diff options
author | Jann Horn <jann@thejh.net> | 2016-03-23 00:25:36 +0300 |
---|---|---|
committer | Sasha Levin <sasha.levin@oracle.com> | 2016-04-18 15:49:38 +0300 |
commit | 1249f099a3ffd474d7531bd558620c233445880c (patch) | |
tree | cfb9a81bc1b40b9c168541ac20f902d49c6f60f5 /fs/fhandle.c | |
parent | 51d109b05dea76910c6b5c95908e9e334888f46f (diff) | |
download | linux-1249f099a3ffd474d7531bd558620c233445880c.tar.xz |
fs/coredump: prevent fsuid=0 dumps into user-controlled directories
[ Upstream commit 378c6520e7d29280f400ef2ceaf155c86f05a71a ]
This commit fixes the following security hole affecting systems where
all of the following conditions are fulfilled:
- The fs.suid_dumpable sysctl is set to 2.
- The kernel.core_pattern sysctl's value starts with "/". (Systems
where kernel.core_pattern starts with "|/" are not affected.)
- Unprivileged user namespace creation is permitted. (This is
true on Linux >=3.8, but some distributions disallow it by
default using a distro patch.)
Under these conditions, if a program executes under secure exec rules,
causing it to run with the SUID_DUMP_ROOT flag, then unshares its user
namespace, changes its root directory and crashes, the coredump will be
written using fsuid=0 and a path derived from kernel.core_pattern - but
this path is interpreted relative to the root directory of the process,
allowing the attacker to control where a coredump will be written with
root privileges.
To fix the security issue, always interpret core_pattern for dumps that
are written under SUID_DUMP_ROOT relative to the root directory of init.
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'fs/fhandle.c')
-rw-r--r-- | fs/fhandle.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/fhandle.c b/fs/fhandle.c index d59712dfa3e7..ca3c3dd01789 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -228,7 +228,7 @@ long do_handle_open(int mountdirfd, path_put(&path); return fd; } - file = file_open_root(path.dentry, path.mnt, "", open_flag); + file = file_open_root(path.dentry, path.mnt, "", open_flag, 0); if (IS_ERR(file)) { put_unused_fd(fd); retval = PTR_ERR(file); |