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![Kees Cook](/assets/img/avatar_default.png)
The actual number of bytes stored in a PRZ is smaller than the bytes requested by platform data, since there is a header on each PRZ. Additionally, if ECC is enabled, there are trailing bytes used as well. Normally this mismatch doesn't matter since PRZs are circular buffers and the leading "overflow" bytes are just thrown away. However, in the case of a compressed record, this rather badly corrupts the results. This corruption was visible with "ramoops.mem_size=204800 ramoops.ecc=1". Any stored crashes would not be uncompressable (producing a pstorefs "dmesg-*.enc.z" file), and triggering errors at boot: [ 2.790759] pstore: crypto_comp_decompress failed, ret = -22! Backporting this depends on commit70ad35db33
("pstore: Convert console write to use ->write_buf") Reported-by: Joel Fernandes <joel@joelfernandes.org> Fixes:b0aad7a99c
("pstore: Add compression support to pstore") Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
280 lines
7.6 KiB
C
280 lines
7.6 KiB
C
/*
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* Persistent Storage - pstore.h
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*
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* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
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*
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* This code is the generic layer to export data records from platform
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* level persistent storage via a file system.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef _LINUX_PSTORE_H
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#define _LINUX_PSTORE_H
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/kmsg_dump.h>
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#include <linux/mutex.h>
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#include <linux/spinlock.h>
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#include <linux/time.h>
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#include <linux/types.h>
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struct module;
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/* pstore record types (see fs/pstore/inode.c for filename templates) */
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enum pstore_type_id {
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PSTORE_TYPE_DMESG = 0,
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PSTORE_TYPE_MCE = 1,
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PSTORE_TYPE_CONSOLE = 2,
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PSTORE_TYPE_FTRACE = 3,
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/* PPC64 partition types */
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PSTORE_TYPE_PPC_RTAS = 4,
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PSTORE_TYPE_PPC_OF = 5,
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PSTORE_TYPE_PPC_COMMON = 6,
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PSTORE_TYPE_PMSG = 7,
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PSTORE_TYPE_PPC_OPAL = 8,
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PSTORE_TYPE_UNKNOWN = 255
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};
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struct pstore_info;
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/**
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* struct pstore_record - details of a pstore record entry
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* @psi: pstore backend driver information
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* @type: pstore record type
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* @id: per-type unique identifier for record
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* @time: timestamp of the record
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* @buf: pointer to record contents
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* @size: size of @buf
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* @ecc_notice_size:
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* ECC information for @buf
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*
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* Valid for PSTORE_TYPE_DMESG @type:
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*
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* @count: Oops count since boot
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* @reason: kdump reason for notification
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* @part: position in a multipart record
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* @compressed: whether the buffer is compressed
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*
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*/
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struct pstore_record {
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struct pstore_info *psi;
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enum pstore_type_id type;
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u64 id;
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struct timespec64 time;
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char *buf;
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ssize_t size;
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ssize_t ecc_notice_size;
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int count;
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enum kmsg_dump_reason reason;
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unsigned int part;
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bool compressed;
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};
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/**
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* struct pstore_info - backend pstore driver structure
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*
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* @owner: module which is repsonsible for this backend driver
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* @name: name of the backend driver
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*
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* @buf_lock: spinlock to serialize access to @buf
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* @buf: preallocated crash dump buffer
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* @bufsize: size of @buf available for crash dump bytes (must match
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* smallest number of bytes available for writing to a
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* backend entry, since compressed bytes don't take kindly
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* to being truncated)
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*
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* @read_mutex: serializes @open, @read, @close, and @erase callbacks
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* @flags: bitfield of frontends the backend can accept writes for
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* @data: backend-private pointer passed back during callbacks
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*
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* Callbacks:
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*
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* @open:
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* Notify backend that pstore is starting a full read of backend
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* records. Followed by one or more @read calls, and a final @close.
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*
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* @psi: in: pointer to the struct pstore_info for the backend
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*
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* Returns 0 on success, and non-zero on error.
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*
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* @close:
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* Notify backend that pstore has finished a full read of backend
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* records. Always preceded by an @open call and one or more @read
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* calls.
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*
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* @psi: in: pointer to the struct pstore_info for the backend
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*
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* Returns 0 on success, and non-zero on error. (Though pstore will
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* ignore the error.)
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*
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* @read:
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* Read next available backend record. Called after a successful
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* @open.
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*
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* @record:
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* pointer to record to populate. @buf should be allocated
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* by the backend and filled. At least @type and @id should
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* be populated, since these are used when creating pstorefs
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* file names.
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*
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* Returns record size on success, zero when no more records are
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* available, or negative on error.
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*
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* @write:
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* A newly generated record needs to be written to backend storage.
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*
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* @record:
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* pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
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* @buf will be pointing to the preallocated @psi.buf, since
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* memory allocation may be broken during an Oops. Regardless,
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* @buf must be proccesed or copied before returning. The
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* backend is also expected to write @id with something that
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* can help identify this record to a future @erase callback.
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* The @time field will be prepopulated with the current time,
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* when available. The @size field will have the size of data
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* in @buf.
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*
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* Returns 0 on success, and non-zero on error.
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*
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* @write_user:
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* Perform a frontend write to a backend record, using a specified
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* buffer that is coming directly from userspace, instead of the
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* @record @buf.
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*
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* @record: pointer to record metadata.
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* @buf: pointer to userspace contents to write to backend
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*
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* Returns 0 on success, and non-zero on error.
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*
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* @erase:
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* Delete a record from backend storage. Different backends
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* identify records differently, so entire original record is
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* passed back to assist in identification of what the backend
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* should remove from storage.
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*
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* @record: pointer to record metadata.
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*
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* Returns 0 on success, and non-zero on error.
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*
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*/
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struct pstore_info {
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struct module *owner;
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char *name;
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spinlock_t buf_lock;
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char *buf;
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size_t bufsize;
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struct mutex read_mutex;
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int flags;
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void *data;
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int (*open)(struct pstore_info *psi);
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int (*close)(struct pstore_info *psi);
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ssize_t (*read)(struct pstore_record *record);
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int (*write)(struct pstore_record *record);
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int (*write_user)(struct pstore_record *record,
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const char __user *buf);
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int (*erase)(struct pstore_record *record);
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};
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/* Supported frontends */
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#define PSTORE_FLAGS_DMESG (1 << 0)
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#define PSTORE_FLAGS_CONSOLE (1 << 1)
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#define PSTORE_FLAGS_FTRACE (1 << 2)
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#define PSTORE_FLAGS_PMSG (1 << 3)
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extern int pstore_register(struct pstore_info *);
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extern void pstore_unregister(struct pstore_info *);
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extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
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struct pstore_ftrace_record {
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unsigned long ip;
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unsigned long parent_ip;
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u64 ts;
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};
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/*
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* ftrace related stuff: Both backends and frontends need these so expose
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* them here.
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*/
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#if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
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#define PSTORE_CPU_IN_IP 0x1
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#elif NR_CPUS <= 4 && defined(CONFIG_ARM)
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#define PSTORE_CPU_IN_IP 0x3
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#endif
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#define TS_CPU_SHIFT 8
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#define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
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/*
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* If CPU number can be stored in IP, store it there, otherwise store it in
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* the time stamp. This means more timestamp resolution is available when
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* the CPU can be stored in the IP.
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*/
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#ifdef PSTORE_CPU_IN_IP
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static inline void
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pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
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{
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rec->ip |= cpu;
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}
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static inline unsigned int
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pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
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{
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return rec->ip & PSTORE_CPU_IN_IP;
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}
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static inline u64
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pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
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{
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return rec->ts;
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}
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static inline void
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pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
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{
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rec->ts = val;
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}
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#else
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static inline void
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pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
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{
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rec->ts &= ~(TS_CPU_MASK);
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rec->ts |= cpu;
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}
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static inline unsigned int
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pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
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{
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return rec->ts & TS_CPU_MASK;
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}
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static inline u64
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pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
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{
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return rec->ts >> TS_CPU_SHIFT;
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}
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static inline void
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pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
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{
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rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
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}
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#endif
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#endif /*_LINUX_PSTORE_H*/
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