diff options
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 176 |
1 files changed, 87 insertions, 89 deletions
diff --git a/fs/namei.c b/fs/namei.c index c83145af4bfc..ffab2e06e147 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -119,15 +119,14 @@ * PATH_MAX includes the nul terminator --RR. */ -#define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) +#define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) struct filename * getname_flags(const char __user *filename, int flags, int *empty) { - struct filename *result, *err; - int len; - long max; + struct filename *result; char *kname; + int len; result = audit_reusename(filename); if (result) @@ -136,22 +135,18 @@ getname_flags(const char __user *filename, int flags, int *empty) result = __getname(); if (unlikely(!result)) return ERR_PTR(-ENOMEM); - result->refcnt = 1; /* * First, try to embed the struct filename inside the names_cache * allocation */ - kname = (char *)result + sizeof(*result); + kname = (char *)result->iname; result->name = kname; - result->separate = false; - max = EMBEDDED_NAME_MAX; -recopy: - len = strncpy_from_user(kname, filename, max); + len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); if (unlikely(len < 0)) { - err = ERR_PTR(len); - goto error; + __putname(result); + return ERR_PTR(len); } /* @@ -160,43 +155,49 @@ recopy: * names_cache allocation for the pathname, and re-do the copy from * userland. */ - if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { + if (unlikely(len == EMBEDDED_NAME_MAX)) { + const size_t size = offsetof(struct filename, iname[1]); kname = (char *)result; - result = kzalloc(sizeof(*result), GFP_KERNEL); - if (!result) { - err = ERR_PTR(-ENOMEM); - result = (struct filename *)kname; - goto error; + /* + * size is chosen that way we to guarantee that + * result->iname[0] is within the same object and that + * kname can't be equal to result->iname, no matter what. + */ + result = kzalloc(size, GFP_KERNEL); + if (unlikely(!result)) { + __putname(kname); + return ERR_PTR(-ENOMEM); } result->name = kname; - result->separate = true; - result->refcnt = 1; - max = PATH_MAX; - goto recopy; + len = strncpy_from_user(kname, filename, PATH_MAX); + if (unlikely(len < 0)) { + __putname(kname); + kfree(result); + return ERR_PTR(len); + } + if (unlikely(len == PATH_MAX)) { + __putname(kname); + kfree(result); + return ERR_PTR(-ENAMETOOLONG); + } } + result->refcnt = 1; /* The empty path is special. */ if (unlikely(!len)) { if (empty) *empty = 1; - err = ERR_PTR(-ENOENT); - if (!(flags & LOOKUP_EMPTY)) - goto error; + if (!(flags & LOOKUP_EMPTY)) { + putname(result); + return ERR_PTR(-ENOENT); + } } - err = ERR_PTR(-ENAMETOOLONG); - if (unlikely(len >= PATH_MAX)) - goto error; - result->uptr = filename; result->aname = NULL; audit_getname(result); return result; - -error: - putname(result); - return err; } struct filename * @@ -216,8 +217,7 @@ getname_kernel(const char * filename) return ERR_PTR(-ENOMEM); if (len <= EMBEDDED_NAME_MAX) { - result->name = (char *)(result) + sizeof(*result); - result->separate = false; + result->name = (char *)result->iname; } else if (len <= PATH_MAX) { struct filename *tmp; @@ -227,7 +227,6 @@ getname_kernel(const char * filename) return ERR_PTR(-ENOMEM); } tmp->name = (char *)result; - tmp->separate = true; result = tmp; } else { __putname(result); @@ -249,7 +248,7 @@ void putname(struct filename *name) if (--name->refcnt > 0) return; - if (name->separate) { + if (name->name != name->iname) { __putname(name->name); kfree(name); } else @@ -1586,7 +1585,7 @@ static inline int walk_component(struct nameidata *nd, struct path *path, inode = path->dentry->d_inode; } err = -ENOENT; - if (!inode || d_is_negative(path->dentry)) + if (d_is_negative(path->dentry)) goto out_path_put; if (should_follow_link(path->dentry, follow)) { @@ -1851,10 +1850,11 @@ static int link_path_walk(const char *name, struct nameidata *nd) return err; } -static int path_init(int dfd, const char *name, unsigned int flags, +static int path_init(int dfd, const struct filename *name, unsigned int flags, struct nameidata *nd) { int retval = 0; + const char *s = name->name; nd->last_type = LAST_ROOT; /* if there are only slashes... */ nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; @@ -1863,7 +1863,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, if (flags & LOOKUP_ROOT) { struct dentry *root = nd->root.dentry; struct inode *inode = root->d_inode; - if (*name) { + if (*s) { if (!d_can_lookup(root)) return -ENOTDIR; retval = inode_permission(inode, MAY_EXEC); @@ -1885,7 +1885,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, nd->root.mnt = NULL; nd->m_seq = read_seqbegin(&mount_lock); - if (*name=='/') { + if (*s == '/') { if (flags & LOOKUP_RCU) { rcu_read_lock(); nd->seq = set_root_rcu(nd); @@ -1919,7 +1919,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, dentry = f.file->f_path.dentry; - if (*name) { + if (*s) { if (!d_can_lookup(dentry)) { fdput(f); return -ENOTDIR; @@ -1949,7 +1949,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, return -ECHILD; done: current->total_link_count = 0; - return link_path_walk(name, nd); + return link_path_walk(s, nd); } static void path_cleanup(struct nameidata *nd) @@ -1972,7 +1972,7 @@ static inline int lookup_last(struct nameidata *nd, struct path *path) } /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ -static int path_lookupat(int dfd, const char *name, +static int path_lookupat(int dfd, const struct filename *name, unsigned int flags, struct nameidata *nd) { struct path path; @@ -2027,31 +2027,17 @@ static int path_lookupat(int dfd, const char *name, static int filename_lookup(int dfd, struct filename *name, unsigned int flags, struct nameidata *nd) { - int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); + int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); if (unlikely(retval == -ECHILD)) - retval = path_lookupat(dfd, name->name, flags, nd); + retval = path_lookupat(dfd, name, flags, nd); if (unlikely(retval == -ESTALE)) - retval = path_lookupat(dfd, name->name, - flags | LOOKUP_REVAL, nd); + retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); if (likely(!retval)) audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); return retval; } -static int do_path_lookup(int dfd, const char *name, - unsigned int flags, struct nameidata *nd) -{ - struct filename *filename = getname_kernel(name); - int retval = PTR_ERR(filename); - - if (!IS_ERR(filename)) { - retval = filename_lookup(dfd, filename, flags, nd); - putname(filename); - } - return retval; -} - /* does lookup, returns the object with parent locked */ struct dentry *kern_path_locked(const char *name, struct path *path) { @@ -2089,9 +2075,15 @@ out: int kern_path(const char *name, unsigned int flags, struct path *path) { struct nameidata nd; - int res = do_path_lookup(AT_FDCWD, name, flags, &nd); - if (!res) - *path = nd.path; + struct filename *filename = getname_kernel(name); + int res = PTR_ERR(filename); + + if (!IS_ERR(filename)) { + res = filename_lookup(AT_FDCWD, filename, flags, &nd); + putname(filename); + if (!res) + *path = nd.path; + } return res; } EXPORT_SYMBOL(kern_path); @@ -2108,15 +2100,22 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, const char *name, unsigned int flags, struct path *path) { - struct nameidata nd; - int err; - nd.root.dentry = dentry; - nd.root.mnt = mnt; + struct filename *filename = getname_kernel(name); + int err = PTR_ERR(filename); + BUG_ON(flags & LOOKUP_PARENT); - /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ - err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); - if (!err) - *path = nd.path; + + /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ + if (!IS_ERR(filename)) { + struct nameidata nd; + nd.root.dentry = dentry; + nd.root.mnt = mnt; + err = filename_lookup(AT_FDCWD, filename, + flags | LOOKUP_ROOT, &nd); + if (!err) + *path = nd.path; + putname(filename); + } return err; } EXPORT_SYMBOL(vfs_path_lookup); @@ -2138,9 +2137,7 @@ static struct dentry *lookup_hash(struct nameidata *nd) * @len: maximum length @len should be interpreted to * * Note that this routine is purely a helper for filesystem usage and should - * not be called by generic code. Also note that by using this function the - * nameidata argument is passed to the filesystem methods and a filesystem - * using this helper needs to be prepared for that. + * not be called by generic code. */ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) { @@ -2313,7 +2310,7 @@ mountpoint_last(struct nameidata *nd, struct path *path) mutex_unlock(&dir->d_inode->i_mutex); done: - if (!dentry->d_inode || d_is_negative(dentry)) { + if (d_is_negative(dentry)) { error = -ENOENT; dput(dentry); goto out; @@ -2341,7 +2338,8 @@ out: * Returns 0 and "path" will be valid on success; Returns error otherwise. */ static int -path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) +path_mountpoint(int dfd, const struct filename *name, struct path *path, + unsigned int flags) { struct nameidata nd; int err; @@ -2370,20 +2368,20 @@ out: } static int -filename_mountpoint(int dfd, struct filename *s, struct path *path, +filename_mountpoint(int dfd, struct filename *name, struct path *path, unsigned int flags) { int error; - if (IS_ERR(s)) - return PTR_ERR(s); - error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); + if (IS_ERR(name)) + return PTR_ERR(name); + error = path_mountpoint(dfd, name, path, flags | LOOKUP_RCU); if (unlikely(error == -ECHILD)) - error = path_mountpoint(dfd, s->name, path, flags); + error = path_mountpoint(dfd, name, path, flags); if (unlikely(error == -ESTALE)) - error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); + error = path_mountpoint(dfd, name, path, flags | LOOKUP_REVAL); if (likely(!error)) - audit_inode(s, path->dentry, 0); - putname(s); + audit_inode(name, path->dentry, 0); + putname(name); return error; } @@ -3040,7 +3038,7 @@ retry_lookup: finish_lookup: /* we _can_ be in RCU mode here */ error = -ENOENT; - if (!inode || d_is_negative(path->dentry)) { + if (d_is_negative(path->dentry)) { path_to_nameidata(path, nd); goto out; } @@ -3079,7 +3077,7 @@ finish_open: error = -ENOTDIR; if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) goto out; - if (!S_ISREG(nd->inode->i_mode)) + if (!d_is_reg(nd->path.dentry)) will_truncate = false; if (will_truncate) { @@ -3156,7 +3154,7 @@ static int do_tmpfile(int dfd, struct filename *pathname, static const struct qstr name = QSTR_INIT("/", 1); struct dentry *dentry, *child; struct inode *dir; - int error = path_lookupat(dfd, pathname->name, + int error = path_lookupat(dfd, pathname, flags | LOOKUP_DIRECTORY, nd); if (unlikely(error)) return error; @@ -3229,7 +3227,7 @@ static struct file *path_openat(int dfd, struct filename *pathname, goto out; } - error = path_init(dfd, pathname->name, flags, nd); + error = path_init(dfd, pathname, flags, nd); if (unlikely(error)) goto out; |