[MDEV-15827] Running mariabackup with insufficient system privileges cause crash / coredump Created: 2018-04-09  Updated: 2023-04-27

Status: Open
Project: MariaDB Server
Component/s: Backup
Affects Version/s: 10.2.14, 10.3.5
Fix Version/s: 10.4

Type: Bug Priority: Minor
Reporter: Anders Karlsson Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: crash
Environment:

Linux CentOS 7.2

Attachments: Text File mariabackup_for_non_root_users_how _to.txt    
Issue Links:
Duplicate
is duplicated by MDEV-20385 Mariabackup crashed with non privileg... Closed

 Description   

As an ordinary user, run:

$ mariabackup -backup

This is an error, but shouldn't cause a core dump like this:

180409 17:26:16 Connecting to MySQL server host: localhost, user: not set, password: not set, port: not set, socket: not set
 
Using server version 10.2.14-MariaDB-log
 
mariabackup based on MariaDB server 10.2.14-MariaDB Linux (x86_64)
 
mariabackup: uses posix_fadvise().
 
mariabackup: cd to /var/lib/mysql/
 
mariabackup: open files limit requested 0, set to 1024
 
mariabackup: using the following InnoDB configuration:
 
mariabackup:   innodb_data_home_dir = .
 
mariabackup:   innodb_data_file_path = ibdata1:12M:autoextend
 
mariabackup:   innodb_log_group_home_dir = ./
 
2018-04-09 17:26:16 139746500786304 [Note] InnoDB: Number of pools: 1
 
2018-04-09 17:26:16 139746500786304 [ERROR] InnoDB: Operating system error number 13 in a file operation.
 
2018-04-09 17:26:16 139746500786304 [ERROR] InnoDB: The error means mysqld does not have the access rights to the directory.
 
2018-04-09 17:26:16 0x7f194489b880  InnoDB: Assertion failure in file /home/buildbot/buildbot/padding_for_CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX/mariadb-10.2.14/storage/innobase/fil/fil0fil.cc line 761
 
InnoDB: Failing assertion: success
 
InnoDB: We intentionally generate a memory trap.
 
InnoDB: Submit a detailed bug report to https://jira.mariadb.org/
 
InnoDB: If you get repeated assertion failures or crashes, even
 
InnoDB: immediately after the mysqld startup, there may be
 
InnoDB: corruption in the InnoDB tablespace. Please refer to
 
InnoDB: https://mariadb.com/kb/en/library/xtradbinnodb-recovery-modes/
 
InnoDB: about forcing recovery.
 
180409 17:26:16 [ERROR] mysqld got signal 6 ;
 
This could be because you hit a bug. It is also possible that this binary
 
or one of the libraries it was linked against is corrupt, improperly built,
 
or misconfigured. This error can also be caused by malfunctioning hardware.
 
 
 
To report this bug, see https://mariadb.com/kb/en/reporting-bugs
 
 
 
We will try our best to scrape up some info that will hopefully help
 
diagnose the problem, but since we have already crashed,
 
something is definitely wrong and this may fail.
 
 
 
Server version: 10.2.14-MariaDB
 
key_buffer_size=0
 
read_buffer_size=131072
 
max_used_connections=0
 
max_threads=1
 
thread_count=0
 
It is possible that mysqld could use up to
 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 5421 K  bytes of memory
 
Hope that's ok; if not, decrease some variables in the equation.
 
 
 
Thread pointer: 0x0
 
Attempting backtrace. You can use the following information to find out
 
where mysqld died. If you see no messages after this, something went
 
terribly wrong...
 
stack_bottom = 0x0 thread_stack 0x49000
 
addr2line: 'mariabackup': No such file
 
mariabackup(my_print_stacktrace+0x2e)[0x7f19454f552e]
 
mariabackup(handle_fatal_signal+0x355)[0x7f1944fe3835]
 
sigaction.c:0(__restore_rt)[0x7f19444ac100]
 
:0(__GI_raise)[0x7f1942a395f7]
 
:0(__GI_abort)[0x7f1942a3ace8]
 
addr2line: 'mariabackup': No such file
 
mariabackup(+0x434b1e)[0x7f1944d11b1e]
 
mariabackup(+0x8d40f5)[0x7f19451b10f5]
 
mariabackup(+0x8d432b)[0x7f19451b132b]
 
mariabackup(+0x8debe2)[0x7f19451bbbe2]
 
mariabackup(+0x989aa6)[0x7f1945266aa6]
 
mariabackup(+0x992245)[0x7f194526f245]
 
mariabackup(+0x457e22)[0x7f1944d34e22]
 
mariabackup(main+0x185)[0x7f1944d13b05]
 
/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f1942a25b15]
 
addr2line: 'mariabackup': No such file
 
mariabackup(+0x45016d)[0x7f1944d2d16d]
 
The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
 
information that should help you find out what is causing the crash.
 
Aborted

Note that the dump says that "mysqld got signal 6", but actually mysqld per se didn't crash at all. In addition, there is a pointer at the end to a page in the MySQL manual that is unliekly to help (http://dev.mysql.com/doc/mysql/en/crashing.html) .

The workaround is to run mariabackup with sudo, obviously.

 Comments   
Comment by Zdravelina Sokolovska (Inactive) [ 2018-04-11 ]

workaround about mariabackup performing for non root user

[root@t4w6 ~]# sudo usermod -aG wheel foo4

[foo4@t4w6 ~]$ sudo chmod +s /usr/bin/mariabackup

[foo4@t4w6 ~]$ sudo chmod g+r /var/lib/mysql/ibdata1

Login as user 'foo4' and perform mariabackup 
 
 
 
 
 
 
login as: foo4
 
foo4@t4w6's password:
 
Last login: Wed Apr 11 13:37:25 2018
 
 
 
 
 
[foo4@t4w6 ~]$  mariabackup -u root -p1  --backup
 
180411 13:41:49 Connecting to MySQL server host: localhost, user: root, password: set, port: not set, socket: not set
 
Using server version 10.3.5-MariaDB
 
mariabackup based on MariaDB server 10.3.5-MariaDB Linux (x86_64)
 
mariabackup: uses posix_fadvise().
 
mariabackup: cd to /var/lib/mysql/
 
mariabackup: open files limit requested 0, set to 1024
 
mariabackup: using the following InnoDB configuration:
 
mariabackup:   innodb_data_home_dir = .
 
mariabackup:   innodb_data_file_path = ibdata1:12M:autoextend
 
mariabackup:   innodb_log_group_home_dir = ./
 
2018-04-11 13:41:49 0 [Note] InnoDB: Number of pools: 1
 
180411 13:41:49 >> log scanned up to (51002181432)
 
mariabackup: Generating a list of tablespaces
 
2018-04-11 13:41:49 0 [Warning] InnoDB: Allocated tablespace ID 127 for md_15252/BRc273a13dfd, old maximum was 0
 
180411 13:41:49 [01] Copying ./ibdata1 to /home/foo4/xtrabackup_backupfiles/ibdata1
 
180411 13:41:50 >> log scanned up to (51002181432)
 
180411 13:42:08 [01]        ...done
 
180411 13:42:08 [01] Copying ./md_15252/BRc273a13dfd.ibd to /home/foo4/xtrabackup_backupfiles/md_15252/BRc273a13dfd.ibd
 
180411 13:42:08 [01]        ...done
 
 
 
~~~~~~ full log attached
 
180411 13:43:12 [01]        ...done
 
180411 13:43:12 Executing FLUSH NO_WRITE_TO_BINLOG ENGINE LOGS...
 
mariabackup: The latest check point (for incremental): '51002181423'
 
mariabackup: Stopping log copying thread.
 
 
 
2018-04-11 13:43:12 0 [Note] InnoDB: Read redo log up to LSN=51002181632
 
180411 13:43:12 >> log scanned up to (51002181432)
 
180411 13:43:12 Executing UNLOCK TABLES
 
180411 13:43:12 All tables unlocked
 
180411 13:43:12 [00] Copying ib_buffer_pool to /home/foo4/xtrabackup_backupfiles/ib_buffer_pool
 
180411 13:43:12 [00]        ...done
 
180411 13:43:12 Backup created in directory '/home/foo4/xtrabackup_backupfiles/'
 
180411 13:43:12 [00] Writing backup-my.cnf
 
180411 13:43:12 [00]        ...done
 
180411 13:43:12 [00] Writing xtrabackup_info
 
180411 13:43:12 [00]        ...done
 
mariabackup: Redo log (from LSN 51002181423 to 51002181432) was copied.
 
180411 13:43:12 completed OK!
 
[foo4@t4w6 ~]$

Comment by Anders Karlsson [ 2018-04-11 ]

Tried workaround with 10.2.14 and I got:
180411 16:06:19 Connecting to MySQL server host: localhost, user: root, password: not set, port: not set, socket: not set
Using server version 10.2.14-MariaDB-log
mariabackup based on MariaDB server 10.2.14-MariaDB Linux (x86_64)
mariabackup: uses posix_fadvise().
mariabackup: cd to /var/lib/mysql/
mariabackup: open files limit requested 0, set to 1024
mariabackup: using the following InnoDB configuration:
mariabackup: innodb_data_home_dir = .
mariabackup: innodb_data_file_path = ibdata1:12M:autoextend
mariabackup: innodb_log_group_home_dir = ./
2018-04-11 16:06:19 140510829865088 [Note] InnoDB: Number of pools: 1
2018-04-11 16:06:19 140510829865088 [ERROR] InnoDB: The innodb_system data file 'ibdata1' must be readable
2018-04-11 16:06:19 140510829865088 [ERROR] InnoDB: The innodb_system data file 'ibdata1' must be readable
mariabackup: could not find data files at the specified datadir
mariabackup: error: xb_load_tablespaces() failed with error Generic error.

Comment by Vladislav Vaintroub [ 2018-04-11 ]

it must be readable . mariabackup copies files. To copy a file, one needs to read a file.

Comment by Anders Karlsson [ 2018-04-11 ]

Yes, that is obvious, which is why I reported it, it doesn't even when the instructions are followed. I assume that you want

  1. sudo usermod -aG mysql foo4
    instead of
  2. sudo usermod -aG wheel foo4
Comment by Zdravelina Sokolovska (Inactive) [ 2018-04-11 ]

actually with ' usermod -aG wheel foo4 '
it's aimed to give to user 'foo4' sudo access – these details was done in the attached file :
edit the /etc/sudoers file and grant sudo access to users in the group wheel
then user may login and get mariabackup even w/o 'sudo'

Comment by Anders Karlsson [ 2018-04-11 ]

Ah, that was the sudoers thing, that was in the attached file but not in the text. Makes sense, but adding the mysql group to the foo4 user also seems to work. All in all, my main issue here wasn't how to run maricbackup but that just a simple error caused a core dump.

Comment by Zdravelina Sokolovska (Inactive) [ 2018-04-11 ]

yes, thank you.
you should receive Error instead message about crash
the workaround is to
avoid the crash with [foo4@t4w6 ~]$ sudo chmod +s /usr/bin/mariabackup
avoid the the error with [foo4@t4w6 ~]$ sudo chmod g+r /var/lib/mysql/ibdata1
and if user is also given sudo access, it may just login and get mariabackup

Comment by Ralf Gebhardt [ 2021-08-12 ]

serg, this issue is marked as priority minor, but results in a crash. Any chance that we get it fixed in a way that an error will be shown instead of a crash?

Comment by Sergei Golubchik [ 2021-08-12 ]

yes, when MDEV-13542 is fixed.

Comment by Marko Mäkelä [ 2022-06-07 ]

I don’t think that any mariabackup --backup code was fixed in MDEV-13542.
mariabackup --prepare yes, but not the backup part.

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