SB_POSIXACL must be set when a filesystem supports POSIX ACLs, but NFSv4 also sets this flag to prevent the VFS from applying the umask on newly-created files. NFSv4 doesn't support POSIX ACLs however, which causes confusion when other subsystems try to test for them. Add a new SB_I_NOUMASK flag that allows filesystems to opt-in to umask stripping without advertising support for POSIX ACLs. Set the new flag on NFSv4 instead of SB_POSIXACL. Also, move mode_strip_umask to namei.h and convert init_mknod and init_mkdir to use it. Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- Yet another approach to fixing this issue. I think this way is probably the best, since makes the purpose of these flags clearer, and stops NFS from relying on SB_POSIXACL to avoid umask stripping. --- Changes in v3: - move new flag to s_iflags - convert init_mkdir and init_mknod to use mode_strip_umask - Link to v2: https://lore.kernel.org/r/20230910-acl-fix-v2-1-38d6caa81419@xxxxxxxxxx Changes in v2: - new approach: add a new SB_NOUMASK flag that NFSv4 can use instead of SB_POSIXACL - Link to v1: https://lore.kernel.org/r/20230908-acl-fix-v1-1-1e6b76c8dcc8@xxxxxxxxxx --- fs/init.c | 6 ++---- fs/namei.c | 19 ------------------- fs/nfs/super.c | 2 +- include/linux/fs.h | 3 ++- include/linux/namei.h | 24 ++++++++++++++++++++++++ 5 files changed, 29 insertions(+), 25 deletions(-) diff --git a/fs/init.c b/fs/init.c index 9684406a8416..e9387b6c4f30 100644 --- a/fs/init.c +++ b/fs/init.c @@ -153,8 +153,7 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev) if (IS_ERR(dentry)) return PTR_ERR(dentry); - if (!IS_POSIXACL(path.dentry->d_inode)) - mode &= ~current_umask(); + mode = mode_strip_umask(d_inode(path.dentry), mode); error = security_path_mknod(&path, dentry, mode, dev); if (!error) error = vfs_mknod(mnt_idmap(path.mnt), path.dentry->d_inode, @@ -229,8 +228,7 @@ int __init init_mkdir(const char *pathname, umode_t mode) dentry = kern_path_create(AT_FDCWD, pathname, &path, LOOKUP_DIRECTORY); if (IS_ERR(dentry)) return PTR_ERR(dentry); - if (!IS_POSIXACL(path.dentry->d_inode)) - mode &= ~current_umask(); + mode = mode_strip_umask(d_inode(path.dentry), mode); error = security_path_mkdir(&path, dentry, mode); if (!error) error = vfs_mkdir(mnt_idmap(path.mnt), path.dentry->d_inode, diff --git a/fs/namei.c b/fs/namei.c index 567ee547492b..94b27370f468 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3103,25 +3103,6 @@ void unlock_rename(struct dentry *p1, struct dentry *p2) } EXPORT_SYMBOL(unlock_rename); -/** - * mode_strip_umask - handle vfs umask stripping - * @dir: parent directory of the new inode - * @mode: mode of the new inode to be created in @dir - * - * Umask stripping depends on whether or not the filesystem supports POSIX - * ACLs. If the filesystem doesn't support it umask stripping is done directly - * in here. If the filesystem does support POSIX ACLs umask stripping is - * deferred until the filesystem calls posix_acl_create(). - * - * Returns: mode - */ -static inline umode_t mode_strip_umask(const struct inode *dir, umode_t mode) -{ - if (!IS_POSIXACL(dir)) - mode &= ~current_umask(); - return mode; -} - /** * vfs_prepare_mode - prepare the mode to be used for a new inode * @idmap: idmap of the mount the inode was found from diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 0d6473cb00cb..9b1cfca8112a 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -1071,7 +1071,7 @@ static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx) sb->s_export_op = &nfs_export_ops; break; case 4: - sb->s_flags |= SB_POSIXACL; + sb->s_iflags |= SB_I_NOUMASK; sb->s_time_gran = 1; sb->s_time_min = S64_MIN; sb->s_time_max = S64_MAX; diff --git a/include/linux/fs.h b/include/linux/fs.h index 4aeb3fa11927..58dea591a341 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1119,7 +1119,7 @@ extern int send_sigurg(struct fown_struct *fown); #define SB_NOATIME BIT(10) /* Do not update access times. */ #define SB_NODIRATIME BIT(11) /* Do not update directory access times */ #define SB_SILENT BIT(15) -#define SB_POSIXACL BIT(16) /* VFS does not apply the umask */ +#define SB_POSIXACL BIT(16) /* Supports POSIX ACLs */ #define SB_INLINECRYPT BIT(17) /* Use blk-crypto for encrypted files */ #define SB_KERNMOUNT BIT(22) /* this is a kern_mount call */ #define SB_I_VERSION BIT(23) /* Update inode I_version field */ @@ -1166,6 +1166,7 @@ extern int send_sigurg(struct fown_struct *fown); #define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */ #define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */ #define SB_I_RETIRED 0x00000800 /* superblock shouldn't be reused */ +#define SB_I_NOUMASK 0x00001000 /* VFS does not apply umask */ /* Possible states of 'frozen' field */ enum { diff --git a/include/linux/namei.h b/include/linux/namei.h index 1463cbda4888..e3619920f9f0 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -92,6 +92,30 @@ extern struct dentry *lock_rename(struct dentry *, struct dentry *); extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); extern void unlock_rename(struct dentry *, struct dentry *); +/** + * mode_strip_umask - handle vfs umask stripping + * @dir: parent directory of the new inode + * @mode: mode of the new inode to be created in @dir + * + * In most filesystems, umask stripping depends on whether or not the + * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask + * stripping is done directly in here. If the filesystem does support POSIX + * ACLs umask stripping is deferred until the filesystem calls + * posix_acl_create(). + * + * Some filesystems (like NFSv4) also want to avoid umask stripping by the + * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK + * to get this effect without declaring that they support POSIX ACLs. + * + * Returns: mode + */ +static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode) +{ + if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK)) + mode &= ~current_umask(); + return mode; +} + extern int __must_check nd_jump_link(const struct path *path); static inline void nd_terminate_link(void *name, size_t len, size_t maxlen) --- base-commit: a48fa7efaf1161c1c898931fe4c7f0070964233a change-id: 20230908-acl-fix-6f8f86930f32 Best regards, -- Jeff Layton <jlayton@xxxxxxxxxx>
