diff options
author | Manfred Spraul <manfred@colorfullife.com> | 2008-04-29 01:00:57 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:14 -0700 |
commit | 9edff4ab1f8d82675277a04e359d0ed8bf14a7b7 (patch) | |
tree | 05e67ca13f78b0eff666a4424e03dd6d0fa964c7 /kernel | |
parent | 44f564a4bf6ac70f2a84806203045cf515bc9367 (diff) |
ipc: sysvsem: implement sys_unshare(CLONE_SYSVSEM)
sys_unshare(CLONE_NEWIPC) doesn't handle the undo lists properly, this can
cause a kernel memory corruption. CLONE_NEWIPC must detach from the existing
undo lists.
Fix, part 1: add support for sys_unshare(CLONE_SYSVSEM)
The original reason to not support it was the potential (inevitable?)
confusion due to the fact that sys_unshare(CLONE_SYSVSEM) has the
inverse meaning of clone(CLONE_SYSVSEM).
Our two most reasonable options then appear to be (1) fully support
CLONE_SYSVSEM, or (2) continue to refuse explicit CLONE_SYSVSEM,
but always do it anyway on unshare(CLONE_SYSVSEM). This patch does
(1).
Changelog:
Apr 16: SEH: switch to Manfred's alternative patch which
removes the unshare_semundo() function which
always refused CLONE_SYSVSEM.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/fork.c | 29 |
1 files changed, 11 insertions, 18 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 156db96ff754..01666979beac 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1669,18 +1669,6 @@ static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp } /* - * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not - * supported yet - */ -static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp) -{ - if (unshare_flags & CLONE_SYSVSEM) - return -EINVAL; - - return 0; -} - -/* * unshare allows a process to 'unshare' part of the process * context which was originally shared using clone. copy_* * functions used by do_fork() cannot be used here directly @@ -1695,8 +1683,8 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) struct sighand_struct *new_sigh = NULL; struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; struct files_struct *fd, *new_fd = NULL; - struct sem_undo_list *new_ulist = NULL; struct nsproxy *new_nsproxy = NULL; + int do_sysvsem = 0; check_unshare_flags(&unshare_flags); @@ -1708,6 +1696,8 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) CLONE_NEWNET)) goto bad_unshare_out; + if (unshare_flags & CLONE_SYSVSEM) + do_sysvsem = 1; if ((err = unshare_thread(unshare_flags))) goto bad_unshare_out; if ((err = unshare_fs(unshare_flags, &new_fs))) @@ -1718,13 +1708,17 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) goto bad_unshare_cleanup_sigh; if ((err = unshare_fd(unshare_flags, &new_fd))) goto bad_unshare_cleanup_vm; - if ((err = unshare_semundo(unshare_flags, &new_ulist))) - goto bad_unshare_cleanup_fd; if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs))) - goto bad_unshare_cleanup_semundo; + goto bad_unshare_cleanup_fd; - if (new_fs || new_mm || new_fd || new_ulist || new_nsproxy) { + if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { + if (do_sysvsem) { + /* + * CLONE_SYSVSEM is equivalent to sys_exit(). + */ + exit_sem(current); + } if (new_nsproxy) { switch_task_namespaces(current, new_nsproxy); @@ -1760,7 +1754,6 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) if (new_nsproxy) put_nsproxy(new_nsproxy); -bad_unshare_cleanup_semundo: bad_unshare_cleanup_fd: if (new_fd) put_files_struct(new_fd); |