Unverified Commit fa204a65 authored by Christian Brauner's avatar Christian Brauner
Browse files

samples/vfs: add STATMOUNT_MNT_{G,U}IDMAP 

Illustrate how to use STATMOUNT_MNT_{G,U}IDMAP.

Link: https://lore.kernel.org/r/20250204-work-mnt_idmap-statmount-v2-4-007720f39f2e@kernel.org


Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent a496dfec

samples/vfs/samples-vfs.h

+13 −1
Original line number Diff line number Diff line
@@ -42,7 +42,11 @@ struct statmount { 
	__u32 opt_array;	/* [str] Array of nul terminated fs options */

	__u32 opt_sec_num;	/* Number of security options */

	__u32 opt_sec_array;	/* [str] Array of nul terminated security options */

	__u64 __spare2[46];

	__u32 mnt_uidmap_num;	/* Number of uid mappings */

	__u32 mnt_uidmap;	/* [str] Array of uid mappings */

	__u32 mnt_gidmap_num;	/* Number of gid mappings */

	__u32 mnt_gidmap;	/* [str] Array of gid mappings */

	__u64 __spare2[44];

	char str[];		/* Variable size part containing strings */

};
@@ -158,6 +162,14 @@ struct mnt_ns_info { 
#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */

#endif



#ifndef STATMOUNT_MNT_UIDMAP

#define STATMOUNT_MNT_UIDMAP		0x00002000U	/* Want/got uidmap... */

#endif



#ifndef STATMOUNT_MNT_GIDMAP

#define STATMOUNT_MNT_GIDMAP		0x00004000U	/* Want/got gidmap... */

#endif



#ifndef MOUNT_ATTR_RDONLY

#define MOUNT_ATTR_RDONLY	0x00000001 /* Mount read-only */

#endif

samples/vfs/test-list-all-mounts.c

+24 −2
Original line number Diff line number Diff line
@@ -128,14 +128,16 @@ int main(int argc, char *argv[]) 
					      STATMOUNT_MNT_POINT |

					      STATMOUNT_MNT_NS_ID |

					      STATMOUNT_MNT_OPTS |

					      STATMOUNT_FS_TYPE, 0);

					      STATMOUNT_FS_TYPE |

					      STATMOUNT_MNT_UIDMAP |

					      STATMOUNT_MNT_GIDMAP, 0);

			if (!stmnt) {

				printf("Failed to statmount(%" PRIu64 ") in mount namespace(%" PRIu64 ")\n",

				       (uint64_t)last_mnt_id, (uint64_t)info.mnt_ns_id);

				continue;

			}



			printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n",

			printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n",

			       (uint64_t)stmnt->mnt_id,

			       (uint64_t)stmnt->mnt_parent_id,

			       (stmnt->mask & STATMOUNT_FS_TYPE)   ? stmnt->str + stmnt->fs_type   : "",
@@ -143,6 +145,26 @@ int main(int argc, char *argv[]) 
			       (stmnt->mask & STATMOUNT_MNT_POINT) ? stmnt->str + stmnt->mnt_point : "",

			       (stmnt->mask & STATMOUNT_MNT_OPTS)  ? stmnt->str + stmnt->mnt_opts  : "");



			if (stmnt->mask & STATMOUNT_MNT_UIDMAP) {

				const char *idmap = stmnt->str + stmnt->mnt_uidmap;



				for (size_t idx = 0; idx < stmnt->mnt_uidmap_num; idx++) {

					printf("mnt_uidmap[%lu]:\t%s\n", idx, idmap);

					idmap += strlen(idmap) + 1;

				}

			}



			if (stmnt->mask & STATMOUNT_MNT_GIDMAP) {

				const char *idmap = stmnt->str + stmnt->mnt_gidmap;



				for (size_t idx = 0; idx < stmnt->mnt_gidmap_num; idx++) {

					printf("mnt_gidmap[%lu]:\t%s\n", idx, idmap);

					idmap += strlen(idmap) + 1;

				}

			}



			printf("\n");



			free(stmnt);

		}

	}