pstore: Remove write_buf() callback

Now that write() and write_buf() are functionally identical, this removes
write_buf(), and renames write_buf_user() to write_user(). Additionally
adds sanity-checks for pstore_info's declared functions and flags at
registration time.

Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index a5506ec6995e0bf46bf9da014c20898be0563013..06aab07b6bb71bdabd8fa794c39a7b11cb8cb0a0 100644 (file)
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -53,7 +53,7 @@ static void notrace pstore_ftrace_call(unsigned long ip,
        rec.parent_ip = parent_ip;
        pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
        pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
-       psinfo->write_buf(&record);
+       psinfo->write(&record);
 
        local_irq_restore(flags);
 }
@@ -122,7 +122,7 @@ void pstore_register_ftrace(void)
 {
        struct dentry *file;
 
-       if (!psinfo->write_buf)
+       if (!psinfo->write)
                return;
 
        pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 1e6642a2063ee7b4e635e479a81c94553b8a8763..e79f170fa79b886a10730eba803334234340b985 100644 (file)
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -604,7 +604,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
                }
                record.buf = (char *)s;
                record.size = c;
-               psinfo->write_buf(&record);
+               psinfo->write(&record);
                spin_unlock_irqrestore(&psinfo->buf_lock, flags);
                s += c;
                c = e - s;
@@ -632,15 +632,8 @@ static void pstore_register_console(void) {}
 static void pstore_unregister_console(void) {}
 #endif
 
-static int pstore_write_compat(struct pstore_record *record)
-{
-       record->buf = psinfo->buf;
-
-       return record->psi->write_buf(record);
-}
-
-static int pstore_write_buf_user_compat(struct pstore_record *record,
-                                       const char __user *buf)
+static int pstore_write_user_compat(struct pstore_record *record,
+                                   const char __user *buf)
 {
        unsigned long flags = 0;
        size_t i, bufsize, total_size = record->size;
@@ -662,7 +655,7 @@ static int pstore_write_buf_user_compat(struct pstore_record *record,
                        break;
                }
                record->size = c;
-               ret = record->psi->write_buf(record);
+               ret = record->psi->write(record);
                if (unlikely(ret < 0))
                        break;
                i += c;
@@ -687,6 +680,20 @@ int pstore_register(struct pstore_info *psi)
                return -EPERM;
        }
 
+       /* Sanity check flags. */
+       if (!psi->flags) {
+               pr_warn("backend '%s' must support at least one frontend\n",
+                       psi->name);
+               return -EINVAL;
+       }
+
+       /* Check for required functions. */
+       if (!psi->read || !psi->write) {
+               pr_warn("backend '%s' must implement read() and write()\n",
+                       psi->name);
+               return -EINVAL;
+       }
+
        spin_lock(&pstore_lock);
        if (psinfo) {
                pr_warn("backend '%s' already loaded: ignoring '%s'\n",
@@ -695,10 +702,8 @@ int pstore_register(struct pstore_info *psi)
                return -EBUSY;
        }
 
-       if (!psi->write)
-               psi->write = pstore_write_compat;
-       if (!psi->write_buf_user)
-               psi->write_buf_user = pstore_write_buf_user_compat;
+       if (!psi->write_user)
+               psi->write_user = pstore_write_user_compat;
        psinfo = psi;
        mutex_init(&psinfo->read_mutex);
        spin_unlock(&pstore_lock);

diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
index ce35907602de642d91f1ffc177dea24bb186be63..c16a2477e106cd426b2d5b93bd1ba463133adf19 100644 (file)
--- a/fs/pstore/pmsg.c
+++ b/fs/pstore/pmsg.c
@@ -33,12 +33,12 @@ static ssize_t write_pmsg(struct file *file, const char __user *buf,
        if (!count)
                return 0;
 
-       /* check outside lock, page in any data. write_buf_user also checks */
+       /* check outside lock, page in any data. write_user also checks */
        if (!access_ok(VERIFY_READ, buf, count))
                return -EFAULT;
 
        mutex_lock(&pmsg_lock);
-       ret = psinfo->write_buf_user(&record, buf);
+       ret = psinfo->write_user(&record, buf);
        mutex_unlock(&pmsg_lock);
        return ret ? ret : count;
 }

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index d85e1adae1b6939038f084226beb3abf988cae68..5523df7f17ef05818d2c444c682e66579c38742d 100644 (file)
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -378,7 +378,7 @@ static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
        return len;
 }
 
-static int notrace ramoops_pstore_write_buf(struct pstore_record *record)
+static int notrace ramoops_pstore_write(struct pstore_record *record)
 {
        struct ramoops_context *cxt = record->psi->data;
        struct persistent_ram_zone *prz;
@@ -451,8 +451,8 @@ static int notrace ramoops_pstore_write_buf(struct pstore_record *record)
        return 0;
 }
 
-static int notrace ramoops_pstore_write_buf_user(struct pstore_record *record,
-                                                const char __user *buf)
+static int notrace ramoops_pstore_write_user(struct pstore_record *record,
+                                            const char __user *buf)
 {
        if (record->type == PSTORE_TYPE_PMSG) {
                struct ramoops_context *cxt = record->psi->data;
@@ -503,8 +503,8 @@ static struct ramoops_context oops_cxt = {
                .name   = "ramoops",
                .open   = ramoops_pstore_open,
                .read   = ramoops_pstore_read,
-               .write_buf      = ramoops_pstore_write_buf,
-               .write_buf_user = ramoops_pstore_write_buf_user,
+               .write  = ramoops_pstore_write,
+               .write_user     = ramoops_pstore_write_user,
                .erase  = ramoops_pstore_erase,
        },
 };

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 9b85d3eeca83ece85d0282b219ead2b880a5d7bb..e2233f50f4284826d2462ea900a2f430c8db8019 100644 (file)
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -130,27 +130,19 @@ struct pstore_record {
  *     available, or negative on error.
  *
  * @write:
- *     Perform a frontend notification of a write to a backend record. The
- *     data to be stored has already been written to the registered @buf
- *     of the @psi structure.
+ *     A newly generated record needs to be written to backend storage.
  *
  *     @record:
- *             pointer to record metadata. Note that @buf is NULL, since
- *             the @buf registered with @psi is what has been written. The
- *             backend is expected to update @id.
+ *             pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
+ *             @buf will be pointing to the preallocated @psi.buf, since
+ *             memory allocation may be broken during an Oops. Regardless,
+ *             @buf must be proccesed or copied before returning. The
+ *             backend is also expected to write @id with something that
+ 8             can help identify this record to a future @erase callback.
  *
  *     Returns 0 on success, and non-zero on error.
  *
- * @write_buf:
- *     Perform a frontend write to a backend record. The record contains
- *     all metadata and the buffer to write to backend storage. (Unlike
- *     @write, this does not use the @psi @buf.)
- *
- *     @record:        pointer to record metadata.
- *
- *     Returns 0 on success, and non-zero on error.
- *
- * @write_buf_user:
+ * @write_user:
  *     Perform a frontend write to a backend record, using a specified
  *     buffer that is coming directly from userspace, instead of the
  *     @record @buf.
@@ -188,9 +180,8 @@ struct pstore_info {
        int             (*close)(struct pstore_info *psi);
        ssize_t         (*read)(struct pstore_record *record);
        int             (*write)(struct pstore_record *record);
-       int             (*write_buf)(struct pstore_record *record);
-       int             (*write_buf_user)(struct pstore_record *record,
-                                         const char __user *buf);
+       int             (*write_user)(struct pstore_record *record,
+                                     const char __user *buf);
        int             (*erase)(struct pstore_record *record);
 };