Re: [PATCH bpf-next v3 1/2] bpf: Add bpf_lsm_set_bprm_opts helper
On Tue, Nov 17, 2020 at 11:41 PM Daniel Borkmann wrote: > > On 11/17/20 3:13 AM, KP Singh wrote: > > From: KP Singh > > > > The helper allows modification of certain bits on the linux_binprm > > struct starting with the secureexec bit which can be updated using the > > BPF_LSM_F_BPRM_SECUREEXEC flag. > > > > secureexec can be set by the LSM for privilege gaining executions to set > > the AT_SECURE auxv for glibc. When set, the dynamic linker disables the > > use of certain environment variables (like LD_PRELOAD). > > > > Signed-off-by: KP Singh > > --- > > include/uapi/linux/bpf.h | 18 ++ > > kernel/bpf/bpf_lsm.c | 27 +++ > > scripts/bpf_helpers_doc.py | 2 ++ > > tools/include/uapi/linux/bpf.h | 18 ++ > > 4 files changed, 65 insertions(+) > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index 162999b12790..bfa79054d106 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3787,6 +3787,18 @@ union bpf_attr { > >* *ARG_PTR_TO_BTF_ID* of type *task_struct*. > >* Return > >* Pointer to the current task. > > + * > > + * long bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) > > + * > > small nit: should have no extra newline (same for the tools/ copy) > > > + * Description > > + * Set or clear certain options on *bprm*: > > + * > > + * **BPF_LSM_F_BPRM_SECUREEXEC** Set the secureexec bit > > + * which sets the **AT_SECURE** auxv for glibc. The bit > > + * is cleared if the flag is not specified. > > + * Return > > + * **-EINVAL** if invalid *flags* are passed. > > + * > >*/ > > #define __BPF_FUNC_MAPPER(FN) \ > > FN(unspec), \ > > @@ -3948,6 +3960,7 @@ union bpf_attr { > > FN(task_storage_get), \ > > FN(task_storage_delete),\ > > FN(get_current_task_btf), \ > > + FN(lsm_set_bprm_opts), \ > > /* */ > > > > /* integer value in 'imm' field of BPF_CALL instruction selects which > > helper > > @@ -4119,6 +4132,11 @@ enum bpf_lwt_encap_mode { > > BPF_LWT_ENCAP_IP, > > }; > > > > +/* Flags for LSM helpers */ > > +enum { > > + BPF_LSM_F_BPRM_SECUREEXEC = (1ULL << 0), > > +}; > > + > > #define __bpf_md_ptr(type, name)\ > > union { \ > > type name; \ > > diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c > > index 553107f4706a..cd85482228a0 100644 > > --- a/kernel/bpf/bpf_lsm.c > > +++ b/kernel/bpf/bpf_lsm.c > > @@ -7,6 +7,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -51,6 +52,30 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, > > return 0; > > } > > > > +/* Mask for all the currently supported BPRM option flags */ > > +#define BPF_LSM_F_BRPM_OPTS_MASK BPF_LSM_F_BPRM_SECUREEXEC > > + > > +BPF_CALL_2(bpf_lsm_set_bprm_opts, struct linux_binprm *, bprm, u64, flags) > > +{ > > + > > ditto > > Would have fixed up these things on the fly while applying, but one small item > I wanted to bring up here given uapi which will then freeze: it would be > cleaner > to call the helper just bpf_bprm_opts_set() or so given it's implied that we > attach to lsm here and we don't use _lsm in the naming for the others either. > Similarly, I'd drop the _LSM from the flag/mask. > Thanks Daniel, this makes sense and is more future proof, I respun this and sent out another version with some minor fixes and the rename. Also added Martin's acks. - KP
Re: [PATCH bpf-next v3 1/2] bpf: Add bpf_lsm_set_bprm_opts helper
On 11/17/20 3:13 AM, KP Singh wrote: From: KP Singh The helper allows modification of certain bits on the linux_binprm struct starting with the secureexec bit which can be updated using the BPF_LSM_F_BPRM_SECUREEXEC flag. secureexec can be set by the LSM for privilege gaining executions to set the AT_SECURE auxv for glibc. When set, the dynamic linker disables the use of certain environment variables (like LD_PRELOAD). Signed-off-by: KP Singh --- include/uapi/linux/bpf.h | 18 ++ kernel/bpf/bpf_lsm.c | 27 +++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 18 ++ 4 files changed, 65 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 162999b12790..bfa79054d106 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3787,6 +3787,18 @@ union bpf_attr { **ARG_PTR_TO_BTF_ID* of type *task_struct*. *Return *Pointer to the current task. + * + * long bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) + * small nit: should have no extra newline (same for the tools/ copy) + * Description + * Set or clear certain options on *bprm*: + * + * **BPF_LSM_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. The bit + * is cleared if the flag is not specified. + * Return + * **-EINVAL** if invalid *flags* are passed. + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3960,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete),\ FN(get_current_task_btf), \ + FN(lsm_set_bprm_opts), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4132,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for LSM helpers */ +enum { + BPF_LSM_F_BPRM_SECUREEXEC = (1ULL << 0), +}; + #define __bpf_md_ptr(type, name) \ union { \ type name; \ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 553107f4706a..cd85482228a0 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -51,6 +52,30 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, return 0; } +/* Mask for all the currently supported BPRM option flags */ +#define BPF_LSM_F_BRPM_OPTS_MASK BPF_LSM_F_BPRM_SECUREEXEC + +BPF_CALL_2(bpf_lsm_set_bprm_opts, struct linux_binprm *, bprm, u64, flags) +{ + ditto Would have fixed up these things on the fly while applying, but one small item I wanted to bring up here given uapi which will then freeze: it would be cleaner to call the helper just bpf_bprm_opts_set() or so given it's implied that we attach to lsm here and we don't use _lsm in the naming for the others either. Similarly, I'd drop the _LSM from the flag/mask. + if (flags & ~BPF_LSM_F_BRPM_OPTS_MASK) + return -EINVAL; + + bprm->secureexec = (flags & BPF_LSM_F_BPRM_SECUREEXEC); + return 0; +} + +BTF_ID_LIST_SINGLE(bpf_lsm_set_bprm_opts_btf_ids, struct, linux_binprm) + +const static struct bpf_func_proto bpf_lsm_set_bprm_opts_proto = { + .func = bpf_lsm_set_bprm_opts, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg1_btf_id= _lsm_set_bprm_opts_btf_ids[0], + .arg2_type = ARG_ANYTHING, +}; + static const struct bpf_func_proto * bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -71,6 +96,8 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return _task_storage_get_proto; case BPF_FUNC_task_storage_delete: return _task_storage_delete_proto; + case BPF_FUNC_lsm_set_bprm_opts: + return _lsm_set_bprm_opts_proto; default: return tracing_prog_func_proto(func_id, prog); }
Re: [PATCH bpf-next v3 1/2] bpf: Add bpf_lsm_set_bprm_opts helper
On Tue, Nov 17, 2020 at 02:13:06AM +, KP Singh wrote: > From: KP Singh > > The helper allows modification of certain bits on the linux_binprm > struct starting with the secureexec bit which can be updated using the > BPF_LSM_F_BPRM_SECUREEXEC flag. > > secureexec can be set by the LSM for privilege gaining executions to set > the AT_SECURE auxv for glibc. When set, the dynamic linker disables the > use of certain environment variables (like LD_PRELOAD). > > Signed-off-by: KP Singh Acked-by: Martin KaFai Lau
[PATCH bpf-next v3 1/2] bpf: Add bpf_lsm_set_bprm_opts helper
From: KP Singh The helper allows modification of certain bits on the linux_binprm struct starting with the secureexec bit which can be updated using the BPF_LSM_F_BPRM_SECUREEXEC flag. secureexec can be set by the LSM for privilege gaining executions to set the AT_SECURE auxv for glibc. When set, the dynamic linker disables the use of certain environment variables (like LD_PRELOAD). Signed-off-by: KP Singh --- include/uapi/linux/bpf.h | 18 ++ kernel/bpf/bpf_lsm.c | 27 +++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 18 ++ 4 files changed, 65 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 162999b12790..bfa79054d106 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3787,6 +3787,18 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * long bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) + * + * Description + * Set or clear certain options on *bprm*: + * + * **BPF_LSM_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. The bit + * is cleared if the flag is not specified. + * Return + * **-EINVAL** if invalid *flags* are passed. + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3960,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete),\ FN(get_current_task_btf), \ + FN(lsm_set_bprm_opts), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4132,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for LSM helpers */ +enum { + BPF_LSM_F_BPRM_SECUREEXEC = (1ULL << 0), +}; + #define __bpf_md_ptr(type, name) \ union {\ type name; \ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 553107f4706a..cd85482228a0 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -51,6 +52,30 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, return 0; } +/* Mask for all the currently supported BPRM option flags */ +#define BPF_LSM_F_BRPM_OPTS_MASK BPF_LSM_F_BPRM_SECUREEXEC + +BPF_CALL_2(bpf_lsm_set_bprm_opts, struct linux_binprm *, bprm, u64, flags) +{ + + if (flags & ~BPF_LSM_F_BRPM_OPTS_MASK) + return -EINVAL; + + bprm->secureexec = (flags & BPF_LSM_F_BPRM_SECUREEXEC); + return 0; +} + +BTF_ID_LIST_SINGLE(bpf_lsm_set_bprm_opts_btf_ids, struct, linux_binprm) + +const static struct bpf_func_proto bpf_lsm_set_bprm_opts_proto = { + .func = bpf_lsm_set_bprm_opts, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg1_btf_id= _lsm_set_bprm_opts_btf_ids[0], + .arg2_type = ARG_ANYTHING, +}; + static const struct bpf_func_proto * bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -71,6 +96,8 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return _task_storage_get_proto; case BPF_FUNC_task_storage_delete: return _task_storage_delete_proto; + case BPF_FUNC_lsm_set_bprm_opts: + return _lsm_set_bprm_opts_proto; default: return tracing_prog_func_proto(func_id, prog); } diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index 31484377b8b1..c5bc947a70ad 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -418,6 +418,7 @@ class PrinterHelpers(Printer): 'struct bpf_tcp_sock', 'struct bpf_tunnel_key', 'struct bpf_xfrm_state', +'struct linux_binprm', 'struct pt_regs', 'struct sk_reuseport_md', 'struct sockaddr', @@ -465,6 +466,7 @@ class PrinterHelpers(Printer): 'struct bpf_tcp_sock', 'struct bpf_tunnel_key', 'struct bpf_xfrm_state', +'struct linux_binprm', 'struct pt_regs', 'struct sk_reuseport_md', 'struct sockaddr', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 162999b12790..bfa79054d106 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3787,6 +3787,18 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * long bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) + *