diff options
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efivars.c | 146 |
1 files changed, 138 insertions, 8 deletions
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index fed08b661711..7320bf891706 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -79,6 +79,7 @@ #include <linux/device.h> #include <linux/slab.h> #include <linux/pstore.h> +#include <linux/ctype.h> #include <linux/fs.h> #include <linux/ramfs.h> @@ -908,6 +909,48 @@ static struct inode *efivarfs_get_inode(struct super_block *sb, return inode; } +/* + * Return true if 'str' is a valid efivarfs filename of the form, + * + * VariableName-12345678-1234-1234-1234-1234567891bc + */ +static bool efivarfs_valid_name(const char *str, int len) +{ + static const char dashes[GUID_LEN] = { + [8] = 1, [13] = 1, [18] = 1, [23] = 1 + }; + const char *s = str + len - GUID_LEN; + int i; + + /* + * We need a GUID, plus at least one letter for the variable name, + * plus the '-' separator + */ + if (len < GUID_LEN + 2) + return false; + + /* GUID should be right after the first '-' */ + if (s - 1 != strchr(str, '-')) + return false; + + /* + * Validate that 's' is of the correct format, e.g. + * + * 12345678-1234-1234-1234-123456789abc + */ + for (i = 0; i < GUID_LEN; i++) { + if (dashes[i]) { + if (*s++ != '-') + return false; + } else { + if (!isxdigit(*s++)) + return false; + } + } + + return true; +} + static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid) { guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]); @@ -936,11 +979,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry, struct efivar_entry *var; int namelen, i = 0, err = 0; - /* - * We need a GUID, plus at least one letter for the variable name, - * plus the '-' separator - */ - if (dentry->d_name.len < GUID_LEN + 2) + if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) return -EINVAL; inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0); @@ -1012,6 +1051,84 @@ 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; @@ -1027,6 +1144,7 @@ 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); @@ -1067,7 +1185,7 @@ 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; @@ -1084,7 +1202,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) mutex_lock(&inode->i_mutex); inode->i_private = entry; - i_size_write(inode, size+4); + i_size_write(inode, size + sizeof(entry->var.Attributes)); mutex_unlock(&inode->i_mutex); d_add(dentry, inode); } @@ -1117,8 +1235,20 @@ 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, }; |