ecryptfs: Replace strcpy with strscpy in ecryptfs_cipher_code_to_string

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
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Tyler Hicks <code@tyhicks.com>

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index c84c7c3..fa49d20 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -862,11 +862,12 @@ 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;
@@ -874,7 +875,8 @@ 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 ba59f97..54e7801 100644 (file)
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -571,7 +571,7 @@ 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 32e5e25..e55bd8f 100644 (file)
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -911,7 +911,9 @@ 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);
@@ -1129,7 +1131,9 @@ 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);
@@ -1395,6 +1399,7 @@ 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;