On Thu, Apr 2, 2026 at 1:02 AM Jeff Layton <[email protected]> wrote: > > On Mon, 2026-03-30 at 21:07 +0600, Dorjoy Chowdhury wrote: > > On Mon, Mar 30, 2026 at 5:49 PM Jeff Layton <[email protected]> wrote: > > > > > > On Sat, 2026-03-28 at 23:22 +0600, Dorjoy Chowdhury wrote: > > > > This flag indicates the path should be opened if it's a regular file. > > > > This is useful to write secure programs that want to avoid being > > > > tricked into opening device nodes with special semantics while thinking > > > > they operate on regular files. This is a requested feature from the > > > > uapi-group[1]. > > > > > > > > A corresponding error code EFTYPE has been introduced. For example, if > > > > openat2 is called on path /dev/null with OPENAT2_REGULAR in the flag > > > > param, it will return -EFTYPE. EFTYPE is already used in BSD systems > > > > like FreeBSD, macOS. > > > > > > > > When used in combination with O_CREAT, either the regular file is > > > > created, or if the path already exists, it is opened if it's a regular > > > > file. Otherwise, -EFTYPE is returned. > > > > > > > > When OPENAT2_REGULAR is combined with O_DIRECTORY, -EINVAL is returned > > > > as it doesn't make sense to open a path that is both a directory and a > > > > regular file. > > > > > > > > [1]: > > > > https://uapi-group.org/kernel-features/#ability-to-only-open-regular-files > > > > > > > > Signed-off-by: Dorjoy Chowdhury <[email protected]> > > > > --- > > > > arch/alpha/include/uapi/asm/errno.h | 2 ++ > > > > arch/alpha/include/uapi/asm/fcntl.h | 1 + > > > > arch/mips/include/uapi/asm/errno.h | 2 ++ > > > > arch/parisc/include/uapi/asm/errno.h | 2 ++ > > > > arch/parisc/include/uapi/asm/fcntl.h | 1 + > > > > arch/sparc/include/uapi/asm/errno.h | 2 ++ > > > > arch/sparc/include/uapi/asm/fcntl.h | 1 + > > > > fs/ceph/file.c | 4 ++++ > > > > fs/fcntl.c | 4 ++-- > > > > fs/gfs2/inode.c | 6 ++++++ > > > > fs/namei.c | 4 ++++ > > > > fs/nfs/dir.c | 4 ++++ > > > > fs/open.c | 8 +++++--- > > > > fs/smb/client/dir.c | 14 +++++++++++++- > > > > include/linux/fcntl.h | 2 ++ > > > > include/uapi/asm-generic/errno.h | 2 ++ > > > > include/uapi/asm-generic/fcntl.h | 4 ++++ > > > > tools/arch/alpha/include/uapi/asm/errno.h | 2 ++ > > > > tools/arch/mips/include/uapi/asm/errno.h | 2 ++ > > > > tools/arch/parisc/include/uapi/asm/errno.h | 2 ++ > > > > tools/arch/sparc/include/uapi/asm/errno.h | 2 ++ > > > > tools/include/uapi/asm-generic/errno.h | 2 ++ > > > > 22 files changed, 67 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/arch/alpha/include/uapi/asm/errno.h > > > > b/arch/alpha/include/uapi/asm/errno.h > > > > index 6791f6508632..1a99f38813c7 100644 > > > > --- a/arch/alpha/include/uapi/asm/errno.h > > > > +++ b/arch/alpha/include/uapi/asm/errno.h > > > > @@ -127,4 +127,6 @@ > > > > > > > > #define EHWPOISON 139 /* Memory page has hardware error */ > > > > > > > > +#define EFTYPE 140 /* Wrong file type for the > > > > intended operation */ > > > > + > > > > #endif > > > > diff --git a/arch/alpha/include/uapi/asm/fcntl.h > > > > b/arch/alpha/include/uapi/asm/fcntl.h > > > > index 50bdc8e8a271..fe488bf7c18e 100644 > > > > --- a/arch/alpha/include/uapi/asm/fcntl.h > > > > +++ b/arch/alpha/include/uapi/asm/fcntl.h > > > > @@ -34,6 +34,7 @@ > > > > > > > > #define O_PATH 040000000 > > > > #define __O_TMPFILE 0100000000 > > > > +#define OPENAT2_REGULAR 0200000000 > > > > > > > > #define F_GETLK 7 > > > > #define F_SETLK 8 > > > > diff --git a/arch/mips/include/uapi/asm/errno.h > > > > b/arch/mips/include/uapi/asm/errno.h > > > > index c01ed91b1ef4..1835a50b69ce 100644 > > > > --- a/arch/mips/include/uapi/asm/errno.h > > > > +++ b/arch/mips/include/uapi/asm/errno.h > > > > @@ -126,6 +126,8 @@ > > > > > > > > #define EHWPOISON 168 /* Memory page has hardware error */ > > > > > > > > +#define EFTYPE 169 /* Wrong file type for the > > > > intended operation */ > > > > + > > > > #define EDQUOT 1133 /* Quota exceeded */ > > > > > > > > > > > > diff --git a/arch/parisc/include/uapi/asm/errno.h > > > > b/arch/parisc/include/uapi/asm/errno.h > > > > index 8cbc07c1903e..93194fbb0a80 100644 > > > > --- a/arch/parisc/include/uapi/asm/errno.h > > > > +++ b/arch/parisc/include/uapi/asm/errno.h > > > > @@ -124,4 +124,6 @@ > > > > > > > > #define EHWPOISON 257 /* Memory page has hardware error */ > > > > > > > > +#define EFTYPE 258 /* Wrong file type for the > > > > intended operation */ > > > > + > > > > #endif > > > > diff --git a/arch/parisc/include/uapi/asm/fcntl.h > > > > b/arch/parisc/include/uapi/asm/fcntl.h > > > > index 03dee816cb13..d46812f2f0f4 100644 > > > > --- a/arch/parisc/include/uapi/asm/fcntl.h > > > > +++ b/arch/parisc/include/uapi/asm/fcntl.h > > > > @@ -19,6 +19,7 @@ > > > > > > > > #define O_PATH 020000000 > > > > #define __O_TMPFILE 040000000 > > > > +#define OPENAT2_REGULAR 0100000000 > > > > > > > > #define F_GETLK64 8 > > > > #define F_SETLK64 9 > > > > diff --git a/arch/sparc/include/uapi/asm/errno.h > > > > b/arch/sparc/include/uapi/asm/errno.h > > > > index 4a41e7835fd5..71940ec9130b 100644 > > > > --- a/arch/sparc/include/uapi/asm/errno.h > > > > +++ b/arch/sparc/include/uapi/asm/errno.h > > > > @@ -117,4 +117,6 @@ > > > > > > > > #define EHWPOISON 135 /* Memory page has hardware error */ > > > > > > > > +#define EFTYPE 136 /* Wrong file type for the > > > > intended operation */ > > > > + > > > > #endif > > > > diff --git a/arch/sparc/include/uapi/asm/fcntl.h > > > > b/arch/sparc/include/uapi/asm/fcntl.h > > > > index 67dae75e5274..bb6e9fa94bc9 100644 > > > > --- a/arch/sparc/include/uapi/asm/fcntl.h > > > > +++ b/arch/sparc/include/uapi/asm/fcntl.h > > > > @@ -37,6 +37,7 @@ > > > > > > > > #define O_PATH 0x1000000 > > > > #define __O_TMPFILE 0x2000000 > > > > +#define OPENAT2_REGULAR 0x4000000 > > > > > > > > #define F_GETOWN 5 /* for sockets. */ > > > > #define F_SETOWN 6 /* for sockets. */ > > > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > > > > index 66bbf6d517a9..6d8d4c7765e6 100644 > > > > --- a/fs/ceph/file.c > > > > +++ b/fs/ceph/file.c > > > > @@ -977,6 +977,10 @@ int ceph_atomic_open(struct inode *dir, struct > > > > dentry *dentry, > > > > ceph_init_inode_acls(newino, &as_ctx); > > > > file->f_mode |= FMODE_CREATED; > > > > } > > > > + if ((flags & OPENAT2_REGULAR) && !d_is_reg(dentry)) { > > > > + err = -EFTYPE; > > > > + goto out_req; > > > > + } > > > > > > ^^^ > > > This doesn't look quite right. Here's a larger chunk of the code: > > > > > > -------------------------8<-------------------------- > > > if (d_in_lookup(dentry)) { > > > dn = ceph_finish_lookup(req, dentry, err); > > > if (IS_ERR(dn)) > > > err = PTR_ERR(dn); > > > } else { > > > /* we were given a hashed negative dentry */ > > > dn = NULL; > > > } > > > if (err) > > > goto out_req; > > > if (dn || d_really_is_negative(dentry) || d_is_symlink(dentry)) { > > > /* make vfs retry on splice, ENOENT, or symlink */ > > > doutc(cl, "finish_no_open on dn %p\n", dn); > > > err = finish_no_open(file, dn); > > > } else { > > > if (IS_ENCRYPTED(dir) && > > > !fscrypt_has_permitted_context(dir, d_inode(dentry))) > > > { > > > pr_warn_client(cl, > > > "Inconsistent encryption context (parent > > > %llx:%llx child %llx:%llx)\n", > > > ceph_vinop(dir), > > > ceph_vinop(d_inode(dentry))); > > > goto out_req; > > > } > > > > > > doutc(cl, "finish_open on dn %p\n", dn); > > > if (req->r_op == CEPH_MDS_OP_CREATE && > > > req->r_reply_info.has_create_ino) { > > > struct inode *newino = d_inode(dentry); > > > > > > cache_file_layout(dir, newino); > > > ceph_init_inode_acls(newino, &as_ctx); > > > file->f_mode |= FMODE_CREATED; > > > } > > > err = finish_open(file, dentry, ceph_open); > > > } > > > -------------------------8<-------------------------- > > > > > > It looks like this won't handle it correctly if the pathwalk terminates > > > on a symlink (re: d_is_symlink() case). You should either set up a test > > > ceph cluster on your own, or reach out to the ceph community and ask > > > them to test this. > > > > > > > Thanks for reviewing. The d_is_symlink() case seems to be calling > > finish_no_open so shouldn't this be okay? > > > > My mistake -- you're correct. I keep forgetting that finish_no_open() > will handle this case regardless of what else happens. > > > > > err = finish_open(file, dentry, ceph_open); > > > > } > > > > out_req: > > > > diff --git a/fs/fcntl.c b/fs/fcntl.c > > > > index beab8080badf..240bb511557a 100644 > > > > --- a/fs/fcntl.c > > > > +++ b/fs/fcntl.c > > > > @@ -1169,9 +1169,9 @@ static int __init fcntl_init(void) > > > > * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY > > > > * is defined as O_NONBLOCK on some platforms and not on others. > > > > */ > > > > - BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != > > > > + BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != > > > > HWEIGHT32( > > > > - (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | > > > > + (VALID_OPENAT2_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | > > > > __FMODE_EXEC)); > > > > > > > > fasync_cache = kmem_cache_create("fasync_cache", > > > > diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c > > > > index 8344040ecaf7..4604e2e8a9cc 100644 > > > > --- a/fs/gfs2/inode.c > > > > +++ b/fs/gfs2/inode.c > > > > @@ -738,6 +738,12 @@ static int gfs2_create_inode(struct inode *dir, > > > > struct dentry *dentry, > > > > inode = gfs2_dir_search(dir, &dentry->d_name, !S_ISREG(mode) || > > > > excl); > > > > error = PTR_ERR(inode); > > > > if (!IS_ERR(inode)) { > > > > + if (file && (file->f_flags & OPENAT2_REGULAR) && > > > > !S_ISREG(inode->i_mode)) { > > > > > > Isn't OPENAT2_REGULAR getting masked off in ->f_flags now? > > > > > Yes, I thought the masking off was happening after this codepath got > > executed. Maybe it's better anyway to pass another flags param to this > > function and forward the flags from the gfs2_atomic_open function and > > in other call sites pass 0 ? What do you think? > > > > Also my mistake. That happens in do_dentry_open() which happens in > finish_open(), so you should be OK here. > > Reviewed-by: Jeff Layton <[email protected]>
Thanks for patiently reviewing this! I am planning on sending patches for man-pages and looking into some xfs-tests for this. But I am not sure if this patch series will get more reviews from others or if it will be picked up in the vfs branch? Regards, Dorjoy
