[patch cr 4/4] c/r: prctl: Extend PR_SET_MM to set up more mm_struct entries

Cyrill Gorcunov
2012-01-30T14:19:34Z

[-- Attachment #1: prctl-restore-mm-members-5 --]
[-- Type: text/plain, Size: 5372 bytes --]

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 | 86 ++++++++++++++++++++++++++++++++------------------
2 files changed, 61 insertions(+), 30 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 +1693,23 @@ 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 mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int error = 0;
- struct mm_struct *mm = current->mm;

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

if (!capable(CAP_SYS_ADMIN))
@@ -1715,7 +1721,9 @@ 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 +1733,8 @@ 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 +1745,8 @@ 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 +1755,6 @@ 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;
@@ -1790,16 +1779,53 @@ 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: {
+ unsigned long user_auxv[AT_VECTOR_SIZE];
+
+ if (arg4 > sizeof(mm->saved_auxv))
+ goto out;
+ up_read(&mm->mmap_sem);
+
+ if (copy_from_user(user_auxv, (const void __user *)addr, arg4))
+ return EFAULT;
+
+ task_lock(current);
+ memcpy(mm->saved_auxv, user_auxv, arg4);
+ task_unlock(current);
+
+ return 0;
+ }
default:
error = -EINVAL;
goto out;
}

error = 0;
-
out:
up_read(&mm->mmap_sem);
-
return error;
}
#else /* CONFIG_CHECKPOINT_RESTORE */