kernel.git/kernel/bpf/syscall.c, branch linux-5.19.y

bpf: Ensure correct locking around vulnerable function find_vpid()

2022-10-24T07:57:11Z

[ Upstream commit 83c10cc362d91c0d8d25e60779ee52fdbbf3894d ] The documentation for find_vpid() clearly states: "Must be called with the tasklist_lock or rcu_read_lock() held." Presently we do neither for find_vpid() instance in bpf_task_fd_query(). Add proper rcu_read_lock/unlock() to fix the issue. Fixes: 41bdc4b40ed6f ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY") Signed-off-by: Lee Jones Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20220912133855.1218900-1-lee@kernel.org Signed-off-by: Sasha Levin

bpf: Fix non-static bpf_func_proto struct definitions

2022-10-24T07:57:04Z

[ Upstream commit dc368e1c658e4f478a45e8d1d5b0c8392ca87506 ] This patch does two things: 1) Marks the dynptr bpf_func_proto structs that were added in [1] as static, as pointed out by the kernel test robot in [2]. 2) There are some bpf_func_proto structs marked as extern which can instead be statically defined. [1] https://lore.kernel.org/bpf/20220523210712.3641569-1-joannelkoong@gmail.com/ [2] https://lore.kernel.org/bpf/62ab89f2.Pko7sI08RAKdF8R6%25lkp@intel.com/ Reported-by: kernel test robot Signed-off-by: Joanne Koong Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220616225407.1878436-1-joannelkoong@gmail.com Stable-dep-of: 883743422ced ("bpf: Fix ref_obj_id for dynptr data slices in verifier") Signed-off-by: Sasha Levin

bpf: Fix resetting logic for unreferenced kptrs

2022-10-12T07:51:26Z

commit 9fad7fe5b29803584c7f17a2abe6c2936fec6828 upstream. Sparse reported a warning at bpf_map_free_kptrs() "warning: Using plain integer as NULL pointer" During the process of fixing this warning, it was discovered that the current code erroneously writes to the pointer variable instead of deferencing and writing to the actual kptr. Hence, Sparse tool accidentally helped to uncover this problem. Fix this by doing WRITE_ONCE(*p, 0) instead of WRITE_ONCE(p, 0). Note that the effect of this bug is that unreferenced kptrs will not be cleared during check_and_free_fields. It is not a problem if the clearing is not done during map_free stage, as there is nothing to free for them. Fixes: 14a324f6a67e ("bpf: Wire up freeing of referenced kptr") Signed-off-by: Jules Irenge Link: https://lore.kernel.org/r/Yxi3pJaK6UDjVJSy@playground Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf: Restrict bpf_sys_bpf to CAP_PERFMON

2022-09-08T09:23:57Z

[ Upstream commit 14b20b784f59bdd95f6f1cfb112c9818bcec4d84 ] The verifier cannot perform sufficient validation of any pointers passed into bpf_attr and treats them as integers rather than pointers. The helper will then read from arbitrary pointers passed into it. Restrict the helper to CAP_PERFMON since the security model in BPF of arbitrary kernel read is CAP_BPF + CAP_PERFMON. Fixes: af2ac3e13e45 ("bpf: Prepare bpf syscall to be used from kernel and user space.") Signed-off-by: YiFei Zhu Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220816205517.682470-1-zhuyifei@google.com Signed-off-by: Sasha Levin

bpf: Disallow bpf programs call prog_run command.

2022-08-25T09:45:13Z

commit 86f44fcec22ce2979507742bc53db8400e454f46 upstream. The verifier cannot perform sufficient validation of bpf_attr->test.ctx_in pointer, therefore bpf programs should not be allowed to call BPF_PROG_RUN command from within the program. To fix this issue split bpf_sys_bpf() bpf helper into normal kern_sys_bpf() kernel function that can only be used by the kernel light skeleton directly. Reported-by: YiFei Zhu Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.") Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf: refine kernel.unprivileged_bpf_disabled behaviour

2022-05-21T02:48:29Z

With unprivileged BPF disabled, all cmds associated with the BPF syscall are blocked to users without CAP_BPF/CAP_SYS_ADMIN. However there are use cases where we may wish to allow interactions with BPF programs without being able to load and attach them. So for example, a process with required capabilities loads/attaches a BPF program, and a process with less capabilities interacts with it; retrieving perf/ring buffer events, modifying map-specified config etc. With all BPF syscall commands blocked as a result of unprivileged BPF being disabled, this mode of interaction becomes impossible for processes without CAP_BPF. As Alexei notes "The bpf ACL model is the same as traditional file's ACL. The creds and ACLs are checked at open(). Then during file's write/read additional checks might be performed. BPF has such functionality already. Different map_creates have capability checks while map_lookup has: map_get_sys_perms(map, f) & FMODE_CAN_READ. In other words it's enough to gate FD-receiving parts of bpf with unprivileged_bpf_disabled sysctl. The rest is handled by availability of FD and access to files in bpffs." So key fd creation syscall commands BPF_PROG_LOAD and BPF_MAP_CREATE are blocked with unprivileged BPF disabled and no CAP_BPF. And as Alexei notes, map creation with unprivileged BPF disabled off blocks creation of maps aside from array, hash and ringbuf maps. Programs responsible for loading and attaching the BPF program can still control access to its pinned representation by restricting permissions on the pin path, as with normal files. Signed-off-by: Alan Maguire Acked-by: Yonghong Song Acked-by: Shung-Hsi Yu Acked-by: KP Singh Link: https://lore.kernel.org/r/1652970334-30510-2-git-send-email-alan.maguire@oracle.com Signed-off-by: Alexei Starovoitov

bpf, x86: Attach a cookie to fentry/fexit/fmod_ret/lsm.

2022-05-11T04:58:31Z

Pass a cookie along with BPF_LINK_CREATE requests. Add a bpf_cookie field to struct bpf_tracing_link to attach a cookie. The cookie of a bpf_tracing_link is available by calling bpf_get_attach_cookie when running the BPF program of the attached link. The value of a cookie will be set at bpf_tramp_run_ctx by the trampoline of the link. Signed-off-by: Kui-Feng Lee Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220510205923.3206889-4-kuifeng@fb.com

bpf, x86: Create bpf_tramp_run_ctx on the caller thread's stack

2022-05-11T00:50:51Z

BPF trampolines will create a bpf_tramp_run_ctx, a bpf_run_ctx, on stacks and set/reset the current bpf_run_ctx before/after calling a bpf_prog. Signed-off-by: Kui-Feng Lee Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220510205923.3206889-3-kuifeng@fb.com

bpf, x86: Generate trampolines from bpf_tramp_links

2022-05-11T00:50:40Z

Replace struct bpf_tramp_progs with struct bpf_tramp_links to collect struct bpf_tramp_link(s) for a trampoline. struct bpf_tramp_link extends bpf_link to act as a linked list node. arch_prepare_bpf_trampoline() accepts a struct bpf_tramp_links to collects all bpf_tramp_link(s) that a trampoline should call. Change BPF trampoline and bpf_struct_ops to pass bpf_tramp_links instead of bpf_tramp_progs. Signed-off-by: Kui-Feng Lee Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220510205923.3206889-2-kuifeng@fb.com

bpf: Add bpf_link iterator

2022-05-10T18:20:45Z

Implement bpf_link iterator to traverse links via bpf_seq_file operations. The changeset is mostly shamelessly copied from commit a228a64fc1e4 ("bpf: Add bpf_prog iterator") Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20220510155233.9815-2-9erthalion6@gmail.com Signed-off-by: Alexei Starovoitov