Re: [PATCH 31/39] convert selinuxfs
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2025-09-22 03:52:25
Also in:
linux-efi, linux-fsdevel, linux-mm, linux-usb, ocfs2-devel
Subsystem:
selinux security module, the rest · Maintainers:
Paul Moore, Stephen Smalley, Linus Torvalds
On Sun, Sep 21, 2025 at 10:50:02PM -0400, Paul Moore wrote:
Looks good to me, ACK below. For me personally, it's a bit late to take non-bugfix stuff for the upcoming merge window so I would defer this for a few weeks, but if you want to take it now that's your call. Also your call if you would prefer this to go in with the rest of the patchset you've working on, or if you want me to take it via the SELinux tree. Let me know.
Seeing that it's already a 41-commit patchset (rpc_pipe conversion pulled in, now +1 from this split) with several more in the pipeline (securityfs conversion, for starters) and it's -rc7... I think I'll post v2 in the middle of the week, but aim for the next cycle. Rebase to -rc1 as soon as it comes, post v3 for review and testing, then shove it into -next. Especially since #work.nfsctl is in -next, so hopefully by -rc1 there won't be any need to put merges in the middle of the series, with conversion of nfsctl included into the series, bringing with it removal of kill_litter_super() and (hopefully) "give configfs and apparmorfs private copies of simple_unlink() and simple_rmdir() doing dput() instead of d_make_discardable(), then make d_make_discardable() complain about being called on non-persistent dentries". Speaking of additional patches into that series: AFAICS there's no reason for selinuxfs to allocate dentry before the inode. Doing it the other way round simplifies the things quite a bit, IMO. Something like this (as followup to the previous patch):
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 482a2cac9640..7bee2d8bdec5 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c@@ -1197,6 +1197,25 @@ static struct inode *sel_make_inode(struct super_block *sb, umode_t mode) return ret; } +static struct dentry *sel_attach(struct dentry *parent, const char *name, + struct inode *inode) +{ + struct dentry *dentry = d_alloc_name(parent, name); + if (unlikely(!dentry)) { + iput(inode); + return ERR_PTR(-ENOMEM); + } + d_add(dentry, inode); + return dentry; +} + +static int sel_attach_file(struct dentry *parent, const char *name, + struct inode *inode) +{ + struct dentry *dentry = sel_attach(parent, name, inode); + return PTR_ERR_OR_ZERO(dentry); +} + static ssize_t sel_read_bool(struct file *filep, char __user *buf, size_t count, loff_t *ppos) {
@@ -1364,8 +1383,7 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_ *bool_num = num; *bool_pending_names = names; - for (i = 0; i < num; i++) { - struct dentry *dentry; + for (i = 0; !ret && i < num; i++) { struct inode *inode; struct inode_security_struct *isec; ssize_t len;
@@ -1376,15 +1394,9 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_ ret = -ENAMETOOLONG; break; } - dentry = d_alloc_name(bool_dir, names[i]); - if (!dentry) { - ret = -ENOMEM; - break; - } inode = sel_make_inode(bool_dir->d_sb, S_IFREG | S_IRUGO | S_IWUSR); if (!inode) { - dput(dentry); ret = -ENOMEM; break; }
@@ -1402,7 +1414,8 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_ isec->initialized = LABEL_INITIALIZED; inode->i_fop = &sel_bool_ops; inode->i_ino = i|SEL_BOOL_INO_OFFSET; - d_add(dentry, inode); + + ret = sel_attach_file(bool_dir, names[i], inode); } out: free_page((unsigned long)page);
@@ -1587,6 +1600,7 @@ static int sel_make_avc_files(struct dentry *dir) struct super_block *sb = dir->d_sb; struct selinux_fs_info *fsi = sb->s_fs_info; unsigned int i; + int err = 0; static const struct tree_descr files[] = { { "cache_threshold", &sel_avc_cache_threshold_ops, S_IRUGO|S_IWUSR },
@@ -1596,26 +1610,20 @@ static int sel_make_avc_files(struct dentry *dir) #endif }; - for (i = 0; i < ARRAY_SIZE(files); i++) { + for (i = 0; !err && i < ARRAY_SIZE(files); i++) { struct inode *inode; - struct dentry *dentry; - - dentry = d_alloc_name(dir, files[i].name); - if (!dentry) - return -ENOMEM; inode = sel_make_inode(dir->d_sb, S_IFREG|files[i].mode); - if (!inode) { - dput(dentry); + if (!inode) return -ENOMEM; - } inode->i_fop = files[i].ops; inode->i_ino = ++fsi->last_ino; - d_add(dentry, inode); + + err = sel_attach_file(dir, files[i].name, inode); } - return 0; + return err; } static int sel_make_ss_files(struct dentry *dir)
@@ -1623,30 +1631,25 @@ static int sel_make_ss_files(struct dentry *dir) struct super_block *sb = dir->d_sb; struct selinux_fs_info *fsi = sb->s_fs_info; unsigned int i; + int err = 0; static const struct tree_descr files[] = { { "sidtab_hash_stats", &sel_sidtab_hash_stats_ops, S_IRUGO }, }; - for (i = 0; i < ARRAY_SIZE(files); i++) { + for (i = 0; !err && i < ARRAY_SIZE(files); i++) { struct inode *inode; - struct dentry *dentry; - - dentry = d_alloc_name(dir, files[i].name); - if (!dentry) - return -ENOMEM; inode = sel_make_inode(dir->d_sb, S_IFREG|files[i].mode); - if (!inode) { - dput(dentry); + if (!inode) return -ENOMEM; - } inode->i_fop = files[i].ops; inode->i_ino = ++fsi->last_ino; - d_add(dentry, inode); + + err = sel_attach_file(dir, files[i].name, inode); } - return 0; + return err; } static ssize_t sel_read_initcon(struct file *file, char __user *buf,
@@ -1674,30 +1677,25 @@ static const struct file_operations sel_initcon_ops = { static int sel_make_initcon_files(struct dentry *dir) { unsigned int i; + int err = 0; - for (i = 1; i <= SECINITSID_NUM; i++) { - struct inode *inode; - struct dentry *dentry; + for (i = 1; !err && i <= SECINITSID_NUM; i++) { const char *s = security_get_initial_sid_context(i); + struct inode *inode; if (!s) continue; - dentry = d_alloc_name(dir, s); - if (!dentry) - return -ENOMEM; inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO); - if (!inode) { - dput(dentry); + if (!inode) return -ENOMEM; - } inode->i_fop = &sel_initcon_ops; inode->i_ino = i|SEL_INITCON_INO_OFFSET; - d_add(dentry, inode); + err = sel_attach_file(dir, s, inode); } - return 0; + return err; } static inline unsigned long sel_class_to_ino(u16 class)
@@ -1779,29 +1777,21 @@ static int sel_make_perm_files(struct selinux_policy *newpolicy, if (rc) return rc; - for (i = 0; i < nperms; i++) { + for (i = 0; !rc && i < nperms; i++) { struct inode *inode; - struct dentry *dentry; - rc = -ENOMEM; - dentry = d_alloc_name(dir, perms[i]); - if (!dentry) - goto out; - - rc = -ENOMEM; inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO); if (!inode) { - dput(dentry); - goto out; + rc = -ENOMEM; + break; } inode->i_fop = &sel_perm_ops; /* i+1 since perm values are 1-indexed */ inode->i_ino = sel_perm_to_ino(classvalue, i + 1); - d_add(dentry, inode); + + rc = sel_attach_file(dir, perms[i], inode); } - rc = 0; -out: for (i = 0; i < nperms; i++) kfree(perms[i]); kfree(perms);
@@ -1816,20 +1806,18 @@ static int sel_make_class_dir_entries(struct selinux_policy *newpolicy, struct selinux_fs_info *fsi = sb->s_fs_info; struct dentry *dentry = NULL; struct inode *inode = NULL; - - dentry = d_alloc_name(dir, "index"); - if (!dentry) - return -ENOMEM; + int err; inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO); - if (!inode) { - dput(dentry); + if (!inode) return -ENOMEM; - } inode->i_fop = &sel_class_ops; inode->i_ino = sel_class_to_ino(index); - d_add(dentry, inode); + + err = sel_attach_file(dir, "index", inode); + if (err) + return err; dentry = sel_make_dir(dir, "perms", &fsi->last_class_ino); if (IS_ERR(dentry))
@@ -1881,58 +1869,47 @@ static int sel_make_policycap(struct dentry *dir) { struct super_block *sb = dir->d_sb; unsigned int iter; - struct dentry *dentry = NULL; struct inode *inode = NULL; + int err = 0; + + for (iter = 0; !err && iter <= POLICYDB_CAP_MAX; iter++) { + const char *name; - for (iter = 0; iter <= POLICYDB_CAP_MAX; iter++) { if (iter < ARRAY_SIZE(selinux_policycap_names)) - dentry = d_alloc_name(dir, - selinux_policycap_names[iter]); + name = selinux_policycap_names[iter]; else - dentry = d_alloc_name(dir, "unknown"); - - if (dentry == NULL) - return -ENOMEM; + name = "unknown"; inode = sel_make_inode(sb, S_IFREG | 0444); - if (inode == NULL) { - dput(dentry); + if (!inode) return -ENOMEM; - } inode->i_fop = &sel_policycap_ops; inode->i_ino = iter | SEL_POLICYCAP_INO_OFFSET; - d_add(dentry, inode); + err = sel_attach_file(dir, name, inode); } - return 0; + return err; } static struct dentry *sel_make_dir(struct dentry *dir, const char *name, unsigned long *ino) { - struct dentry *dentry = d_alloc_name(dir, name); struct inode *inode; - if (!dentry) - return ERR_PTR(-ENOMEM); - inode = sel_make_inode(dir->d_sb, S_IFDIR | S_IRUGO | S_IXUGO); - if (!inode) { - dput(dentry); + if (!inode) return ERR_PTR(-ENOMEM); - } inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; inode->i_ino = ++(*ino); /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); - d_add(dentry, inode); /* bump link count on parent directory, too */ inc_nlink(d_inode(dir)); - return dentry; + return sel_attach(dir, name, inode); } static int reject_all(struct mnt_idmap *idmap, struct inode *inode, int mask)
@@ -2020,17 +1997,10 @@ static int sel_fill_super(struct super_block *sb, struct fs_context *fc) goto err; } - ret = -ENOMEM; - dentry = d_alloc_name(sb->s_root, NULL_FILE_NAME); - if (!dentry) - goto err; - ret = -ENOMEM; inode = sel_make_inode(sb, S_IFCHR | S_IRUGO | S_IWUGO); - if (!inode) { - dput(dentry); + if (!inode) goto err; - } inode->i_ino = ++fsi->last_ino; isec = selinux_inode(inode);
@@ -2039,7 +2009,9 @@ static int sel_fill_super(struct super_block *sb, struct fs_context *fc) isec->initialized = LABEL_INITIALIZED; init_special_inode(inode, S_IFCHR | S_IRUGO | S_IWUGO, MKDEV(MEM_MAJOR, 3)); - d_add(dentry, inode); + ret = sel_attach_file(sb->s_root, NULL_FILE_NAME, inode); + if (ret) + goto err; dentry = sel_make_dir(sb->s_root, "avc", &fsi->last_ino); if (IS_ERR(dentry)) {