From: Tyler Hicks <code@tyhicks.com>
To: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Eric Biggers <ebiggers@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
Christian Brauner <brauner@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
ecryptfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] ecryptfs: Replace strcpy with strscpy in ecryptfs_cipher_code_to_string
Date: Tue, 23 Dec 2025 14:59:16 -0600 [thread overview]
Message-ID: <aUsCpC_80ZCoUdDM@yaupon> (raw)
In-Reply-To: <20251213110502.302950-4-thorsten.blum@linux.dev>
On 2025-12-13 12:04:52, Thorsten Blum wrote:
> strcpy() has been deprecated [1] because it performs no bounds checking
> on the destination buffer, which can lead to buffer overflows. Since
> the parameter 'char *str' is just a pointer with no size information,
> extend the function with a 'size' parameter to pass the destination
> buffer's size as an additional argument. Adjust the call sites
> accordingly.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Acked-by: Tyler Hicks <code@tyhicks.com>
> ---
> fs/ecryptfs/crypto.c | 6 ++++--
> fs/ecryptfs/ecryptfs_kernel.h | 2 +-
> fs/ecryptfs/keystore.c | 9 +++++++--
> 3 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> index 2c37ee6a8be1..c99fc60a4e3b 100644
> --- a/fs/ecryptfs/crypto.c
> +++ b/fs/ecryptfs/crypto.c
> @@ -934,11 +934,12 @@ u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
> /**
> * ecryptfs_cipher_code_to_string
> * @str: Destination to write out the cipher name
> + * @size: Destination buffer size
> * @cipher_code: The code to convert to cipher name string
> *
> * Returns zero on success
> */
> -int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
> +int ecryptfs_cipher_code_to_string(char *str, size_t size, u8 cipher_code)
> {
> int rc = 0;
> int i;
> @@ -946,7 +947,8 @@ int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
> str[0] = '\0';
> for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
> if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
> - strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
> + strscpy(str, ecryptfs_cipher_code_str_map[i].cipher_str,
> + size);
> if (str[0] == '\0') {
> ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
> "[%d]\n", cipher_code);
> diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
> index 9e6ab0b41337..0d824350f31a 100644
> --- a/fs/ecryptfs/ecryptfs_kernel.h
> +++ b/fs/ecryptfs/ecryptfs_kernel.h
> @@ -577,7 +577,7 @@ int ecryptfs_read_and_validate_header_region(struct inode *inode);
> int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
> struct inode *inode);
> u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
> -int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);
> +int ecryptfs_cipher_code_to_string(char *str, size_t size, u8 cipher_code);
> void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
> int ecryptfs_generate_key_packet_set(char *dest_base,
> struct ecryptfs_crypt_stat *crypt_stat,
> diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
> index 7f9f68c00ef6..b5204ab3150d 100644
> --- a/fs/ecryptfs/keystore.c
> +++ b/fs/ecryptfs/keystore.c
> @@ -954,7 +954,9 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
> s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
> (*packet_size) += ECRYPTFS_SIG_SIZE;
> s->cipher_code = data[(*packet_size)++];
> - rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
> + rc = ecryptfs_cipher_code_to_string(s->cipher_string,
> + sizeof(s->cipher_string),
> + s->cipher_code);
> if (rc) {
> printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
> __func__, s->cipher_code);
> @@ -1172,7 +1174,9 @@ decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
> memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
> auth_tok->session_key.decrypted_key_size);
> crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
> - rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
> + rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
> + sizeof(crypt_stat->cipher),
> + cipher_code);
> if (rc) {
> ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
> cipher_code);
> @@ -1438,6 +1442,7 @@ parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
> goto out_free;
> }
> rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
> + sizeof(crypt_stat->cipher),
> (u16)data[(*packet_size)]);
> if (rc)
> goto out_free;
> --
> Thorsten Blum <thorsten.blum@linux.dev>
> GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4
>
next prev parent reply other threads:[~2025-12-23 20:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-13 11:04 [PATCH 1/3] ecryptfs: Replace strcpy with strscpy in ecryptfs_set_default_crypt_stat_vals Thorsten Blum
2025-12-13 11:04 ` [PATCH 2/3] ecryptfs: Replace strcpy with strscpy in ecryptfs_cipher_code_to_string Thorsten Blum
2025-12-23 20:59 ` Tyler Hicks [this message]
2025-12-13 11:04 ` [PATCH 3/3] ecryptfs: Replace strcpy with strscpy in ecryptfs_validate_options Thorsten Blum
2025-12-23 21:00 ` Tyler Hicks
2025-12-23 20:57 ` [PATCH 1/3] ecryptfs: Replace strcpy with strscpy in ecryptfs_set_default_crypt_stat_vals Tyler Hicks
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