Currently we don't have a way how to determing from which mount point
file has been opened. This information is required for proper dumping
and restoring file descriptos due to presence of mount namespaces. It's
possible, that two file descriptors are opened using the same paths, but
one fd references mount point from one namespace while the other fd --
from other namespace.
$ ls -l /proc/1/fd/1
lrwx------ 1 root root 64 Mar 19 23:54 /proc/1/fd/1 -> /dev/null
$ cat /proc/1/fdinfo/1
pos: 0
flags: 0100002
mnt_id: 16
$ cat /proc/1/mountinfo | grep ^16
16 32 0:4 / /dev rw,nosuid shared:2 - devtmpfs devtmpfs rw,size=1013356k,nr_inodes=253339,mode=755
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Rob Landley <rob@landley.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
proc_fd_permission() says "process can still access /proc/self/fd after it
has executed a setuid()", but the "task_pid() = proc_pid() check only
helps if the task is group leader, /proc/self points to
/proc/<leader-pid>.
Change this check to use task_tgid() so that the whole thread group can
access its /proc/self/fd or /proc/<tid-of-sub-thread>/fd.
Notes:
- CLONE_THREAD does not require CLONE_FILES so task->files
can differ, but I don't think this can lead to any security
problem. And this matches same_thread_group() in
__ptrace_may_access().
- /proc/self should probably point to /proc/<thread-tid>, but
it is too late to change the rules. Perhaps it makes sense
to add /proc/thread though.
Test-case:
void *tfunc(void *arg)
{
assert(opendir("/proc/self/fd"));
return NULL;
}
int main(void)
{
pthread_t t;
pthread_create(&t, NULL, tfunc, NULL);
pthread_join(t, NULL);
return 0;
}
fails if, say, this executable is not readable and suid_dumpable = 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
proc_readfd_common() does dir_emit_dots() twice in a row,
we need to do this only once.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch brings ability to print out auxiliary data associated with
file in procfs interface /proc/pid/fdinfo/fd.
In particular further patches make eventfd, evenpoll, signalfd and
fsnotify to print additional information complete enough to restore
these objects after checkpoint.
To simplify the code we add show_fdinfo callback inside struct
file_operations (as Al and Pavel are proposing).
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Helsley <matt.helsley@gmail.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch converts /proc/pid/fdinfo/ handling routines to seq-file which
is needed to extend seq operations and plug in auxiliary fdinfo provides
from subsystems like eventfd/eventpoll/fsnotify.
Note the proc_fd_link no longer call for proc_fd_info, simply because
the guts of proc_fd_info() got merged into ->show() of that seq_file
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch prepares the ground for further extension of
/proc/pid/fd[info] handling code by moving fdinfo handling
code into fs/proc/fd.c.
I think such move makes both fs/proc/base.c and fs/proc/fd.c
easier to read.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
CC: Al Viro <viro@ZenIV.linux.org.uk>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: James Bottomley <jbottomley@parallels.com>
CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Matthew Helsley <matt.helsley@gmail.com>
CC: "J. Bruce Fields" <bfields@fieldses.org>
CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
