bpf_obj_get(path) is entirely equivalent to mapRetrieveRW(path)
See implementation in frameworks/libs/net common/native/bpf_syscall_wrappers/include/BpfSyscallWrappers.h:
inline int bpfFdGet(const char* pathname, uint32_t flag) {
return bpf(BPF_OBJ_GET, {
.pathname = ptr_to_u64(pathname),
.file_flags = flag,
});
}
inline int mapRetrieve(const char* pathname, uint32_t flag) { return bpfFdGet(pathname, flag); }
inline int mapRetrieveRW(const char* pathname) { return mapRetrieve(pathname, 0); }
inline int mapRetrieveRO(const char* pathname) { return mapRetrieve(pathname, BPF_F_RDONLY); }
inline int mapRetrieveWO(const char* pathname) { return mapRetrieve(pathname, BPF_F_WRONLY); }
inline int retrieveProgram(const char* pathname) { return bpfFdGet(pathname, BPF_F_RDONLY); }
However, this requires selinux file:write access which bpfloader
currently lacks, ie. we would need:
system/sepolicy private/bpfloader.te:
-allow bpfloader bpffs_type:file { create read rename setattr };
+allow bpfloader bpffs_type:file { create read rename setattr write };
Switching from mapRetrieveRW() to mapRetrieveRO() eliminates this problem.
BpfLoader itself does not need to write to the maps, while bpf program write
access is controlled by a different bit (it is independent of the r/w access
bits of the file descriptor itself).
Verified by re-opening the maps after pinning them.
Bug: 218408035
Bug: 237716689
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ica7ac8ee48d4a73e5f92dbf47cd441c3bfba38cf
am skip reason: Merged-In I553e90e0414453f8f3aaca8cf05d5decc8b911a2 with SHA-1 37b3d06333 is already in history
Original change: https://android-review.googlesource.com/c/platform/system/bpf/+/2133348
Change-Id: I1fa112613b2fc0229c58bf145a3b678e84d76873
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
BTF support was added to bpfloader during Android T dev cycle.
As it causes bpfloader boot time process to shell out to a new
btfloader subprocess for every bpf.o file with BTF debugging
information compiled in, I'm worried this might have unforeseen
consequences - things like crashes or boot time bpfloader cpu
regressions.
However, BTF is exceedingly useful for debugging,
and it would be a huge pity if we were forced to disable it
and keep it disabled in mainline tethering module just to support
Android T devices for the next 5+ years.
It would also be a pity if the bpf.o files in prebuilt mainline
tethering apex in dev branches (like tm-dev) did not include
BTF debug information simply due to compatibility with older
kernels or OSes, since this would require rebuilding the module
everytime BTF information could be of use.
One of the things functioning BTF enables is 'cat /sys/fs/bpf/map_*'
as root on a userdebug build. Among other things this can be
used to verify that in kernel bpf map state matches that dumped
by the mainline module's pretty dump code.
Even if there's issues wrt. BTF in Android T (or on older kernels),
we can always fix them in Android U or later (for example build
btfloader into bpfloader to avoid exec overhead, etc...).
Bug: 218408035
Bug: 230585250
Bug: 235559605
Test: TreeHugger, cuttlefish devices boots, and:
adb root && adb shell cat /sys/fs/bpf/map_time_in_state_cpu_last_pid_map
continues to show information which is available due to BTF debug provided
in /system/etc/bpf/time_in_state.o file (due to "btf: true" in Android.bp)
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I553e90e0414453f8f3aaca8cf05d5decc8b911a2
(cherry picked from commit 37b3d06333)
Merged-In: I553e90e0414453f8f3aaca8cf05d5decc8b911a2
BTF support was added to bpfloader during Android T dev cycle.
As it causes bpfloader boot time process to shell out to a new
btfloader subprocess for every bpf.o file with BTF debugging
information compiled in, I'm worried this might have unforeseen
consequences - things like crashes or boot time bpfloader cpu
regressions.
However, BTF is exceedingly useful for debugging,
and it would be a huge pity if we were forced to disable it
and keep it disabled in mainline tethering module just to support
Android T devices for the next 5+ years.
It would also be a pity if the bpf.o files in prebuilt mainline
tethering apex in dev branches (like tm-dev) did not include
BTF debug information simply due to compatibility with older
kernels or OSes, since this would require rebuilding the module
everytime BTF information could be of use.
One of the things functioning BTF enables is 'cat /sys/fs/bpf/map_*'
as root on a userdebug build. Among other things this can be
used to verify that in kernel bpf map state matches that dumped
by the mainline module's pretty dump code.
Even if there's issues wrt. BTF in Android T (or on older kernels),
we can always fix them in Android U or later (for example build
btfloader into bpfloader to avoid exec overhead, etc...).
Bug: 218408035
Bug: 230585250
Bug: 235559605
Test: TreeHugger, cuttlefish devices boots, and:
adb root && adb shell cat /sys/fs/bpf/map_time_in_state_cpu_last_pid_map
continues to show information which is available due to BTF debug provided
in /system/etc/bpf/time_in_state.o file (due to "btf: true" in Android.bp)
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I553e90e0414453f8f3aaca8cf05d5decc8b911a2
This reverts commit 8e5e239dd0a7856e486a9e2d772ef3a9e38021eb.
No longer required now that selinux change has landed.
(while we're at it bump the bpfloader version to v0.19 just
to make sure we can tell these apart in the future)
This is a cherrypick to tm-dev of reviewed/approved but unsubmitted:
https://android-review.googlesource.com/c/platform/system/bpf/+/2132534
Ignore-AOSP-First: will be cherrypicked to aosp master
Bug: 218408035
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I0b3349ef908bbfd225b8b7f83b2a4a8870c1e409
This reverts commit 8e5e239dd0a7856e486a9e2d772ef3a9e38021eb.
No longer required now that selinux change has landed.
(while we're at it bump the bpfloader version to v0.19 just
to make sure we can tell these apart in the future)
Bug: 218408035
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I0b3349ef908bbfd225b8b7f83b2a4a8870c1e409
(it requires bpfloader to be granted rename priv by selinux)
Bug: 218408035
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ic27d0e5f3c6b78db39c6742fe9e1955f65d2b1f5
This is needed to make it safe to share maps across different .o's.
Bug: 218408035
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I9e8a5893ed4f91354f6544be587b10a97d179de6
(cherry picked from commit 12bb520707)
Merged-In: I9e8a5893ed4f91354f6544be587b10a97d179de6
For use by:
- maps netd should have read but not write access to
(needed due to netd being root with DAC_OVERRIDE,
and thus not obeying standard unix permissions)
- programs that netd should have access to but
not netutils_wrappers (which due to being able to
run iptables, needs access to xt_bpf programs)
Bug: 218408035
Test: booted on cuttlefish
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I72b106692a25077ff54252fd93db81f46b52125d
(cherry picked from commit 32c0b8f46e)
Merged-In: I72b106692a25077ff54252fd93db81f46b52125d
This is needed to make it safe to share maps across different .o's.
Bug: 218408035
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I9e8a5893ed4f91354f6544be587b10a97d179de6
For use by:
- maps netd should have read but not write access to
(needed due to netd being root with DAC_OVERRIDE,
and thus not obeying standard unix permissions)
- programs that netd should have access to but
not netutils_wrappers (which due to being able to
run iptables, needs access to xt_bpf programs)
Bug: 218408035
Test: booted on cuttlefish
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I72b106692a25077ff54252fd93db81f46b52125d
