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exec: introduce exec_binprm() for "depth == 0" code

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task_pid_nr_ns() and trace/ptrace code in the middle of the recursive
search_binary_handler() looks confusing and imho annoying.  We only need
this code if "depth == 0", lets add a simple helper which calls
search_binary_handler() and does trace_sched_process_exec() +
ptrace_event().

The patch also moves the setting of task->did_exec, we need to do this
only once.

Note: we can kill either task->did_exec or PF_FORKNOEXEC.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Zach Levis <zml@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2013-09-11 14:24:38 -07:00 committed by Linus Torvalds
parent 96d0df79f2
commit 5d1baf3b63
1 changed files with 22 additions and 14 deletions
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36
fs/exec.c
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@ -1373,7 +1373,6 @@ int search_binary_handler(struct linux_binprm *bprm)
unsigned int depth = bprm->recursion_depth;
int try,retval;
struct linux_binfmt *fmt;
pid_t old_pid, old_vpid;
/* This allows 4 levels of binfmt rewrites before failing hard. */
if (depth > 5)
@ -1387,12 +1386,6 @@ int search_binary_handler(struct linux_binprm *bprm)
if (retval)
return retval;
/* Need to fetch pid before load_binary changes it */
old_pid = current->pid;
rcu_read_lock();
old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
rcu_read_unlock();
retval = -ENOENT;
for (try=0; try<2; try++) {
read_lock(&binfmt_lock);
@ -1407,16 +1400,11 @@ int search_binary_handler(struct linux_binprm *bprm)
retval = fn(bprm);
bprm->recursion_depth = depth;
if (retval >= 0) {
if (depth == 0) {
trace_sched_process_exec(current, old_pid, bprm);
ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
}
put_binfmt(fmt);
allow_write_access(bprm->file);
if (bprm->file)
fput(bprm->file);
bprm->file = NULL;
current->did_exec = 1;
proc_exec_connector(current);
return retval;
}
@ -1450,9 +1438,29 @@ int search_binary_handler(struct linux_binprm *bprm)
}
return retval;
}
EXPORT_SYMBOL(search_binary_handler);
static int exec_binprm(struct linux_binprm *bprm)
{
pid_t old_pid, old_vpid;
int ret;
/* Need to fetch pid before load_binary changes it */
old_pid = current->pid;
rcu_read_lock();
old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
rcu_read_unlock();
ret = search_binary_handler(bprm);
if (ret >= 0) {
trace_sched_process_exec(current, old_pid, bprm);
ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
current->did_exec = 1;
}
return ret;
}
/*
* sys_execve() executes a new program.
*/
@ -1541,7 +1549,7 @@ static int do_execve_common(const char *filename,
if (retval < 0)
goto out;
retval = search_binary_handler(bprm);
retval = exec_binprm(bprm);
if (retval < 0)
goto out;