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authorAl Viro <viro@zeniv.linux.org.uk>2012-09-30 13:20:09 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2012-09-30 13:36:39 -0400
commit282124d18626379a20b41d25e0c580f290cd09d4 (patch)
tree48adb982843cbb133c8079f06abad2911e019f12 /fs/exec.c
parenta3460a59747cfddfa7be4758e5ef08bf5d751d59 (diff)
generic kernel_execve()
based mostly on arm and alpha versions. Architectures can define __ARCH_WANT_KERNEL_EXECVE and use it, provided that * they have working current_pt_regs(), even for kernel threads. * kernel_thread-spawned threads do have space for pt_regs in the normal location. Normally that's as simple as switching to generic kernel_thread() and making sure that kernel threads do *not* go through return from syscall path; call the payload from equivalent of ret_from_fork if we are in a kernel thread (or just have separate ret_from_kernel_thread and make copy_thread() use it instead of ret_from_fork in kernel thread case). * they have ret_from_kernel_execve(); it is called after successful do_execve() done by kernel_execve() and gets normal pt_regs location passed to it as argument. It's essentially a longjmp() analog - it should set sp, etc. to the situation expected at the return for syscall and go there. Eventually the need for that sucker will disappear, but that'll take some surgery on kernel_thread() payloads. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c
index d7f9e14f897..48c525115fe 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2318,3 +2318,25 @@ int dump_seek(struct file *file, loff_t off)
return ret;
}
EXPORT_SYMBOL(dump_seek);
+
+#ifdef __ARCH_WANT_KERNEL_EXECVE
+int kernel_execve(const char *filename,
+ const char *const argv[],
+ const char *const envp[])
+{
+ struct pt_regs *p = current_pt_regs();
+ int ret;
+
+ ret = do_execve(filename,
+ (const char __user *const __user *)argv,
+ (const char __user *const __user *)envp, p);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * We were successful. We won't be returning to our caller, but
+ * instead to user space by manipulating the kernel stack.
+ */
+ ret_from_kernel_execve(p);
+}
+#endif