AppArmor was putting the reference to i_private data on its end after
removing the original entry from the file system. However the inode
can aand does live beyond that point and it is possible that some of
the fs call back functions will be invoked after the reference has
been put, which results in a race between freeing the data and
accessing it through the fs.
While the rawdata/loaddata is the most likely candidate to fail the
race, as it has the fewest references. If properly crafted it might be
possible to trigger a race for the other types stored in i_private.
Fix this by moving the put of i_private referenced data to the correct
place which is during inode eviction.
Fixes: c961ee5f21 ("apparmor: convert from securityfs to apparmorfs for policy ns files")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Reviewed-by: Maxime Bélair <maxime.belair@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
There is a race condition that leads to a use-after-free situation:
because the rawdata inodes are not refcounted, an attacker can start
open()ing one of the rawdata files, and at the same time remove the
last reference to this rawdata (by removing the corresponding profile,
for example), which frees its struct aa_loaddata; as a result, when
seq_rawdata_open() is reached, i_private is a dangling pointer and
freed memory is accessed.
The rawdata inodes weren't refcounted to avoid a circular refcount and
were supposed to be held by the profile rawdata reference. However
during profile removal there is a window where the vfs and profile
destruction race, resulting in the use after free.
Fix this by moving to a double refcount scheme. Where the profile
refcount on rawdata is used to break the circular dependency. Allowing
for freeing of the rawdata once all inode references to the rawdata
are put.
Fixes: 5d5182cae4 ("apparmor: move to per loaddata files, instead of replicating in profiles")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Reviewed-by: Maxime Bélair <maxime.belair@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Differential encoding allows loops to be created if it is abused. To
prevent this the unpack should verify that a diff-encode chain
terminates.
Unfortunately the differential encode verification had two bugs.
1. it conflated states that had gone through check and already been
marked, with states that were currently being checked and marked.
This means that loops in the current chain being verified are treated
as a chain that has already been verified.
2. the order bailout on already checked states compared current chain
check iterators j,k instead of using the outer loop iterator i.
Meaning a step backwards in states in the current chain verification
was being mistaken for moving to an already verified state.
Move to a double mark scheme where already verified states get a
different mark, than the current chain being kept. This enables us
to also drop the backwards verification check that was the cause of
the second error as any already verified state is already marked.
Fixes: 031dcc8f4e ("apparmor: dfa add support for state differential encoding")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
An unprivileged local user can load, replace, and remove profiles by
opening the apparmorfs interfaces, via a confused deputy attack, by
passing the opened fd to a privileged process, and getting the
privileged process to write to the interface.
This does require a privileged target that can be manipulated to do
the write for the unprivileged process, but once such access is
achieved full policy management is possible and all the possible
implications that implies: removing confinement, DoS of system or
target applications by denying all execution, by-passing the
unprivileged user namespace restriction, to exploiting kernel bugs for
a local privilege escalation.
The policy management interface can not have its permissions simply
changed from 0666 to 0600 because non-root processes need to be able
to load policy to different policy namespaces.
Instead ensure the task writing the interface has privileges that
are a subset of the task that opened the interface. This is already
done via policy for confined processes, but unconfined can delegate
access to the opened fd, by-passing the usual policy check.
Fixes: b7fd2c0340 ("apparmor: add per policy ns .load, .replace, .remove interface files")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Currently the number of policy namespaces is not bounded relying on
the user namespace limit. However policy namespaces aren't strictly
tied to user namespaces and it is possible to create them and nest
them arbitrarily deep which can be used to exhaust system resource.
Hard cap policy namespaces to the same depth as user namespaces.
Fixes: c88d4c7b04 ("AppArmor: core policy routines")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Reviewed-by: Ryan Lee <ryan.lee@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This patch doesn't change current functionality, it switches the two
uses of the in_ns fns and macros into the two semantically different
cases they are used for.
xxx_in_scope for checking mediation interaction between profiles
xxx_in_view to determine which profiles are visible.The scope will
always be a subset of the view as profiles that can not see each
other can not interact.
The split can not be completely done for label_match because it has to
distinct uses matching permission against label in scope, and checking
if a transition to a profile is allowed. The transition to a profile
can include profiles that are in view but not in scope, so retain this
distinction as a parameter.
While at the moment the two uses are very similar, in the future there
will be additional differences. So make sure the semantics differences
are present in the code.
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
aa_cred_raw_label() and cred_label() now do the same things so
consolidate to cred_label()
Document the crit section use and constraints better and refactor
__begin_current_label_crit_section() into a base fn
__begin_cred_crit_section() and a wrapper that calls the base with
current cred.
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Add support for the per permission tag index for a given permission
set. This will be used by both meta-data tagging, to allow annotating
accept states with context and debug information. As well as by rule
tainting and triggers to specify the taint or trigger to be applied.
Since these are low frequency ancillary data items they are stored
in a tighter packed format to that allows for sharing and reuse of the
strings between permissions and accept states. Reducing the amount of
kernel memory use at the cost of having to go through a couple if
index based indirections.
The tags are just strings that has no meaning with out context. When
used as meta-data for auditing and debugging its entirely information
for userspace, but triggers, and tainting can be used to affect the
domain. However they all exist in the same packed data set and can
be shared between different uses.
Signed-off-by: John Johansen <john.johansen@canonical.com>
The strtable is currently limited to a single entry string on unpack
even though domain has the concept of multiple entries within it. Make
this a reality as it will be used for tags and more advanced domain
transitions.
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Source blob may come from userspace and might be unaligned.
Try to optize the copying process by avoiding unaligned memory accesses.
- Added Fixes tag
- Added "Fix &" to description as this doesn't just optimize but fixes
a potential unaligned memory access
Fixes: e6e8bf4188 ("apparmor: fix restricted endian type warnings for dfa unpack")
Signed-off-by: Helge Deller <deller@gmx.de>
[jj: remove duplicate word "convert" in comment trigger checkpatch warning]
Signed-off-by: John Johansen <john.johansen@canonical.com>
Pull apparmor updates from John Johansen:
"This has one major feature, it pulls in a cleaned up version of
af_unix mediation that Ubuntu has been carrying for years. It is
placed behind a new abi to ensure that it does cause policy
regressions. With pulling in the af_unix mediation there have been
cleanups and some refactoring of network socket mediation. This
accounts for the majority of the changes in the diff.
In addition there are a few improvements providing minor code
optimizations. several code cleanups, and bug fixes.
Features:
- improve debug printing
- carry mediation check on label (optimization)
- improve ability for compiler to optimize
__begin_current_label_crit_section
- transition for a linked list of rulesets to a vector of rulesets
- don't hardcode profile signal, allow it to be set by policy
- ability to mediate caps via the state machine instead of lut
- Add Ubuntu af_unix mediation, put it behind new v9 abi
Cleanups:
- fix typos and spelling errors
- cleanup kernel doc and code inconsistencies
- remove redundant checks/code
- remove unused variables
- Use str_yes_no() helper function
- mark tables static where appropriate
- make all generated string array headers const char *const
- refactor to doc semantics of file_perm checks
- replace macro calls to network/socket fns with explicit calls
- refactor/cleanup socket mediation code preparing for finer grained
mediation of different network families
- several updates to kernel doc comments
Bug fixes:
- fix incorrect profile->signal range check
- idmap mount fixes
- policy unpack unaligned access fixes
- kfree_sensitive() where appropriate
- fix oops when freeing policy
- fix conflicting attachment resolution
- fix exec table look-ups when stacking isn't first
- fix exec auditing
- mitigate userspace generating overly large xtables"
* tag 'apparmor-pr-2025-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor: (60 commits)
apparmor: fix: oops when trying to free null ruleset
apparmor: fix Regression on linux-next (next-20250721)
apparmor: fix test error: WARNING in apparmor_unix_stream_connect
apparmor: Remove the unused variable rules
apparmor: fix: accept2 being specifie even when permission table is presnt
apparmor: transition from a list of rules to a vector of rules
apparmor: fix documentation mismatches in val_mask_to_str and socket functions
apparmor: remove redundant perms.allow MAY_EXEC bitflag set
apparmor: fix kernel doc warnings for kernel test robot
apparmor: Fix unaligned memory accesses in KUnit test
apparmor: Fix 8-byte alignment for initial dfa blob streams
apparmor: shift uid when mediating af_unix in userns
apparmor: shift ouid when mediating hard links in userns
apparmor: make sure unix socket labeling is correctly updated.
apparmor: fix regression in fs based unix sockets when using old abi
apparmor: fix AA_DEBUG_LABEL()
apparmor: fix af_unix auditing to include all address information
apparmor: Remove use of the double lock
apparmor: update kernel doc comments for xxx_label_crit_section
apparmor: make __begin_current_label_crit_section() indicate whether put is needed
...
The set of rules on a profile is not dynamically extended, instead
if a new ruleset is needed a new version of the profile is created.
This allows us to use a vector of rules instead of a list, slightly
reducing memory usage and simplifying the code.
Signed-off-by: John Johansen <john.johansen@canonical.com>
When a unix socket is passed into a different confinement domain make
sure its cached mediation labeling is updated to correctly reflect
which domains are using the socket.
Fixes: c05e705812 ("apparmor: add fine grained af_unix mediation")
Signed-off-by: John Johansen <john.johansen@canonical.com>
Policy loaded using abi 7 socket mediation was not being applied
correctly in all cases. In some cases with fs based unix sockets a
subset of permissions where allowed when they should have been denied.
This was happening because the check for if the socket was an fs based
unix socket came before the abi check. But the abi check is where the
correct path is selected, so having the fs unix socket check occur
early would cause the wrong code path to be used.
Fix this by pushing the fs unix to be done after the abi check.
Fixes: dcd7a55941 ("apparmor: gate make fine grained unix mediation behind v9 abi")
Signed-off-by: John Johansen <john.johansen@canonical.com>
AA_DEBUG_LABEL() was not specifying it vargs, which is needed so it can
output debug parameters.
Fixes: 71e6cff3e0 ("apparmor: Improve debug print infrastructure")
Signed-off-by: John Johansen <john.johansen@canonical.com>
The auditing of addresses currently doesn't include the source address
and mixes source and foreign/peer under the same audit name. Fix this
so source is always addr, and the foreign/peer is peer_addr.
Fixes: c05e705812 ("apparmor: add fine grained af_unix mediation")
Signed-off-by: John Johansen <john.johansen@canonical.com>
The use of the double lock is not necessary and problematic. Instead
pull the bits that need locks into their own sections and grab the
needed references.
Fixes: c05e705812 ("apparmor: add fine grained af_unix mediation")
Signed-off-by: John Johansen <john.johansen@canonical.com>
Add a kernel doc header for __end_current_label_crit_section(), and
update the header for __begin_current_label_crit_section().
Fixes: b42ecc5f58ef ("apparmor: make __begin_current_label_crit_section() indicate whether put is needed")
Signed-off-by: John Johansen <john.johansen@canonical.com>
Same as aa_get_newest_cred_label_condref().
This avoids a bunch of work overall and allows the compiler to note when no
clean up is necessary, allowing for tail calls.
This in particular happens in apparmor_file_permission(), which manages to
tail call aa_file_perm() 105 bytes in (vs a regular call 112 bytes in
followed by branches to figure out if clean up is needed).
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Some versions of the parser are generating an xtable transition per
state in the state machine, even when the state machine isn't using
the transition table.
The parser bug is triggered by
commit 2e12c5f060 ("apparmor: add additional flags to extended permission.")
In addition to fixing this in userspace, mitigate this in the kernel
as part of the policy verification checks by detecting this situation
and adjusting to what is actually used, or if not used at all freeing
it, so we are not wasting unneeded memory on policy.
Fixes: 2e12c5f060 ("apparmor: add additional flags to extended permission.")
Signed-off-by: John Johansen <john.johansen@canonical.com>
The label struct is variable length. While its use in struct aa_profile
is fixed length at 2 entries the variable length member needs to be
the last member in the structure.
The code already does this but the comment has it in the wrong location.
Also add a comment to ensure it stays at the end of the structure.
While we are at it, update the documentation for other profile members
as well.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Conflicting attachment resolution is based on the number of states
traversed to reach an accepting state in the attachment DFA, accounting
for DFA loops traversed during the matching process. However, the loop
counting logic had multiple bugs:
- The inc_wb_pos macro increments both position and length, but length
is supposed to saturate upon hitting buffer capacity, instead of
wrapping around.
- If no revisited state is found when traversing the history, is_loop
would still return true, as if there was a loop found the length of
the history buffer, instead of returning false and signalling that
no loop was found. As a result, the adjustment step of
aa_dfa_leftmatch would sometimes produce negative counts with loop-
free DFAs that traversed enough states.
- The iteration in the is_loop for loop is supposed to stop before
i = wb->len, so the conditional should be < instead of <=.
This patch fixes the above bugs as well as the following nits:
- The count and size fields in struct match_workbuf were not used,
so they can be removed.
- The history buffer in match_workbuf semantically stores aa_state_t
and not unsigned ints, even if aa_state_t is currently unsigned int.
- The local variables in is_loop are counters, and thus should be
unsigned ints instead of aa_state_t's.
Fixes: 21f6066105 ("apparmor: improve overlapping domain attachment resolution")
Signed-off-by: Ryan Lee <ryan.lee@canonical.com>
Co-developed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
WB_HISTORY_SIZE was defined to be a value not a power of 2, despite a
comment in the declaration of struct match_workbuf stating it is and a
modular arithmetic usage in the inc_wb_pos macro assuming that it is. Bump
WB_HISTORY_SIZE's value up to 32 and add a BUILD_BUG_ON_NOT_POWER_OF_2
line to ensure that any future changes to the value of WB_HISTORY_SIZE
respect this requirement.
Fixes: 136db99485 ("apparmor: increase left match history buffer size")
Signed-off-by: Ryan Lee <ryan.lee@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
John Johansen
Helge DellerandJohn Johansen
Paul Moore
Linus Torvalds
Mateusz GuzikandJohn Johansen
Ryan LeeandJohn Johansen