From bafb282df29c1524b1617019adebd6d0c3eb7a47 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 7 Jun 2012 14:21:11 -0700 Subject: c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal A fix for commit b32dfe377102 ("c/r: prctl: add ability to set new mm_struct::exe_file"). After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(), it never becomes NULL while task is alive. We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas, and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file. Signed-off-by: Konstantin Khlebnikov Reviewed-by: Cyrill Gorcunov Cc: Oleg Nesterov Cc: Matt Helsley Cc: Kees Cook Cc: KOSAKI Motohiro Cc: Tejun Heo Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 6029d8c54476..c688d4cc2e40 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -439,6 +439,7 @@ extern int get_dumpable(struct mm_struct *mm); /* leave room for more dump flags */ #define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */ #define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */ +#define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */ #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK) -- cgit v1.2.3 From 300f786b2683f8bb1ec0afb6e1851183a479c86d Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Thu, 7 Jun 2012 14:21:12 -0700 Subject: c/r: prctl: add ability to get clear_tid_address Zero is written at clear_tid_address when the process exits. This functionality is used by pthread_join(). We already have sys_set_tid_address() to change this address for the current task but there is no way to obtain it from user space. Without the ability to find this address and dump it we can't restore pthread'ed apps which call pthread_join() once they have been restored. This patch introduces the PR_GET_TID_ADDRESS prctl option which allows the current process to obtain own clear_tid_address. This feature is available iif CONFIG_CHECKPOINT_RESTORE is set. [akpm@linux-foundation.org: fix prctl numbering] Signed-off-by: Andrew Vagin Signed-off-by: Cyrill Gorcunov Cc: Pedro Alves Cc: Oleg Nesterov Cc: Pavel Emelyanov Cc: Tejun Heo Acked-by: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/prctl.h | 10 ++++++---- kernel/sys.c | 13 +++++++++++++ 2 files changed, 19 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/prctl.h b/include/linux/prctl.h index 711e0a30aacc..3988012255dc 100644 --- a/include/linux/prctl.h +++ b/include/linux/prctl.h @@ -127,8 +127,8 @@ #define PR_SET_PTRACER 0x59616d61 # define PR_SET_PTRACER_ANY ((unsigned long)-1) -#define PR_SET_CHILD_SUBREAPER 36 -#define PR_GET_CHILD_SUBREAPER 37 +#define PR_SET_CHILD_SUBREAPER 36 +#define PR_GET_CHILD_SUBREAPER 37 /* * If no_new_privs is set, then operations that grant new privileges (i.e. @@ -142,7 +142,9 @@ * asking selinux for a specific new context (e.g. with runcon) will result * in execve returning -EPERM. */ -#define PR_SET_NO_NEW_PRIVS 38 -#define PR_GET_NO_NEW_PRIVS 39 +#define PR_SET_NO_NEW_PRIVS 38 +#define PR_GET_NO_NEW_PRIVS 39 + +#define PR_GET_TID_ADDRESS 40 #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index 19a2c7139960..0ec1942ba7ea 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1988,12 +1988,22 @@ out: up_read(&mm->mmap_sem); return error; } + +static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr) +{ + return put_user(me->clear_child_tid, tid_addr); +} + #else /* CONFIG_CHECKPOINT_RESTORE */ static int prctl_set_mm(int opt, unsigned long addr, unsigned long arg4, unsigned long arg5) { return -EINVAL; } +static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr) +{ + return -EINVAL; +} #endif SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, @@ -2131,6 +2141,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, else return -EINVAL; break; + case PR_GET_TID_ADDRESS: + error = prctl_get_tid_address(me, (int __user **)arg2); + break; default: return -EINVAL; } -- cgit v1.2.3