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authorTopi Miettinen <toiwoton@gmail.com>2020-01-23 15:58:38 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-02-11 02:39:28 +0300
commit901cff7cb96140a658a848a568b606ba764239bc (patch)
treea4e15360014c4c945460187dd5ec110356944369 /fs/exec.c
parent469e1906a1b121ecb0c2ef43f28a98fd9d453831 (diff)
downloadlinux-901cff7cb96140a658a848a568b606ba764239bc.tar.xz
firmware_loader: load files from the mount namespace of init
I have an experimental setup where almost every possible system service (even early startup ones) runs in separate namespace, using a dedicated, minimal file system. In process of minimizing the contents of the file systems with regards to modules and firmware files, I noticed that in my system, the firmware files are loaded from three different mount namespaces, those of systemd-udevd, init and systemd-networkd. The logic of the source namespace is not very clear, it seems to depend on the driver, but the namespace of the current process is used. So, this patch tries to make things a bit clearer and changes the loading of firmware files only from the mount namespace of init. This may also improve security, though I think that using firmware files as attack vector could be too impractical anyway. Later, it might make sense to make the mount namespace configurable, for example with a new file in /proc/sys/kernel/firmware_config/. That would allow a dedicated file system only for firmware files and those need not be present anywhere else. This configurability would make more sense if made also for kernel modules and /sbin/modprobe. Modules are already loaded from init namespace (usermodehelper uses kthreadd namespace) except when directly loaded by systemd-udevd. Instead of using the mount namespace of the current process to load firmware files, use the mount namespace of init process. Link: https://lore.kernel.org/lkml/bb46ebae-4746-90d9-ec5b-fce4c9328c86@gmail.com/ Link: https://lore.kernel.org/lkml/0e3f7653-c59d-9341-9db2-c88f5b988c68@gmail.com/ Signed-off-by: Topi Miettinen <toiwoton@gmail.com> Link: https://lore.kernel.org/r/20200123125839.37168-1-toiwoton@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c
index db17be51b112..688c824cdac8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -985,6 +985,32 @@ int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
+int kernel_read_file_from_path_initns(const char *path, void **buf,
+ loff_t *size, loff_t max_size,
+ enum kernel_read_file_id id)
+{
+ struct file *file;
+ struct path root;
+ int ret;
+
+ if (!path || !*path)
+ return -EINVAL;
+
+ task_lock(&init_task);
+ get_fs_root(init_task.fs, &root);
+ task_unlock(&init_task);
+
+ file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
+ path_put(&root);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ ret = kernel_read_file(file, buf, size, max_size, id);
+ fput(file);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
+
int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
enum kernel_read_file_id id)
{