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new helper: user_path_locked_at()
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Equivalent of kern_path_locked() taking dfd/userland name.
User introduced in the next commit.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro committed Nov 16, 2023
1 parent b85ea95 commit 74d016e
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Showing 2 changed files with 14 additions and 3 deletions.
16 changes: 13 additions & 3 deletions fs/namei.c
Original file line number Diff line number Diff line change
Expand Up @@ -2573,13 +2573,13 @@ static int filename_parentat(int dfd, struct filename *name,
}

/* does lookup, returns the object with parent locked */
static struct dentry *__kern_path_locked(struct filename *name, struct path *path)
static struct dentry *__kern_path_locked(int dfd, struct filename *name, struct path *path)
{
struct dentry *d;
struct qstr last;
int type, error;

error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type);
error = filename_parentat(dfd, name, 0, path, &last, &type);
if (error)
return ERR_PTR(error);
if (unlikely(type != LAST_NORM)) {
Expand All @@ -2598,12 +2598,22 @@ static struct dentry *__kern_path_locked(struct filename *name, struct path *pat
struct dentry *kern_path_locked(const char *name, struct path *path)
{
struct filename *filename = getname_kernel(name);
struct dentry *res = __kern_path_locked(filename, path);
struct dentry *res = __kern_path_locked(AT_FDCWD, filename, path);

putname(filename);
return res;
}

struct dentry *user_path_locked_at(int dfd, const char __user *name, struct path *path)
{
struct filename *filename = getname(name);
struct dentry *res = __kern_path_locked(dfd, filename, path);

putname(filename);
return res;
}
EXPORT_SYMBOL(user_path_locked_at);

int kern_path(const char *name, unsigned int flags, struct path *path)
{
struct filename *filename = getname_kernel(name);
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1 change: 1 addition & 0 deletions include/linux/namei.h
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne
extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
extern void done_path_create(struct path *, struct dentry *);
extern struct dentry *kern_path_locked(const char *, struct path *);
extern struct dentry *user_path_locked_at(int , const char __user *, struct path *);
int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
struct path *parent, struct qstr *last, int *type,
const struct path *root);
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