diff options
Diffstat (limited to 'qga/commands-windows-ssh.c')
| -rw-r--r-- | qga/commands-windows-ssh.c | 712 |
1 files changed, 712 insertions, 0 deletions
diff --git a/qga/commands-windows-ssh.c b/qga/commands-windows-ssh.c new file mode 100644 index 0000000000..6a642e3ba8 --- /dev/null +++ b/qga/commands-windows-ssh.c @@ -0,0 +1,712 @@ +/* + * QEMU Guest Agent win32-specific command implementations for SSH keys. + * The implementation is opinionated and expects the SSH implementation to + * be OpenSSH. + * + * Copyright Schweitzer Engineering Laboratories. 2024 + * + * Authors: + * Aidan Leuck <aidan_leuck@selinc.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include <aclapi.h> +#include <qga-qapi-types.h> + +#include "commands-common-ssh.h" +#include "commands-windows-ssh.h" +#include "guest-agent-core.h" +#include "limits.h" +#include "lmaccess.h" +#include "lmapibuf.h" +#include "lmerr.h" +#include "qapi/error.h" + +#include "qga-qapi-commands.h" +#include "sddl.h" +#include "shlobj.h" +#include "userenv.h" + +#define AUTHORIZED_KEY_FILE "authorized_keys" +#define AUTHORIZED_KEY_FILE_ADMIN "administrators_authorized_keys" +#define LOCAL_SYSTEM_SID "S-1-5-18" +#define ADMIN_SID "S-1-5-32-544" + +/* + * Frees userInfo structure. This implements the g_auto cleanup + * for the structure. + */ +void free_userInfo(PWindowsUserInfo info) +{ + g_free(info->sshDirectory); + g_free(info->authorizedKeyFile); + LocalFree(info->SSID); + g_free(info->username); + g_free(info); +} + +/* + * Gets the admin SSH folder for OpenSSH. OpenSSH does not store + * the authorized_key file in the users home directory for security reasons and + * instead stores it at %PROGRAMDATA%/ssh. This function returns the path to + * that directory on the users machine + * + * parameters: + * errp -> error structure to set when an error occurs + * returns: The path to the ssh folder in %PROGRAMDATA% or NULL if an error + * occurred. + */ +static char *get_admin_ssh_folder(Error **errp) +{ + /* Allocate memory for the program data path */ + g_autofree char *programDataPath = NULL; + char *authkeys_path = NULL; + PWSTR pgDataW = NULL; + g_autoptr(GError) gerr = NULL; + + /* Get the KnownFolderPath on the machine. */ + HRESULT folderResult = + SHGetKnownFolderPath(&FOLDERID_ProgramData, 0, NULL, &pgDataW); + if (folderResult != S_OK) { + error_setg(errp, "Failed to retrieve ProgramData folder"); + return NULL; + } + + /* Convert from a wide string back to a standard character string. */ + programDataPath = g_utf16_to_utf8(pgDataW, -1, NULL, NULL, &gerr); + CoTaskMemFree(pgDataW); + if (!programDataPath) { + error_setg(errp, + "Failed converting ProgramData folder path to UTF-16 %s", + gerr->message); + return NULL; + } + + /* Build the path to the file. */ + authkeys_path = g_build_filename(programDataPath, "ssh", NULL); + return authkeys_path; +} + +/* + * Gets the path to the SSH folder for the specified user. If the user is an + * admin it returns the ssh folder located at %PROGRAMDATA%/ssh. If the user is + * not an admin it returns %USERPROFILE%/.ssh + * + * parameters: + * username -> Username to get the SSH folder for + * isAdmin -> Whether the user is an admin or not + * errp -> Error structure to set any errors that occur. + * returns: path to the ssh folder as a string. + */ +static char *get_ssh_folder(const char *username, const bool isAdmin, + Error **errp) +{ + DWORD maxSize = MAX_PATH; + g_autofree char *profilesDir = g_new0(char, maxSize); + + if (isAdmin) { + return get_admin_ssh_folder(errp); + } + + /* If not an Admin the SSH key is in the user directory. */ + /* Get the user profile directory on the machine. */ + BOOL ret = GetProfilesDirectory(profilesDir, &maxSize); + if (!ret) { + error_setg_win32(errp, GetLastError(), + "failed to retrieve profiles directory"); + return NULL; + } + + /* Builds the filename */ + return g_build_filename(profilesDir, username, ".ssh", NULL); +} + +/* + * Creates an entry for the user so they can access the ssh folder in their + * userprofile. + * + * parameters: + * userInfo -> Information about the current user + * pACL -> Pointer to an ACL structure + * errp -> Error structure to set any errors that occur + * returns -> 1 on success, 0 otherwise + */ +static bool create_acl_user(PWindowsUserInfo userInfo, PACL *pACL, Error **errp) +{ + const int aclSize = 1; + PACL newACL = NULL; + EXPLICIT_ACCESS eAccess[1]; + PSID userPSID = NULL; + + /* Get a pointer to the internal SID object in Windows */ + bool converted = ConvertStringSidToSid(userInfo->SSID, &userPSID); + if (!converted) { + error_setg_win32(errp, GetLastError(), "failed to retrieve user %s SID", + userInfo->username); + goto error; + } + + /* Set the permissions for the user. */ + eAccess[0].grfAccessPermissions = GENERIC_ALL; + eAccess[0].grfAccessMode = SET_ACCESS; + eAccess[0].grfInheritance = NO_INHERITANCE; + eAccess[0].Trustee.TrusteeForm = TRUSTEE_IS_SID; + eAccess[0].Trustee.TrusteeType = TRUSTEE_IS_USER; + eAccess[0].Trustee.ptstrName = (LPTSTR)userPSID; + + /* Set the ACL entries */ + DWORD setResult; + + /* + * If we are given a pointer that is already initialized, then we can merge + * the existing entries instead of overwriting them. + */ + if (*pACL) { + setResult = SetEntriesInAcl(aclSize, eAccess, *pACL, &newACL); + } else { + setResult = SetEntriesInAcl(aclSize, eAccess, NULL, &newACL); + } + + if (setResult != ERROR_SUCCESS) { + error_setg_win32(errp, GetLastError(), + "failed to set ACL entries for user %s %lu", + userInfo->username, setResult); + goto error; + } + + /* Free any old memory since we are going to overwrite the users pointer. */ + LocalFree(*pACL); + *pACL = newACL; + + LocalFree(userPSID); + return true; +error: + LocalFree(userPSID); + return false; +} + +/* + * Creates a base ACL for both normal users and admins to share + * pACL -> Pointer to an ACL structure + * errp -> Error structure to set any errors that occur + * returns: 1 on success, 0 otherwise + */ +static bool create_acl_base(PACL *pACL, Error **errp) +{ + PSID adminGroupPSID = NULL; + PSID systemPSID = NULL; + + const int aclSize = 2; + EXPLICIT_ACCESS eAccess[2]; + + /* Create an entry for the system user. */ + const char *systemSID = LOCAL_SYSTEM_SID; + bool converted = ConvertStringSidToSid(systemSID, &systemPSID); + if (!converted) { + error_setg_win32(errp, GetLastError(), "failed to retrieve system SID"); + goto error; + } + + /* set permissions for system user */ + eAccess[0].grfAccessPermissions = GENERIC_ALL; + eAccess[0].grfAccessMode = SET_ACCESS; + eAccess[0].grfInheritance = NO_INHERITANCE; + eAccess[0].Trustee.TrusteeForm = TRUSTEE_IS_SID; + eAccess[0].Trustee.TrusteeType = TRUSTEE_IS_USER; + eAccess[0].Trustee.ptstrName = (LPTSTR)systemPSID; + + /* Create an entry for the admin user. */ + const char *adminSID = ADMIN_SID; + converted = ConvertStringSidToSid(adminSID, &adminGroupPSID); + if (!converted) { + error_setg_win32(errp, GetLastError(), "failed to retrieve Admin SID"); + goto error; + } + + /* Set permissions for admin group. */ + eAccess[1].grfAccessPermissions = GENERIC_ALL; + eAccess[1].grfAccessMode = SET_ACCESS; + eAccess[1].grfInheritance = NO_INHERITANCE; + eAccess[1].Trustee.TrusteeForm = TRUSTEE_IS_SID; + eAccess[1].Trustee.TrusteeType = TRUSTEE_IS_GROUP; + eAccess[1].Trustee.ptstrName = (LPTSTR)adminGroupPSID; + + /* Put the entries in an ACL object. */ + PACL pNewACL = NULL; + DWORD setResult; + + /* + *If we are given a pointer that is already initialized, then we can merge + *the existing entries instead of overwriting them. + */ + if (*pACL) { + setResult = SetEntriesInAcl(aclSize, eAccess, *pACL, &pNewACL); + } else { + setResult = SetEntriesInAcl(aclSize, eAccess, NULL, &pNewACL); + } + + if (setResult != ERROR_SUCCESS) { + error_setg_win32(errp, GetLastError(), + "failed to set base ACL entries for system user and " + "admin group %lu", + setResult); + goto error; + } + + LocalFree(adminGroupPSID); + LocalFree(systemPSID); + + /* Free any old memory since we are going to overwrite the users pointer. */ + LocalFree(*pACL); + + *pACL = pNewACL; + + return true; + +error: + LocalFree(adminGroupPSID); + LocalFree(systemPSID); + return false; +} + +/* + * Sets the access control on the authorized_keys file and any ssh folders that + * need to be created. For administrators the required permissions on the + * file/folders are that only administrators and the LocalSystem account can + * access the folders. For normal user accounts only the specified user, + * LocalSystem and Administrators can have access to the key. + * + * parameters: + * userInfo -> pointer to structure that contains information about the user + * PACL -> pointer to an access control structure that will be set upon + * successful completion of the function. + * errp -> error structure that will be set upon error. + * returns: 1 upon success 0 upon failure. + */ +static bool create_acl(PWindowsUserInfo userInfo, PACL *pACL, Error **errp) +{ + /* + * Creates a base ACL that both admins and users will share + * This adds the Administrators group and the SYSTEM group + */ + if (!create_acl_base(pACL, errp)) { + return false; + } + + /* + * If the user is not an admin give the user creating the key permission to + * access the file. + */ + if (!userInfo->isAdmin) { + if (!create_acl_user(userInfo, pACL, errp)) { + return false; + } + + return true; + } + + return true; +} +/* + * Create the SSH directory for the user and d sets appropriate permissions. + * In general the directory will be %PROGRAMDATA%/ssh if the user is an admin. + * %USERPOFILE%/.ssh if not an admin + * + * parameters: + * userInfo -> Contains information about the user + * errp -> Structure that will contain errors if the function fails. + * returns: zero upon failure, 1 upon success + */ +static bool create_ssh_directory(WindowsUserInfo *userInfo, Error **errp) +{ + PACL pNewACL = NULL; + g_autofree PSECURITY_DESCRIPTOR pSD = NULL; + + /* Gets the appropriate ACL for the user */ + if (!create_acl(userInfo, &pNewACL, errp)) { + goto error; + } + + /* Allocate memory for a security descriptor */ + pSD = g_malloc(SECURITY_DESCRIPTOR_MIN_LENGTH); + if (!InitializeSecurityDescriptor(pSD, SECURITY_DESCRIPTOR_REVISION)) { + error_setg_win32(errp, GetLastError(), + "Failed to initialize security descriptor"); + goto error; + } + + /* Associate the security descriptor with the ACL permissions. */ + if (!SetSecurityDescriptorDacl(pSD, TRUE, pNewACL, FALSE)) { + error_setg_win32(errp, GetLastError(), + "Failed to set security descriptor ACL"); + goto error; + } + + /* Set the security attributes on the folder */ + SECURITY_ATTRIBUTES sAttr; + sAttr.bInheritHandle = FALSE; + sAttr.nLength = sizeof(SECURITY_ATTRIBUTES); + sAttr.lpSecurityDescriptor = pSD; + + /* Create the directory with the created permissions */ + BOOL created = CreateDirectory(userInfo->sshDirectory, &sAttr); + if (!created) { + error_setg_win32(errp, GetLastError(), "failed to create directory %s", + userInfo->sshDirectory); + goto error; + } + + /* Free memory */ + LocalFree(pNewACL); + return true; +error: + LocalFree(pNewACL); + return false; +} + +/* + * Sets permissions on the authorized_key_file that is created. + * + * parameters: userInfo -> Information about the user + * errp -> error structure that will contain errors upon failure + * returns: 1 upon success, zero upon failure. + */ +static bool set_file_permissions(PWindowsUserInfo userInfo, Error **errp) +{ + PACL pACL = NULL; + PSID userPSID; + + /* Creates the access control structure */ + if (!create_acl(userInfo, &pACL, errp)) { + goto error; + } + + /* Get the PSID structure for the user based off the string SID. */ + bool converted = ConvertStringSidToSid(userInfo->SSID, &userPSID); + if (!converted) { + error_setg_win32(errp, GetLastError(), "failed to retrieve user %s SID", + userInfo->username); + goto error; + } + + /* Prevents permissions from being inherited and use the DACL provided. */ + const SE_OBJECT_TYPE securityBitFlags = + DACL_SECURITY_INFORMATION | PROTECTED_DACL_SECURITY_INFORMATION; + + /* Set the ACL on the file. */ + if (SetNamedSecurityInfo(userInfo->authorizedKeyFile, SE_FILE_OBJECT, + securityBitFlags, userPSID, NULL, pACL, + NULL) != ERROR_SUCCESS) { + error_setg_win32(errp, GetLastError(), + "failed to set file security for file %s", + userInfo->authorizedKeyFile); + goto error; + } + + LocalFree(pACL); + LocalFree(userPSID); + return true; + +error: + LocalFree(pACL); + LocalFree(userPSID); + + return false; +} + +/* + * Writes the specified keys to the authenticated keys file. + * parameters: + * userInfo: Information about the user we are writing the authkeys file to. + * authkeys: Array of keys to write to disk + * errp: Error structure that will contain any errors if they occur. + * returns: 1 if successful, 0 otherwise. + */ +static bool write_authkeys(WindowsUserInfo *userInfo, GStrv authkeys, + Error **errp) +{ + g_autofree char *contents = NULL; + g_autoptr(GError) err = NULL; + + contents = g_strjoinv("\n", authkeys); + + if (!g_file_set_contents(userInfo->authorizedKeyFile, contents, -1, &err)) { + error_setg(errp, "failed to write to '%s': %s", + userInfo->authorizedKeyFile, err->message); + return false; + } + + if (!set_file_permissions(userInfo, errp)) { + return false; + } + + return true; +} + +/* + * Retrieves information about a Windows user by their username + * + * parameters: + * userInfo -> Double pointer to a WindowsUserInfo structure. Upon success, it + * will be allocated with information about the user and need to be freed. + * username -> Name of the user to lookup. + * errp -> Contains any errors that occur. + * returns: 1 upon success, 0 upon failure. + */ +static bool get_user_info(PWindowsUserInfo *userInfo, const char *username, + Error **errp) +{ + DWORD infoLevel = 4; + LPUSER_INFO_4 uBuf = NULL; + g_autofree wchar_t *wideUserName = NULL; + g_autoptr(GError) gerr = NULL; + PSID psid = NULL; + + /* + * Converts a string to a Windows wide string since the GetNetUserInfo + * function requires it. + */ + wideUserName = g_utf8_to_utf16(username, -1, NULL, NULL, &gerr); + if (!wideUserName) { + goto error; + } + + /* allocate data */ + PWindowsUserInfo uData = g_new0(WindowsUserInfo, 1); + + /* Set pointer so it can be cleaned up by the callee, even upon error. */ + *userInfo = uData; + + /* Find the information */ + NET_API_STATUS result = + NetUserGetInfo(NULL, wideUserName, infoLevel, (LPBYTE *)&uBuf); + if (result != NERR_Success) { + /* Give a friendlier error message if the user was not found. */ + if (result == NERR_UserNotFound) { + error_setg(errp, "User %s was not found", username); + goto error; + } + + error_setg(errp, + "Received unexpected error when asking for user info: Error " + "Code %lu", + result); + goto error; + } + + /* Get information from the buffer returned by NetUserGetInfo. */ + uData->username = g_strdup(username); + uData->isAdmin = uBuf->usri4_priv == USER_PRIV_ADMIN; + psid = uBuf->usri4_user_sid; + + char *sidStr = NULL; + + /* + * We store the string representation of the SID not SID structure in + * memory. Callees wanting to use the SID structure should call + * ConvertStringSidToSID. + */ + if (!ConvertSidToStringSid(psid, &sidStr)) { + error_setg_win32(errp, GetLastError(), + "failed to get SID string for user %s", username); + goto error; + } + + /* Store the SSID */ + uData->SSID = sidStr; + + /* Get the SSH folder for the user. */ + char *sshFolder = get_ssh_folder(username, uData->isAdmin, errp); + if (sshFolder == NULL) { + goto error; + } + + /* Get the authorized key file path */ + const char *authorizedKeyFile = + uData->isAdmin ? AUTHORIZED_KEY_FILE_ADMIN : AUTHORIZED_KEY_FILE; + char *authorizedKeyPath = + g_build_filename(sshFolder, authorizedKeyFile, NULL); + uData->sshDirectory = sshFolder; + uData->authorizedKeyFile = authorizedKeyPath; + + /* Free */ + NetApiBufferFree(uBuf); + return true; +error: + if (uBuf) { + NetApiBufferFree(uBuf); + } + + return false; +} + +/* + * Gets the list of authorized keys for a user. + * + * parameters: + * username -> Username to retrieve the keys for. + * errp -> Error structure that will display any errors through QMP. + * returns: List of keys associated with the user. + */ +GuestAuthorizedKeys *qmp_guest_ssh_get_authorized_keys(const char *username, + Error **errp) +{ + GuestAuthorizedKeys *keys = NULL; + g_auto(GStrv) authKeys = NULL; + g_autoptr(GuestAuthorizedKeys) ret = NULL; + g_auto(PWindowsUserInfo) userInfo = NULL; + + /* Gets user information */ + if (!get_user_info(&userInfo, username, errp)) { + return NULL; + } + + /* Reads authkeys for the user */ + authKeys = read_authkeys(userInfo->authorizedKeyFile, errp); + if (authKeys == NULL) { + return NULL; + } + + /* Set the GuestAuthorizedKey struct with keys from the file */ + ret = g_new0(GuestAuthorizedKeys, 1); + for (int i = 0; authKeys[i] != NULL; i++) { + g_strstrip(authKeys[i]); + if (!authKeys[i][0] || authKeys[i][0] == '#') { + continue; + } + + QAPI_LIST_PREPEND(ret->keys, g_strdup(authKeys[i])); + } + + /* + * Steal the pointer because it is up for the callee to deallocate the + * memory. + */ + keys = g_steal_pointer(&ret); + return keys; +} + +/* + * Adds an ssh key for a user. + * + * parameters: + * username -> User to add the SSH key to + * strList -> Array of keys to add to the list + * has_reset -> Whether the keys have been reset + * reset -> Boolean to reset the keys (If this is set the existing list will be + * cleared) and the other key reset. errp -> Pointer to an error structure that + * will get returned over QMP if anything goes wrong. + */ +void qmp_guest_ssh_add_authorized_keys(const char *username, strList *keys, + bool has_reset, bool reset, Error **errp) +{ + g_auto(PWindowsUserInfo) userInfo = NULL; + g_auto(GStrv) authkeys = NULL; + strList *k; + size_t nkeys, nauthkeys; + + /* Make sure the keys given are valid */ + if (!check_openssh_pub_keys(keys, &nkeys, errp)) { + return; + } + + /* Gets user information */ + if (!get_user_info(&userInfo, username, errp)) { + return; + } + + /* Determine whether we should reset the keys */ + reset = has_reset && reset; + if (!reset) { + /* Read existing keys into memory */ + authkeys = read_authkeys(userInfo->authorizedKeyFile, NULL); + } + + /* Check that the SSH key directory exists for the user. */ + if (!g_file_test(userInfo->sshDirectory, G_FILE_TEST_IS_DIR)) { + BOOL success = create_ssh_directory(userInfo, errp); + if (!success) { + return; + } + } + + /* Reallocates the buffer to fit the new keys. */ + nauthkeys = authkeys ? g_strv_length(authkeys) : 0; + authkeys = g_realloc_n(authkeys, nauthkeys + nkeys + 1, sizeof(char *)); + + /* zero out the memory for the reallocated buffer */ + memset(authkeys + nauthkeys, 0, (nkeys + 1) * sizeof(char *)); + + /* Adds the keys */ + for (k = keys; k != NULL; k = k->next) { + /* Check that the key doesn't already exist */ + if (g_strv_contains((const gchar *const *)authkeys, k->value)) { + continue; + } + + authkeys[nauthkeys++] = g_strdup(k->value); + } + + /* Write the authkeys to the file. */ + write_authkeys(userInfo, authkeys, errp); +} + +/* + * Removes an SSH key for a user + * + * parameters: + * username -> Username to remove the key from + * strList -> List of strings to remove + * errp -> Contains any errors that occur. + */ +void qmp_guest_ssh_remove_authorized_keys(const char *username, strList *keys, + Error **errp) +{ + g_auto(PWindowsUserInfo) userInfo = NULL; + g_autofree struct passwd *p = NULL; + g_autofree GStrv new_keys = NULL; /* do not own the strings */ + g_auto(GStrv) authkeys = NULL; + GStrv a; + size_t nkeys = 0; + + /* Validates the keys passed in by the user */ + if (!check_openssh_pub_keys(keys, NULL, errp)) { + return; + } + + /* Gets user information */ + if (!get_user_info(&userInfo, username, errp)) { + return; + } + + /* Reads the authkeys for the user */ + authkeys = read_authkeys(userInfo->authorizedKeyFile, errp); + if (authkeys == NULL) { + return; + } + + /* Create a new buffer to hold the keys */ + new_keys = g_new0(char *, g_strv_length(authkeys) + 1); + for (a = authkeys; *a != NULL; a++) { + strList *k; + + /* Filters out keys that are equal to ones the user specified. */ + for (k = keys; k != NULL; k = k->next) { + if (g_str_equal(k->value, *a)) { + break; + } + } + + if (k != NULL) { + continue; + } + + new_keys[nkeys++] = *a; + } + + /* Write the new authkeys to the file. */ + write_authkeys(userInfo, new_keys, errp); +} |