Fix attaching fentry/fexit/fmod_ret/lsm to modules #4159
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Upstream branch: ab0350c |
kernel-patches-bot
force-pushed
the
bpf-next_base
branch
from
9b23ff9
to
05cf506
Compare
added 3 commits
December 5, 2022 11:15
Until now, the only way to look up a symbol in kallsyms of a particular module was using the "module_kallsyms_lookup_name" function with the "module:symbol" string passed as a parameter. This syntax often requires to build the parameter string on stack, needlessly wasting space. This commit introduces function "kallsyms_lookup_name_in_module" which takes the module and the symbol names as separate parameters and therefore allows more space-efficient lookup. Signed-off-by: Viktor Malik <vmalik@redhat.com>
When attaching fentry/fexit/fmod_ret/lsm to a function located in a module without specifying the target program, the verifier tries to find the address to attach to in kallsyms. This is always done by searching the entire kallsyms, not respecting the module in which the function is located. This approach causes an incorrect attachment address to be computed if the function to attach to is shadowed by a function of the same name located earlier in kallsyms. Since the attachment must contain the BTF of the program to attach to, we may extract the module name from it (if the attach target is a module) and search for the function address in the correct module. Signed-off-by: Viktor Malik <vmalik@redhat.com> Acked-by: Hao Luo <haoluo@google.com>
Adds a new test that tries to attach a program to fentry of two functions of the same name, one located in vmlinux and the other in bpf_testmod. To avoid conflicts with existing tests, a new function "bpf_fentry_shadow_test" was created both in vmlinux and in bpf_testmod. The previous commit fixed a bug which caused this test to fail. The verifier would always use the vmlinux function's address as the target trampoline address, hence trying to attach two programs to the same trampoline. Signed-off-by: Viktor Malik <vmalik@redhat.com>
|
Upstream branch: ab0350c |
kernel-patches-bot
force-pushed
the
series/699592=>bpf-next
branch
from
e0fb92b
to
54c36bd
Compare
|
At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=701852 expired. Closing PR. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull request for series with
subject: Fix attaching fentry/fexit/fmod_ret/lsm to modules
version: 3
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=701852