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authorAl Viro <viro@zeniv.linux.org.uk>2011-03-14 18:56:51 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-03-14 19:12:20 -0400
commitf52e0c11305aa09ed56cad97ffc8f0cdc3d78b5d (patch)
treeb04070034f8a941fe5d7e9e1b335a02784686bd5
parent5fe0c2378884e68beb532f5890cc0e3539ac747b (diff)
New AT_... flag: AT_EMPTY_PATH
For name_to_handle_at(2) we'll want both ...at()-style syscall that would be usable for non-directory descriptors (with empty relative pathname). Introduce new flag (AT_EMPTY_PATH) to deal with that and corresponding LOOKUP_EMPTY; teach user_path_at() and path_init() to deal with the latter. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/namei.c29
-rw-r--r--include/linux/fcntl.h1
-rw-r--r--include/linux/namei.h1
3 files changed, 21 insertions, 10 deletions
diff --git a/fs/namei.c b/fs/namei.c
index abc8d2df121c..83e92bab79a6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -136,7 +136,7 @@ static int do_getname(const char __user *filename, char *page)
return retval;
}
-char * getname(const char __user * filename)
+static char *getname_flags(const char __user * filename, int flags)
{
char *tmp, *result;
@@ -147,14 +147,21 @@ char * getname(const char __user * filename)
result = tmp;
if (retval < 0) {
- __putname(tmp);
- result = ERR_PTR(retval);
+ if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
+ __putname(tmp);
+ result = ERR_PTR(retval);
+ }
}
}
audit_getname(result);
return result;
}
+char *getname(const char __user * filename)
+{
+ return getname_flags(filename, 0);
+}
+
#ifdef CONFIG_AUDITSYSCALL
void putname(const char *name)
{
@@ -1544,13 +1551,15 @@ static int path_init(int dfd, const char *name, unsigned int flags,
dentry = file->f_path.dentry;
- retval = -ENOTDIR;
- if (!S_ISDIR(dentry->d_inode->i_mode))
- goto fput_fail;
+ if (*name) {
+ retval = -ENOTDIR;
+ if (!S_ISDIR(dentry->d_inode->i_mode))
+ goto fput_fail;
- retval = file_permission(file, MAY_EXEC);
- if (retval)
- goto fput_fail;
+ retval = file_permission(file, MAY_EXEC);
+ if (retval)
+ goto fput_fail;
+ }
nd->path = file->f_path;
if (flags & LOOKUP_RCU) {
@@ -1759,7 +1768,7 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
struct path *path)
{
struct nameidata nd;
- char *tmp = getname(name);
+ char *tmp = getname_flags(name, flags);
int err = PTR_ERR(tmp);
if (!IS_ERR(tmp)) {
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index a562fa5fb4e3..f550f894ba15 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -46,6 +46,7 @@
unlinking file. */
#define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */
+#define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */
#ifdef __KERNEL__
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 83cd6e5cd7dc..9c8603872c36 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -64,6 +64,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
#define LOOKUP_JUMPED 0x1000
#define LOOKUP_ROOT 0x2000
+#define LOOKUP_EMPTY 0x4000
extern int user_path_at(int, const char __user *, unsigned, struct path *);