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From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>
Cc: passt-dev@passt.top, David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH 04/10] Remove unhelpful drop_caps() call in pasta_start_ns()
Date: Tue, 11 Oct 2022 16:40:12 +1100	[thread overview]
Message-ID: <20221011054018.1449506-5-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20221011054018.1449506-1-david@gibson.dropbear.id.au>

drop_caps() has a number of bugs which mean it doesn't do what you'd
expect.  However, even if we fixed those, the call in pasta_start_ns()
doesn't do anything useful:

* In the common case, we're UID 0 at this point.  In this case drop_caps()
  doesn't accomplish anything, because even with capabilities dropped, we
  are still privileged.
* When attaching to an existing namespace with --userns or --netns-only
  we might not be UID 0.  In this case it's too early to drop all
  capabilities: we need at least CAP_NET_ADMIN to configure the
  tap device in the namespace.

Remove this call - we will still drop capabilities a little later in
sandbox().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 pasta.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pasta.c b/pasta.c
index 1ad63fb..4ff322c 100644
--- a/pasta.c
+++ b/pasta.c
@@ -223,8 +223,6 @@ void pasta_start_ns(struct ctx *c, int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
-	drop_caps();
-
 	NS_CALL(pasta_wait_for_ns, c);
 }
 
-- 
@@ -223,8 +223,6 @@ void pasta_start_ns(struct ctx *c, int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
-	drop_caps();
-
 	NS_CALL(pasta_wait_for_ns, c);
 }
 
-- 
2.37.3


  parent reply	other threads:[~2022-10-11  5:40 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-11  5:40 [PATCH 00/10] Fixes and cleanups for capability handling David Gibson
2022-10-11  5:40 ` [PATCH 01/10] test: Move slower tests to end of test run David Gibson
2022-10-11  5:40 ` [PATCH 02/10] pasta: More general way of starting spawned shell as a login shell David Gibson
2022-10-13  2:16   ` Stefano Brivio
2022-10-13  8:22     ` David Gibson
2022-10-13  9:48       ` Stefano Brivio
2022-10-13 23:24         ` David Gibson
2022-10-11  5:40 ` [PATCH 03/10] pasta_start_ns() always ends in parent context David Gibson
2022-10-11  5:40 ` David Gibson [this message]
2022-10-11  5:40 ` [PATCH 05/10] Clarify various self-isolation steps David Gibson
2022-10-13  2:17   ` Stefano Brivio
2022-10-13  8:31     ` David Gibson
2022-10-13 12:49   ` Stefano Brivio
2022-10-13 23:25     ` David Gibson
2022-10-11  5:40 ` [PATCH 06/10] Replace FWRITE with a function David Gibson
2022-10-13  2:17   ` Stefano Brivio
2022-10-13  8:51     ` David Gibson
2022-10-11  5:40 ` [PATCH 07/10] isolation: Replace drop_caps() with a version that actually does something David Gibson
2022-10-13  2:18   ` Stefano Brivio
2022-10-13  9:44     ` David Gibson
2022-10-13  4:01   ` Stefano Brivio
2022-10-13 13:08     ` Stefano Brivio
2022-10-13 16:37       ` Stefano Brivio
2022-10-13 23:42         ` David Gibson
2022-10-11  5:40 ` [PATCH 08/10] isolation: Prevent any child processes gaining capabilities David Gibson
2022-10-13  2:17   ` Stefano Brivio
2022-10-13  9:33     ` David Gibson
2022-10-13  9:50       ` Stefano Brivio
2022-10-11  5:40 ` [PATCH 09/10] isolation: Only configure UID/GID mappings in userns when spawning shell David Gibson
2022-10-13  2:18   ` Stefano Brivio
2022-10-13  9:36     ` David Gibson
2022-10-11  5:40 ` [PATCH 10/10] Rename pasta_setup_ns() to pasta_spawn_cmd() David Gibson
2022-10-13  2:44 ` [PATCH 00/10] Fixes and cleanups for capability handling Stefano Brivio

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