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From: "Michał Górny" <mgorny@gentoo.org>
To: gentoo-commits@lists.gentoo.org
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Reply-To: gentoo-dev@lists.gentoo.org, "Michał Górny" <mgorny@gentoo.org>
Message-ID: <1543763859.fcb399f5a685f088b9f10d9d57e326ee78f9e6dd.mgorny@gentoo>
Subject: [gentoo-commits] proj/sandbox:master commit in: libsandbox/
X-VCS-Repository: proj/sandbox
X-VCS-Files: libsandbox/libsandbox.c
X-VCS-Directories: libsandbox/
X-VCS-Committer: mgorny
X-VCS-Committer-Name: Michał Górny
X-VCS-Revision: fcb399f5a685f088b9f10d9d57e326ee78f9e6dd
X-VCS-Branch: master
Date: Sun, 2 Dec 2018 15:22:15 +0000 (UTC)
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commit: fcb399f5a685f088b9f10d9d57e326ee78f9e6dd
Author: Zac Medico <zmedico <AT> gentoo <DOT> org>
AuthorDate: Mon Nov 12 03:56:24 2018 +0000
Commit: Michał Górny <mgorny <AT> gentoo <DOT> org>
CommitDate: Sun Dec 2 15:17:39 2018 +0000
URL: https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=fcb399f5
libsandbox: resolve_dirfd_path /proc/<pid> namespace safety
If /proc was mounted by a process in a different pid namespace,
getpid cannot be used create a valid /proc/<pid> path. Instead
use sb_get_fd_dir() which works in any case. This implements
option 3 of these choices:
1) Always create a mount namespace when creating a pid namespace,
and remount /proc so that /proc/<pid> entries are always consistent
with the current pid namespace.
2) Use readlink on /proc/self instead of getpid to determine the pid
of self in the pid namespace of the /proc mount.
3) Use /proc/self or /dev/fd directly.
Bug: https://bugs.gentoo.org/670966
Signed-off-by: Zac Medico <zmedico <AT> gentoo.org>
Closes: https://github.com/gentoo/sandbox/pull/1
Signed-off-by: Michał Górny <mgorny <AT> gentoo.org>
libsandbox/libsandbox.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/libsandbox/libsandbox.c b/libsandbox/libsandbox.c
index 9ef13b1..e0c9d1a 100644
--- a/libsandbox/libsandbox.c
+++ b/libsandbox/libsandbox.c
@@ -125,7 +125,14 @@ int resolve_dirfd_path(int dirfd, const char *path, char *resolved_path,
save_errno();
size_t at_len = resolved_path_len - 1 - 1 - (path ? strlen(path) : 0);
- sprintf(resolved_path, "/proc/%i/fd/%i", trace_pid ? : getpid(), dirfd);
+ if (trace_pid)
+ sprintf(resolved_path, "/proc/%i/fd/%i", trace_pid, dirfd);
+ else
+ /* If /proc was mounted by a process in a different pid namespace,
+ * getpid cannot be used to create a valid /proc/<pid> path. Instead
+ * use sb_get_fd_dir() which works in any case.
+ */
+ sprintf(resolved_path, "%s/%i", sb_get_fd_dir(), dirfd);
ssize_t ret = readlink(resolved_path, resolved_path, at_len);
if (ret == -1) {
/* see comments at end of check_syscall() */