diff options
| -rw-r--r-- | drivers/firmware/efivars.c | 95 |
1 files changed, 93 insertions, 2 deletions
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 868cea5cd4b8..8bcb5958f21a 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -1043,6 +1043,84 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) return -EINVAL; }; +/* + * Compare two efivarfs file names. + * + * An efivarfs filename is composed of two parts, + * + * 1. A case-sensitive variable name + * 2. A case-insensitive GUID + * + * So we need to perform a case-sensitive match on part 1 and a + * case-insensitive match on part 2. + */ +static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode, + const struct dentry *dentry, const struct inode *inode, + unsigned int len, const char *str, + const struct qstr *name) +{ + int guid = len - GUID_LEN; + + if (name->len != len) + return 1; + + /* Case-sensitive compare for the variable name */ + if (memcmp(str, name->name, guid)) + return 1; + + /* Case-insensitive compare for the GUID */ + return strncasecmp(name->name + guid, str + guid, GUID_LEN); +} + +static int efivarfs_d_hash(const struct dentry *dentry, + const struct inode *inode, struct qstr *qstr) +{ + unsigned long hash = init_name_hash(); + const unsigned char *s = qstr->name; + unsigned int len = qstr->len; + + if (!efivarfs_valid_name(s, len)) + return -EINVAL; + + while (len-- > GUID_LEN) + hash = partial_name_hash(*s++, hash); + + /* GUID is case-insensitive. */ + while (len--) + hash = partial_name_hash(tolower(*s++), hash); + + qstr->hash = end_name_hash(hash); + return 0; +} + +/* + * Retaining negative dentries for an in-memory filesystem just wastes + * memory and lookup time: arrange for them to be deleted immediately. + */ +static int efivarfs_delete_dentry(const struct dentry *dentry) +{ + return 1; +} + +static struct dentry_operations efivarfs_d_ops = { + .d_compare = efivarfs_d_compare, + .d_hash = efivarfs_d_hash, + .d_delete = efivarfs_delete_dentry, +}; + +static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) +{ + struct qstr q; + + q.name = name; + q.len = strlen(name); + + if (efivarfs_d_hash(NULL, NULL, &q)) + return NULL; + + return d_alloc(parent, &q); +} + static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode = NULL; @@ -1058,6 +1136,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = EFIVARFS_MAGIC; sb->s_op = &efivarfs_ops; + sb->s_d_op = &efivarfs_d_ops; sb->s_time_gran = 1; inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0); @@ -1098,7 +1177,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) if (!inode) goto fail_name; - dentry = d_alloc_name(root, name); + dentry = efivarfs_alloc_dentry(root, name); if (!dentry) goto fail_inode; @@ -1148,8 +1227,20 @@ static struct file_system_type efivarfs_type = { .kill_sb = efivarfs_kill_sb, }; +/* + * Handle negative dentry. + */ +static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + if (dentry->d_name.len > NAME_MAX) + return ERR_PTR(-ENAMETOOLONG); + d_add(dentry, NULL); + return NULL; +} + static const struct inode_operations efivarfs_dir_inode_operations = { - .lookup = simple_lookup, + .lookup = efivarfs_lookup, .unlink = efivarfs_unlink, .create = efivarfs_create, }; |