Add support to set and remove xattr from BPF program. Also add security.bpf. xattr name prefix. kfuncs are added to set and remove xattrs with security.bpf. name prefix. Update kfuncs bpf_get_[file|dentry]_xattr to read xattrs with security.bpf. name prefix. Note that BPF programs can read user. xattrs, but not write and remove them. To pick the right version of kfunc to use, a remap logic is added to btf_kfunc_id_set. This helps move some kfunc specific logic off the verifier core code. Also use this remap logic to select bpf_dynptr_from_skb or bpf_dynptr_from_skb_rdonly. Cover letter of v1 and v2: Follow up discussion in LPC 2024 [1], that we need security.bpf xattr prefix. This set adds "security.bpf." xattr name prefix, and allows bpf kfuncs bpf_get_[file|dentry]_xattr() to read these xattrs. [1] https://lpc.events/event/18/contributions/1940/ Changes v6 => v7 1. Move btf_kfunc_id_remap() to the right place. (Bug reported by CI) v6: https://lore.kernel.org/bpf/20241219202536.1625216-1-song@xxxxxxxxxx/ Changes v5 => v6 1. Hide _locked version of the kfuncs from vmlinux.h (Alexei) 2. Add remap logic to btf_kfunc_id_set and use that to pick the correct version of kfuncs to use. 3. Also use the remap logic for bpf_dynptr_from_skb[|_rdonly]. v5: https://lore.kernel.org/bpf/20241218044711.1723221-1-song@xxxxxxxxxx/ Changes v4 => v5 1. Let verifier pick proper kfunc (_locked or not _locked) based on the calling context. (Alexei) 2. Remove the __failure test (6/6 of v4). v4: https://lore.kernel.org/bpf/20241217063821.482857-1-song@xxxxxxxxxx/ Changes v3 => v4 1. Do write permission check with inode locked. (Jan Kara) 2. Fix some source_inline warnings. v3: https://lore.kernel.org/bpf/20241210220627.2800362-1-song@xxxxxxxxxx/ Changes v2 => v3 1. Add kfuncs to set and remove xattr from BPF programs. v2: https://lore.kernel.org/bpf/20241016070955.375923-1-song@xxxxxxxxxx/ Changes v1 => v2 1. Update comment of bpf_get_[file|dentry]_xattr. (Jiri Olsa) 2. Fix comment for return value of bpf_get_[file|dentry]_xattr. v1: https://lore.kernel.org/bpf/20241002214637.3625277-1-song@xxxxxxxxxx/ Song Liu (7): fs/xattr: bpf: Introduce security.bpf. xattr name prefix selftests/bpf: Extend test fs_kfuncs to cover security.bpf. xattr names bpf: lsm: Add two more sleepable hooks bpf: Extend btf_kfunc_id_set to handle kfunc polymorphism bpf: Use btf_kfunc_id_set.remap logic for bpf_dynptr_from_skb bpf: fs/xattr: Add BPF kfuncs to set and remove xattrs selftests/bpf: Test kfuncs that set and remove xattr from BPF programs fs/bpf_fs_kfuncs.c | 246 +++++++++++++++++- include/linux/bpf_lsm.h | 2 + include/linux/btf.h | 20 ++ include/linux/btf_ids.h | 3 + include/uapi/linux/xattr.h | 4 + kernel/bpf/bpf_lsm.c | 2 + kernel/bpf/btf.c | 117 +++++++-- kernel/bpf/verifier.c | 34 +-- net/core/filter.c | 49 +++- tools/testing/selftests/bpf/bpf_kfuncs.h | 5 + .../selftests/bpf/prog_tests/fs_kfuncs.c | 162 +++++++++++- .../selftests/bpf/progs/test_get_xattr.c | 28 +- .../bpf/progs/test_set_remove_xattr.c | 133 ++++++++++ 13 files changed, 742 insertions(+), 63 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_set_remove_xattr.c -- 2.43.5
