Adding d_path helper function that returns full path for given 'struct path' object, which needs to be the kernel BTF 'path' object. The path is returned in buffer provided 'buf' of size 'sz' and is zero terminated. bpf_d_path(&file->f_path, buf, size); The helper calls directly d_path function, so there's only limited set of function it can be called from. Adding just very modest set for the start. Updating also bpf.h tools uapi header and adding 'path' to bpf_helpers_doc.py script.
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| @@ -3513,6 +3513,7 @@ union bpf_attr { · 3512 unmodified lines | ||
| 3513 | 3513 | * |
| 3514 | 3514 | * **-EPERM** This helper cannot be used under the |
| 3515 | 3515 | * current sock_ops->op. |
| 3516 | + * | |
| 3516 | 3517 | * void *bpf_inode_storage_get(struct bpf_map *map, void *inode, void *value, u64 flags) |
| 3517 | 3518 | * Description |
| 3518 | 3519 | * Get a bpf_local_storage from an *inode*. |
| @@ -3548,6 +3549,18 @@ union bpf_attr { · 29 unmodified lines | ||
| 3548 | 3549 | * 0 on success. |
| 3549 | 3550 | * |
| 3550 | 3551 | * **-ENOENT** if the bpf_local_storage cannot be found. |
| 3552 | + * | |
| 3553 | + * long bpf_d_path(struct path *path, char *buf, u32 sz) | |
| 3554 | + * Description | |
| 3555 | + * Return full path for given 'struct path' object, which | |
| 3556 | + * needs to be the kernel BTF 'path' object. The path is | |
| 3557 | + * returned in the provided buffer 'buf' of size 'sz' and | |
| 3558 | + * is zero terminated. | |
| 3559 | + * | |
| 3560 | + * Return | |
| 3561 | + * On success, the strictly positive length of the string, | |
| 3562 | + * including the trailing NUL character. On error, a negative | |
| 3563 | + * value. | |
| 3551 | 3564 | */ |
| 3552 | 3565 | #define __BPF_FUNC_MAPPER(FN) \ |
| 3553 | 3566 | FN(unspec), \ |
| @@ -3697,6 +3710,7 @@ union bpf_attr { · 143 unmodified lines | ||
| 3697 | 3710 | FN(reserve_hdr_opt), \ |
| 3698 | 3711 | FN(inode_storage_get), \ |
| 3699 | 3712 | FN(inode_storage_delete), \ |
| 3713 | + FN(d_path), \ | |
| 3700 | 3714 | /* */ |
| 3701 | 3715 | |
| 3702 | 3716 | /* integer value in 'imm' field of BPF_CALL instruction selects which helper |