diff options
Diffstat (limited to 'drivers/firmware/efivars.c')
-rw-r--r-- | drivers/firmware/efivars.c | 266 |
1 files changed, 229 insertions, 37 deletions
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index fed08b661711..bea32d1ef7d5 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> @@ -425,6 +426,44 @@ get_var_data(struct efivars *efivars, struct efi_variable *var) return status; } +static efi_status_t +check_var_size_locked(struct efivars *efivars, u32 attributes, + unsigned long size) +{ + u64 storage_size, remaining_size, max_size; + efi_status_t status; + const struct efivar_operations *fops = efivars->ops; + + if (!efivars->ops->query_variable_info) + return EFI_UNSUPPORTED; + + status = fops->query_variable_info(attributes, &storage_size, + &remaining_size, &max_size); + + if (status != EFI_SUCCESS) + return status; + + if (!storage_size || size > remaining_size || size > max_size || + (remaining_size - size) < (storage_size / 2)) + return EFI_OUT_OF_RESOURCES; + + return status; +} + + +static efi_status_t +check_var_size(struct efivars *efivars, u32 attributes, unsigned long size) +{ + efi_status_t status; + unsigned long flags; + + spin_lock_irqsave(&efivars->lock, flags); + status = check_var_size_locked(efivars, attributes, size); + spin_unlock_irqrestore(&efivars->lock, flags); + + return status; +} + static ssize_t efivar_guid_read(struct efivar_entry *entry, char *buf) { @@ -546,11 +585,16 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count) } spin_lock_irq(&efivars->lock); - status = efivars->ops->set_variable(new_var->VariableName, - &new_var->VendorGuid, - new_var->Attributes, - new_var->DataSize, - new_var->Data); + + status = check_var_size_locked(efivars, new_var->Attributes, + new_var->DataSize + utf16_strsize(new_var->VariableName, 1024)); + + if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED) + status = efivars->ops->set_variable(new_var->VariableName, + &new_var->VendorGuid, + new_var->Attributes, + new_var->DataSize, + new_var->Data); spin_unlock_irq(&efivars->lock); @@ -701,8 +745,7 @@ static ssize_t efivarfs_file_write(struct file *file, u32 attributes; struct inode *inode = file->f_mapping->host; unsigned long datasize = count - sizeof(attributes); - unsigned long newdatasize; - u64 storage_size, remaining_size, max_size; + unsigned long newdatasize, varsize; ssize_t bytes = 0; if (count < sizeof(attributes)) @@ -721,28 +764,18 @@ static ssize_t efivarfs_file_write(struct file *file, * amounts of memory. Pick a default size of 64K if * QueryVariableInfo() isn't supported by the firmware. */ - spin_lock_irq(&efivars->lock); - - if (!efivars->ops->query_variable_info) - status = EFI_UNSUPPORTED; - else { - const struct efivar_operations *fops = efivars->ops; - status = fops->query_variable_info(attributes, &storage_size, - &remaining_size, &max_size); - } - spin_unlock_irq(&efivars->lock); + varsize = datasize + utf16_strsize(var->var.VariableName, 1024); + status = check_var_size(efivars, attributes, varsize); if (status != EFI_SUCCESS) { if (status != EFI_UNSUPPORTED) return efi_status_to_err(status); - remaining_size = 65536; + if (datasize > 65536) + return -ENOSPC; } - if (datasize > remaining_size) - return -ENOSPC; - data = kmalloc(datasize, GFP_KERNEL); if (!data) return -ENOMEM; @@ -764,6 +797,19 @@ static ssize_t efivarfs_file_write(struct file *file, */ spin_lock_irq(&efivars->lock); + /* + * Ensure that the available space hasn't shrunk below the safe level + */ + + status = check_var_size_locked(efivars, attributes, varsize); + + if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) { + spin_unlock_irq(&efivars->lock); + kfree(data); + + return efi_status_to_err(status); + } + status = efivars->ops->set_variable(var->var.VariableName, &var->var.VendorGuid, attributes, datasize, @@ -908,6 +954,48 @@ 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 must be preceded by a '-' */ + if (*(s - 1) != '-') + 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 +1024,7 @@ 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 +1096,91 @@ 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 dentry *d; + struct qstr q; + int err; + + q.name = name; + q.len = strlen(name); + + err = efivarfs_d_hash(NULL, NULL, &q); + if (err) + return ERR_PTR(err); + + d = d_alloc(parent, &q); + if (d) + return d; + + return ERR_PTR(-ENOMEM); +} + static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode = NULL; @@ -1019,6 +1188,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) struct efivar_entry *entry, *n; struct efivars *efivars = &__efivars; char *name; + int err = -ENOMEM; efivarfs_sb = sb; @@ -1027,6 +1197,7 @@ 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); @@ -1067,9 +1238,11 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) if (!inode) goto fail_name; - dentry = d_alloc_name(root, name); - if (!dentry) + dentry = efivarfs_alloc_dentry(root, name); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); goto fail_inode; + } /* copied by the above to local storage in the dentry. */ kfree(name); @@ -1084,7 +1257,7 @@ 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); } @@ -1096,7 +1269,7 @@ fail_inode: fail_name: kfree(name); fail: - return -ENOMEM; + return err; } static struct dentry *efivarfs_mount(struct file_system_type *fs_type, @@ -1117,8 +1290,20 @@ 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, }; @@ -1215,7 +1400,6 @@ static int efi_pstore_write(enum pstore_type_id type, efi_guid_t vendor = LINUX_EFI_CRASH_GUID; struct efivars *efivars = psi->data; int i, ret = 0; - u64 storage_space, remaining_space, max_variable_size; efi_status_t status = EFI_NOT_FOUND; unsigned long flags; @@ -1235,11 +1419,11 @@ static int efi_pstore_write(enum pstore_type_id type, * size: a size of logging data * DUMP_NAME_LEN * 2: a maximum size of variable name */ - status = efivars->ops->query_variable_info(PSTORE_EFI_ATTRIBUTES, - &storage_space, - &remaining_space, - &max_variable_size); - if (status || remaining_space < size + DUMP_NAME_LEN * 2) { + + status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES, + size + DUMP_NAME_LEN * 2); + + if (status) { spin_unlock_irqrestore(&efivars->lock, flags); *id = part; return -ENOSPC; @@ -1414,6 +1598,14 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, return -EINVAL; } + status = check_var_size_locked(efivars, new_var->Attributes, + new_var->DataSize + utf16_strsize(new_var->VariableName, 1024)); + + if (status && status != EFI_UNSUPPORTED) { + spin_unlock_irq(&efivars->lock); + return efi_status_to_err(status); + } + /* now *really* create the variable via EFI */ status = efivars->ops->set_variable(new_var->VariableName, &new_var->VendorGuid, |