* [PATCH v3] keys: Replace deprecated strncpy in ecryptfs_fill_auth_tok
@ 2025-10-13 15:26 Thorsten Blum
2025-10-13 16:11 ` Paul Menzel
0 siblings, 1 reply; 3+ messages in thread
From: Thorsten Blum @ 2025-10-13 15:26 UTC (permalink / raw)
To: Mimi Zohar, David Howells, Jarkko Sakkinen, Paul Moore,
James Morris, Serge E. Hallyn
Cc: linux-hardening, Thorsten Blum, Kees Cook, linux-integrity,
keyrings, linux-security-module, linux-kernel
strncpy() is deprecated for NUL-terminated destination buffers; use
strscpy_pad() instead to retain the NUL-padding behavior of strncpy().
The destination buffer is initialized using kzalloc() with a 'signature'
size of ECRYPTFS_PASSWORD_SIG_SIZE + 1. strncpy() then copies up to
ECRYPTFS_PASSWORD_SIG_SIZE bytes from 'key_desc', NUL-padding any
remaining bytes if needed, but expects the last byte to be zero.
strscpy_pad() also copies the source string to 'signature', and NUL-pads
the destination buffer if needed, but ensures it's always NUL-terminated
without relying on it being zero-initialized.
strscpy_pad() automatically determines the size of the fixed-length
destination buffer via sizeof() when the optional size argument is
omitted, making an explicit size unnecessary.
In encrypted_init(), the source string 'key_desc' is validated by
valid_ecryptfs_desc() before calling ecryptfs_fill_auth_tok(), and is
therefore NUL-terminated and satisfies the __must_be_cstr() requirement
of strscpy_pad().
Link: https://github.com/KSPP/linux/issues/90
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v3:
- Improve commit message
- Link to v2: https://lore.kernel.org/lkml/20251010161340.458707-2-thorsten.blum@linux.dev/
Changes in v2:
- Improve commit message as suggested by Jarkko and Kees
- Link to v1: https://lore.kernel.org/lkml/20251009180316.394708-3-thorsten.blum@linux.dev/
---
security/keys/encrypted-keys/ecryptfs_format.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/security/keys/encrypted-keys/ecryptfs_format.c b/security/keys/encrypted-keys/ecryptfs_format.c
index 8fdd76105ce3..2fc6f3a66135 100644
--- a/security/keys/encrypted-keys/ecryptfs_format.c
+++ b/security/keys/encrypted-keys/ecryptfs_format.c
@@ -54,8 +54,7 @@ int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
| ((uint16_t)minor & 0x00FF));
auth_tok->token_type = ECRYPTFS_PASSWORD;
- strncpy((char *)auth_tok->token.password.signature, key_desc,
- ECRYPTFS_PASSWORD_SIG_SIZE);
+ strscpy_pad(auth_tok->token.password.signature, key_desc);
auth_tok->token.password.session_key_encryption_key_bytes =
ECRYPTFS_MAX_KEY_BYTES;
/*
--
2.51.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] keys: Replace deprecated strncpy in ecryptfs_fill_auth_tok
2025-10-13 15:26 [PATCH v3] keys: Replace deprecated strncpy in ecryptfs_fill_auth_tok Thorsten Blum
@ 2025-10-13 16:11 ` Paul Menzel
2025-10-15 11:06 ` Jarkko Sakkinen
0 siblings, 1 reply; 3+ messages in thread
From: Paul Menzel @ 2025-10-13 16:11 UTC (permalink / raw)
To: Thorsten Blum
Cc: Mimi Zohar, David Howells, Jarkko Sakkinen, Paul Moore,
James Morris, Serge E. Hallyn, linux-hardening, Kees Cook,
linux-integrity, keyrings, linux-security-module, linux-kernel
Dear Thorsten,
Thank you for the patch.
Am 13.10.25 um 17:26 schrieb Thorsten Blum:
> strncpy() is deprecated for NUL-terminated destination buffers; use
> strscpy_pad() instead to retain the NUL-padding behavior of strncpy().
>
> The destination buffer is initialized using kzalloc() with a 'signature'
> size of ECRYPTFS_PASSWORD_SIG_SIZE + 1. strncpy() then copies up to
> ECRYPTFS_PASSWORD_SIG_SIZE bytes from 'key_desc', NUL-padding any
> remaining bytes if needed, but expects the last byte to be zero.
>
> strscpy_pad() also copies the source string to 'signature', and NUL-pads
> the destination buffer if needed, but ensures it's always NUL-terminated
> without relying on it being zero-initialized.
>
> strscpy_pad() automatically determines the size of the fixed-length
> destination buffer via sizeof() when the optional size argument is
> omitted, making an explicit size unnecessary.
>
> In encrypted_init(), the source string 'key_desc' is validated by
> valid_ecryptfs_desc() before calling ecryptfs_fill_auth_tok(), and is
> therefore NUL-terminated and satisfies the __must_be_cstr() requirement
> of strscpy_pad().
>
> Link: https://github.com/KSPP/linux/issues/90
> Reviewed-by: Kees Cook <kees@kernel.org>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
> Changes in v3:
> - Improve commit message
> - Link to v2: https://lore.kernel.org/lkml/20251010161340.458707-2-thorsten.blum@linux.dev/
>
> Changes in v2:
> - Improve commit message as suggested by Jarkko and Kees
> - Link to v1: https://lore.kernel.org/lkml/20251009180316.394708-3-thorsten.blum@linux.dev/
> ---
> security/keys/encrypted-keys/ecryptfs_format.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/security/keys/encrypted-keys/ecryptfs_format.c b/security/keys/encrypted-keys/ecryptfs_format.c
> index 8fdd76105ce3..2fc6f3a66135 100644
> --- a/security/keys/encrypted-keys/ecryptfs_format.c
> +++ b/security/keys/encrypted-keys/ecryptfs_format.c
> @@ -54,8 +54,7 @@ int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
> auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
> | ((uint16_t)minor & 0x00FF));
> auth_tok->token_type = ECRYPTFS_PASSWORD;
> - strncpy((char *)auth_tok->token.password.signature, key_desc,
> - ECRYPTFS_PASSWORD_SIG_SIZE);
> + strscpy_pad(auth_tok->token.password.signature, key_desc);
> auth_tok->token.password.session_key_encryption_key_bytes =
> ECRYPTFS_MAX_KEY_BYTES;
> /*
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Kind regards,
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] keys: Replace deprecated strncpy in ecryptfs_fill_auth_tok
2025-10-13 16:11 ` Paul Menzel
@ 2025-10-15 11:06 ` Jarkko Sakkinen
0 siblings, 0 replies; 3+ messages in thread
From: Jarkko Sakkinen @ 2025-10-15 11:06 UTC (permalink / raw)
To: Paul Menzel, David Howells
Cc: Thorsten Blum, Mimi Zohar, David Howells, Paul Moore,
James Morris, Serge E. Hallyn, linux-hardening, Kees Cook,
linux-integrity, keyrings, linux-security-module, linux-kernel
On Mon, Oct 13, 2025 at 06:11:38PM +0200, Paul Menzel wrote:
> Dear Thorsten,
>
>
> Thank you for the patch.
>
> Am 13.10.25 um 17:26 schrieb Thorsten Blum:
> > strncpy() is deprecated for NUL-terminated destination buffers; use
> > strscpy_pad() instead to retain the NUL-padding behavior of strncpy().
> >
> > The destination buffer is initialized using kzalloc() with a 'signature'
> > size of ECRYPTFS_PASSWORD_SIG_SIZE + 1. strncpy() then copies up to
> > ECRYPTFS_PASSWORD_SIG_SIZE bytes from 'key_desc', NUL-padding any
> > remaining bytes if needed, but expects the last byte to be zero.
> >
> > strscpy_pad() also copies the source string to 'signature', and NUL-pads
> > the destination buffer if needed, but ensures it's always NUL-terminated
> > without relying on it being zero-initialized.
> >
> > strscpy_pad() automatically determines the size of the fixed-length
> > destination buffer via sizeof() when the optional size argument is
> > omitted, making an explicit size unnecessary.
> >
> > In encrypted_init(), the source string 'key_desc' is validated by
> > valid_ecryptfs_desc() before calling ecryptfs_fill_auth_tok(), and is
> > therefore NUL-terminated and satisfies the __must_be_cstr() requirement
> > of strscpy_pad().
> >
> > Link: https://github.com/KSPP/linux/issues/90
> > Reviewed-by: Kees Cook <kees@kernel.org>
> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> > ---
> > Changes in v3:
> > - Improve commit message
> > - Link to v2: https://lore.kernel.org/lkml/20251010161340.458707-2-thorsten.blum@linux.dev/
> >
> > Changes in v2:
> > - Improve commit message as suggested by Jarkko and Kees
> > - Link to v1: https://lore.kernel.org/lkml/20251009180316.394708-3-thorsten.blum@linux.dev/
> > ---
> > security/keys/encrypted-keys/ecryptfs_format.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/security/keys/encrypted-keys/ecryptfs_format.c b/security/keys/encrypted-keys/ecryptfs_format.c
> > index 8fdd76105ce3..2fc6f3a66135 100644
> > --- a/security/keys/encrypted-keys/ecryptfs_format.c
> > +++ b/security/keys/encrypted-keys/ecryptfs_format.c
> > @@ -54,8 +54,7 @@ int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
> > auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
> > | ((uint16_t)minor & 0x00FF));
> > auth_tok->token_type = ECRYPTFS_PASSWORD;
> > - strncpy((char *)auth_tok->token.password.signature, key_desc,
> > - ECRYPTFS_PASSWORD_SIG_SIZE);
> > + strscpy_pad(auth_tok->token.password.signature, key_desc);
> > auth_tok->token.password.session_key_encryption_key_bytes =
> > ECRYPTFS_MAX_KEY_BYTES;
> > /*
>
> Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Thanks for the review Paul.
David: and also this is in my tree now.
>
>
> Kind regards,
>
> Paul
BR, Jarkko
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-10-15 11:06 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-10-13 15:26 [PATCH v3] keys: Replace deprecated strncpy in ecryptfs_fill_auth_tok Thorsten Blum
2025-10-13 16:11 ` Paul Menzel
2025-10-15 11:06 ` Jarkko Sakkinen
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).