From 8df9d1a4142311c084ffeeacb67cd34d190eff74 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:41 +0200 Subject: vfs: show unreachable paths in getcwd and proc Prepend "(unreachable)" to path strings if the path is not reachable from the current root. Two places updated are - the return string from getcwd() - and symlinks under /proc/$PID. Other uses of d_path() are left unchanged (we know that some old software crashes if /proc/mounts is changed). Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 50 insertions(+), 4 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 7fccb00f498d..166d35d56868 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2019,6 +2019,11 @@ static int path_with_deleted(const struct path *path, struct path *root, return prepend_path(path, root, buf, buflen); } +static int prepend_unreachable(char **buffer, int *buflen) +{ + return prepend(buffer, buflen, "(unreachable)", 13); +} + /** * d_path - return the path of a dentry * @path: path to report @@ -2064,6 +2069,39 @@ char *d_path(const struct path *path, char *buf, int buflen) } EXPORT_SYMBOL(d_path); +/** + * d_path_with_unreachable - return the path of a dentry + * @path: path to report + * @buf: buffer to return value in + * @buflen: buffer length + * + * The difference from d_path() is that this prepends "(unreachable)" + * to paths which are unreachable from the current process' root. + */ +char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) +{ + char *res = buf + buflen; + struct path root; + struct path tmp; + int error; + + if (path->dentry->d_op && path->dentry->d_op->d_dname) + return path->dentry->d_op->d_dname(path->dentry, buf, buflen); + + get_fs_root(current->fs, &root); + spin_lock(&dcache_lock); + tmp = root; + error = path_with_deleted(path, &tmp, &res, &buflen); + if (!error && !path_equal(&tmp, &root)) + error = prepend_unreachable(&res, &buflen); + spin_unlock(&dcache_lock); + path_put(&root); + if (error) + res = ERR_PTR(error); + + return res; +} + /* * Helper function for dentry_operations.d_dname() members */ @@ -2173,15 +2211,23 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) if (!d_unlinked(pwd.dentry)) { unsigned long len; struct path tmp = root; - char * cwd; + char *cwd = page + PAGE_SIZE; + int buflen = PAGE_SIZE; - cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE); + prepend(&cwd, &buflen, "\0", 1); + error = prepend_path(&pwd, &tmp, &cwd, &buflen); spin_unlock(&dcache_lock); - error = PTR_ERR(cwd); - if (IS_ERR(cwd)) + if (error) goto out; + /* Unreachable from current root */ + if (!path_equal(&tmp, &root)) { + error = prepend_unreachable(&cwd, &buflen); + if (error) + goto out; + } + error = -ERANGE; len = PAGE_SIZE + page - cwd; if (len <= size) { -- cgit v1.2.1