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authorJustin Stitt <justinstitt@google.com>2024-03-21 03:38:54 +0300
committerKees Cook <keescook@chromium.org>2024-04-25 02:57:38 +0300
commitf700b71927017ca5697e8a24fd2ad5d3e06489d6 (patch)
tree8cc4493a1072272ba229f3334dfbff50838c8297 /fs/ecryptfs
parent7dcbf17e3f917f691d2ae9ed4a34283bd0e74a95 (diff)
downloadlinux-f700b71927017ca5697e8a24fd2ad5d3e06489d6.tar.xz
fs: ecryptfs: replace deprecated strncpy with strscpy
strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. A good alternative is strscpy() as it guarantees NUL-termination on the destination buffer. In crypto.c: We expect cipher_name to be NUL-terminated based on its use with the C-string format specifier %s and with other string apis like strlen(): | printk(KERN_ERR "Error attempting to initialize key TFM " | "cipher with name = [%s]; rc = [%d]\n", | tmp_tfm->cipher_name, rc); and | int cipher_name_len = strlen(cipher_name); In main.c: We can remove the manual NUL-byte assignments as well as the pointers to destinations (which I assume only existed to trim down on line length?) in favor of directly using the destination buffer which allows the compiler to get size information -- enabling the usage of the new 2-argument strscpy(). Note that this patch relies on the _new_ 2-argument versions of strscpy() and strscpy_pad() introduced in Commit e6584c3964f2f ("string: Allow 2-argument strscpy()"). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: <linux-hardening@vger.kernel.org> Signed-off-by: Justin Stitt <justinstitt@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20240321-strncpy-fs-ecryptfs-crypto-c-v1-1-d78b74c214ac@google.com Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'fs/ecryptfs')
-rw-r--r--fs/ecryptfs/crypto.c4
-rw-r--r--fs/ecryptfs/main.c26
2 files changed, 7 insertions, 23 deletions
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 2fe0f3af1a08..d39a1a69fecc 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1606,9 +1606,7 @@ ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
goto out;
}
mutex_init(&tmp_tfm->key_tfm_mutex);
- strncpy(tmp_tfm->cipher_name, cipher_name,
- ECRYPTFS_MAX_CIPHER_NAME_SIZE);
- tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
+ strscpy(tmp_tfm->cipher_name, cipher_name);
tmp_tfm->key_size = key_size;
rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
tmp_tfm->cipher_name,
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 2dc927ba067f..577c56302314 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -256,11 +256,8 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
substring_t args[MAX_OPT_ARGS];
int token;
char *sig_src;
- char *cipher_name_dst;
char *cipher_name_src;
- char *fn_cipher_name_dst;
char *fn_cipher_name_src;
- char *fnek_dst;
char *fnek_src;
char *cipher_key_bytes_src;
char *fn_cipher_key_bytes_src;
@@ -293,12 +290,8 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
case ecryptfs_opt_cipher:
case ecryptfs_opt_ecryptfs_cipher:
cipher_name_src = args[0].from;
- cipher_name_dst =
- mount_crypt_stat->
- global_default_cipher_name;
- strncpy(cipher_name_dst, cipher_name_src,
- ECRYPTFS_MAX_CIPHER_NAME_SIZE);
- cipher_name_dst[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
+ strscpy(mount_crypt_stat->global_default_cipher_name,
+ cipher_name_src);
cipher_name_set = 1;
break;
case ecryptfs_opt_ecryptfs_key_bytes:
@@ -326,11 +319,8 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
break;
case ecryptfs_opt_fnek_sig:
fnek_src = args[0].from;
- fnek_dst =
- mount_crypt_stat->global_default_fnek_sig;
- strncpy(fnek_dst, fnek_src, ECRYPTFS_SIG_SIZE_HEX);
- mount_crypt_stat->global_default_fnek_sig[
- ECRYPTFS_SIG_SIZE_HEX] = '\0';
+ strscpy(mount_crypt_stat->global_default_fnek_sig,
+ fnek_src);
rc = ecryptfs_add_global_auth_tok(
mount_crypt_stat,
mount_crypt_stat->global_default_fnek_sig,
@@ -348,12 +338,8 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
break;
case ecryptfs_opt_fn_cipher:
fn_cipher_name_src = args[0].from;
- fn_cipher_name_dst =
- mount_crypt_stat->global_default_fn_cipher_name;
- strncpy(fn_cipher_name_dst, fn_cipher_name_src,
- ECRYPTFS_MAX_CIPHER_NAME_SIZE);
- mount_crypt_stat->global_default_fn_cipher_name[
- ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
+ strscpy(mount_crypt_stat->global_default_fn_cipher_name,
+ fn_cipher_name_src);
fn_cipher_name_set = 1;
break;
case ecryptfs_opt_fn_cipher_key_bytes: