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* syscalls: implement execveat() system callDavid Drysdale2014-12-131-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patchset adds execveat(2) for x86, and is derived from Meredydd Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528). The primary aim of adding an execveat syscall is to allow an implementation of fexecve(3) that does not rely on the /proc filesystem, at least for executables (rather than scripts). The current glibc version of fexecve(3) is implemented via /proc, which causes problems in sandboxed or otherwise restricted environments. Given the desire for a /proc-free fexecve() implementation, HPA suggested (https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be an appropriate generalization. Also, having a new syscall means that it can take a flags argument without back-compatibility concerns. The current implementation just defines the AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be added in future -- for example, flags for new namespaces (as suggested at https://lkml.org/lkml/2006/7/11/474). Related history: - https://lkml.org/lkml/2006/12/27/123 is an example of someone realizing that fexecve() is likely to fail in a chroot environment. - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered documenting the /proc requirement of fexecve(3) in its manpage, to "prevent other people from wasting their time". - https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a problem where a process that did setuid() could not fexecve() because it no longer had access to /proc/self/fd; this has since been fixed. This patch (of 4): Add a new execveat(2) system call. execveat() is to execve() as openat() is to open(): it takes a file descriptor that refers to a directory, and resolves the filename relative to that. In addition, if the filename is empty and AT_EMPTY_PATH is specified, execveat() executes the file to which the file descriptor refers. This replicates the functionality of fexecve(), which is a system call in other UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/<fd>" (and so relies on /proc being mounted). The filename fed to the executed program as argv[0] (or the name of the script fed to a script interpreter) will be of the form "/dev/fd/<fd>" (for an empty filename) or "/dev/fd/<fd>/<filename>", effectively reflecting how the executable was found. This does however mean that execution of a script in a /proc-less environment won't work; also, script execution via an O_CLOEXEC file descriptor fails (as the file will not be accessible after exec). Based on patches by Meredydd Luff. Signed-off-by: David Drysdale <drysdale@google.com> Cc: Meredydd Luff <meredydd@senatehouse.org> Cc: Shuah Khan <shuah.kh@samsung.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Rich Felker <dalias@aerifal.cx> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: kill bprm->tcomm[], simplify the "basename" logicOleg Nesterov2014-04-071-1/+0
| | | | | | | | | | | | | | | | | | | | Starting from commit c4ad8f98bef7 ("execve: use 'struct filename *' for executable name passing") bprm->filename can not go away after flush_old_exec(), so we do not need to save the binary name in bprm->tcomm[] added by 96e02d158678 ("exec: fix use-after-free bug in setup_new_exec()"). And there was never need for filename_to_taskname-like code, we can simply do set_task_comm(kbasename(filename). This patch has to change set_task_comm() and trace_task_rename() to accept "const char *", but I think this change is also good. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* execve: use 'struct filename *' for executable name passingLinus Torvalds2014-02-051-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This changes 'do_execve()' to get the executable name as a 'struct filename', and to free it when it is done. This is what the normal users want, and it simplifies and streamlines their error handling. The controlled lifetime of the executable name also fixes a use-after-free problem with the trace_sched_process_exec tracepoint: the lifetime of the passed-in string for kernel users was not at all obvious, and the user-mode helper code used UMH_WAIT_EXEC to serialize the pathname allocation lifetime with the execve() having finished, which in turn meant that the trace point that happened after mm_release() of the old process VM ended up using already free'd memory. To solve the kernel string lifetime issue, this simply introduces "getname_kernel()" that works like the normal user-space getname() function, except with the source coming from kernel memory. As Oleg points out, this also means that we could drop the tcomm[] array from 'struct linux_binprm', since the pathname lifetime now covers setup_new_exec(). That would be a separate cleanup. Reported-by: Igor Zhbanov <i.zhbanov@samsung.com> Tested-by: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'akpm' (patches from Andrew Morton)Linus Torvalds2013-11-131-3/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge first patch-bomb from Andrew Morton: "Quite a lot of other stuff is banked up awaiting further next->mainline merging, but this batch contains: - Lots of random misc patches - OCFS2 - Most of MM - backlight updates - lib/ updates - printk updates - checkpatch updates - epoll tweaking - rtc updates - hfs - hfsplus - documentation - procfs - update gcov to gcc-4.7 format - IPC" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (269 commits) ipc, msg: fix message length check for negative values ipc/util.c: remove unnecessary work pending test devpts: plug the memory leak in kill_sb ./Makefile: export initial ramdisk compression config option init/Kconfig: add option to disable kernel compression drivers: w1: make w1_slave::flags long to avoid memory corruption drivers/w1/masters/ds1wm.cuse dev_get_platdata() drivers/memstick/core/ms_block.c: fix unreachable state in h_msb_read_page() drivers/memstick/core/mspro_block.c: fix attributes array allocation drivers/pps/clients/pps-gpio.c: remove redundant of_match_ptr kernel/panic.c: reduce 1 byte usage for print tainted buffer gcov: reuse kbasename helper kernel/gcov/fs.c: use pr_warn() kernel/module.c: use pr_foo() gcov: compile specific gcov implementation based on gcc version gcov: add support for gcc 4.7 gcov format gcov: move gcov structs definitions to a gcc version specific file kernel/taskstats.c: return -ENOMEM when alloc memory fails in add_del_listener() kernel/taskstats.c: add nla_nest_cancel() for failure processing between nla_nest_start() and nla_nest_end() kernel/sysctl_binary.c: use scnprintf() instead of snprintf() ...
| * exec/ptrace: fix get_dumpable() incorrect testsKees Cook2013-11-131-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <segoon@openwall.com> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | constify do_coredump() argumentAl Viro2013-11-091-1/+1
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | new helper: dump_emit()Al Viro2013-11-091-0/+1
|/ | | | | | | | dump_write() analog, takes core_dump_params instead of file, keeps track of the amount written in cprm->written and checks for cprm->limit. Start using it in binfmt_elf.c... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* exec: kill "int depth" in search_binary_handler()Oleg Nesterov2013-09-111-1/+1
| | | | | | | | | | | | | | | | | Nobody except search_binary_handler() should touch ->recursion_depth, "int depth" buys nothing but complicates the code, kill it. Probably we should also kill "fn" and the !NULL check, ->load_binary should be always defined. And it can not go away after read_unlock() or this code is buggy anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Evgeniy Polyakov <zbr@ioremap.net> Cc: Zach Levis <zml@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* new helper: read_code()Al Viro2013-04-291-0/+1
| | | | | | | | switch binfmts that use ->read() to that (and to kernel_read() in several cases in binfmt_flat - sure, it's nommu, but still, doing ->read() into kmalloc'ed buffer...) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/exec.c: make bprm_mm_init() staticYuanhan Liu2013-02-261-1/+0
| | | | | | | | There is only one user of bprm_mm_init, and it's inside the same file. Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds2012-12-201-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge the rest of Andrew's patches for -rc1: "A bunch of fixes and misc missed-out-on things. That'll do for -rc1. I still have a batch of IPC patches which still have a possible bug report which I'm chasing down." * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (25 commits) keys: use keyring_alloc() to create module signing keyring keys: fix unreachable code sendfile: allows bypassing of notifier events SGI-XP: handle non-fatal traps fat: fix incorrect function comment Documentation: ABI: remove testing/sysfs-devices-node proc: fix inconsistent lock state linux/kernel.h: fix DIV_ROUND_CLOSEST with unsigned divisors memcg: don't register hotcpu notifier from ->css_alloc() checkpatch: warn on uapi #includes that #include <uapi/... revert "rtc: recycle id when unloading a rtc driver" mm: clean up transparent hugepage sysfs error messages hfsplus: add error message for the case of failure of sync fs in delayed_sync_fs() method hfsplus: rework processing of hfs_btree_write() returned error hfsplus: rework processing errors in hfsplus_free_extents() hfsplus: avoid crash on failed block map free kcmp: include linux/ptrace.h drivers/rtc/rtc-imxdi.c: must include <linux/spinlock.h> mm: cma: WARN if freed memory is still in use exec: do not leave bprm->interp on stack ...
| * exec: do not leave bprm->interp on stackKees Cook2012-12-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a series of scripts are executed, each triggering module loading via unprintable bytes in the script header, kernel stack contents can leak into the command line. Normally execution of binfmt_script and binfmt_misc happens recursively. However, when modules are enabled, and unprintable bytes exist in the bprm->buf, execution will restart after attempting to load matching binfmt modules. Unfortunately, the logic in binfmt_script and binfmt_misc does not expect to get restarted. They leave bprm->interp pointing to their local stack. This means on restart bprm->interp is left pointing into unused stack memory which can then be copied into the userspace argv areas. After additional study, it seems that both recursion and restart remains the desirable way to handle exec with scripts, misc, and modules. As such, we need to protect the changes to interp. This changes the logic to require allocation for any changes to the bprm->interp. To avoid adding a new kmalloc to every exec, the default value is left as-is. Only when passing through binfmt_script or binfmt_misc does an allocation take place. For a proof of concept, see DoTest.sh from: http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/ Signed-off-by: Kees Cook <keescook@chromium.org> Cc: halfdog <me@halfdog.net> Cc: P J P <ppandit@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge branch 'for-linus' of ↵Linus Torvalds2012-12-201-4/+0
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull signal handling cleanups from Al Viro: "sigaltstack infrastructure + conversion for x86, alpha and um, COMPAT_SYSCALL_DEFINE infrastructure. Note that there are several conflicts between "unify SS_ONSTACK/SS_DISABLE definitions" and UAPI patches in mainline; resolution is trivial - just remove definitions of SS_ONSTACK and SS_DISABLED from arch/*/uapi/asm/signal.h; they are all identical and include/uapi/linux/signal.h contains the unified variant." Fixed up conflicts as per Al. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: alpha: switch to generic sigaltstack new helpers: __save_altstack/__compat_save_altstack, switch x86 and um to those generic compat_sys_sigaltstack() introduce generic sys_sigaltstack(), switch x86 and um to it new helper: compat_user_stack_pointer() new helper: restore_altstack() unify SS_ONSTACK/SS_DISABLE definitions new helper: current_user_stack_pointer() missing user_stack_pointer() instances Bury the conditionals from kernel_thread/kernel_execve series COMPAT_SYSCALL_DEFINE: infrastructure
| * Bury the conditionals from kernel_thread/kernel_execve seriesAl Viro2012-12-191-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | All architectures have CONFIG_GENERIC_KERNEL_THREAD CONFIG_GENERIC_KERNEL_EXECVE __ARCH_WANT_SYS_EXECVE None of them have __ARCH_WANT_KERNEL_EXECVE and there are only two callers of kernel_execve() (which is a trivial wrapper for do_execve() now) left. Kill the conditionals and make both callers use do_execve(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | exec: use -ELOOP for max recursion depthKees Cook2012-12-171-2/+0
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To avoid an explosion of request_module calls on a chain of abusive scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon as maximum recursion depth is hit, the error will fail all the way back up the chain, aborting immediately. This also has the side-effect of stopping the user's shell from attempting to reexecute the top-level file as a shell script. As seen in the dash source: if (cmd != path_bshell && errno == ENOEXEC) { *argv-- = cmd; *argv = cmd = path_bshell; goto repeat; } The above logic was designed for running scripts automatically that lacked the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC, things continue to behave as the shell expects. Additionally, when tracking recursion, the binfmt handlers should not be involved. The recursion being tracked is the depth of calls through search_binary_handler(), so that function should be exclusively responsible for tracking the depth. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: halfdog <me@halfdog.net> Cc: P J P <ppandit@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* get rid of pt_regs argument of ->load_binary()Al Viro2012-11-281-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* get rid of pt_regs argument of search_binary_handler()Al Viro2012-11-281-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* UAPI: (Scripted) Disintegrate include/linuxDavid Howells2012-10-131-18/+1
| | | | | | | | | Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dave Jones <davej@redhat.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-10-101-0/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull generic execve() changes from Al Viro: "This introduces the generic kernel_thread() and kernel_execve() functions, and switches x86, arm, alpha, um and s390 over to them." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (26 commits) s390: convert to generic kernel_execve() s390: switch to generic kernel_thread() s390: fold kernel_thread_helper() into ret_from_fork() s390: fold execve_tail() into start_thread(), convert to generic sys_execve() um: switch to generic kernel_thread() x86, um/x86: switch to generic sys_execve and kernel_execve x86: split ret_from_fork alpha: introduce ret_from_kernel_execve(), switch to generic kernel_execve() alpha: switch to generic kernel_thread() alpha: switch to generic sys_execve() arm: get rid of execve wrapper, switch to generic execve() implementation arm: optimized current_pt_regs() arm: introduce ret_from_kernel_execve(), switch to generic kernel_execve() arm: split ret_from_fork, simplify kernel_thread() [based on patch by rmk] generic sys_execve() generic kernel_execve() new helper: current_pt_regs() preparation for generic kernel_thread() um: kill thread->forking um: let signal_delivered() do SIGTRAP on singlestepping into handler ...
| * generic kernel_execve()Al Viro2012-09-301-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | based mostly on arm and alpha versions. Architectures can define __ARCH_WANT_KERNEL_EXECVE and use it, provided that * they have working current_pt_regs(), even for kernel threads. * kernel_thread-spawned threads do have space for pt_regs in the normal location. Normally that's as simple as switching to generic kernel_thread() and making sure that kernel threads do *not* go through return from syscall path; call the payload from equivalent of ret_from_fork if we are in a kernel thread (or just have separate ret_from_kernel_thread and make copy_thread() use it instead of ret_from_fork in kernel thread case). * they have ret_from_kernel_execve(); it is called after successful do_execve() done by kernel_execve() and gets normal pt_regs location passed to it as argument. It's essentially a longjmp() analog - it should set sp, etc. to the situation expected at the return for syscall and go there. Eventually the need for that sucker will disappear, but that'll take some surgery on kernel_thread() payloads. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * the only place that needs to include asm/exec.h is linux/binfmts.hAl Viro2012-09-201-0/+1
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | coredump: pass siginfo_t* to do_coredump() and below, not merely signrDenys Vlasenko2012-10-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a preparatory patch for the introduction of NT_SIGINFO elf note. With this patch we pass "siginfo_t *siginfo" instead of "int signr" to do_coredump() and put it into coredump_params. It will be used by the next patch. Most changes are simple s/signr/siginfo->si_signo/. Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Amerigo Wang <amwang@redhat.com> Cc: "Jonathan M. Foote" <jmfoote@cert.org> Cc: Roland McGrath <roland@hack.frob.com> Cc: Pedro Alves <palves@redhat.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | coredump: update coredump-related headersAlex Kelly2012-10-061-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | Create a new header file, fs/coredump.h, which contains functions only used by the new coredump.c. It also moves do_coredump to the include/linux/coredump.h header file, for consistency. Signed-off-by: Alex Kelly <alex.page.kelly@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | coredump: make core dump functionality optionalAlex Kelly2012-10-061-0/+4
|/ | | | | | | | | | | | | | | | | | Adds an expert Kconfig option, CONFIG_COREDUMP, which allows disabling of core dump. This saves approximately 2.6k in the compiled kernel, and complements CONFIG_ELF_CORE, which now depends on it. CONFIG_COREDUMP also disables coredump-related sysctls, except for suid_dumpable and related functions, which are necessary for ptrace. [akpm@linux-foundation.org: fix binfmt_aout.c build] Signed-off-by: Alex Kelly <alex.page.kelly@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* __register_binfmt() made voidAl Viro2012-03-201-5/+5
| | | | | | Just don't pass NULL to it - nobody does, anyway. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* exec: fix use-after-free bug in setup_new_exec()Heiko Carstens2012-02-061-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Setting the task name is done within setup_new_exec() by accessing bprm->filename. However this happens after flush_old_exec(). This may result in a use after free bug, flush_old_exec() may "complete" vfork_done, which will wake up the parent which in turn may free the passed in filename. To fix this add a new tcomm field in struct linux_binprm which contains the now early generated task name until it is used. Fixes this bug on s390: Unable to handle kernel pointer dereference at virtual kernel address 0000000039768000 Process kworker/u:3 (pid: 245, task: 000000003a3dc840, ksp: 0000000039453818) Krnl PSW : 0704000180000000 0000000000282e94 (setup_new_exec+0xa0/0x374) Call Trace: ([<0000000000282e2c>] setup_new_exec+0x38/0x374) [<00000000002dd12e>] load_elf_binary+0x402/0x1bf4 [<0000000000280a42>] search_binary_handler+0x38e/0x5bc [<0000000000282b6c>] do_execve_common+0x410/0x514 [<0000000000282cb6>] do_execve+0x46/0x58 [<00000000005bce58>] kernel_execve+0x28/0x70 [<000000000014ba2e>] ____call_usermodehelper+0x102/0x140 [<00000000005bc8da>] kernel_thread_starter+0x6/0xc [<00000000005bc8d4>] kernel_thread_starter+0x0/0xc Last Breaking-Event-Address: [<00000000002830f0>] setup_new_exec+0x2fc/0x374 Kernel panic - not syncing: Fatal exception: panic_on_oops Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* consolidate BINPRM_FLAGS_ENFORCE_NONDUMP handlingAl Viro2011-07-201-0/+1
| | | | | | | | new helper: would_dump(bprm, file). Checks if we are allowed to read the file and if we are not - sets ENFORCE_NODUMP. Exported, used in places that previously open-coded the same logics. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* exec: unify do_execve/compat_do_execve codeOleg Nesterov2011-04-091-4/+0
| | | | | | | | | | | | | | | | | | | | Add the appropriate members into struct user_arg_ptr and teach get_user_arg_ptr() to handle is_compat = T case correctly. This allows us to remove the compat_do_execve() code from fs/compat.c and reimplement compat_do_execve() as the trivial wrapper on top of do_execve_common(is_compat => true). In fact, this fixes another (minor) bug. "compat_uptr_t str" can overflow after "str += len" in compat_copy_strings() if a 64bit application execs via sys32_execve(). Unexport acct_arg_size() and get_arg_page(), fs/compat.c doesn't need them any longer. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
* binfmt_elf: cleanupsMikael Pettersson2011-01-131-3/+2
| | | | | | | | | | | | | | | | | | | | | This cleans up a few bits in binfmt_elf.c and binfmts.h: - the hasvdso field in struct linux_binfmt is unused, so remove it and the only initialization of it - the elf_map CPP symbol is not defined anywhere in the kernel, so remove an unnecessary #ifndef elf_map - reduce excessive indentation in elf_format's initializer - add missing spaces, remove extraneous spaces No functional changes, but tested on x86 (32 and 64 bit), powerpc (32 and 64 bit), sparc64, arm, and alpha. Signed-off-by: Mikael Pettersson <mikpe@it.uu.se> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: copy-and-paste the fixes into compat_do_execve() pathsOleg Nesterov2010-11-301-0/+4
| | | | | | | | | | | | | | | | | | | | | | | Note: this patch targets 2.6.37 and tries to be as simple as possible. That is why it adds more copy-and-paste horror into fs/compat.c and uglifies fs/exec.c, this will be cleanuped later. compat_copy_strings() plays with bprm->vma/mm directly and thus has two problems: it lacks the RLIMIT_STACK check and argv/envp memory is not visible to oom killer. Export acct_arg_size() and get_arg_page(), change compat_copy_strings() to use get_arg_page(), change compat_do_execve() to do acct_arg_size(0) as do_execve() does. Add the fatal_signal_pending/cond_resched checks into compat_count() and compat_copy_strings(), this matches the code in fs/exec.c and certainly makes sense. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: make argv/envp memory visible to oom-killerOleg Nesterov2010-11-301-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Brad Spengler published a local memory-allocation DoS that evades the OOM-killer (though not the virtual memory RLIMIT): http://www.grsecurity.net/~spender/64bit_dos.c execve()->copy_strings() can allocate a lot of memory, but this is not visible to oom-killer, nobody can see the nascent bprm->mm and take it into account. With this patch get_arg_page() increments current's MM_ANONPAGES counter every time we allocate the new page for argv/envp. When do_execve() succeds or fails, we change this counter back. Technically this is not 100% correct, we can't know if the new page is swapped out and turn MM_ANONPAGES into MM_SWAPENTS, but I don't think this really matters and everything becomes correct once exec changes ->mm or fails. Reported-by: Brad Spengler <spender@grsecurity.net> Reviewed-and-discussed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Make do_execve() take a const filename pointerDavid Howells2010-08-171-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | Make do_execve() take a const filename pointer so that kernel_execve() compiles correctly on ARM: arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type This also requires the argv and envp arguments to be consted twice, once for the pointer array and once for the strings the array points to. This is because do_execve() passes a pointer to the filename (now const) to copy_strings_kernel(). A simpler alternative would be to cast the filename pointer in do_execve() when it's passed to copy_strings_kernel(). do_execve() may not change any of the strings it is passed as part of the argv or envp lists as they are some of them in .rodata, so marking these strings as const should be fine. Further kernel_execve() and sys_execve() need to be changed to match. This has been test built on x86_64, frv, arm and mips. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: pass mm->flags as a coredump parameter for consistencyMasami Hiramatsu2010-03-061-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pass mm->flags as a coredump parameter for consistency. --- 1787 if (mm->core_state || !get_dumpable(mm)) { <- (1) 1788 up_write(&mm->mmap_sem); 1789 put_cred(cred); 1790 goto fail; 1791 } 1792 [...] 1798 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ <-(2) 1799 flag = O_EXCL; /* Stop rewrite attacks */ 1800 cred->fsuid = 0; /* Dump root private */ 1801 } --- Since dumpable bits are not protected by lock, there is a chance to change these bits between (1) and (2). To solve this issue, this patch copies mm->flags to coredump_params.mm_flags at the beginning of do_coredump() and uses it instead of get_dumpable() while dumping core. This copy is also passed to binfmt->core_dump, since elf*_core_dump() uses dump_filter bits in mm->flags. [akpm@linux-foundation.org: fix merge] Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Split 'flush_old_exec' into two functionsLinus Torvalds2010-01-291-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | 'flush_old_exec()' is the point of no return when doing an execve(), and it is pretty badly misnamed. It doesn't just flush the old executable environment, it also starts up the new one. Which is very inconvenient for things like setting up the new personality, because we want the new personality to affect the starting of the new environment, but at the same time we do _not_ want the new personality to take effect if flushing the old one fails. As a result, the x86-64 '32-bit' personality is actually done using this insane "I'm going to change the ABI, but I haven't done it yet" bit (TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the personality, but just the "pending" bit, so that "flush_thread()" can do the actual personality magic. This patch in no way changes any of that insanity, but it does split the 'flush_old_exec()' function up into a preparatory part that can fail (still called flush_old_exec()), and a new part that will actually set up the new exec environment (setup_new_exec()). All callers are changed to trivially comply with the new world order. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce coredump parameter structureMasami Hiramatsu2009-12-171-1/+9
| | | | | | | | | | | | | | Introduce coredump parameter data structure (struct coredump_params) to simplify binfmt->core_dump() arguments. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Suggested-by: Ingo Molnar <mingo@elte.hu> Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: fix set_binfmt() vs sys_delete_module() raceOleg Nesterov2009-09-241-1/+1
| | | | | | | | | | | | | | | | | | | sys_delete_module() can set MODULE_STATE_GOING after search_binary_handler() does try_module_get(). In this case set_binfmt()->try_module_get() fails but since none of the callers check the returned error, the task will run with the wrong old ->binfmt. The proper fix should change all ->load_binary() methods, but we can rely on fact that the caller must hold a reference to binfmt->module and use __module_get() which never fails. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: do not sleep in TASK_TRACED under ->cred_guard_mutexOleg Nesterov2009-09-051-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tom Horsley reports that his debugger hangs when it tries to read /proc/pid_of_tracee/maps, this happens since "mm_for_maps: take ->cred_guard_mutex to fix the race with exec" 04b836cbf19e885f8366bccb2e4b0474346c02d commit in 2.6.31. But the root of the problem lies in the fact that do_execve() path calls tracehook_report_exec() which can stop if the tracer sets PT_TRACE_EXEC. The tracee must not sleep in TASK_TRACED holding this mutex. Even if we remove ->cred_guard_mutex from mm_for_maps() and proc_pid_attr_write(), another task doing PTRACE_ATTACH should not hang until it is killed or the tracee resumes. With this patch do_execve() does not use ->cred_guard_mutex directly and we do not hold it throughout, instead: - introduce prepare_bprm_creds() helper, it locks the mutex and calls prepare_exec_creds() to initialize bprm->cred. - install_exec_creds() drops the mutex after commit_creds(), and thus before tracehook_report_exec()->ptrace_stop(). or, if exec fails, free_bprm() drops this mutex when bprm->cred != NULL which indicates install_exec_creds() was not called. Reported-by: Tom Horsley <tom.horsley@att.net> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* alpha: binfmt_aout fixIvan Kokshaysky2009-05-021-1/+13
| | | | | | | | | | | | | | | | | | | | | This fixes the problem introduced by commit 3bfacef412 (get rid of special-casing the /sbin/loader on alpha): osf/1 ecoff binary segfaults when binfmt_aout built as module. That happens because aout binary handler gets on the top of the binfmt list due to late registration, and kernel attempts to execute the binary without preparatory work that must be done by binfmt_loader. Fixed by changing the registration order of the default binfmt handlers using list_add_tail() and introducing insert_binfmt() function which places new handler on the top of the binfmt list. This might be generally useful for installing arch-specific frontends for default handlers or just for overriding them. Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Richard Henderson <rth@twiddle.net Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* struct linux_binprm: drop unused fieldsKirill A. Shutemov2009-04-021-2/+1
| | | | | | Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/exec.c: make do_coredump() voidWANG Cong2009-01-061-1/+1
| | | | | | | | | | | No one cares do_coredump()'s return value, and also it seems that it is also not necessary. So make it void. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: WANG Cong <wangcong@zeuux.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* binfmts.h: include list.hHiroshi Shimamoto2009-01-061-0/+1
| | | | | | | | | linux_binfmt uses list_head, so list.h is needed. [akpm@linux-foundation.org: fix `make headerscheck'] Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* CRED: Make execve() take advantage of copy-on-write credentialsDavid Howells2008-11-141-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make execve() take advantage of copy-on-write credentials, allowing it to set up the credentials in advance, and then commit the whole lot after the point of no return. This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). The credential bits from struct linux_binprm are, for the most part, replaced with a single credentials pointer (bprm->cred). This means that all the creds can be calculated in advance and then applied at the point of no return with no possibility of failure. I would like to replace bprm->cap_effective with: cap_isclear(bprm->cap_effective) but this seems impossible due to special behaviour for processes of pid 1 (they always retain their parent's capability masks where normally they'd be changed - see cap_bprm_set_creds()). The following sequence of events now happens: (a) At the start of do_execve, the current task's cred_exec_mutex is locked to prevent PTRACE_ATTACH from obsoleting the calculation of creds that we make. (a) prepare_exec_creds() is then called to make a copy of the current task's credentials and prepare it. This copy is then assigned to bprm->cred. This renders security_bprm_alloc() and security_bprm_free() unnecessary, and so they've been removed. (b) The determination of unsafe execution is now performed immediately after (a) rather than later on in the code. The result is stored in bprm->unsafe for future reference. (c) prepare_binprm() is called, possibly multiple times. (i) This applies the result of set[ug]id binaries to the new creds attached to bprm->cred. Personality bit clearance is recorded, but now deferred on the basis that the exec procedure may yet fail. (ii) This then calls the new security_bprm_set_creds(). This should calculate the new LSM and capability credentials into *bprm->cred. This folds together security_bprm_set() and parts of security_bprm_apply_creds() (these two have been removed). Anything that might fail must be done at this point. (iii) bprm->cred_prepared is set to 1. bprm->cred_prepared is 0 on the first pass of the security calculations, and 1 on all subsequent passes. This allows SELinux in (ii) to base its calculations only on the initial script and not on the interpreter. (d) flush_old_exec() is called to commit the task to execution. This performs the following steps with regard to credentials: (i) Clear pdeath_signal and set dumpable on certain circumstances that may not be covered by commit_creds(). (ii) Clear any bits in current->personality that were deferred from (c.i). (e) install_exec_creds() [compute_creds() as was] is called to install the new credentials. This performs the following steps with regard to credentials: (i) Calls security_bprm_committing_creds() to apply any security requirements, such as flushing unauthorised files in SELinux, that must be done before the credentials are changed. This is made up of bits of security_bprm_apply_creds() and security_bprm_post_apply_creds(), both of which have been removed. This function is not allowed to fail; anything that might fail must have been done in (c.ii). (ii) Calls commit_creds() to apply the new credentials in a single assignment (more or less). Possibly pdeath_signal and dumpable should be part of struct creds. (iii) Unlocks the task's cred_replace_mutex, thus allowing PTRACE_ATTACH to take place. (iv) Clears The bprm->cred pointer as the credentials it was holding are now immutable. (v) Calls security_bprm_committed_creds() to apply any security alterations that must be done after the creds have been changed. SELinux uses this to flush signals and signal handlers. (f) If an error occurs before (d.i), bprm_free() will call abort_creds() to destroy the proposed new credentials and will then unlock cred_replace_mutex. No changes to the credentials will have been made. (2) LSM interface. A number of functions have been changed, added or removed: (*) security_bprm_alloc(), ->bprm_alloc_security() (*) security_bprm_free(), ->bprm_free_security() Removed in favour of preparing new credentials and modifying those. (*) security_bprm_apply_creds(), ->bprm_apply_creds() (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds() Removed; split between security_bprm_set_creds(), security_bprm_committing_creds() and security_bprm_committed_creds(). (*) security_bprm_set(), ->bprm_set_security() Removed; folded into security_bprm_set_creds(). (*) security_bprm_set_creds(), ->bprm_set_creds() New. The new credentials in bprm->creds should be checked and set up as appropriate. bprm->cred_prepared is 0 on the first call, 1 on the second and subsequent calls. (*) security_bprm_committing_creds(), ->bprm_committing_creds() (*) security_bprm_committed_creds(), ->bprm_committed_creds() New. Apply the security effects of the new credentials. This includes closing unauthorised files in SELinux. This function may not fail. When the former is called, the creds haven't yet been applied to the process; when the latter is called, they have. The former may access bprm->cred, the latter may not. (3) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) The bprm_security_struct struct has been removed in favour of using the credentials-under-construction approach. (c) flush_unauthorized_files() now takes a cred pointer and passes it on to inode_has_perm(), file_has_perm() and dentry_open(). Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* Allow recursion in binfmt_script and binfmt_miscKirill A. Shutemov2008-10-161-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | binfmt_script and binfmt_misc disallow recursion to avoid stack overflow using sh_bang and misc_bang. It causes problem in some cases: $ echo '#!/bin/ls' > /tmp/t0 $ echo '#!/tmp/t0' > /tmp/t1 $ echo '#!/tmp/t1' > /tmp/t2 $ chmod +x /tmp/t* $ /tmp/t2 zsh: exec format error: /tmp/t2 Similar problem with binfmt_misc. This patch introduces field 'recursion_depth' into struct linux_binprm to track recursion level in binfmt_misc and binfmt_script. If recursion level more then BINPRM_MAX_RECURSION it generates -ENOEXEC. [akpm@linux-foundation.org: make linux_binprm.recursion_depth a uint] Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* alpha: introduce field 'taso' into struct linux_binprmKirill A. Shutemov2008-10-161-0/+3
| | | | | | | | | | | | | | This change is Alpha-specific. It adds field 'taso' into struct linux_binprm to remember if the application is TASO. Previously, field sh_bang was used for this purpose. Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* security: protect legacy applications from executing with insufficient privilegeAndrew G. Morgan2008-07-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | When cap_bset suppresses some of the forced (fP) capabilities of a file, it is generally only safe to execute the program if it understands how to recognize it doesn't have enough privilege to work correctly. For legacy applications (fE!=0), which have no non-destructive way to determine that they are missing privilege, we fail to execute (EPERM) any executable that requires fP capabilities, but would otherwise get pP' < fP. This is a fail-safe permission check. For some discussion of why it is problematic for (legacy) privileged applications to run with less than the set of capabilities requested for them, see: http://userweb.kernel.org/~morgan/sendmail-capabilities-war-story.html With this iteration of this support, we do not include setuid-0 based privilege protection from the bounding set. That is, the admin can still (ab)use the bounding set to suppress the privileges of a setuid-0 program. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: cleanup] Signed-off-by: Andrew G. Morgan <morgan@kernel.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] get rid of leak in compat_execve()Al Viro2008-05-161-0/+1
| | | | | | | | | | | Even though copy_compat_strings() doesn't cache the pages, copy_strings_kernel() and stuff indirectly called by e.g. ->load_binary() is doing that, so we need to drop the cache contents in the end. [found by WANG Cong <wangcong@zeuux.org>] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* binfmt_misc.c: avoid potential kernel stack overflowPavel Emelyanov2008-04-291-1/+2
| | | | | | | | | | | | | | | | | | | | | | This can be triggered with root help only, but... Register the ":text:E::txt::/root/cat.txt:' rule in binfmt_misc (by root) and try launching the cat.txt file (by anyone) :) The result is - the endless recursion in the load_misc_binary -> open_exec -> load_misc_binary chain and stack overflow. There's a similar problem with binfmt_script, and there's a sh_bang memner on linux_binprm structure to handle this, but simply raising this in binfmt_misc may break some setups when the interpreter of some misc binaries is a script. So the proposal is to turn sh_bang into a bit, add a new one (the misc_bang) and raise it in load_misc_binary. After this, even if we set up the misc -> script -> misc loop for binfmts one of them will step on its own bang and exit. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: remove argv_len from struct linux_binprmTetsuo Handa2008-04-291-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | I noticed that 2.6.24.2 calculates bprm->argv_len at do_execve(). But it doesn't update bprm->argv_len after "remove_arg_zero() + copy_strings_kernel()" at load_script() etc. audit_bprm() is called from search_binary_handler() and search_binary_handler() is called from load_script() etc. Thus, I think the condition check if (bprm->argv_len > (audit_argv_kb << 10)) return -E2BIG; in audit_bprm() might return wrong result when strlen(removed_arg) != strlen(spliced_args). Why not update bprm->argv_len at load_script() etc. ? By the way, 2.6.25-rc3 seems to not doing the condition check. Is the field bprm->argv_len no longer needed? Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Ollie Wild <aaw@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Implement file posix capabilitiesSerge E. Hallyn2007-10-171-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement file posix capabilities. This allows programs to be given a subset of root's powers regardless of who runs them, without having to use setuid and giving the binary all of root's powers. This version works with Kaigai Kohei's userspace tools, found at http://www.kaigai.gr.jp/index.php. For more information on how to use this patch, Chris Friedhoff has posted a nice page at http://www.friedhoff.org/fscaps.html. Changelog: Nov 27: Incorporate fixes from Andrew Morton (security-introduce-file-caps-tweaks and security-introduce-file-caps-warning-fix) Fix Kconfig dependency. Fix change signaling behavior when file caps are not compiled in. Nov 13: Integrate comments from Alexey: Remove CONFIG_ ifdef from capability.h, and use %zd for printing a size_t. Nov 13: Fix endianness warnings by sparse as suggested by Alexey Dobriyan. Nov 09: Address warnings of unused variables at cap_bprm_set_security when file capabilities are disabled, and simultaneously clean up the code a little, by pulling the new code into a helper function. Nov 08: For pointers to required userspace tools and how to use them, see http://www.friedhoff.org/fscaps.html. Nov 07: Fix the calculation of the highest bit checked in check_cap_sanity(). Nov 07: Allow file caps to be enabled without CONFIG_SECURITY, since capabilities are the default. Hook cap_task_setscheduler when !CONFIG_SECURITY. Move capable(TASK_KILL) to end of cap_task_kill to reduce audit messages. Nov 05: Add secondary calls in selinux/hooks.c to task_setioprio and task_setscheduler so that selinux and capabilities with file cap support can be stacked. Sep 05: As Seth Arnold points out, uid checks are out of place for capability code. Sep 01: Define task_setscheduler, task_setioprio, cap_task_kill, and task_setnice to make sure a user cannot affect a process in which they called a program with some fscaps. One remaining question is the note under task_setscheduler: are we ok with CAP_SYS_NICE being sufficient to confine a process to a cpuset? It is a semantic change, as without fsccaps, attach_task doesn't allow CAP_SYS_NICE to override the uid equivalence check. But since it uses security_task_setscheduler, which elsewhere is used where CAP_SYS_NICE can be used to override the uid equivalence check, fixing it might be tough. task_setscheduler note: this also controls cpuset:attach_task. Are we ok with CAP_SYS_NICE being used to confine to a cpuset? task_setioprio task_setnice sys_setpriority uses this (through set_one_prio) for another process. Need same checks as setrlimit Aug 21: Updated secureexec implementation to reflect the fact that euid and uid might be the same and nonzero, but the process might still have elevated caps. Aug 15: Handle endianness of xattrs. Enforce capability version match between kernel and disk. Enforce that no bits beyond the known max capability are set, else return -EPERM. With this extra processing, it may be worth reconsidering doing all the work at bprm_set_security rather than d_instantiate. Aug 10: Always call getxattr at bprm_set_security, rather than caching it at d_instantiate. [morgan@kernel.org: file-caps clean up for linux/capability.h] [bunk@kernel.org: unexport cap_inode_killpriv] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Andrew Morgan <morgan@kernel.org> Signed-off-by: Andrew Morgan <morgan@kernel.org> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* core_pattern: ignore RLIMIT_CORE if core_pattern is a pipeNeil Horman2007-10-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For some time /proc/sys/kernel/core_pattern has been able to set its output destination as a pipe, allowing a user space helper to receive and intellegently process a core. This infrastructure however has some shortcommings which can be enhanced. Specifically: 1) The coredump code in the kernel should ignore RLIMIT_CORE limitation when core_pattern is a pipe, since file system resources are not being consumed in this case, unless the user application wishes to save the core, at which point the app is restricted by usual file system limits and restrictions. 2) The core_pattern code should be able to parse and pass options to the user space helper as an argv array. The real core limit of the uid of the crashing proces should also be passable to the user space helper (since it is overridden to zero when called). 3) Some miscellaneous bugs need to be cleaned up (specifically the recognition of a recursive core dump, should the user mode helper itself crash. Also, the core dump code in the kernel should not wait for the user mode helper to exit, since the same context is responsible for writing to the pipe, and a read of the pipe by the user mode helper will result in a deadlock. This patch: Remove the check of RLIMIT_CORE if core_pattern is a pipe. In the event that core_pattern is a pipe, the entire core will be fed to the user mode helper. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Cc: <martin.pitt@ubuntu.com> Cc: <wwoods@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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