File permission issues for mariadb-dump --dir #4478
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Pull request overview
This PR fixes file permission issues when using the --dir parameter in mariadb-dump. The change allows mariadb-dump and mariadbd to run under different OS users by ensuring that newly created database subdirectories inherit the same permissions and ownership as the root backup directory.
Key changes:
- Added
fix_permissions_and_owner()function to replicate permissions/ownership from the root backup directory to subdirectories - Integrated the new function into
ensure_out_dir_exists()to apply permission fixes after creating each database directory - Used static variables to cache root directory metadata and track which permission operations have failed
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When mariadb-dump runs with the --dir parameter, it creates new directories. These directories must allow both mariadb-dump and mariadbd to create new files in them. If mariadb-dump and mariadbd run under different users, this is not guaranteed. One problem is my_mkdir(), which by default creates directories writable only by the current user and group, due to the default my_umask_dir value of 0700. This fix tries to preserve the permissions and owner of the original backup directory passed with --dir when creating subdirectories. If this fails, a warning is issued and mariadb-dump continues. This is a best-effort approach. Failures may still occur later when the server tries to write to a newly created directory. In such cases, the permissions of the backup root directory (which mariadb-dump does not create) would already be incorrect.
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Description
When mariadb-dump runs with the --dir parameter, it creates new directories. These directories must allow both mariadb-dump and mariadbd to create new files in them.
If mariadb-dump and mariadbd run under different users, this is not guaranteed. One problem is my_mkdir(), which by default creates directories writable only by the current user and group, due to the default
my_umask_dirvalue of 0700.This fix tries to preserve the permissions and owner of the original backup directory passed with --dir when creating subdirectories. This makes mariabackup --dir behave similarly wrt file permissions as with older option --tab.
If setting permissions or owner fail, a warning is issued and mariadb-dump continues. This is a best-effort approach. Failures may still occur later when the server tries to write to a newly created directory. In such cases, the permissions of the backup root directory (which mariadb-dump does not create) would already be incorrect.
Release Notes
mariadb-dump using --dir parameter can now run under different OS user from mariadbd (e.g as root), on Unix-like operating
systems.
How can this PR be tested?
Unfortunately, the changes can't be automatically tested, since MTR runs all processes as the same OS user account.
To test it manually, start mariadbd as non-root user, and backup using mariadb-dump --dir as root.
Or backup , using mariadb-dump as different user in the same group as the one that runs mariadbd.
In all cases, make sure that the server can write into directory pointed to by --dir.
Basing the PR against the correct MariaDB version
mainbranch.PR quality check