74b23f79f1
commit 378c6520e7d29280f400ef2ceaf155c86f05a71a upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|---|---|---|
| .. | ||
| chan_kern.c | ||
| chan_user.c | ||
| chan_user.h | ||
| chan.h | ||
| cow_sys.h | ||
| cow_user.c | ||
| cow.h | ||
| daemon_kern.c | ||
| daemon_user.c | ||
| daemon.h | ||
| fd.c | ||
| harddog_kern.c | ||
| harddog_user.c | ||
| hostaudio_kern.c | ||
| line.c | ||
| line.h | ||
| Makefile | ||
| mconsole_kern.c | ||
| mconsole_kern.h | ||
| mconsole_user.c | ||
| mconsole.h | ||
| mmapper_kern.c | ||
| net_kern.c | ||
| net_user.c | ||
| null.c | ||
| pcap_kern.c | ||
| pcap_user.c | ||
| pcap_user.h | ||
| port_kern.c | ||
| port_user.c | ||
| port.h | ||
| pty.c | ||
| random.c | ||
| slip_common.c | ||
| slip_common.h | ||
| slip_kern.c | ||
| slip_user.c | ||
| slip.h | ||
| slirp_kern.c | ||
| slirp_user.c | ||
| slirp.h | ||
| ssl.c | ||
| ssl.h | ||
| stderr_console.c | ||
| stdio_console.c | ||
| stdio_console.h | ||
| tty.c | ||
| ubd_kern.c | ||
| ubd_user.c | ||
| ubd.h | ||
| umcast_kern.c | ||
| umcast_user.c | ||
| umcast.h | ||
| vde_kern.c | ||
| vde_user.c | ||
| vde.h | ||
| xterm_kern.c | ||
| xterm.c | ||
| xterm.h | ||