[v2] scsi: fcoe: use sysfs_match_string over fcoe_parse_mode

Instead of copying @buf into a new buffer and carefully managing its
newline/null-terminating status, we can just use sysfs_match_string()
as it uses sysfs_streq() internally which handles newline/null-term:

|  /**
|   * sysfs_streq - return true if strings are equal, modulo trailing newline
|   * @s1: one string
|   * @s2: another string
|   *
|   * This routine returns true iff two strings are equal, treating both
|   * NUL and newline-then-NUL as equivalent string terminations.  It's
|   * geared for use with sysfs input strings, which generally terminate
|   * with newlines but are compared against values without newlines.
|   */
|  bool sysfs_streq(const char *s1, const char *s2)
|  ...

Then entirely drop the now unused fcoe_parse_mode, being careful to
change if condition from checking for FIP_CONN_TYPE_UNKNOWN to < 0 as
sysfs_match_string can return -EINVAL. Also check explicitly if
ctlr->mode is equal to FIP_CONN_TYPE_UNKNOWN -- this is probably
preferred to "<=" as the behavior is more obvious while maintaining
functionality.

To get the compiler not to complain, make fip_conn_type_names
const char * const. Perhaps, this should also be done for
fcf_state_names.

This also removes an instance of strncpy() which helps [1].

Link: https://github.com/KSPP/linux/issues/90 [1]
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Changes in v2:
- update if-cond to check for unknown type (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20231211-strncpy-drivers-scsi-fcoe-fcoe_sysfs-c-v1-1-73b942238396@google.com
---
Builds upon patch and feedback from [2]:

However, this is different enough to warrant its own patch and not be a
continuation.

[2]: https://lore.kernel.org/all/9f38f4aa-c6b5-4786-a641-d02d8bd92f7f@acm.org/
---
 drivers/scsi/fcoe/fcoe_sysfs.c | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)


---
base-commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
change-id: 20231024-strncpy-drivers-scsi-fcoe-fcoe_sysfs-c-0e1dffe82855

Best regards,
--
Justin Stitt <justinstitt@google.com>

On Tue, Dec 12, 2023 at 11:19:06PM +0000, Justin Stitt wrote:
> Instead of copying @buf into a new buffer and carefully managing its
> newline/null-terminating status, we can just use sysfs_match_string()
> as it uses sysfs_streq() internally which handles newline/null-term:
> 
> |  /**
> |   * sysfs_streq - return true if strings are equal, modulo trailing newline
> |   * @s1: one string
> |   * @s2: another string
> |   *
> |   * This routine returns true iff two strings are equal, treating both
> |   * NUL and newline-then-NUL as equivalent string terminations.  It's
> |   * geared for use with sysfs input strings, which generally terminate
> |   * with newlines but are compared against values without newlines.
> |   */
> |  bool sysfs_streq(const char *s1, const char *s2)
> |  ...
> 
> Then entirely drop the now unused fcoe_parse_mode, being careful to
> change if condition from checking for FIP_CONN_TYPE_UNKNOWN to < 0 as
> sysfs_match_string can return -EINVAL. Also check explicitly if
> ctlr->mode is equal to FIP_CONN_TYPE_UNKNOWN -- this is probably
> preferred to "<=" as the behavior is more obvious while maintaining
> functionality.
> 
> To get the compiler not to complain, make fip_conn_type_names
> const char * const. Perhaps, this should also be done for
> fcf_state_names.
> 
> This also removes an instance of strncpy() which helps [1].
> 
> Link: https://github.com/KSPP/linux/issues/90 [1]
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Looks great; thanks!

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

On 12/13/23 00:19, Justin Stitt wrote:
> Instead of copying @buf into a new buffer and carefully managing its
> newline/null-terminating status, we can just use sysfs_match_string()
> as it uses sysfs_streq() internally which handles newline/null-term:
> 
> |  /**
> |   * sysfs_streq - return true if strings are equal, modulo trailing newline
> |   * @s1: one string
> |   * @s2: another string
> |   *
> |   * This routine returns true iff two strings are equal, treating both
> |   * NUL and newline-then-NUL as equivalent string terminations.  It's
> |   * geared for use with sysfs input strings, which generally terminate
> |   * with newlines but are compared against values without newlines.
> |   */
> |  bool sysfs_streq(const char *s1, const char *s2)
> |  ...
> 
> Then entirely drop the now unused fcoe_parse_mode, being careful to
> change if condition from checking for FIP_CONN_TYPE_UNKNOWN to < 0 as
> sysfs_match_string can return -EINVAL. Also check explicitly if
> ctlr->mode is equal to FIP_CONN_TYPE_UNKNOWN -- this is probably
> preferred to "<=" as the behavior is more obvious while maintaining
> functionality.
> 
> To get the compiler not to complain, make fip_conn_type_names
> const char * const. Perhaps, this should also be done for
> fcf_state_names.
> 
> This also removes an instance of strncpy() which helps [1].
> 
> Link: https://github.com/KSPP/linux/issues/90 [1]
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> Changes in v2:
> - update if-cond to check for unknown type (thanks Kees)
> - Link to v1: https://lore.kernel.org/r/20231211-strncpy-drivers-scsi-fcoe-fcoe_sysfs-c-v1-1-73b942238396@google.com
> ---
> Builds upon patch and feedback from [2]:
> 
> However, this is different enough to warrant its own patch and not be a
> continuation.
> 
> [2]: https://lore.kernel.org/all/9f38f4aa-c6b5-4786-a641-d02d8bd92f7f@acm.org/
> ---
>   drivers/scsi/fcoe/fcoe_sysfs.c | 26 ++++----------------------
>   1 file changed, 4 insertions(+), 22 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes

Justin,

> Instead of copying @buf into a new buffer and carefully managing its
> newline/null-terminating status, we can just use sysfs_match_string()
> as it uses sysfs_streq() internally which handles newline/null-term:

Applied to 6.8/scsi-staging, thanks!

On Tue, 12 Dec 2023 23:19:06 +0000, Justin Stitt wrote:

> Instead of copying @buf into a new buffer and carefully managing its
> newline/null-terminating status, we can just use sysfs_match_string()
> as it uses sysfs_streq() internally which handles newline/null-term:
> 
> |  /**
> |   * sysfs_streq - return true if strings are equal, modulo trailing newline
> |   * @s1: one string
> |   * @s2: another string
> |   *
> |   * This routine returns true iff two strings are equal, treating both
> |   * NUL and newline-then-NUL as equivalent string terminations.  It's
> |   * geared for use with sysfs input strings, which generally terminate
> |   * with newlines but are compared against values without newlines.
> |   */
> |  bool sysfs_streq(const char *s1, const char *s2)
> |  ...
> 
> [...]

Applied to 6.8/scsi-queue, thanks!

[1/1] scsi: fcoe: use sysfs_match_string over fcoe_parse_mode
      https://git.kernel.org/mkp/scsi/c/edc22a7c8688