From d389d610b143d487e50fe898e0ee9d329c279a1b Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 12 Nov 2013 15:11:17 -0800 Subject: exec/ptrace: fix get_dumpable() incorrect tests commit d049f74f2dbe71354d43d393ac3a188947811348 upstream. The get_dumpable() return value is not boolean. Most users of the function actually want to be testing for non-SUID_DUMP_USER(1) rather than SUID_DUMP_DISABLE(0). The SUID_DUMP_ROOT(2) is also considered a protected state. Almost all places did this correctly, excepting the two places fixed in this patch. Wrong logic: if (dumpable == SUID_DUMP_DISABLE) { /* be protective */ } or if (dumpable == 0) { /* be protective */ } or if (!dumpable) { /* be protective */ } Correct logic: if (dumpable != SUID_DUMP_USER) { /* be protective */ } or if (dumpable != 1) { /* be protective */ } Without this patch, if the system had set the sysctl fs/suid_dumpable=2, a user was able to ptrace attach to processes that had dropped privileges to that user. (This may have been partially mitigated if Yama was enabled.) The macros have been moved into the file that declares get/set_dumpable(), which means things like the ia64 code can see them too. CVE-2013-2929 Reported-by: Vasily Kulikov Signed-off-by: Kees Cook Cc: "Luck, Tony" Cc: Oleg Nesterov Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/ptrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 335a7ae697f..afadcf7b4a2 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -257,7 +257,8 @@ ok: if (task->mm) dumpable = get_dumpable(task->mm); rcu_read_lock(); - if (!dumpable && !ptrace_has_cap(__task_cred(task)->user_ns, mode)) { + if (dumpable != SUID_DUMP_USER && + !ptrace_has_cap(__task_cred(task)->user_ns, mode)) { rcu_read_unlock(); return -EPERM; } -- cgit v1.2.3