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    SubjectRe: [patch 4/4] c/r: prctl: Extend PR_SET_MM to set up more mm_struct entries
    On Mon, Jan 23, 2012 at 06:20:40PM +0400, Cyrill Gorcunov wrote:
    > After restore we would like the 'ps' command show the command
    > line and evironment exactly the same it was at checkpoint time.
    >
    > So this additional PR_SET_MM_ allow us to do so. Note that
    > these members of mm_struct is rather used for output in
    > procfs, except auxv vector which is used by ld.so mostly.
    >
    > Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    > Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    > Cc: Kees Cook <keescook@chromium.org>
    > Cc: Tejun Heo <tj@kernel.org>
    > Cc: Andrew Vagin <avagin@openvz.org>
    > Cc: Serge Hallyn <serge.hallyn@canonical.com>
    > Cc: Pavel Emelyanov <xemul@parallels.com>
    > Cc: Vasiliy Kulikov <segoon@openwall.com>
    > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    > Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    > Cc: Andrew Morton <akpm@linux-foundation.org>
    > ---

    This one is with typo fixed.

    Cyrill
    ---
    From: Cyrill Gorcunov <gorcunov@openvz.org>
    Subject: c/r: prctl: Extend PR_SET_MM to set up more mm_struct entries

    After restore we would like the 'ps' command show the command
    line and evironment exactly the same it was at checkpoint time.

    So this additional PR_SET_MM_ allow us to do so. Note that
    these members of mm_struct is rather used for output in
    procfs, except auxv vector which is used by ld.so mostly.

    Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Andrew Vagin <avagin@openvz.org>
    Cc: Serge Hallyn <serge.hallyn@canonical.com>
    Cc: Pavel Emelyanov <xemul@parallels.com>
    Cc: Vasiliy Kulikov <segoon@openwall.com>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    ---
    include/linux/prctl.h | 5 +++
    kernel/sys.c | 73 +++++++++++++++++++++++++++++++-------------------
    2 files changed, 51 insertions(+), 27 deletions(-)

    Index: linux-2.6.git/include/linux/prctl.h
    ===================================================================
    --- linux-2.6.git.orig/include/linux/prctl.h
    +++ linux-2.6.git/include/linux/prctl.h
    @@ -113,5 +113,10 @@
    # define PR_SET_MM_START_STACK 5
    # define PR_SET_MM_START_BRK 6
    # define PR_SET_MM_BRK 7
    +# define PR_SET_MM_ARG_START 8
    +# define PR_SET_MM_ARG_END 9
    +# define PR_SET_MM_ENV_START 10
    +# define PR_SET_MM_ENV_END 11
    +# define PR_SET_MM_AUXV 12

    #endif /* _LINUX_PRCTL_H */
    Index: linux-2.6.git/kernel/sys.c
    ===================================================================
    --- linux-2.6.git.orig/kernel/sys.c
    +++ linux-2.6.git/kernel/sys.c
    @@ -1693,17 +1693,25 @@ SYSCALL_DEFINE1(umask, int, mask)
    }

    #ifdef CONFIG_CHECKPOINT_RESTORE
    +static bool vma_flags_mismatch(struct vm_area_struct *vma,
    + unsigned long required,
    + unsigned long banned)
    +{
    + return (vma->vm_flags & required) != required ||
    + (vma->vm_flags & banned);
    +}
    +
    static int prctl_set_mm(int opt, unsigned long addr,
    unsigned long arg4, unsigned long arg5)
    {
    unsigned long rlim = rlimit(RLIMIT_DATA);
    - unsigned long vm_req_flags;
    - unsigned long vm_bad_flags;
    struct vm_area_struct *vma;
    int error = 0;
    struct mm_struct *mm = current->mm;

    - if (arg4 | arg5)
    + if (arg4 && opt != PR_SET_MM_AUXV)
    + return -EINVAL;
    + else if (arg4 | arg5)
    return -EINVAL;

    if (!capable(CAP_SYS_ADMIN))
    @@ -1715,7 +1723,9 @@ static int prctl_set_mm(int opt, unsigne
    down_read(&mm->mmap_sem);
    vma = find_vma(mm, addr);

    - if (opt != PR_SET_MM_START_BRK && opt != PR_SET_MM_BRK) {
    + if (opt != PR_SET_MM_START_BRK &&
    + opt != PR_SET_MM_BRK &&
    + opt != PR_SET_MM_AUXV) {
    /* It must be existing VMA */
    if (!vma || vma->vm_start > addr)
    goto out;
    @@ -1725,11 +1735,8 @@ static int prctl_set_mm(int opt, unsigne
    switch (opt) {
    case PR_SET_MM_START_CODE:
    case PR_SET_MM_END_CODE:
    - vm_req_flags = VM_READ | VM_EXEC;
    - vm_bad_flags = VM_WRITE | VM_MAYSHARE;
    -
    - if ((vma->vm_flags & vm_req_flags) != vm_req_flags ||
    - (vma->vm_flags & vm_bad_flags))
    + if (vma_flags_mismatch(vma, VM_READ | VM_EXEC,
    + VM_WRITE | VM_MAYSHARE))
    goto out;

    if (opt == PR_SET_MM_START_CODE)
    @@ -1740,11 +1747,8 @@ static int prctl_set_mm(int opt, unsigne

    case PR_SET_MM_START_DATA:
    case PR_SET_MM_END_DATA:
    - vm_req_flags = VM_READ | VM_WRITE;
    - vm_bad_flags = VM_EXEC | VM_MAYSHARE;
    -
    - if ((vma->vm_flags & vm_req_flags) != vm_req_flags ||
    - (vma->vm_flags & vm_bad_flags))
    + if (vma_flags_mismatch(vma, VM_READ | VM_WRITE,
    + VM_EXEC | VM_MAYSHARE))
    goto out;

    if (opt == PR_SET_MM_START_DATA)
    @@ -1753,19 +1757,6 @@ static int prctl_set_mm(int opt, unsigne
    mm->end_data = addr;
    break;

    - case PR_SET_MM_START_STACK:
    -
    -#ifdef CONFIG_STACK_GROWSUP
    - vm_req_flags = VM_READ | VM_WRITE | VM_GROWSUP;
    -#else
    - vm_req_flags = VM_READ | VM_WRITE | VM_GROWSDOWN;
    -#endif
    - if ((vma->vm_flags & vm_req_flags) != vm_req_flags)
    - goto out;
    -
    - mm->start_stack = addr;
    - break;
    -
    case PR_SET_MM_START_BRK:
    if (addr <= mm->end_data)
    goto out;
    @@ -1790,6 +1781,34 @@ static int prctl_set_mm(int opt, unsigne
    mm->brk = addr;
    break;

    + case PR_SET_MM_START_STACK:
    + case PR_SET_MM_ARG_START:
    + case PR_SET_MM_ARG_END:
    + case PR_SET_MM_ENV_START:
    + case PR_SET_MM_ENV_END:
    +#ifdef CONFIG_STACK_GROWSUP
    + if (vma_flags_mismatch(vma, VM_READ | VM_WRITE | VM_GROWSUP, 0))
    +#else
    + if (vma_flags_mismatch(vma, VM_READ | VM_WRITE | VM_GROWSDOWN, 0))
    +#endif
    + goto out;
    + if (opt == PR_SET_MM_START_STACK)
    + mm->start_stack = addr;
    + else if (opt == PR_SET_MM_ARG_START)
    + mm->arg_start = addr;
    + else if (opt == PR_SET_MM_ARG_END)
    + mm->arg_end = addr;
    + else if (opt == PR_SET_MM_ENV_START)
    + mm->env_start = addr;
    + else if (opt == PR_SET_MM_ENV_END)
    + mm->env_end = addr;
    + break;
    +
    + case PR_SET_MM_AUXV:
    + if (arg4 > sizeof(mm->saved_auxv))
    + goto out;
    + error = copy_from_user(mm->saved_auxv, (const void __user *)addr, arg4);
    + break;
    default:
    error = -EINVAL;
    goto out;

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