diff options
| -rw-r--r-- | fs/overlayfs/copy_up.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index d894e7cd9a86..959bdcf2f9e8 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -7,6 +7,7 @@ * the Free Software Foundation. */ +#include <linux/module.h> #include <linux/fs.h> #include <linux/slab.h> #include <linux/file.h> @@ -16,10 +17,41 @@ #include <linux/uaccess.h> #include <linux/sched.h> #include <linux/namei.h> +#include <linux/fdtable.h> +#include <linux/ratelimit.h> #include "overlayfs.h" #define OVL_COPY_UP_CHUNK_SIZE (1 << 20) +static bool __read_mostly ovl_check_copy_up; +module_param_named(check_copy_up, ovl_check_copy_up, bool, + S_IWUSR | S_IRUGO); +MODULE_PARM_DESC(ovl_check_copy_up, + "Warn on copy-up when causing process also has a R/O fd open"); + +static int ovl_check_fd(const void *data, struct file *f, unsigned int fd) +{ + const struct dentry *dentry = data; + + if (f->f_inode == d_inode(dentry)) + pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n", + f, fd, current->pid, current->comm); + return 0; +} + +/* + * Check the fds open by this process and warn if something like the following + * scenario is about to occur: + * + * fd1 = open("foo", O_RDONLY); + * fd2 = open("foo", O_RDWR); + */ +static void ovl_do_check_copy_up(struct dentry *dentry) +{ + if (ovl_check_copy_up) + iterate_fd(current->files, 0, ovl_check_fd, dentry); +} + int ovl_copy_xattr(struct dentry *old, struct dentry *new) { ssize_t list_size, size, value_size = 0; @@ -309,6 +341,8 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, if (WARN_ON(!workdir)) return -EROFS; + ovl_do_check_copy_up(lowerpath->dentry); + ovl_path_upper(parent, &parentpath); upperdir = parentpath.dentry; |