[RFC PATCH v2 3/7] lib/cpio: use non __init filesystem related functions

From: Jonathan McDowell
Date: Thu Jul 28 2022 - 10:10:06 EST

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In preparation for making the cpio functions generally available rather
than just at init make sure we're using versions of the filesystem
related functions that aren't in the __init section. Remove functions
only used by us from fs/init.c while folding into the cpio code
directly.

Signed-off-by: Jonathan McDowell <noodles@xxxxxx>
---
v2:
- Fold in directory EEXIST checking from patch 4
- Add EEXIST checking for device nodes (kernel test reboot boot test)
---
fs/init.c | 101 ---------------------
fs/internal.h | 4 -
include/linux/fs.h | 4 +
include/linux/init_syscalls.h | 6 --
lib/cpio.c | 162 +++++++++++++++++++++++++++++-----
5 files changed, 145 insertions(+), 132 deletions(-)

diff --git a/fs/init.c b/fs/init.c
index 5c36adaa9b44..a946ad672dee 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -79,37 +79,6 @@ int __init init_chroot(const char *filename)
return error;
}

-int __init init_chown(const char *filename, uid_t user, gid_t group, int flags)
-{
- int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
- struct path path;
- int error;
-
- error = kern_path(filename, lookup_flags, &path);
- if (error)
- return error;
- error = mnt_want_write(path.mnt);
- if (!error) {
- error = chown_common(&path, user, group);
- mnt_drop_write(path.mnt);
- }
- path_put(&path);
- return error;
-}
-
-int __init init_chmod(const char *filename, umode_t mode)
-{
- struct path path;
- int error;
-
- error = kern_path(filename, LOOKUP_FOLLOW, &path);
- if (error)
- return error;
- error = chmod_common(&path, mode);
- path_put(&path);
- return error;
-}
-
int __init init_eaccess(const char *filename)
{
struct path path;
@@ -163,58 +132,6 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
return error;
}

-int __init init_link(const char *oldname, const char *newname)
-{
- struct dentry *new_dentry;
- struct path old_path, new_path;
- struct user_namespace *mnt_userns;
- int error;
-
- error = kern_path(oldname, 0, &old_path);
- if (error)
- return error;
-
- new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0);
- error = PTR_ERR(new_dentry);
- if (IS_ERR(new_dentry))
- goto out;
-
- error = -EXDEV;
- if (old_path.mnt != new_path.mnt)
- goto out_dput;
- mnt_userns = mnt_user_ns(new_path.mnt);
- error = may_linkat(mnt_userns, &old_path);
- if (unlikely(error))
- goto out_dput;
- error = security_path_link(old_path.dentry, &new_path, new_dentry);
- if (error)
- goto out_dput;
- error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
- new_dentry, NULL);
-out_dput:
- done_path_create(&new_path, new_dentry);
-out:
- path_put(&old_path);
- return error;
-}
-
-int __init init_symlink(const char *oldname, const char *newname)
-{
- struct dentry *dentry;
- struct path path;
- int error;
-
- dentry = kern_path_create(AT_FDCWD, newname, &path, 0);
- if (IS_ERR(dentry))
- return PTR_ERR(dentry);
- error = security_path_symlink(&path, dentry, oldname);
- if (!error)
- error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode,
- dentry, oldname);
- done_path_create(&path, dentry);
- return error;
-}
-
int __init init_unlink(const char *pathname)
{
return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
@@ -239,24 +156,6 @@ int __init init_mkdir(const char *pathname, umode_t mode)
return error;
}

-int __init init_rmdir(const char *pathname)
-{
- return do_rmdir(AT_FDCWD, getname_kernel(pathname));
-}
-
-int __init init_utimes(char *filename, struct timespec64 *ts)
-{
- struct path path;
- int error;
-
- error = kern_path(filename, 0, &path);
- if (error)
- return error;
- error = vfs_utimes(&path, ts);
- path_put(&path);
- return error;
-}
-
int __init init_dup(struct file *file)
{
int fd;
diff --git a/fs/internal.h b/fs/internal.h
index 87e96b9024ce..c57d5f0aa731 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -60,9 +60,6 @@ extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
struct path *path, struct path *root);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
-int do_rmdir(int dfd, struct filename *name);
-int do_unlinkat(int dfd, struct filename *name);
-int may_linkat(struct user_namespace *mnt_userns, struct path *link);
int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
struct filename *newname, unsigned int flags);
int do_mkdirat(int dfd, struct filename *name, umode_t mode);
@@ -132,7 +129,6 @@ long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
int chmod_common(const struct path *path, umode_t mode);
int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
int flag);
-int chown_common(const struct path *path, uid_t user, gid_t group);
extern int vfs_open(const struct path *, struct file *);

/*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9ad5e3520fae..1cb51a54799b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2636,11 +2636,15 @@ static inline struct file *file_clone_open(struct file *file)
return dentry_open(&file->f_path, file->f_flags, file->f_cred);
}
extern int filp_close(struct file *, fl_owner_t id);
+extern int chown_common(const struct path *path, uid_t user, gid_t group);

+extern int do_rmdir(int dfd, struct filename *name);
+extern int do_unlinkat(int dfd, struct filename *name);
extern struct filename *getname_flags(const char __user *, int, int *);
extern struct filename *getname_uflags(const char __user *, int);
extern struct filename *getname(const char __user *);
extern struct filename *getname_kernel(const char *);
+extern int may_linkat(struct user_namespace *mnt_userns, struct path *link);
extern void putname(struct filename *name);

extern int finish_open(struct file *file, struct dentry *dentry,
diff --git a/include/linux/init_syscalls.h b/include/linux/init_syscalls.h
index 92045d18cbfc..196030cd958d 100644
--- a/include/linux/init_syscalls.h
+++ b/include/linux/init_syscalls.h
@@ -5,15 +5,9 @@ int __init init_mount(const char *dev_name, const char *dir_name,
int __init init_umount(const char *name, int flags);
int __init init_chdir(const char *filename);
int __init init_chroot(const char *filename);
-int __init init_chown(const char *filename, uid_t user, gid_t group, int flags);
-int __init init_chmod(const char *filename, umode_t mode);
int __init init_eaccess(const char *filename);
int __init init_stat(const char *filename, struct kstat *stat, int flags);
int __init init_mknod(const char *filename, umode_t mode, unsigned int dev);
-int __init init_link(const char *oldname, const char *newname);
-int __init init_symlink(const char *oldname, const char *newname);
int __init init_unlink(const char *pathname);
int __init init_mkdir(const char *pathname, umode_t mode);
-int __init init_rmdir(const char *pathname);
-int __init init_utimes(char *filename, struct timespec64 *ts);
int __init init_dup(struct file *file);
diff --git a/lib/cpio.c b/lib/cpio.c
index 5d150939704f..9a0120c638db 100644
--- a/lib/cpio.c
+++ b/lib/cpio.c
@@ -3,8 +3,9 @@
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init.h>
-#include <linux/init_syscalls.h>
#include <linux/list.h>
+#include <linux/namei.h>
+#include <linux/security.h>
#include <linux/slab.h>

static ssize_t __init xwrite(struct cpio_context *ctx, struct file *file,
@@ -92,18 +93,25 @@ static void __init free_hash(struct cpio_context *ctx)
}

#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
-static void __init do_utime(char *filename, time64_t mtime)
+static void __init do_utime_path(const struct path *path, time64_t mtime)
{
struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };

- init_utimes(filename, t);
+ vfs_utimes(path, t);
}

-static void __init do_utime_path(const struct path *path, time64_t mtime)
+static int __init do_utime(char *filename, time64_t mtime)
{
- struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
+ struct path path;
+ int error;

- vfs_utimes(path, t);
+ error = kern_path(filename, 0, &path);
+ if (error)
+ return error;
+ do_utime_path(&path, mtime);
+ path_put(&path);
+
+ return error;
}

static int __init dir_add(struct cpio_context *ctx, const char *name, time64_t mtime)
@@ -133,12 +141,31 @@ static void __init dir_utime(struct cpio_context *ctx)
}
}
#else
-static void __init do_utime(char *filename, time64_t mtime) {}
+static int __init do_utime(char *filename, time64_t mtime) { return 0; }
static void __init do_utime_path(const struct path *path, time64_t mtime) {}
static int __init dir_add(struct cpio_context *ctx, const char *name, time64_t mtime) { return 0; }
static void __init dir_utime(struct cpio_context *ctx) {}
#endif

+static int __init cpio_chown(const char *filename, uid_t user, gid_t group,
+ int flags)
+{
+ int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+ struct path path;
+ int error;
+
+ error = kern_path(filename, lookup_flags, &path);
+ if (error)
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = chown_common(&path, user, group);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
+ return error;
+}
+
/* cpio header parsing */

static void __init parse_header(struct cpio_context *ctx, char *s)
@@ -269,27 +296,67 @@ static int __init do_reset(struct cpio_context *ctx)
return 1;
}

-static void __init clean_path(char *path, umode_t fmode)
+static void __init clean_path(char *pathname, umode_t fmode)
{
+ struct path path;
struct kstat st;
+ int error;

- if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
- (st.mode ^ fmode) & S_IFMT) {
+ error = kern_path(pathname, 0, &path);
+ if (error)
+ return;
+ error = vfs_getattr(&path, &st, STATX_BASIC_STATS, AT_NO_AUTOMOUNT);
+ path_put(&path);
+ if (error)
+ return;
+
+ if ((st.mode ^ fmode) & S_IFMT) {
if (S_ISDIR(st.mode))
- init_rmdir(path);
+ do_rmdir(AT_FDCWD, getname_kernel(pathname));
else
- init_unlink(path);
+ do_unlinkat(AT_FDCWD, getname_kernel(pathname));
}
}

static int __init maybe_link(struct cpio_context *ctx)
{
+ struct dentry *new_dentry;
+ struct path old_path, new_path;
+ struct user_namespace *mnt_userns;
+ int error;
+
if (ctx->nlink >= 2) {
char *old = find_link(ctx, ctx->major, ctx->minor, ctx->ino,
ctx->mode, ctx->collected);
if (old) {
clean_path(ctx->collected, 0);
- return (init_link(old, ctx->collected) < 0) ? -1 : 1;
+
+ error = kern_path(old, 0, &old_path);
+ if (error)
+ return error;
+
+ new_dentry = kern_path_create(AT_FDCWD, ctx->collected, &new_path, 0);
+ error = PTR_ERR(new_dentry);
+ if (IS_ERR(new_dentry))
+ goto out;
+
+ error = -EXDEV;
+ if (old_path.mnt != new_path.mnt)
+ goto out_dput;
+ mnt_userns = mnt_user_ns(new_path.mnt);
+ error = may_linkat(mnt_userns, &old_path);
+ if (unlikely(error))
+ goto out_dput;
+ error = security_path_link(old_path.dentry, &new_path, new_dentry);
+ if (error)
+ goto out_dput;
+ error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
+ new_dentry, NULL);
+out_dput:
+ done_path_create(&new_path, new_dentry);
+out:
+ path_put(&old_path);
+ return (error < 0) ? error : 1;
}
}
return 0;
@@ -297,6 +364,10 @@ static int __init maybe_link(struct cpio_context *ctx)

static int __init do_name(struct cpio_context *ctx)
{
+ struct dentry *dentry;
+ struct path path;
+ int error;
+
ctx->state = CPIO_SKIPIT;
ctx->next_state = CPIO_RESET;
if (strcmp(ctx->collected, "TRAILER!!!") == 0) {
@@ -325,16 +396,48 @@ static int __init do_name(struct cpio_context *ctx)
ctx->state = CPIO_COPYFILE;
}
} else if (S_ISDIR(ctx->mode)) {
- init_mkdir(ctx->collected, ctx->mode);
- init_chown(ctx->collected, ctx->uid, ctx->gid, 0);
- init_chmod(ctx->collected, ctx->mode);
+ dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, LOOKUP_DIRECTORY);
+
+ if (!IS_ERR(dentry)) {
+ error = security_path_mkdir(&path, dentry, ctx->mode);
+ if (!error)
+ error = vfs_mkdir(mnt_user_ns(path.mnt),
+ path.dentry->d_inode,
+ dentry, ctx->mode);
+ done_path_create(&path, dentry);
+ } else {
+ error = PTR_ERR(dentry);
+ }
+
+ if (error && error != -EEXIST)
+ return error;
+
+ cpio_chown(ctx->collected, ctx->uid, ctx->gid, 0);
dir_add(ctx, ctx->collected, ctx->mtime);
} else if (S_ISBLK(ctx->mode) || S_ISCHR(ctx->mode) ||
S_ISFIFO(ctx->mode) || S_ISSOCK(ctx->mode)) {
if (maybe_link(ctx) == 0) {
- init_mknod(ctx->collected, ctx->mode, ctx->rdev);
- init_chown(ctx->collected, ctx->uid, ctx->gid, 0);
- init_chmod(ctx->collected, ctx->mode);
+ if (S_ISFIFO(ctx->mode) || S_ISSOCK(ctx->mode))
+ ctx->rdev = 0;
+
+ dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, 0);
+ if (!IS_ERR(dentry)) {
+ error = security_path_mknod(&path, dentry, ctx->mode,
+ ctx->rdev);
+ if (!error)
+ error = vfs_mknod(mnt_user_ns(path.mnt),
+ path.dentry->d_inode,
+ dentry, ctx->mode,
+ new_decode_dev(ctx->rdev));
+ done_path_create(&path, dentry);
+ } else {
+ error = PTR_ERR(dentry);
+ }
+
+ if (error && error != -EEXIST)
+ return error;
+
+ cpio_chown(ctx->collected, ctx->uid, ctx->gid, 0);
do_utime(ctx->collected, ctx->mtime);
}
}
@@ -373,10 +476,27 @@ static int __init do_copy(struct cpio_context *ctx)

static int __init do_symlink(struct cpio_context *ctx)
{
+ struct dentry *dentry;
+ struct path path;
+ int error;
+
ctx->collected[N_ALIGN(ctx->name_len) + ctx->body_len] = '\0';
clean_path(ctx->collected, 0);
- init_symlink(ctx->collected + N_ALIGN(ctx->name_len), ctx->collected);
- init_chown(ctx->collected, ctx->uid, ctx->gid, AT_SYMLINK_NOFOLLOW);
+
+ dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, 0);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ error = security_path_symlink(&path, dentry,
+ ctx->collected + N_ALIGN(ctx->name_len));
+ if (!error)
+ error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode,
+ dentry,
+ ctx->collected + N_ALIGN(ctx->name_len));
+ done_path_create(&path, dentry);
+ if (error)
+ return error;
+
+ cpio_chown(ctx->collected, ctx->uid, ctx->gid, AT_SYMLINK_NOFOLLOW);
do_utime(ctx->collected, ctx->mtime);
ctx->state = CPIO_SKIPIT;
ctx->next_state = CPIO_RESET;
--
2.30.2

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