| Message ID | 20240718115153.1967859-2-yikai.lin@vivo.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | add bpf_file_d_path helper and selftests | expand |
On Thu, Jul 18, 2024 at 4:53 AM Lin Yikai <yikai.lin@vivo.com> wrote: > > Add the "bpf_file_d_path" helper function > to retrieve the path from a struct file object. > But there is no need to include vmlinux.h > or reference the definition of struct file. > > Additionally, update the bpf.h tools uapi header. > > Signed-off-by: Lin Yikai <yikai.lin@vivo.com> > --- > include/uapi/linux/bpf.h | 20 ++++++++++++++++++++ > kernel/trace/bpf_trace.c | 34 ++++++++++++++++++++++++++++++++++ > tools/include/uapi/linux/bpf.h | 20 ++++++++++++++++++++ > 3 files changed, 74 insertions(+) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 35bcf52dbc65..7e5cec61a877 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -5792,6 +5792,25 @@ union bpf_attr { > * 0 on success. > * > * **-ENOENT** if the bpf_local_storage cannot be found. > + * > + * long bpf_file_d_path(void *file, char *dst, u32 size) > + * Description > + * Return full path for the given *file* object. > + * > + * In order to solve issues where certain eBPF programs can not include > + * the definition of struct file or vmlinux.h > + * due to their complexity and conflicts on some operating system, > + * the variable *file* here is declared as type void* > + * instead of the traditional struct file*. > + * It will be forcibly converted into type struct file* later. > + * > + * If the path is larger than *size*, then only *size* > + * bytes will be copied to *dst* > + * > + * Return > + * On success, the strictly positive length of the string, > + * including the trailing NULL character. On error, a negative > + * value. > */ > #define ___BPF_FUNC_MAPPER(FN, ctx...) \ > FN(unspec, 0, ##ctx) \ > @@ -6006,6 +6025,7 @@ union bpf_attr { > FN(user_ringbuf_drain, 209, ##ctx) \ > FN(cgrp_storage_get, 210, ##ctx) \ > FN(cgrp_storage_delete, 211, ##ctx) \ > + FN(file_d_path, 212, ##ctx) \ > /* */ > > /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index cd098846e251..70fde7f20e97 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1257,6 +1257,38 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = { > .arg1_type = ARG_PTR_TO_CTX, > }; > > +BPF_CALL_3(bpf_file_d_path, void *, file, char*, dst, u32, size) > +{ > + long len; > + struct file copy; > + char *ptr; > + > + if (!size) > + return 0; > + > + len = copy_from_kernel_nofault(©, (struct file *)file, sizeof(struct file)); > + if (len < 0) > + return len; > + > + ptr = d_path(&(copy.f_path), dst, size); > + if (IS_ERR(ptr)) { > + len = PTR_ERR(ptr); > + } else { > + len = dst + size - ptr; > + memmove(dst, ptr, len); > + } > + return len; > +} > + > +const struct bpf_func_proto bpf_file_d_path_proto = { > + .func = bpf_file_d_path, > + .gpl_only = false, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_ANYTHING, you can't just accept any random value as `struct file *`, this is a complete no-go. It will have to accept some sort of PTR_TRUSTED argument, be added as kfunc, etc, etc. We had earlier discussion around this, I don't remember all the details, but this is definitely not the way forward. > + .arg2_type = ARG_PTR_TO_MEM, > + .arg3_type = ARG_CONST_SIZE_OR_ZERO, > +}; > + > #ifdef CONFIG_KEYS > __bpf_kfunc_start_defs(); > > @@ -1629,6 +1661,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > return &bpf_find_vma_proto; > case BPF_FUNC_trace_vprintk: > return bpf_get_trace_vprintk_proto(); > + case BPF_FUNC_file_d_path: > + return &bpf_file_d_path_proto; > default: > return bpf_base_func_proto(func_id, prog); > } > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h > index 35bcf52dbc65..7e5cec61a877 100644 > --- a/tools/include/uapi/linux/bpf.h > +++ b/tools/include/uapi/linux/bpf.h > @@ -5792,6 +5792,25 @@ union bpf_attr { > * 0 on success. > * > * **-ENOENT** if the bpf_local_storage cannot be found. > + * > + * long bpf_file_d_path(void *file, char *dst, u32 size) > + * Description > + * Return full path for the given *file* object. > + * > + * In order to solve issues where certain eBPF programs can not include > + * the definition of struct file or vmlinux.h > + * due to their complexity and conflicts on some operating system, > + * the variable *file* here is declared as type void* > + * instead of the traditional struct file*. > + * It will be forcibly converted into type struct file* later. > + * > + * If the path is larger than *size*, then only *size* > + * bytes will be copied to *dst* > + * > + * Return > + * On success, the strictly positive length of the string, > + * including the trailing NULL character. On error, a negative > + * value. > */ > #define ___BPF_FUNC_MAPPER(FN, ctx...) \ > FN(unspec, 0, ##ctx) \ > @@ -6006,6 +6025,7 @@ union bpf_attr { > FN(user_ringbuf_drain, 209, ##ctx) \ > FN(cgrp_storage_get, 210, ##ctx) \ > FN(cgrp_storage_delete, 211, ##ctx) \ > + FN(file_d_path, 212, ##ctx) \ > /* */ > > /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't > -- > 2.34.1 >
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 35bcf52dbc65..7e5cec61a877 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5792,6 +5792,25 @@ union bpf_attr { * 0 on success. * * **-ENOENT** if the bpf_local_storage cannot be found. + * + * long bpf_file_d_path(void *file, char *dst, u32 size) + * Description + * Return full path for the given *file* object. + * + * In order to solve issues where certain eBPF programs can not include + * the definition of struct file or vmlinux.h + * due to their complexity and conflicts on some operating system, + * the variable *file* here is declared as type void* + * instead of the traditional struct file*. + * It will be forcibly converted into type struct file* later. + * + * If the path is larger than *size*, then only *size* + * bytes will be copied to *dst* + * + * Return + * On success, the strictly positive length of the string, + * including the trailing NULL character. On error, a negative + * value. */ #define ___BPF_FUNC_MAPPER(FN, ctx...) \ FN(unspec, 0, ##ctx) \ @@ -6006,6 +6025,7 @@ union bpf_attr { FN(user_ringbuf_drain, 209, ##ctx) \ FN(cgrp_storage_get, 210, ##ctx) \ FN(cgrp_storage_delete, 211, ##ctx) \ + FN(file_d_path, 212, ##ctx) \ /* */ /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index cd098846e251..70fde7f20e97 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1257,6 +1257,38 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = { .arg1_type = ARG_PTR_TO_CTX, }; +BPF_CALL_3(bpf_file_d_path, void *, file, char*, dst, u32, size) +{ + long len; + struct file copy; + char *ptr; + + if (!size) + return 0; + + len = copy_from_kernel_nofault(©, (struct file *)file, sizeof(struct file)); + if (len < 0) + return len; + + ptr = d_path(&(copy.f_path), dst, size); + if (IS_ERR(ptr)) { + len = PTR_ERR(ptr); + } else { + len = dst + size - ptr; + memmove(dst, ptr, len); + } + return len; +} + +const struct bpf_func_proto bpf_file_d_path_proto = { + .func = bpf_file_d_path, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_ANYTHING, + .arg2_type = ARG_PTR_TO_MEM, + .arg3_type = ARG_CONST_SIZE_OR_ZERO, +}; + #ifdef CONFIG_KEYS __bpf_kfunc_start_defs(); @@ -1629,6 +1661,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_find_vma_proto; case BPF_FUNC_trace_vprintk: return bpf_get_trace_vprintk_proto(); + case BPF_FUNC_file_d_path: + return &bpf_file_d_path_proto; default: return bpf_base_func_proto(func_id, prog); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 35bcf52dbc65..7e5cec61a877 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5792,6 +5792,25 @@ union bpf_attr { * 0 on success. * * **-ENOENT** if the bpf_local_storage cannot be found. + * + * long bpf_file_d_path(void *file, char *dst, u32 size) + * Description + * Return full path for the given *file* object. + * + * In order to solve issues where certain eBPF programs can not include + * the definition of struct file or vmlinux.h + * due to their complexity and conflicts on some operating system, + * the variable *file* here is declared as type void* + * instead of the traditional struct file*. + * It will be forcibly converted into type struct file* later. + * + * If the path is larger than *size*, then only *size* + * bytes will be copied to *dst* + * + * Return + * On success, the strictly positive length of the string, + * including the trailing NULL character. On error, a negative + * value. */ #define ___BPF_FUNC_MAPPER(FN, ctx...) \ FN(unspec, 0, ##ctx) \ @@ -6006,6 +6025,7 @@ union bpf_attr { FN(user_ringbuf_drain, 209, ##ctx) \ FN(cgrp_storage_get, 210, ##ctx) \ FN(cgrp_storage_delete, 211, ##ctx) \ + FN(file_d_path, 212, ##ctx) \ /* */ /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
Add the "bpf_file_d_path" helper function to retrieve the path from a struct file object. But there is no need to include vmlinux.h or reference the definition of struct file. Additionally, update the bpf.h tools uapi header. Signed-off-by: Lin Yikai <yikai.lin@vivo.com> --- include/uapi/linux/bpf.h | 20 ++++++++++++++++++++ kernel/trace/bpf_trace.c | 34 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 20 ++++++++++++++++++++ 3 files changed, 74 insertions(+)