Re: [PATCH ghak21 V2 0/4] audit: address ANOM_LINK excess records

[Richard Guy Briggs]

On 2018-03-12 02:31, Richard Guy Briggs wrote:
> Audit link denied events were being unexpectedly produced in a disjoint
> way when audit was disabled, and when they were expected, there were
> duplicate PATH records.  This patchset addresses both issues for
> symlinks and hardlinks.
> 
> This was introduced with
> 	commit b24a30a7305418ff138ff51776fc555ec57c011a
> 	("audit: fix event coverage of AUDIT_ANOM_LINK")
> 	commit a51d9eaa41866ab6b4b6ecad7b621f8b66ece0dc
> 	("fs: add link restriction audit reporting")
> 
> Here are the resulting events:
> 
> symlink:
> type=PROCTITLE msg=audit(03/12/2018 02:21:49.578:310) : proctitle=ls ./my-passwd 
> type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=1 name=/tmp/ inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 
> type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=0 name=./my-passwd inode=17090 dev=00:27 mode=link,777 ouid=rgb ogid=rgb rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 
> type=CWD msg=audit(03/12/2018 02:21:49.578:310) : cwd=/tmp 
> type=SYSCALL msg=audit(03/12/2018 02:21:49.578:310) : arch=x86_64 syscall=stat success=no exit=EACCES(Permission denied) a0=0x7ffd79950dda a1=0x563f658a03c8 a2=0x563f658a03c8 a3=0x79950d00 items=2 ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) 
> type=ANOM_LINK msg=audit(03/12/2018 02:21:49.578:310) : op=follow_link ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no 
> ----
> hardlink:
> type=PROCTITLE msg=audit(03/12/2018 02:24:39.813:314) : proctitle=ln test test-ln 
> type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=1 name=/tmp inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 
> type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=0 name=test inode=18112 dev=00:27 mode=file,700 ouid=root ogid=root rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 
> type=CWD msg=audit(03/12/2018 02:24:39.813:314) : cwd=/tmp 
> type=SYSCALL msg=audit(03/12/2018 02:24:39.813:314) : arch=x86_64 syscall=linkat success=no exit=EPERM(Operation not permitted) a0=0xffffff9c a1=0x7ffccba77629 a2=0xffffff9c a3=0x7ffccba7762e items=2 ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) 
> type=ANOM_LINK msg=audit(03/12/2018 02:24:39.813:314) : op=linkat ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no 
> 
> See: https://github.com/linux-audit/audit-kernel/issues/21
> See also: https://github.com/linux-audit/audit-kernel/issues/51
> 
> Richard Guy Briggs (4):
>   audit: make ANOM_LINK obey audit_enabled and audit_dummy_context
>   audit: link denied should not directly generate PATH record
>   audit: add refused symlink to audit_names
>   audit: add parent of refused symlink to audit_names
> 
>  fs/namei.c            |  5 +++--
>  include/linux/audit.h |  9 +++++----
>  kernel/audit.c        | 43 ++++++++++++++++++++++++++++++++-----------
>  3 files changed, 40 insertions(+), 17 deletions(-)
> 
> -- 

Changelog:
v2:
- remove now supperfluous struct path * parameter from audit_log_link_denied()
- refactor audit_log_symlink_denied() to properly free memory (pathname, filename)

> 1.8.3.1
> 

- RGB

--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635