20 Jul, 2011

1 commit


09 Apr, 2011

1 commit

  • 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
    Reviewed-by: KOSAKI Motohiro
    Tested-by: KOSAKI Motohiro

    Oleg Nesterov
     

14 Jan, 2011

1 commit

  • 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
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mikael Pettersson
     

01 Dec, 2010

2 commits

  • 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
    Cc: KOSAKI Motohiro
    Cc: stable@kernel.org
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 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
    Reviewed-and-discussed-by: KOSAKI Motohiro
    Signed-off-by: Oleg Nesterov
    Cc: stable@kernel.org
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

18 Aug, 2010

1 commit

  • 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
    Tested-by: Ralf Baechle
    Acked-by: Russell King
    Signed-off-by: Linus Torvalds

    David Howells
     

07 Mar, 2010

1 commit

  • Pass mm->flags as a coredump parameter for consistency.

    ---
    1787 if (mm->core_state || !get_dumpable(mm)) { mmap_sem);
    1789 put_cred(cred);
    1790 goto fail;
    1791 }
    1792
    [...]
    1798 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ 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
    Acked-by: Roland McGrath
    Cc: Hidehiro Kawai
    Cc: Oleg Nesterov
    Cc: Ingo Molnar
    Reviewed-by: KOSAKI Motohiro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Masami Hiramatsu
     

30 Jan, 2010

1 commit

  • '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
    Cc: stable@kernel.org
    Signed-off-by: Linus Torvalds

    Linus Torvalds
     

18 Dec, 2009

1 commit

  • Introduce coredump parameter data structure (struct coredump_params) to
    simplify binfmt->core_dump() arguments.

    Signed-off-by: Masami Hiramatsu
    Suggested-by: Ingo Molnar
    Cc: Hidehiro Kawai
    Cc: Oleg Nesterov
    Cc: Roland McGrath
    Cc: KOSAKI Motohiro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Masami Hiramatsu
     

24 Sep, 2009

1 commit

  • 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
    Acked-by: Rusty Russell
    Cc: Hiroshi Shimamoto
    Cc: Roland McGrath
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

06 Sep, 2009

1 commit

  • 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
    Signed-off-by: Oleg Nesterov
    Acked-by: David Howells
    Cc: Roland McGrath
    Cc: James Morris
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

03 May, 2009

1 commit

  • 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
    Cc: Al Viro
    Cc: Richard Henderson
    Signed-off-by: Linus Torvalds

    Ivan Kokshaysky
     

03 Apr, 2009

1 commit


07 Jan, 2009

2 commits

  • 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
    Cc: Alexander Viro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    WANG Cong
     
  • linux_binfmt uses list_head, so list.h is needed.

    [akpm@linux-foundation.org: fix `make headerscheck']
    Signed-off-by: Hiroshi Shimamoto
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Hiroshi Shimamoto
     

14 Nov, 2008

1 commit

  • 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
    Acked-by: James Morris
    Acked-by: Serge Hallyn
    Signed-off-by: James Morris

    David Howells
     

17 Oct, 2008

2 commits

  • 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
    Cc: Pavel Emelyanov
    Cc: Alexander Viro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kirill A. Shutemov
     
  • 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
    Cc: Richard Henderson
    Cc: Ivan Kokshaysky
    Cc: Pavel Emelyanov
    Cc: Alexander Viro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kirill A. Shutemov
     

25 Jul, 2008

1 commit

  • 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
    Acked-by: Serge Hallyn
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrew G. Morgan
     

17 May, 2008

1 commit

  • 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 ]

    Signed-off-by: Al Viro

    Al Viro
     

29 Apr, 2008

2 commits

  • 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
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Pavel Emelyanov
     
  • 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
    Cc: Ollie Wild
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Tetsuo Handa
     

17 Oct, 2007

4 commits

  • 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
    Cc: Stephen Smalley
    Cc: James Morris
    Cc: Chris Wright
    Cc: Andrew Morgan
    Signed-off-by: Andrew Morgan
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Serge E. Hallyn
     
  • 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
    Cc:
    Cc:
    Cc: Jeremy Fitzhardinge
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Neil Horman
     
  • list_del() hardly can fail, so checking for return value is pointless
    (and current code always return 0).

    Nobody really cared that return value anyway.

    Signed-off-by: Alexey Dobriyan
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alexey Dobriyan
     
  • Switch single-linked binfmt formats list to usual list_head's. This leads
    to one-liners in register_binfmt() and unregister_binfmt(). The downside
    is one pointer more in struct linux_binfmt. This is not a problem, since
    the set of registered binfmts on typical box is very small -- (ELF +
    something distro enabled for you).

    Test-booted, played with executable .txt files, modprobe/rmmod binfmt_misc.

    Signed-off-by: Alexey Dobriyan
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alexey Dobriyan
     

20 Jul, 2007

2 commits

  • Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
    the old mm into the new mm.

    We create the new mm before the binfmt code runs, and place the new stack at
    the very top of the address space. Once the binfmt code runs and figures out
    where the stack should be, we move it downwards.

    It is a bit peculiar in that we have one task with two mm's, one of which is
    inactive.

    [a.p.zijlstra@chello.nl: limit stack size]
    Signed-off-by: Ollie Wild
    Signed-off-by: Peter Zijlstra
    Cc:
    Cc: Hugh Dickins
    [bunk@stusta.de: unexport bprm_mm_init]
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ollie Wild
     
  • The purpose of audit_bprm() is to log the argv array to a userspace daemon at
    the end of the execve system call. Since user-space hasn't had time to run,
    this array is still in pristine state on the process' stack; so no need to
    copy it, we can just grab it from there.

    In order to minimize the damage to audit_log_*() copy each string into a
    temporary kernel buffer first.

    Currently the audit code requires that the full argument vector fits in a
    single packet. So currently it does clip the argv size to a (sysctl) limit,
    but only when execve auditing is enabled.

    If the audit protocol gets extended to allow for multiple packets this check
    can be removed.

    Signed-off-by: Peter Zijlstra
    Signed-off-by: Ollie Wild
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Peter Zijlstra
     

17 May, 2007

1 commit


13 Feb, 2007

1 commit


24 Jun, 2005

1 commit

  • Add a new `suid_dumpable' sysctl:

    This value can be used to query and set the core dump mode for setuid
    or otherwise protected/tainted binaries. The modes are

    0 - (default) - traditional behaviour. Any process which has changed
    privilege levels or is execute only will not be dumped

    1 - (debug) - all processes dump core when possible. The core dump is
    owned by the current user and no security is applied. This is intended
    for system debugging situations only. Ptrace is unchecked.

    2 - (suidsafe) - any binary which normally would not be dumped is dumped
    readable by root only. This allows the end user to remove such a dump but
    not access it directly. For security reasons core dumps in this mode will
    not overwrite one another or other files. This mode is appropriate when
    adminstrators are attempting to debug problems in a normal environment.

    (akpm:

    > > +EXPORT_SYMBOL(suid_dumpable);
    >
    > EXPORT_SYMBOL_GPL?

    No problem to me.

    > > if (current->euid == current->uid && current->egid == current->gid)
    > > current->mm->dumpable = 1;
    >
    > Should this be SUID_DUMP_USER?

    Actually the feedback I had from last time was that the SUID_ defines
    should go because its clearer to follow the numbers. They can go
    everywhere (and there are lots of places where dumpable is tested/used
    as a bool in untouched code)

    > Maybe this should be renamed to `dump_policy' or something. Doing that
    > would help us catch any code which isn't using the #defines, too.

    Fair comment. The patch was designed to be easy to maintain for Red Hat
    rather than for merging. Changing that field would create a gigantic
    diff because it is used all over the place.

    )

    Signed-off-by: Alan Cox
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alan Cox
     

06 May, 2005

1 commit


17 Apr, 2005

1 commit

  • Initial git repository build. I'm not bothering with the full history,
    even though we have it. We can create a separate "historical" git
    archive of that later if we want to, and in the meantime it's about
    3.2GB when imported into git - space that would just make the early
    git days unnecessarily complicated, when we don't have a lot of good
    infrastructure for it.

    Let it rip!

    Linus Torvalds