From 52a4c95f4d24b8bcb50745732f7b9f8513c49c5f Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Thu, 25 Mar 2021 11:18:22 -0400 Subject: fuse: extend FUSE_SETXATTR request Fuse client needs to send additional information to file server when it calls SETXATTR(system.posix_acl_access), so add extra flags field to the structure. Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi --- include/uapi/linux/fuse.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 54442612c48b..390f7b4c889d 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -179,6 +179,7 @@ * 7.33 * - add FUSE_HANDLE_KILLPRIV_V2, FUSE_WRITE_KILL_SUIDGID, FATTR_KILL_SUIDGID * - add FUSE_OPEN_KILL_SUIDGID + * - extend fuse_setxattr_in, add FUSE_SETXATTR_EXT */ #ifndef _LINUX_FUSE_H @@ -330,6 +331,7 @@ struct fuse_file_lock { * does not have CAP_FSETID. Additionally upon * write/truncate sgid is killed only if file has group * execute permission. (Same as Linux VFS behavior). + * FUSE_SETXATTR_EXT: Server supports extended struct fuse_setxattr_in */ #define FUSE_ASYNC_READ (1 << 0) #define FUSE_POSIX_LOCKS (1 << 1) @@ -360,6 +362,7 @@ struct fuse_file_lock { #define FUSE_MAP_ALIGNMENT (1 << 26) #define FUSE_SUBMOUNTS (1 << 27) #define FUSE_HANDLE_KILLPRIV_V2 (1 << 28) +#define FUSE_SETXATTR_EXT (1 << 29) /** * CUSE INIT request/reply flags @@ -681,9 +684,13 @@ struct fuse_fsync_in { uint32_t padding; }; +#define FUSE_COMPAT_SETXATTR_IN_SIZE 8 + struct fuse_setxattr_in { uint32_t size; uint32_t flags; + uint32_t setxattr_flags; + uint32_t padding; }; struct fuse_getxattr_in { -- cgit v1.3-8-gc7d7 From 550a7d3bc0c4049ef8d36ff4d9ed7082ee8cb5ec Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Thu, 25 Mar 2021 11:18:23 -0400 Subject: fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID When posix access ACL is set, it can have an effect on file mode and it can also need to clear SGID if. - None of caller's group/supplementary groups match file owner group. AND - Caller is not priviliged (No CAP_FSETID). As of now fuser server is responsible for changing the file mode as well. But it does not know whether to clear SGID or not. So add a flag FUSE_SETXATTR_ACL_KILL_SGID and send this info with SETXATTR to let file server know that sgid needs to be cleared as well. Reported-by: Luis Henriques Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi --- fs/fuse/acl.c | 7 ++++++- include/uapi/linux/fuse.h | 7 +++++++ 2 files changed, 13 insertions(+), 1 deletion(-) (limited to 'include/uapi/linux') diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c index d31260a139d4..52b165319be1 100644 --- a/fs/fuse/acl.c +++ b/fs/fuse/acl.c @@ -71,6 +71,7 @@ int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode, return -EINVAL; if (acl) { + unsigned int extra_flags = 0; /* * Fuse userspace is responsible for updating access * permissions in the inode, if needed. fuse_setxattr @@ -94,7 +95,11 @@ int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode, return ret; } - ret = fuse_setxattr(inode, name, value, size, 0, 0); + if (!in_group_p(i_gid_into_mnt(&init_user_ns, inode)) && + !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) + extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID; + + ret = fuse_setxattr(inode, name, value, size, 0, extra_flags); kfree(value); } else { ret = fuse_removexattr(inode, name); diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 390f7b4c889d..271ae90a9bb7 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -180,6 +180,7 @@ * - add FUSE_HANDLE_KILLPRIV_V2, FUSE_WRITE_KILL_SUIDGID, FATTR_KILL_SUIDGID * - add FUSE_OPEN_KILL_SUIDGID * - extend fuse_setxattr_in, add FUSE_SETXATTR_EXT + * - add FUSE_SETXATTR_ACL_KILL_SGID */ #ifndef _LINUX_FUSE_H @@ -454,6 +455,12 @@ struct fuse_file_lock { */ #define FUSE_OPEN_KILL_SUIDGID (1 << 0) +/** + * setxattr flags + * FUSE_SETXATTR_ACL_KILL_SGID: Clear SGID when system.posix_acl_access is set + */ +#define FUSE_SETXATTR_ACL_KILL_SGID (1 << 0) + enum fuse_opcode { FUSE_LOOKUP = 1, FUSE_FORGET = 2, /* no reply */ -- cgit v1.3-8-gc7d7