From f700b71927017ca5697e8a24fd2ad5d3e06489d6 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Thu, 21 Mar 2024 00:38:54 +0000 Subject: 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: Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20240321-strncpy-fs-ecryptfs-crypto-c-v1-1-d78b74c214ac@google.com Signed-off-by: Kees Cook --- fs/ecryptfs/crypto.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'fs/ecryptfs/crypto.c') 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, -- cgit