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Date: Tue, 23 Oct 2012 09:48:27 -0700
From: Kees Cook <keescook@...omium.org>
To: Irina Tirdea <irina.tirdea@...el.com>
Cc: Anton Vorontsov <cbouatmailru@...il.com>,
Colin Cross <ccross@...roid.com>,
Tony Luck <tony.luck@...el.com>, Chris Ball <cjb@...top.org>,
linux-kernel@...r.kernel.org,
Adrian Hunter <adrian.hunter@...el.com>,
Octavian Purdila <octavian.purdila@...el.com>
Subject: Re: [PATCH 01/26] pstore: allow for big files
On Tue, Oct 23, 2012 at 6:47 AM, Irina Tirdea <irina.tirdea@...el.com> wrote:
> From: Adrian Hunter <adrian.hunter@...el.com>
>
> pstore reads all files into memory at mount time. To allow for back ends
> that will store arbitrarily large files, enhance pstore also to be able
> to read from the back end as needed.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> Signed-off-by: Irina Tirdea <irina.tirdea@...el.com>
> ---
> drivers/acpi/apei/erst.c | 16 +++++++++-------
> fs/pstore/inode.c | 26 ++++++++++++++++++++------
> fs/pstore/internal.h | 5 +++--
> fs/pstore/platform.c | 11 +++++++----
> fs/pstore/ram.c | 15 +++++++--------
> include/linux/pstore.h | 7 +++++--
> 6 files changed, 51 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
> index e4d9d24..f70ba37 100644
> --- a/drivers/acpi/apei/erst.c
> +++ b/drivers/acpi/apei/erst.c
> @@ -931,9 +931,9 @@ static int erst_check_table(struct acpi_table_erst *erst_tab)
>
> static int erst_open_pstore(struct pstore_info *psi);
> static int erst_close_pstore(struct pstore_info *psi);
> -static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
> - struct timespec *time, char **buf,
> - struct pstore_info *psi);
> +static int erst_reader(u64 *id, enum pstore_type_id *type,
> + struct timespec *time, char **buf, loff_t *size,
> + struct pstore_info *psi);
> static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
> u64 *id, unsigned int part,
> size_t size, struct pstore_info *psi);
> @@ -987,9 +987,9 @@ static int erst_close_pstore(struct pstore_info *psi)
> return 0;
> }
>
> -static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
> - struct timespec *time, char **buf,
> - struct pstore_info *psi)
> +static int erst_reader(u64 *id, enum pstore_type_id *type,
> + struct timespec *time, char **buf, loff_t *size,
> + struct pstore_info *psi)
> {
> int rc;
> ssize_t len = 0;
> @@ -1051,7 +1051,9 @@ skip:
>
> out:
> kfree(rcd);
> - return (rc < 0) ? rc : (len - sizeof(*rcd));
> + if (!rc)
> + *size = len - sizeof(*rcd);
> + return rc;
> }
>
> static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 4ab572e..ff0970f 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -49,7 +49,8 @@ struct pstore_private {
> struct pstore_info *psi;
> enum pstore_type_id type;
> u64 id;
> - ssize_t size;
> + loff_t size;
> + bool big;
> char data[];
> };
>
> @@ -65,12 +66,13 @@ static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
> {
> struct pstore_private *ps = s->private;
> struct pstore_ftrace_seq_data *data;
> + loff_t size = ps->size;
>
> data = kzalloc(sizeof(*data), GFP_KERNEL);
> if (!data)
> return NULL;
>
> - data->off = ps->size % REC_SIZE;
> + data->off = do_div(size, REC_SIZE);
This modifies ps->size. I don't think you want that?
-Kees
> data->off += *pos * REC_SIZE;
> if (data->off + REC_SIZE > ps->size) {
> kfree(data);
> @@ -127,6 +129,12 @@ static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
>
> if (ps->type == PSTORE_TYPE_FTRACE)
> return seq_read(file, userbuf, count, ppos);
> + if (ps->big) {
> + if (ps->psi->file_read)
> + return ps->psi->file_read(ps->id, ps->type, userbuf,
> + count, ppos, ps->psi);
> + return -EFBIG;
> + }
> return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
> }
>
> @@ -271,8 +279,8 @@ int pstore_is_mounted(void)
> * Set the mtime & ctime to the date that this record was originally stored.
> */
> int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
> - char *data, size_t size, struct timespec time,
> - struct pstore_info *psi)
> + char *data, loff_t size, struct timespec time,
> + struct pstore_info *psi, bool big)
> {
> struct dentry *root = pstore_sb->s_root;
> struct dentry *dentry;
> @@ -281,6 +289,7 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
> char name[PSTORE_NAMELEN];
> struct pstore_private *private, *pos;
> unsigned long flags;
> + size_t inline_size;
>
> spin_lock_irqsave(&allpstore_lock, flags);
> list_for_each_entry(pos, &allpstore, list) {
> @@ -301,12 +310,17 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
> goto fail;
> inode->i_mode = S_IFREG | 0444;
> inode->i_fop = &pstore_file_operations;
> - private = kmalloc(sizeof *private + size, GFP_KERNEL);
> + if (big)
> + inline_size = 0;
> + else
> + inline_size = size;
> + private = kmalloc(sizeof(*private) + inline_size, GFP_KERNEL);
> if (!private)
> goto fail_alloc;
> private->type = type;
> private->id = id;
> private->psi = psi;
> + private->big = big;
>
> switch (type) {
> case PSTORE_TYPE_DMESG:
> @@ -336,7 +350,7 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
> if (IS_ERR(dentry))
> goto fail_lockedalloc;
>
> - memcpy(private->data, data, size);
> + memcpy(private->data, data, inline_size);
> inode->i_size = private->size = size;
>
> inode->i_private = private;
> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
> index 4847f58..f840159 100644
> --- a/fs/pstore/internal.h
> +++ b/fs/pstore/internal.h
> @@ -50,8 +50,9 @@ extern struct pstore_info *psinfo;
> extern void pstore_set_kmsg_bytes(int);
> extern void pstore_get_records(int);
> extern int pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
> - char *data, size_t size,
> - struct timespec time, struct pstore_info *psi);
> + char *data, loff_t size,
> + struct timespec time, struct pstore_info *psi,
> + bool big);
> extern int pstore_is_mounted(void);
>
> #endif
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index a40da07..108bd69 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -264,7 +264,7 @@ void pstore_get_records(int quiet)
> {
> struct pstore_info *psi = psinfo;
> char *buf = NULL;
> - ssize_t size;
> + loff_t size;
> u64 id;
> enum pstore_type_id type;
> struct timespec time;
> @@ -277,9 +277,12 @@ void pstore_get_records(int quiet)
> if (psi->open && psi->open(psi))
> goto out;
>
> - while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
> - rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
> - time, psi);
> + while (1) {
> + rc = psi->read(&id, &type, &time, &buf, &size, psi);
> + if (rc && rc != -EFBIG)
> + break;
> + rc = pstore_mkfile(type, psi->name, id, buf, size,
> + time, psi, rc == -EFBIG);
> kfree(buf);
> buf = NULL;
> if (rc && (rc != -EEXIST || !quiet))
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 1a4f6da..dd47a87 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -131,12 +131,11 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
> return prz;
> }
>
> -static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
> +static int ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
> struct timespec *time,
> - char **buf,
> + char **buf, loff_t *size,
> struct pstore_info *psi)
> {
> - ssize_t size;
> struct ramoops_context *cxt = psi->data;
> struct persistent_ram_zone *prz;
>
> @@ -150,19 +149,19 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
> prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
> 1, id, type, PSTORE_TYPE_FTRACE, 0);
> if (!prz)
> - return 0;
> + return -EINVAL;
>
> /* TODO(kees): Bogus time for the moment. */
> time->tv_sec = 0;
> time->tv_nsec = 0;
>
> - size = persistent_ram_old_size(prz);
> - *buf = kmalloc(size, GFP_KERNEL);
> + *size = persistent_ram_old_size(prz);
> + *buf = kmalloc(*size, GFP_KERNEL);
> if (*buf == NULL)
> return -ENOMEM;
> - memcpy(*buf, persistent_ram_old(prz), size);
> + memcpy(*buf, persistent_ram_old(prz), *size);
>
> - return size;
> + return 0;
> }
>
> static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz)
> diff --git a/include/linux/pstore.h b/include/linux/pstore.h
> index ee3034a..3a293ff 100644
> --- a/include/linux/pstore.h
> +++ b/include/linux/pstore.h
> @@ -49,8 +49,11 @@ struct pstore_info {
> struct mutex read_mutex; /* serialize open/read/close */
> int (*open)(struct pstore_info *psi);
> int (*close)(struct pstore_info *psi);
> - ssize_t (*read)(u64 *id, enum pstore_type_id *type,
> - struct timespec *time, char **buf,
> + int (*read)(u64 *id, enum pstore_type_id *type,
> + struct timespec *time, char **buf, loff_t *size,
> + struct pstore_info *psi);
> + ssize_t (*file_read)(u64 id, enum pstore_type_id type,
> + char __user *userbuf, size_t count, loff_t *ppos,
> struct pstore_info *psi);
> int (*write)(enum pstore_type_id type,
> enum kmsg_dump_reason reason, u64 *id,
> --
> 1.7.9.5
>
--
Kees Cook
Chrome OS Security
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