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authorMiklos Szeredi <mszeredi@suse.cz>2010-08-10 11:41:41 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2010-08-11 00:29:47 -0400
commit8df9d1a4142311c084ffeeacb67cd34d190eff74 (patch)
tree512e018114ea506659fac73d838bfca0fb97a5a4
parentffd1f4ed5bddccf2277e3d8525bcedf1983319f8 (diff)
downloadop-kernel-dev-8df9d1a4142311c084ffeeacb67cd34d190eff74.zip
op-kernel-dev-8df9d1a4142311c084ffeeacb67cd34d190eff74.tar.gz
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 <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/dcache.c54
-rw-r--r--fs/proc/base.c2
-rw-r--r--include/linux/dcache.h1
-rw-r--r--include/linux/path.h5
4 files changed, 57 insertions, 5 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 7fccb00..166d35d 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) {
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 4cf5abf..a1c43e7 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1526,7 +1526,7 @@ static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
if (!tmp)
return -ENOMEM;
- pathname = d_path(path, tmp, PAGE_SIZE);
+ pathname = d_path_with_unreachable(path, tmp, PAGE_SIZE);
len = PTR_ERR(pathname);
if (IS_ERR(pathname))
goto out;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index d23be038..6a4aea3 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -315,6 +315,7 @@ extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
extern char *__d_path(const struct path *path, struct path *root, char *, int);
extern char *d_path(const struct path *, char *, int);
+extern char *d_path_with_unreachable(const struct path *, char *, int);
extern char *__dentry_path(struct dentry *, char *, int);
extern char *dentry_path(struct dentry *, char *, int);
diff --git a/include/linux/path.h b/include/linux/path.h
index 915e0c3..edc98de 100644
--- a/include/linux/path.h
+++ b/include/linux/path.h
@@ -12,4 +12,9 @@ struct path {
extern void path_get(struct path *);
extern void path_put(struct path *);
+static inline int path_equal(const struct path *path1, const struct path *path2)
+{
+ return path1->mnt == path2->mnt && path1->dentry == path2->dentry;
+}
+
#endif /* _LINUX_PATH_H */
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