT: Optionally copy all routes and addresses for pasta, allow gateway-less routes Stefano Brivio
2023-05-14 18:14 ` [PATCH 01/10] netlink: Fix comment about response buffer size for nl_req() Stefano Brivio
2023-05-16  3:23   ` David Gibson
2023-05-14 18:14 ` Stefano Brivio [this message]
2023-05-16  3:24   ` [PATCH 02/10] pasta: Improve error handling on failure to join network namespace David Gibson
2023-05-14 18:14 ` [PATCH 03/10] netlink: Add functionality to copy routes from outer namespace Stefano Brivio
2023-05-14 18:14 ` [PATCH 04/10] conf: --config-net option is for pasta mode only Stefano Brivio
2023-05-16  3:59   ` David Gibson
2023-05-14 18:14 ` [PATCH 05/10] conf, pasta: With --config-net, copy all routes by default Stefano Brivio
2023-05-14 18:14 ` [PATCH 06/10] Revert "conf: Adjust netmask on mismatch between IPv4 address/netmask and gateway" Stefano Brivio
2023-05-16  4:00   ` David Gibson
2023-05-14 18:14 ` [PATCH 07/10] conf: Don't exit if sourced default route has no gateway Stefano Brivio
2023-05-14 18:14 ` [PATCH 08/10] netlink: Add functionality to copy addresses from outer namespace Stefano Brivio
2023-05-14 18:14 ` [PATCH 09/10] conf, pasta: With --config-net, copy all addresses by default Stefano Brivio
2023-05-14 18:14 ` [PATCH 10/10] passt.h: Fix description of pasta_ifi in struct ctx Stefano Brivio
2023-05-16  4:03   ` David Gibson
2023-05-16  5:06 ` [PATCH 00/10] RFC/RFT: Optionally copy all routes and addresses for pasta, allow gateway-less routes David Gibson
2023-05-16 21:42   ` Stefano Brivio
2023-05-17  1:15     ` David Gibson
2023-05-17  6:52       ` Stefano Brivio
2023-05-18  3:26         ` David Gibson

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