[FIX] Improve code security by prevent buffer overflow.

1 files changed, 43 insertions, 18 deletions

diff --git a/src/main.c b/src/main.c
index c2a21c4..dd68079 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,6 +28,8 @@ struct arg_file *seckey, *pubkey, *infile, *outfile;
 struct arg_end *end;
 struct arg_int *taglen, *noncelen, *cipherlen;
 
+int file_exist (const char *filename);
+
 int main(int argc, char *argv[]) {
     /* the global arg_xxx structs are initialised within the argtable */
     void *argtable[] = {
@@ -53,7 +55,7 @@ int main(int argc, char *argv[]) {
 
     int exitcode = 0;
     const char progname[] = "inexact";
-    const char ver[] = "beta 1.01";
+    const char ver[] = "beta 1.02";
     FILE *fo = NULL;
 
     int nerrors;
@@ -186,7 +188,7 @@ int main(int argc, char *argv[]) {
             exitcode = 1;
             goto exit;
         }
-        if (access(seckey->filename[0], F_OK) != -1) {
+        if (file_exist(seckey->filename[0]) == 1) {
             char ch;
             printf("Overwrite '%s' ? ", seckey->filename[0]);
             int res = scanf("%c", &ch);
@@ -195,7 +197,7 @@ int main(int argc, char *argv[]) {
                 goto exit;
             }
         }
-        if (access(pubkey->filename[0], F_OK) != -1) {
+        if (file_exist(pubkey->filename[0]) == 1) {
             char ch;
             printf("Overwrite '%s' ? ", pubkey->filename[0]);
             int res = scanf(" %c", &ch);
@@ -245,7 +247,7 @@ int main(int argc, char *argv[]) {
         }
         data[len - 1] = '\0';
         data_len = len - 1;
-    } else if (access(infile->filename[0], F_OK) == -1) {
+    } else if (file_exist(infile->filename[0]) == 0) {
         printf("Input file '%s' not found.\n", infile->filename[0]);
         exitcode = 1;
         goto exit;
@@ -379,7 +381,8 @@ int main(int argc, char *argv[]) {
 
     int base64_transformation = (base64->count == 0);
     if (cipherlen->count == 1) {
-        if (dencrypt->count == 0 || noncelen->count == 1 || base64->count == 1) {
+        if (dencrypt->count == 0 || noncelen->count == 1 ||
+            base64->count == 1) {
             printf("Invalid options.\n");
             printf("Try '%s --help' for more information.\n", progname);
             exitcode = 1;
@@ -395,7 +398,7 @@ int main(int argc, char *argv[]) {
             total_encrypted_len - rand_nonce_len;
 
         if (symmetric->count == 1) {
-            total_encrypted_len_without_rand1 = 
+            total_encrypted_len_without_rand1 =
                 total_encrypted_len_without_rand1 + 64;
         }
 
@@ -417,8 +420,8 @@ int main(int argc, char *argv[]) {
     }
 
     if (weak->count == 1) {
-        if (dencrypt->count == 0 || noncelen->count == 1 || taglen->count == 1 ||
-            cipherlen->count == 1) {
+        if (dencrypt->count == 0 || noncelen->count == 1 ||
+            taglen->count == 1 || cipherlen->count == 1) {
             printf("Invalid options.\n");
             printf("Try '%s --help' for more information.\n", progname);
             exitcode = 1;
@@ -428,10 +431,16 @@ int main(int argc, char *argv[]) {
         auth_tag_len = 4;
     }
 
+    unsigned char *secretkey = malloc(32);
+    unsigned char *publickey = malloc(32);
+    unsigned char *salt = malloc(32);
+    if (secretkey == NULL || publickey == NULL || salt == NULL) {
+        printf("Malloc failed\n");
+        exitcode = 1;
+        goto exit;
+    }
+
     if (dencrypt->count == 1) {
-        unsigned char secretkey[32] = {0};
-        unsigned char publickey[32] = {0};
-        unsigned char salt[32] = {0};
         unsigned char *psalt = NULL;
 
         if (symmetric->count == 1) {
@@ -442,7 +451,7 @@ int main(int argc, char *argv[]) {
             }
             psalt = &salt[0];
         } else {
-            if (access(seckey->filename[0], F_OK) == -1) {
+            if (file_exist(seckey->filename[0]) == 0) {
                 printf("Secret key file '%s' not found.\n",
                        seckey->filename[0]);
                 exitcode = 1;
@@ -453,7 +462,7 @@ int main(int argc, char *argv[]) {
                 exitcode = 1;
                 goto exit;
             }
-            if (access(pubkey->filename[0], F_OK) == -1) {
+            if (file_exist(pubkey->filename[0]) == 0) {
                 printf("Public key file '%s' not found.\n",
                        pubkey->filename[0]);
                 exitcode = 1;
@@ -487,9 +496,6 @@ int main(int argc, char *argv[]) {
     }
 
     if (ddecrypt->count == 1) {
-        unsigned char secretkey[32] = {0};
-        unsigned char publickey[32] = {0};
-
         if (base64->count == 1) {
             printf("Invalid options.\n");
             printf("Try '%s --help' for more information.\n", progname);
@@ -503,7 +509,7 @@ int main(int argc, char *argv[]) {
                 goto exit;
             }
         } else {
-            if (access(seckey->filename[0], F_OK) == -1) {
+            if (file_exist(seckey->filename[0]) == 0) {
                 printf("Secret key file '%s' not found.\n",
                        seckey->filename[0]);
                 exitcode = 1;
@@ -514,7 +520,7 @@ int main(int argc, char *argv[]) {
                 exitcode = 1;
                 goto exit;
             }
-            if (access(pubkey->filename[0], F_OK) == -1) {
+            if (file_exist(pubkey->filename[0]) == 0) {
                 printf("Public key file '%s' not found.\n",
                        pubkey->filename[0]);
                 exitcode = 1;
@@ -542,8 +548,12 @@ int main(int argc, char *argv[]) {
         memset(decrypted, 0, decrypted_len);
         memset(secretkey, 0, 32);
         memset(publickey, 0, 32);
+        memset(salt, 0, 32);
         memset(data, 0, data_len);
         free(decrypted);
+        free(secretkey);
+        free(salt);
+        free(publickey);
     }
 
 exit:
@@ -553,3 +563,18 @@ exit:
     arg_freetable(argtable, sizeof(argtable) / sizeof(argtable[0]));
     return exitcode;
 }
+
+int file_exist(const char *filename) {
+    int exist = 0;
+    FILE *file;
+    if ((file = fopen(filename, "r")) == NULL) {
+        if (errno != ENOENT) {
+            printf("Some other error occured");
+        }
+    } else {
+        exist = 1;
+        fclose(file);
+    }
+    return exist;
+}
+