Fantastic Friday All,
I was tracking down a problem with SFTP retrieved files having unexpected file permissions.
The remote file permissions were 0070.
The local file did not exist before the transfer request.
The local account had a umask of 0022.
The local file permissions after the transfer were 0250.
The code below is from the sftp-client.c file : in the do_download function [that starts around Line 1197 in a recent snapshot].
----------------------------------------------------------------------------------------------------------------------------------------------------
(My comment: This gets the permissions of the remote file and stores them in the variable "mode")
/* Do not preserve set[ug]id here, as we do not preserve ownership */
if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS)
mode = a->perm & 0777;
else
mode = 0666;
----------------------------------------------------------------------------------------------------------------------------------------------------
(My comment: This opens and creates the local file with the permissions of the remote file with a user write bit added and masked by the local umask)
local_fd = open(local_path,
O_WRONLY | O_CREAT | (resume_flag ? 0 : O_TRUNC), mode | S_IWUSR)
----------------------------------------------------------------------------------------------------------------------------------------------------
(My comment: After all is transferred, change the local file permissions if they should be preserved (e.g. get -p) by applying what is stored in the "mode" variable)
/* Override umask and utimes if asked */
#ifdef HAVE_FCHMOD
if (preserve_flag && fchmod(local_fd, mode) == -1)
#else
if (preserve_flag && chmod(local_path, mode) == -1)
#endif /* HAVE_FCHMOD */
error("Couldn't set mode on \"%s\": %s", local_path,
strerror(errno));
----------------------------------------------------------------------------------------------------------------------------------------------------
MY QUESTION: Why is the local file create the following code:
local_fd = open(local_path, O_WRONLY | O_CREAT | (resume_flag ? 0 : O_TRUNC), mode | S_IWUSR)
Why is it created with the remote file permissions but the local umask?
Why is it not something like the following (apply the local account umask to 0666)?
local_fd = open(local_path, O_WRONLY | O_CREAT | (resume_flag ? 0 : O_TRUNC), S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)
What am I missing? Is there a controlling standard?
Thanks,
Matt S
_______________________________________________
openssh-unix-dev mailing list
openssh-unix-dev@xxxxxxxxxxx
https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
