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-rw-r--r--fs/overlayfs/copy_up.c17
-rw-r--r--fs/overlayfs/inode.c50
-rw-r--r--fs/overlayfs/overlayfs.h13
-rw-r--r--fs/overlayfs/util.c85
4 files changed, 158 insertions, 7 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index daf2afa603d3..9d8ebf0e7237 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -131,7 +131,8 @@ out:
return error;
}
-static int ovl_copy_fileattr(struct path *old, struct path *new)
+static int ovl_copy_fileattr(struct inode *inode, struct path *old,
+ struct path *new)
{
struct fileattr oldfa = { .flags_valid = true };
struct fileattr newfa = { .flags_valid = true };
@@ -145,6 +146,18 @@ static int ovl_copy_fileattr(struct path *old, struct path *new)
if (err)
return err;
+ /*
+ * We cannot set immutable and append-only flags on upper inode,
+ * because we would not be able to link upper inode to upper dir
+ * not set overlay private xattr on upper inode.
+ * Store these flags in overlay.protattr xattr instead.
+ */
+ if (oldfa.flags & OVL_PROT_FS_FLAGS_MASK) {
+ err = ovl_set_protattr(inode, new->dentry, &oldfa);
+ if (err)
+ return err;
+ }
+
BUILD_BUG_ON(OVL_COPY_FS_FLAGS_MASK & ~FS_COMMON_FL);
newfa.flags &= ~OVL_COPY_FS_FLAGS_MASK;
newfa.flags |= (oldfa.flags & OVL_COPY_FS_FLAGS_MASK);
@@ -550,7 +563,7 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
* Copy the fileattr inode flags that are the source of already
* copied i_flags
*/
- err = ovl_copy_fileattr(&c->lowerpath, &upperpath);
+ err = ovl_copy_fileattr(inode, &c->lowerpath, &upperpath);
if (err)
return err;
}
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index b288843e6b42..37300e972a39 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -162,7 +162,8 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
enum ovl_path_type type;
struct path realpath;
const struct cred *old_cred;
- bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
+ struct inode *inode = d_inode(dentry);
+ bool is_dir = S_ISDIR(inode->i_mode);
int fsid = 0;
int err;
bool metacopy_blocks = false;
@@ -175,6 +176,9 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
if (err)
goto out;
+ /* Report the effective immutable/append-only STATX flags */
+ generic_fill_statx_attr(inode, stat);
+
/*
* For non-dir or same fs, we use st_ino of the copy up origin.
* This guaranties constant st_dev/st_ino across copy up.
@@ -542,6 +546,7 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
struct inode *inode = d_inode(dentry);
struct path upperpath;
const struct cred *old_cred;
+ unsigned int flags;
int err;
err = ovl_want_write(dentry);
@@ -553,15 +558,49 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
ovl_path_real(dentry, &upperpath);
old_cred = ovl_override_creds(inode->i_sb);
- err = ovl_real_fileattr_set(&upperpath, fa);
+ /*
+ * Store immutable/append-only flags in xattr and clear them
+ * in upper fileattr (in case they were set by older kernel)
+ * so children of "ovl-immutable" directories lower aliases of
+ * "ovl-immutable" hardlinks could be copied up.
+ * Clear xattr when flags are cleared.
+ */
+ err = ovl_set_protattr(inode, upperpath.dentry, fa);
+ if (!err)
+ err = ovl_real_fileattr_set(&upperpath, fa);
revert_creds(old_cred);
- ovl_copyflags(ovl_inode_real(inode), inode);
+
+ /*
+ * Merge real inode flags with inode flags read from
+ * overlay.protattr xattr
+ */
+ flags = ovl_inode_real(inode)->i_flags & OVL_COPY_I_FLAGS_MASK;
+
+ BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
+ flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
+ inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
}
ovl_drop_write(dentry);
out:
return err;
}
+/* Convert inode protection flags to fileattr flags */
+static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
+{
+ BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
+ BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
+
+ if (inode->i_flags & S_APPEND) {
+ fa->flags |= FS_APPEND_FL;
+ fa->fsx_xflags |= FS_XFLAG_APPEND;
+ }
+ if (inode->i_flags & S_IMMUTABLE) {
+ fa->flags |= FS_IMMUTABLE_FL;
+ fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
+ }
+}
+
int ovl_real_fileattr_get(struct path *realpath, struct fileattr *fa)
{
int err;
@@ -584,6 +623,7 @@ int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
old_cred = ovl_override_creds(inode->i_sb);
err = ovl_real_fileattr_get(&realpath, fa);
+ ovl_fileattr_prot_flags(inode, fa);
revert_creds(old_cred);
return err;
@@ -1136,6 +1176,10 @@ struct inode *ovl_get_inode(struct super_block *sb,
}
}
+ /* Check for immutable/append-only inode flags in xattr */
+ if (upperdentry)
+ ovl_check_protattr(inode, upperdentry);
+
if (inode->i_state & I_NEW)
unlock_new_inode(inode);
out:
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 2cbebe06d9ad..2433cc030c87 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -34,6 +34,7 @@ enum ovl_xattr {
OVL_XATTR_NLINK,
OVL_XATTR_UPPER,
OVL_XATTR_METACOPY,
+ OVL_XATTR_PROTATTR,
};
enum ovl_inode_flag {
@@ -520,14 +521,22 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
/* vfs inode flags copied from real to ovl inode */
#define OVL_COPY_I_FLAGS_MASK (S_SYNC | S_NOATIME | S_APPEND | S_IMMUTABLE)
+/* vfs inode flags read from overlay.protattr xattr to ovl inode */
+#define OVL_PROT_I_FLAGS_MASK (S_APPEND | S_IMMUTABLE)
/*
* fileattr flags copied from lower to upper inode on copy up.
- * We cannot copy immutable/append-only flags, because that would prevevnt
- * linking temp inode to upper dir.
+ * We cannot copy up immutable/append-only flags, because that would prevent
+ * linking temp inode to upper dir, so we store them in xattr instead.
*/
#define OVL_COPY_FS_FLAGS_MASK (FS_SYNC_FL | FS_NOATIME_FL)
#define OVL_COPY_FSX_FLAGS_MASK (FS_XFLAG_SYNC | FS_XFLAG_NOATIME)
+#define OVL_PROT_FS_FLAGS_MASK (FS_APPEND_FL | FS_IMMUTABLE_FL)
+#define OVL_PROT_FSX_FLAGS_MASK (FS_XFLAG_APPEND | FS_XFLAG_IMMUTABLE)
+
+void ovl_check_protattr(struct inode *inode, struct dentry *upper);
+int ovl_set_protattr(struct inode *inode, struct dentry *upper,
+ struct fileattr *fa);
static inline void ovl_copyflags(struct inode *from, struct inode *to)
{
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 81b8f135445a..f48284a2a896 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -10,6 +10,7 @@
#include <linux/cred.h>
#include <linux/xattr.h>
#include <linux/exportfs.h>
+#include <linux/fileattr.h>
#include <linux/uuid.h>
#include <linux/namei.h>
#include <linux/ratelimit.h>
@@ -585,6 +586,7 @@ bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
#define OVL_XATTR_NLINK_POSTFIX "nlink"
#define OVL_XATTR_UPPER_POSTFIX "upper"
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
+#define OVL_XATTR_PROTATTR_POSTFIX "protattr"
#define OVL_XATTR_TAB_ENTRY(x) \
[x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
@@ -598,6 +600,7 @@ const char *const ovl_xattr_table[][2] = {
OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
+ OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
};
int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
@@ -639,6 +642,88 @@ int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
return err;
}
+
+#define OVL_PROTATTR_MAX 32 /* Reserved for future flags */
+
+void ovl_check_protattr(struct inode *inode, struct dentry *upper)
+{
+ struct ovl_fs *ofs = OVL_FS(inode->i_sb);
+ u32 iflags = inode->i_flags & OVL_PROT_I_FLAGS_MASK;
+ char buf[OVL_PROTATTR_MAX+1];
+ int res, n;
+
+ res = ovl_do_getxattr(ofs, upper, OVL_XATTR_PROTATTR, buf,
+ OVL_PROTATTR_MAX);
+ if (res < 0)
+ return;
+
+ /*
+ * Initialize inode flags from overlay.protattr xattr and upper inode
+ * flags. If upper inode has those fileattr flags set (i.e. from old
+ * kernel), we do not clear them on ovl_get_inode(), but we will clear
+ * them on next fileattr_set().
+ */
+ for (n = 0; n < res; n++) {
+ if (buf[n] == 'a')
+ iflags |= S_APPEND;
+ else if (buf[n] == 'i')
+ iflags |= S_IMMUTABLE;
+ else
+ break;
+ }
+
+ if (!res || n < res) {
+ pr_warn_ratelimited("incompatible overlay.protattr format (%pd2, len=%d)\n",
+ upper, res);
+ } else {
+ inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
+ }
+}
+
+int ovl_set_protattr(struct inode *inode, struct dentry *upper,
+ struct fileattr *fa)
+{
+ struct ovl_fs *ofs = OVL_FS(inode->i_sb);
+ char buf[OVL_PROTATTR_MAX];
+ int len = 0, err = 0;
+ u32 iflags = 0;
+
+ BUILD_BUG_ON(HWEIGHT32(OVL_PROT_FS_FLAGS_MASK) > OVL_PROTATTR_MAX);
+
+ if (fa->flags & FS_APPEND_FL) {
+ buf[len++] = 'a';
+ iflags |= S_APPEND;
+ }
+ if (fa->flags & FS_IMMUTABLE_FL) {
+ buf[len++] = 'i';
+ iflags |= S_IMMUTABLE;
+ }
+
+ /*
+ * Do not allow to set protection flags when upper doesn't support
+ * xattrs, because we do not set those fileattr flags on upper inode.
+ * Remove xattr if it exist and all protection flags are cleared.
+ */
+ if (len) {
+ err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
+ buf, len, -EPERM);
+ } else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
+ err = ovl_do_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
+ if (err == -EOPNOTSUPP || err == -ENODATA)
+ err = 0;
+ }
+ if (err)
+ return err;
+
+ inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
+
+ /* Mask out the fileattr flags that should not be set in upper inode */
+ fa->flags &= ~OVL_PROT_FS_FLAGS_MASK;
+ fa->fsx_xflags &= ~OVL_PROT_FSX_FLAGS_MASK;
+
+ return 0;
+}
+
/**
* Caller must hold a reference to inode to prevent it from being freed while
* it is marked inuse.
generated by cgit v1.2.3-70-g09d2 (git 2.47.1) at 2025-01-28 02:56:53 +0000