user/sven/linux.git/kernel/ptrace.c, branch v3.4.97

exec/ptrace: fix get_dumpable() incorrect tests

2013-11-29T18:50:34Z

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

ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL

2013-01-28T04:47:43Z

commit 9899d11f654474d2d54ea52ceaa2a1f4db3abd68 upstream. putreg() assumes that the tracee is not running and pt_regs_access() can safely play with its stack. However a killed tracee can return from ptrace_stop() to the low-level asm code and do RESTORE_REST, this means that debugger can actually read/modify the kernel stack until the tracee does SAVE_REST again. set_task_blockstep() can race with SIGKILL too and in some sense this race is even worse, the very fact the tracee can be woken up breaks the logic. As Linus suggested we can clear TASK_WAKEKILL around the arch_ptrace() call, this ensures that nobody can ever wakeup the tracee while the debugger looks at it. Not only this fixes the mentioned problems, we can do some cleanups/simplifications in arch_ptrace() paths. Probably ptrace_unfreeze_traced() needs more callers, for example it makes sense to make the tracee killable for oom-killer before access_process_vm(). While at it, add the comment into may_ptrace_stop() to explain why ptrace_stop() still can't rely on SIGKILL and signal_pending_state(). Reported-by: Salman Qazi Reported-by: Suleiman Souhlal Suggested-by: Linus Torvalds Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ptrace: introduce signal_wake_up_state() and ptrace_signal_wake_up()

2013-01-28T04:47:43Z

commit 910ffdb18a6408e14febbb6e4b6840fd2c928c82 upstream. Cleanup and preparation for the next change. signal_wake_up(resume => true) is overused. None of ptrace/jctl callers actually want to wakeup a TASK_WAKEKILL task, but they can't specify the necessary mask. Turn signal_wake_up() into signal_wake_up_state(state), reintroduce signal_wake_up() as a trivial helper, and add ptrace_signal_wake_up() which adds __TASK_TRACED. This way ptrace_signal_wake_up() can work "inside" ptrace_request() even if the tracee doesn't have the TASK_WAKEKILL bit set. Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ptrace: remove PTRACE_SEIZE_DEVEL bit

2012-03-23T23:58:41Z

PTRACE_SEIZE code is tested and ready for production use, remove the code which requires special bit in data argument to make PTRACE_SEIZE work. Strace team prepares for a new release of strace, and we would like to ship the code which uses PTRACE_SEIZE, preferably after this change goes into released kernel. Signed-off-by: Denys Vlasenko Acked-by: Tejun Heo Acked-by: Oleg Nesterov Cc: Pedro Alves Cc: Jan Kratochvil Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ptrace: make PTRACE_SEIZE set ptrace options specified in 'data' parameter

2012-03-23T23:58:40Z

This can be used to close a few corner cases in strace where we get unwanted racy behavior after attach, but before we have a chance to set options (the notorious post-execve SIGTRAP comes to mind), and removes the need to track "did we set opts for this task" state in strace internals. While we are at it: Make it possible to extend SEIZE in the future with more functionality by passing non-zero 'addr' parameter. To that end, error out if 'addr' is non-zero. PTRACE_ATTACH did not (and still does not) have such check, and users (strace) do pass garbage there... let's avoid repeating this mistake with SEIZE. Set all task->ptrace bits in one operation - before this change, we were adding PT_SEIZED and PT_PTRACE_CAP with task->ptrace |= BIT ops. This was probably ok (not a bug), but let's be on a safer side. Changes since v2: use (unsigned long) casts instead of (long) ones, move PTRACE_SEIZE_DEVEL-related code to separate lines of code. Signed-off-by: Denys Vlasenko Acked-by: Tejun Heo Cc: Pedro Alves Reviewed-by: Oleg Nesterov Cc: Jan Kratochvil Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ptrace: simplify PTRACE_foo constants and PTRACE_SETOPTIONS code

2012-03-23T23:58:40Z

Exchange PT_TRACESYSGOOD and PT_PTRACE_CAP bit positions, which makes PT_option bits contiguous and therefore makes code in ptrace_setoptions() much simpler. Every PTRACE_O_TRACEevent is defined to (1 << PTRACE_EVENT_event) instead of using explicit numeric constants, to ensure we don't mess up relationship between bit positions and event ids. PT_EVENT_FLAG_SHIFT was not particularly useful, PT_OPT_FLAG_SHIFT with value of PT_EVENT_FLAG_SHIFT-1 is easier to use. PT_TRACE_MASK constant is nuked, the only its use is replaced by (PTRACE_O_MASK << PT_OPT_FLAG_SHIFT). Signed-off-by: Denys Vlasenko Acked-by: Tejun Heo Reviewed-by: Oleg Nesterov Cc: Pedro Alves Cc: Jan Kratochvil Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ptrace: don't modify flags on PTRACE_SETOPTIONS failure

2012-03-23T23:58:40Z

On ptrace(PTRACE_SETOPTIONS, pid, 0, ), we used to set those option bits which are known, and then fail with -EINVAL if there are some unknown bits in . This is inconsistent with typical error handling, which does not change any state if input is invalid. This patch changes PTRACE_SETOPTIONS behavior so that in this case, we return -EINVAL and don't change any bits in task->ptrace. It's very unlikely that there is userspace code in the wild which will be affected by this change: it should have the form ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_BOGUSOPT) where PTRACE_O_BOGUSOPT is a constant unknown to the kernel. But kernel headers, naturally, don't contain any PTRACE_O_BOGUSOPTs, thus the only way userspace can use one if it defines one itself. I can't see why anyone would do such a thing deliberately. Signed-off-by: Denys Vlasenko Acked-by: Tejun Heo Reviewed-by: Oleg Nesterov Cc: Pedro Alves Cc: Jan Kratochvil Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-security

2012-01-15T02:36:33Z

* 'for-linus' of git://selinuxproject.org/~jmorris/linux-security: capabilities: remove __cap_full_set definition security: remove the security_netlink_recv hook as it is equivalent to capable() ptrace: do not audit capability check when outputing /proc/pid/stat capabilities: remove task_ns_* functions capabitlies: ns_capable can use the cap helpers rather than lsm call capabilities: style only - move capable below ns_capable capabilites: introduce new has_ns_capabilities_noaudit capabilities: call has_ns_capability from has_capability capabilities: remove all _real_ interfaces capabilities: introduce security_capable_noaudit capabilities: reverse arguments to security_capable capabilities: remove the task from capable LSM hook entirely selinux: sparse fix: fix several warnings in the security server cod selinux: sparse fix: fix warnings in netlink code selinux: sparse fix: eliminate warnings for selinuxfs selinux: sparse fix: declare selinux_disable() in security.h selinux: sparse fix: move selinux_complete_init selinux: sparse fix: make selinux_secmark_refcount static SELinux: Fix RCU deref check warning in sel_netport_insert() Manually fix up a semantic mis-merge wrt security_netlink_recv(): - the interface was removed in commit fd7784615248 ("security: remove the security_netlink_recv hook as it is equivalent to capable()") - a new user of it appeared in commit a38f7907b926 ("crypto: Add userspace configuration API") causing no automatic merge conflict, but Eric Paris pointed out the issue.

ptrace: do not audit capability check when outputing /proc/pid/stat

2012-01-05T23:53:00Z

Reading /proc/pid/stat of another process checks if one has ptrace permissions on that process. If one does have permissions it outputs some data about the process which might have security and attack implications. If the current task does not have ptrace permissions the read still works, but those fields are filled with inocuous (0) values. Since this check and a subsequent denial is not a violation of the security policy we should not audit such denials. This can be quite useful to removing ptrace broadly across a system without flooding the logs when ps is run or something which harmlessly walks proc. Signed-off-by: Eric Paris Acked-by: Serge E. Hallyn

capabilities: remove task_ns_* functions

2012-01-05T23:52:59Z

task_ in the front of a function, in the security subsystem anyway, means to me at least, that we are operating with that task as the subject of the security decision. In this case what it means is that we are using current as the subject but we use the task to get the right namespace. Who in the world would ever realize that's what task_ns_capability means just by the name? This patch eliminates the task_ns functions entirely and uses the has_ns_capability function instead. This means we explicitly open code the ns in question in the caller. I think it makes the caller a LOT more clear what is going on. Signed-off-by: Eric Paris Acked-by: Serge E. Hallyn