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New AT_... flag: AT_EMPTY_PATH

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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>
This commit is contained in:
Al Viro 2011-03-14 18:56:51 -04:00
parent 5fe0c23788
commit f52e0c1130
3 changed files with 21 additions and 10 deletions
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29
fs/namei.c
View file

@ -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)) {

1
include/linux/fcntl.h
View file

@ -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__

1
include/linux/namei.h
View file

@ -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 *);