* [PATCH v2] scsi: target: Replace strlcpy with strscpy
@ 2023-08-30 21:07 Azeem Shaikh
2023-08-30 21:53 ` Justin Stitt
2023-08-30 22:38 ` Kees Cook
0 siblings, 2 replies; 5+ messages in thread
From: Azeem Shaikh @ 2023-08-30 21:07 UTC (permalink / raw
To: Martin K. Petersen
Cc: linux-hardening, Azeem Shaikh, linux-scsi, target-devel,
linux-kernel
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
v2:
* Replace all instances of strlcpy in this file instead of just 1.
v1:
* https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/
drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 936e5ff1b209..10a22a428267 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
unsigned char buf[INQUIRY_VENDOR_LEN + 2];
char *stripped = NULL;
- size_t len;
+ ssize_t len;
ssize_t ret;
- len = strlcpy(buf, page, sizeof(buf));
- if (len < sizeof(buf)) {
+ len = strscpy(buf, page, sizeof(buf));
+ if (len > 0) {
/* Strip any newline added from userspace. */
stripped = strstrip(buf);
- len = strlen(stripped);
}
- if (len > INQUIRY_VENDOR_LEN) {
+ if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
pr_err("Emulated T10 Vendor Identification exceeds"
" INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
"\n");
@@ -1448,16 +1447,15 @@ static ssize_t target_wwn_product_id_store(struct config_item *item,
/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
unsigned char buf[INQUIRY_MODEL_LEN + 2];
char *stripped = NULL;
- size_t len;
+ ssize_t len;
ssize_t ret;
- len = strlcpy(buf, page, sizeof(buf));
- if (len < sizeof(buf)) {
+ len = strscpy(buf, page, sizeof(buf));
+ if (len > 0) {
/* Strip any newline added from userspace. */
stripped = strstrip(buf);
- len = strlen(stripped);
}
- if (len > INQUIRY_MODEL_LEN) {
+ if (len < 0 || strlen(stripped) > INQUIRY_MODEL_LEN) {
pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: "
__stringify(INQUIRY_MODEL_LEN)
"\n");
@@ -1504,16 +1502,15 @@ static ssize_t target_wwn_revision_store(struct config_item *item,
/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
unsigned char buf[INQUIRY_REVISION_LEN + 2];
char *stripped = NULL;
- size_t len;
+ ssize_t len;
ssize_t ret;
- len = strlcpy(buf, page, sizeof(buf));
- if (len < sizeof(buf)) {
+ len = strscpy(buf, page, sizeof(buf));
+ if (len > 0) {
/* Strip any newline added from userspace. */
stripped = strstrip(buf);
- len = strlen(stripped);
}
- if (len > INQUIRY_REVISION_LEN) {
+ if (len < 0 || strlen(stripped) > INQUIRY_REVISION_LEN) {
pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: "
__stringify(INQUIRY_REVISION_LEN)
"\n");
--
2.42.0.283.g2d96d420d3-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] scsi: target: Replace strlcpy with strscpy
2023-08-30 21:07 [PATCH v2] scsi: target: Replace strlcpy with strscpy Azeem Shaikh
@ 2023-08-30 21:53 ` Justin Stitt
2023-08-30 22:01 ` Azeem Shaikh
2023-08-30 22:40 ` Kees Cook
2023-08-30 22:38 ` Kees Cook
1 sibling, 2 replies; 5+ messages in thread
From: Justin Stitt @ 2023-08-30 21:53 UTC (permalink / raw
To: Azeem Shaikh
Cc: Martin K. Petersen, linux-hardening, linux-scsi, target-devel,
linux-kernel
On Wed, Aug 30, 2023 at 09:07:24PM +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
>
> Direct replacement is safe here since return value of -errno
> is used to check for truncation instead of sizeof(dest).
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
> ---
> v2:
> * Replace all instances of strlcpy in this file instead of just 1.
>
> v1:
> * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/
>
> drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
> 1 file changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
> index 936e5ff1b209..10a22a428267 100644
> --- a/drivers/target/target_core_configfs.c
> +++ b/drivers/target/target_core_configfs.c
> @@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_VENDOR_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_VENDOR_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
> pr_err("Emulated T10 Vendor Identification exceeds"
> " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
> "\n");
Should we be explicitly checking for `len == -E2BIG` instead of the more
generic `len < 0`? Perhaps this is a nitpick but I prefer the former.
...
> @@ -1448,16 +1447,15 @@ static ssize_t target_wwn_product_id_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_MODEL_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_MODEL_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_MODEL_LEN) {
> pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: "
> __stringify(INQUIRY_MODEL_LEN)
> "\n");
... and here
> @@ -1504,16 +1502,15 @@ static ssize_t target_wwn_revision_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_REVISION_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_REVISION_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_REVISION_LEN) {
> pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: "
> __stringify(INQUIRY_REVISION_LEN)
> "\n");
... and here
> --
> 2.42.0.283.g2d96d420d3-goog
>
>
At any rate, this is a worthwhile change for the reasons you mentioned.
Reviewed-by: Justin Stitt <justinstitt@google.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] scsi: target: Replace strlcpy with strscpy
2023-08-30 21:53 ` Justin Stitt
@ 2023-08-30 22:01 ` Azeem Shaikh
2023-08-30 22:40 ` Kees Cook
1 sibling, 0 replies; 5+ messages in thread
From: Azeem Shaikh @ 2023-08-30 22:01 UTC (permalink / raw
To: Justin Stitt
Cc: Martin K. Petersen, linux-hardening, linux-scsi, target-devel,
linux-kernel
On Wed, Aug 30, 2023 at 5:53 PM Justin Stitt <justinstitt@google.com> wrote:
>
> On Wed, Aug 30, 2023 at 09:07:24PM +0000, Azeem Shaikh wrote:
> > strlcpy() reads the entire source buffer first.
> > This read may exceed the destination size limit.
> > This is both inefficient and can lead to linear read
> > overflows if a source string is not NUL-terminated [1].
> > In an effort to remove strlcpy() completely [2], replace
> > strlcpy() here with strscpy().
> >
> > Direct replacement is safe here since return value of -errno
> > is used to check for truncation instead of sizeof(dest).
> >
> > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> > [2] https://github.com/KSPP/linux/issues/89
> >
> > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
> > ---
> > v2:
> > * Replace all instances of strlcpy in this file instead of just 1.
> >
> > v1:
> > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/
> >
> > drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
> > 1 file changed, 12 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
> > index 936e5ff1b209..10a22a428267 100644
> > --- a/drivers/target/target_core_configfs.c
> > +++ b/drivers/target/target_core_configfs.c
> > @@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
> > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> > unsigned char buf[INQUIRY_VENDOR_LEN + 2];
> > char *stripped = NULL;
> > - size_t len;
> > + ssize_t len;
> > ssize_t ret;
> >
> > - len = strlcpy(buf, page, sizeof(buf));
> > - if (len < sizeof(buf)) {
> > + len = strscpy(buf, page, sizeof(buf));
> > + if (len > 0) {
> > /* Strip any newline added from userspace. */
> > stripped = strstrip(buf);
> > - len = strlen(stripped);
> > }
> > - if (len > INQUIRY_VENDOR_LEN) {
> > + if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
> > pr_err("Emulated T10 Vendor Identification exceeds"
> > " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
> > "\n");
>
> Should we be explicitly checking for `len == -E2BIG` instead of the more
> generic `len < 0`? Perhaps this is a nitpick but I prefer the former.
>
Most maintainers to whom I have sent such patches in the past have
preferred `len < 0` since it is not "rigid" in checking for -E2BIG
which is an implementation detail of strscpy.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] scsi: target: Replace strlcpy with strscpy
2023-08-30 21:07 [PATCH v2] scsi: target: Replace strlcpy with strscpy Azeem Shaikh
2023-08-30 21:53 ` Justin Stitt
@ 2023-08-30 22:38 ` Kees Cook
1 sibling, 0 replies; 5+ messages in thread
From: Kees Cook @ 2023-08-30 22:38 UTC (permalink / raw
To: Azeem Shaikh
Cc: Martin K. Petersen, linux-hardening, linux-scsi, target-devel,
linux-kernel
On Wed, Aug 30, 2023 at 09:07:24PM +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
>
> Direct replacement is safe here since return value of -errno
> is used to check for truncation instead of sizeof(dest).
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
> ---
> v2:
> * Replace all instances of strlcpy in this file instead of just 1.
>
> v1:
> * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/
>
> drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
> 1 file changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
> index 936e5ff1b209..10a22a428267 100644
> --- a/drivers/target/target_core_configfs.c
> +++ b/drivers/target/target_core_configfs.c
> @@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_VENDOR_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_VENDOR_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
> pr_err("Emulated T10 Vendor Identification exceeds"
> " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
> "\n");
I would find these more readable if the "len = strlen" were left and the
final "if" becomes:
if (len < 0 || len > INQUIRY_VENDOR_LEN)
> @@ -1448,16 +1447,15 @@ static ssize_t target_wwn_product_id_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_MODEL_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_MODEL_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_MODEL_LEN) {
> pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: "
> __stringify(INQUIRY_MODEL_LEN)
> "\n");
> @@ -1504,16 +1502,15 @@ static ssize_t target_wwn_revision_store(struct config_item *item,
> /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> unsigned char buf[INQUIRY_REVISION_LEN + 2];
> char *stripped = NULL;
> - size_t len;
> + ssize_t len;
> ssize_t ret;
>
> - len = strlcpy(buf, page, sizeof(buf));
> - if (len < sizeof(buf)) {
> + len = strscpy(buf, page, sizeof(buf));
> + if (len > 0) {
> /* Strip any newline added from userspace. */
> stripped = strstrip(buf);
> - len = strlen(stripped);
> }
> - if (len > INQUIRY_REVISION_LEN) {
> + if (len < 0 || strlen(stripped) > INQUIRY_REVISION_LEN) {
> pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: "
> __stringify(INQUIRY_REVISION_LEN)
> "\n");
> --
> 2.42.0.283.g2d96d420d3-goog
>
>
--
Kees Cook
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] scsi: target: Replace strlcpy with strscpy
2023-08-30 21:53 ` Justin Stitt
2023-08-30 22:01 ` Azeem Shaikh
@ 2023-08-30 22:40 ` Kees Cook
1 sibling, 0 replies; 5+ messages in thread
From: Kees Cook @ 2023-08-30 22:40 UTC (permalink / raw
To: Justin Stitt
Cc: Azeem Shaikh, Martin K. Petersen, linux-hardening, linux-scsi,
target-devel, linux-kernel
On Wed, Aug 30, 2023 at 09:53:30PM +0000, Justin Stitt wrote:
> On Wed, Aug 30, 2023 at 09:07:24PM +0000, Azeem Shaikh wrote:
> > strlcpy() reads the entire source buffer first.
> > This read may exceed the destination size limit.
> > This is both inefficient and can lead to linear read
> > overflows if a source string is not NUL-terminated [1].
> > In an effort to remove strlcpy() completely [2], replace
> > strlcpy() here with strscpy().
> >
> > Direct replacement is safe here since return value of -errno
> > is used to check for truncation instead of sizeof(dest).
> >
> > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> > [2] https://github.com/KSPP/linux/issues/89
> >
> > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
> > ---
> > v2:
> > * Replace all instances of strlcpy in this file instead of just 1.
> >
> > v1:
> > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/
> >
> > drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
> > 1 file changed, 12 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
> > index 936e5ff1b209..10a22a428267 100644
> > --- a/drivers/target/target_core_configfs.c
> > +++ b/drivers/target/target_core_configfs.c
> > @@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
> > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */
> > unsigned char buf[INQUIRY_VENDOR_LEN + 2];
> > char *stripped = NULL;
> > - size_t len;
> > + ssize_t len;
> > ssize_t ret;
> >
> > - len = strlcpy(buf, page, sizeof(buf));
> > - if (len < sizeof(buf)) {
> > + len = strscpy(buf, page, sizeof(buf));
> > + if (len > 0) {
> > /* Strip any newline added from userspace. */
> > stripped = strstrip(buf);
> > - len = strlen(stripped);
> > }
> > - if (len > INQUIRY_VENDOR_LEN) {
> > + if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
> > pr_err("Emulated T10 Vendor Identification exceeds"
> > " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
> > "\n");
>
> Should we be explicitly checking for `len == -E2BIG` instead of the more
> generic `len < 0`? Perhaps this is a nitpick but I prefer the former.
For robustness, we want to just do the "< 0" test -- that way if
strscpy() gains a new errno (for some unimaginable reason) then all the
code testing for "< 0" will continue to work sanely.
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 5+ messages in thread
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2023-08-30 21:07 [PATCH v2] scsi: target: Replace strlcpy with strscpy Azeem Shaikh
2023-08-30 21:53 ` Justin Stitt
2023-08-30 22:01 ` Azeem Shaikh
2023-08-30 22:40 ` Kees Cook
2023-08-30 22:38 ` Kees Cook
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