[PATCH] ecryptfs.mount_private.c: check_username, add newlines This patch adds a check_username() function, that painstakingly compares each character in a username against a whitelist of acceptable characters. Previously, we had only blacklisted commas. This implementation is far more comprehensive.
Additionally, this patch adds a newline character at the end of each fputs() error messages. (Although puts() adds a newline character, fputs() does not!) Signed-off-by: Dustin Kirkland <[EMAIL PROTECTED]> -- :-Dustin Dustin Kirkland Ubuntu Server Developer Canonical, LTD [EMAIL PROTECTED] GPG: 1024D/83A61194
diff --git a/src/utils/mount.ecryptfs_private.c b/src/utils/mount.ecryptfs_private.c
index aaaaf14..108fd3f 100644
--- a/src/utils/mount.ecryptfs_private.c
+++ b/src/utils/mount.ecryptfs_private.c
@@ -47,6 +47,38 @@
#define FSTYPE "ecryptfs"
+int check_username(char *u) {
+/* We follow the username guidelines used by the adduser program. Quoting its
+ * error message:
+ * adduser: To avoid problems, the username should consist only of
+ * letters, digits, underscores, periods, at signs and dashes, and not start
+ * with a dash (as defined by IEEE Std 1003.1-2001). For compatibility with
+ * Samba machine accounts $ is also supported at the end of the username
+ */
+ int i;
+ char c;
+ int len;
+ len = strlen(u);
+ if (u == NULL || len == 0) {
+ fputs("Username is empty\n", stderr);
+ return 1;
+ }
+ for (i=0; i<len; i++) {
+ c = u[i];
+ if ( !(c>='a' && c<='z') && !(c>='A' && c<='Z') &&
+ !(c>='0' && c<='9') &&
+ !(c=='_') && !(c=='.') && !(c=='@') &&
+ !(c=='-' && i!=0) &&
+ !(c=='$' && i==(len-1))
+ ) {
+ fputs("Username has unsupported characters\n", stderr);
+ return 1;
+ }
+ }
+ return 0;
+}
+
+
char *fetch_sig(char *pw_dir) {
/* Read ecryptfs signature from file and validate
* Return signature as a string, or NULL on failure
@@ -79,14 +111,14 @@ char *fetch_sig(char *pw_dir) {
sig[i] = c;
i++;
} else {
- fputs("Invalid hex signature", stderr);
+ fputs("Invalid hex signature\n", stderr);
return NULL;
}
}
fclose(fh);
/* Check signature length */
if (i != KEY_BYTES) {
- fputs("Invalid hex signature length", stderr);
+ fputs("Invalid hex signature length\n", stderr);
return NULL;
}
sig[KEY_BYTES] = '\0';
@@ -107,23 +139,23 @@ int check_ownerships(int uid, char *dev, char *mnt) {
*/
struct stat s;
if (stat(dev, &s) != 0) {
- fputs("Cannot examine encrypted directory", stderr);
+ fputs("Cannot examine encrypted directory\n", stderr);
return 1;
}
if (!S_ISDIR(s.st_mode)) {
- fputs("Device or mountpoint is not a directory", stderr);
+ fputs("Device or mountpoint is not a directory\n", stderr);
return 1;
}
if (s.st_uid != uid) {
- fputs("You do not own that encrypted directory", stderr);
+ fputs("You do not own that encrypted directory\n", stderr);
return 1;
}
if (stat(mnt, &s) != 0) {
- fputs("Cannot examine mount directory", stderr);
+ fputs("Cannot examine mount directory\n", stderr);
return 1;
}
if (s.st_uid != uid) {
- fputs("You do not own that mount directory", stderr);
+ fputs("You do not own that mount directory\n", stderr);
return 1;
}
return 0;
@@ -277,12 +309,10 @@ int main(int argc, char *argv[]) {
return 1;
}
- if (strstr(pwd->pw_name, ",") != NULL) {
+ if (check_username(pwd->pw_name) != 0) {
/* Must protect against a crafted user=john,suid from entering
* filesystem options
*/
- fputs("A username with a comma cannot perform mounts/unmounts",
- stderr);
return 1;
}
@@ -327,7 +357,7 @@ int main(int argc, char *argv[]) {
if (mounting == 1) {
/* Mounting, so exit if already mounted */
if (is_mounted(dev, mnt, sig, mounting) == 1) {
- fputs("Already mounted", stderr);
+ fputs("Already mounted\n", stderr);
return 1;
}
/* We must maintain our real uid as the user who called this
@@ -352,7 +382,7 @@ int main(int argc, char *argv[]) {
} else {
/* Unmounting, so exit if not mounted */
if (is_mounted(dev, mnt, sig, mounting) == 0) {
- fputs("Not currently mounted", stderr);
+ fputs("Not currently mounted\n", stderr);
return 1;
}
/* The key is not needed for unmounting, so we set res=0.
signature.asc
Description: This is a digitally signed message part
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