![Andrzej Zaborowski](/assets/img/avatar_default.png)
In generic_id the long int timestamp is multiplied by 100000 and needs an explicit cast to u64. Without that the id in the resulting pstore filename is wrong and userspace may have problems parsing it, but more importantly files in pstore can never be deleted and may fill the EFI flash (brick device?). This happens because when generic pstore code wants to delete a file, it passes the id to the EFI backend which reinterpretes it and a wrong variable name is attempted to be deleted. There's no error message but after remounting pstore, deleted files would reappear. Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
403 lines
9.8 KiB
C
403 lines
9.8 KiB
C
#include <linux/efi.h>
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#include <linux/module.h>
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#include <linux/pstore.h>
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#include <linux/slab.h>
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#include <linux/ucs2_string.h>
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#define DUMP_NAME_LEN 52
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static bool efivars_pstore_disable =
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IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
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module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
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#define PSTORE_EFI_ATTRIBUTES \
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(EFI_VARIABLE_NON_VOLATILE | \
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EFI_VARIABLE_BOOTSERVICE_ACCESS | \
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EFI_VARIABLE_RUNTIME_ACCESS)
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static int efi_pstore_open(struct pstore_info *psi)
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{
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psi->data = NULL;
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return 0;
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}
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static int efi_pstore_close(struct pstore_info *psi)
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{
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psi->data = NULL;
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return 0;
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}
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struct pstore_read_data {
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u64 *id;
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enum pstore_type_id *type;
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int *count;
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struct timespec *timespec;
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bool *compressed;
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char **buf;
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};
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static inline u64 generic_id(unsigned long timestamp,
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unsigned int part, int count)
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{
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return ((u64) timestamp * 100 + part) * 1000 + count;
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}
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static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
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{
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efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
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struct pstore_read_data *cb_data = data;
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char name[DUMP_NAME_LEN], data_type;
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int i;
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int cnt;
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unsigned int part;
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unsigned long time, size;
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if (efi_guidcmp(entry->var.VendorGuid, vendor))
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return 0;
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for (i = 0; i < DUMP_NAME_LEN; i++)
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name[i] = entry->var.VariableName[i];
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if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
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cb_data->type, &part, &cnt, &time, &data_type) == 5) {
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*cb_data->id = generic_id(time, part, cnt);
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*cb_data->count = cnt;
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cb_data->timespec->tv_sec = time;
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cb_data->timespec->tv_nsec = 0;
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if (data_type == 'C')
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*cb_data->compressed = true;
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else
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*cb_data->compressed = false;
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} else if (sscanf(name, "dump-type%u-%u-%d-%lu",
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cb_data->type, &part, &cnt, &time) == 4) {
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*cb_data->id = generic_id(time, part, cnt);
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*cb_data->count = cnt;
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cb_data->timespec->tv_sec = time;
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cb_data->timespec->tv_nsec = 0;
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*cb_data->compressed = false;
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} else if (sscanf(name, "dump-type%u-%u-%lu",
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cb_data->type, &part, &time) == 3) {
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/*
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* Check if an old format,
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* which doesn't support holding
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* multiple logs, remains.
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*/
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*cb_data->id = generic_id(time, part, 0);
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*cb_data->count = 0;
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cb_data->timespec->tv_sec = time;
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cb_data->timespec->tv_nsec = 0;
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*cb_data->compressed = false;
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} else
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return 0;
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entry->var.DataSize = 1024;
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__efivar_entry_get(entry, &entry->var.Attributes,
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&entry->var.DataSize, entry->var.Data);
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size = entry->var.DataSize;
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memcpy(*cb_data->buf, entry->var.Data,
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(size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));
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return size;
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}
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/**
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* efi_pstore_scan_sysfs_enter
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* @entry: scanning entry
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* @next: next entry
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* @head: list head
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*/
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static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
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struct efivar_entry *next,
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struct list_head *head)
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{
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pos->scanning = true;
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if (&next->list != head)
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next->scanning = true;
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}
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/**
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* __efi_pstore_scan_sysfs_exit
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* @entry: deleting entry
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* @turn_off_scanning: Check if a scanning flag should be turned off
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*/
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static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
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bool turn_off_scanning)
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{
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if (entry->deleting) {
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list_del(&entry->list);
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efivar_entry_iter_end();
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efivar_unregister(entry);
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efivar_entry_iter_begin();
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} else if (turn_off_scanning)
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entry->scanning = false;
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}
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/**
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* efi_pstore_scan_sysfs_exit
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* @pos: scanning entry
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* @next: next entry
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* @head: list head
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* @stop: a flag checking if scanning will stop
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*/
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static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
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struct efivar_entry *next,
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struct list_head *head, bool stop)
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{
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__efi_pstore_scan_sysfs_exit(pos, true);
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if (stop)
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__efi_pstore_scan_sysfs_exit(next, &next->list != head);
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}
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/**
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* efi_pstore_sysfs_entry_iter
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*
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* @data: function-specific data to pass to callback
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* @pos: entry to begin iterating from
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*
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* You MUST call efivar_enter_iter_begin() before this function, and
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* efivar_entry_iter_end() afterwards.
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*
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* It is possible to begin iteration from an arbitrary entry within
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* the list by passing @pos. @pos is updated on return to point to
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* the next entry of the last one passed to efi_pstore_read_func().
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* To begin iterating from the beginning of the list @pos must be %NULL.
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*/
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static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
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{
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struct efivar_entry *entry, *n;
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struct list_head *head = &efivar_sysfs_list;
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int size = 0;
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if (!*pos) {
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list_for_each_entry_safe(entry, n, head, list) {
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efi_pstore_scan_sysfs_enter(entry, n, head);
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size = efi_pstore_read_func(entry, data);
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efi_pstore_scan_sysfs_exit(entry, n, head, size < 0);
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if (size)
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break;
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}
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*pos = n;
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return size;
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}
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list_for_each_entry_safe_from((*pos), n, head, list) {
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efi_pstore_scan_sysfs_enter((*pos), n, head);
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size = efi_pstore_read_func((*pos), data);
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efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
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if (size)
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break;
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}
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*pos = n;
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return size;
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}
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/**
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* efi_pstore_read
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*
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* This function returns a size of NVRAM entry logged via efi_pstore_write().
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* The meaning and behavior of efi_pstore/pstore are as below.
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*
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* size > 0: Got data of an entry logged via efi_pstore_write() successfully,
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* and pstore filesystem will continue reading subsequent entries.
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* size == 0: Entry was not logged via efi_pstore_write(),
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* and efi_pstore driver will continue reading subsequent entries.
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* size < 0: Failed to get data of entry logging via efi_pstore_write(),
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* and pstore will stop reading entry.
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*/
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static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
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int *count, struct timespec *timespec,
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char **buf, bool *compressed,
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struct pstore_info *psi)
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{
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struct pstore_read_data data;
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ssize_t size;
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data.id = id;
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data.type = type;
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data.count = count;
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data.timespec = timespec;
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data.compressed = compressed;
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data.buf = buf;
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*data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
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if (!*data.buf)
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return -ENOMEM;
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efivar_entry_iter_begin();
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size = efi_pstore_sysfs_entry_iter(&data,
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(struct efivar_entry **)&psi->data);
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efivar_entry_iter_end();
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if (size <= 0)
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kfree(*data.buf);
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return size;
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}
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static int efi_pstore_write(enum pstore_type_id type,
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enum kmsg_dump_reason reason, u64 *id,
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unsigned int part, int count, bool compressed, size_t size,
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struct pstore_info *psi)
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{
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char name[DUMP_NAME_LEN];
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efi_char16_t efi_name[DUMP_NAME_LEN];
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efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
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int i, ret = 0;
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sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
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get_seconds(), compressed ? 'C' : 'D');
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for (i = 0; i < DUMP_NAME_LEN; i++)
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efi_name[i] = name[i];
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efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
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!pstore_cannot_block_path(reason),
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size, psi->buf);
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if (reason == KMSG_DUMP_OOPS)
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efivar_run_worker();
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*id = part;
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return ret;
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};
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struct pstore_erase_data {
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u64 id;
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enum pstore_type_id type;
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int count;
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struct timespec time;
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efi_char16_t *name;
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};
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/*
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* Clean up an entry with the same name
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*/
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static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
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{
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struct pstore_erase_data *ed = data;
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efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
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efi_char16_t efi_name_old[DUMP_NAME_LEN];
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efi_char16_t *efi_name = ed->name;
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unsigned long ucs2_len = ucs2_strlen(ed->name);
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char name_old[DUMP_NAME_LEN];
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int i;
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if (efi_guidcmp(entry->var.VendorGuid, vendor))
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return 0;
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if (ucs2_strncmp(entry->var.VariableName,
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efi_name, (size_t)ucs2_len)) {
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/*
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* Check if an old format, which doesn't support
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* holding multiple logs, remains.
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*/
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sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
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(unsigned int)ed->id, ed->time.tv_sec);
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for (i = 0; i < DUMP_NAME_LEN; i++)
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efi_name_old[i] = name_old[i];
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if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
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ucs2_strlen(efi_name_old)))
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return 0;
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}
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if (entry->scanning) {
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/*
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* Skip deletion because this entry will be deleted
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* after scanning is completed.
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*/
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entry->deleting = true;
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} else
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list_del(&entry->list);
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/* found */
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__efivar_entry_delete(entry);
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return 1;
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}
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static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
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struct timespec time, struct pstore_info *psi)
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{
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struct pstore_erase_data edata;
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struct efivar_entry *entry = NULL;
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char name[DUMP_NAME_LEN];
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efi_char16_t efi_name[DUMP_NAME_LEN];
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int found, i;
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unsigned int part;
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do_div(id, 1000);
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part = do_div(id, 100);
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sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);
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for (i = 0; i < DUMP_NAME_LEN; i++)
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efi_name[i] = name[i];
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edata.id = part;
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edata.type = type;
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edata.count = count;
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edata.time = time;
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edata.name = efi_name;
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efivar_entry_iter_begin();
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found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
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if (found && !entry->scanning) {
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efivar_entry_iter_end();
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efivar_unregister(entry);
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} else
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efivar_entry_iter_end();
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return 0;
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}
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static struct pstore_info efi_pstore_info = {
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.owner = THIS_MODULE,
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.name = "efi",
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.flags = PSTORE_FLAGS_FRAGILE,
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.open = efi_pstore_open,
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.close = efi_pstore_close,
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.read = efi_pstore_read,
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.write = efi_pstore_write,
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.erase = efi_pstore_erase,
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};
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static __init int efivars_pstore_init(void)
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{
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if (!efi_enabled(EFI_RUNTIME_SERVICES))
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return 0;
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if (!efivars_kobject())
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return 0;
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if (efivars_pstore_disable)
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return 0;
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efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
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if (!efi_pstore_info.buf)
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return -ENOMEM;
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efi_pstore_info.bufsize = 1024;
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spin_lock_init(&efi_pstore_info.buf_lock);
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if (pstore_register(&efi_pstore_info)) {
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kfree(efi_pstore_info.buf);
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efi_pstore_info.buf = NULL;
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efi_pstore_info.bufsize = 0;
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}
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return 0;
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}
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static __exit void efivars_pstore_exit(void)
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{
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}
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module_init(efivars_pstore_init);
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module_exit(efivars_pstore_exit);
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MODULE_DESCRIPTION("EFI variable backend for pstore");
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MODULE_LICENSE("GPL");
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