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author | Amir Goldstein <amir73il@gmail.com> | 2023-10-10 14:17:59 +0300 |
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committer | Amir Goldstein <amir73il@gmail.com> | 2023-10-31 01:12:59 +0300 |
commit | 420a62dde6ebca7bc22e6c57c9cb25d7967ff1ea (patch) | |
tree | e10c1749020124aee4257a5d5b477f6503d651b1 /fs/overlayfs/xattrs.c | |
parent | 5b02bfc1e7e3811c5bf7f0fa626a0694d0dbbd77 (diff) | |
download | linux-420a62dde6ebca7bc22e6c57c9cb25d7967ff1ea.tar.xz |
ovl: Move xattr support to new xattrs.c file
This moves the code from super.c and inode.c, and makes ovl_xattr_get/set()
static.
This is in preparation for doing more work on xattrs support.
Signed-off-by: Alexander Larsson <alexl@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Diffstat (limited to 'fs/overlayfs/xattrs.c')
-rw-r--r-- | fs/overlayfs/xattrs.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c new file mode 100644 index 000000000000..8e7e4ca62448 --- /dev/null +++ b/fs/overlayfs/xattrs.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include <linux/fs.h> +#include <linux/xattr.h> +#include "overlayfs.h" + +bool ovl_is_private_xattr(struct super_block *sb, const char *name) +{ + struct ovl_fs *ofs = OVL_FS(sb); + + if (ofs->config.userxattr) + return strncmp(name, OVL_XATTR_USER_PREFIX, + sizeof(OVL_XATTR_USER_PREFIX) - 1) == 0; + else + return strncmp(name, OVL_XATTR_TRUSTED_PREFIX, + sizeof(OVL_XATTR_TRUSTED_PREFIX) - 1) == 0; +} + +static int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, + const void *value, size_t size, int flags) +{ + int err; + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *upperdentry = ovl_i_dentry_upper(inode); + struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); + struct path realpath; + const struct cred *old_cred; + + if (!value && !upperdentry) { + ovl_path_lower(dentry, &realpath); + old_cred = ovl_override_creds(dentry->d_sb); + err = vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0); + revert_creds(old_cred); + if (err < 0) + goto out; + } + + if (!upperdentry) { + err = ovl_copy_up(dentry); + if (err) + goto out; + + realdentry = ovl_dentry_upper(dentry); + } + + err = ovl_want_write(dentry); + if (err) + goto out; + + old_cred = ovl_override_creds(dentry->d_sb); + if (value) { + err = ovl_do_setxattr(ofs, realdentry, name, value, size, + flags); + } else { + WARN_ON(flags != XATTR_REPLACE); + err = ovl_do_removexattr(ofs, realdentry, name); + } + revert_creds(old_cred); + ovl_drop_write(dentry); + + /* copy c/mtime */ + ovl_copyattr(inode); +out: + return err; +} + +static int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, + void *value, size_t size) +{ + ssize_t res; + const struct cred *old_cred; + struct path realpath; + + ovl_i_path_real(inode, &realpath); + old_cred = ovl_override_creds(dentry->d_sb); + res = vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry, name, value, size); + revert_creds(old_cred); + return res; +} + +static bool ovl_can_list(struct super_block *sb, const char *s) +{ + /* Never list private (.overlay) */ + if (ovl_is_private_xattr(sb, s)) + return false; + + /* List all non-trusted xattrs */ + if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0) + return true; + + /* list other trusted for superuser only */ + return ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN); +} + +ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) +{ + struct dentry *realdentry = ovl_dentry_real(dentry); + ssize_t res; + size_t len; + char *s; + const struct cred *old_cred; + + old_cred = ovl_override_creds(dentry->d_sb); + res = vfs_listxattr(realdentry, list, size); + revert_creds(old_cred); + if (res <= 0 || size == 0) + return res; + + /* filter out private xattrs */ + for (s = list, len = res; len;) { + size_t slen = strnlen(s, len) + 1; + + /* underlying fs providing us with an broken xattr list? */ + if (WARN_ON(slen > len)) + return -EIO; + + len -= slen; + if (!ovl_can_list(dentry->d_sb, s)) { + res -= slen; + memmove(s, s + slen, len); + } else { + s += slen; + } + } + + return res; +} + +static int ovl_own_xattr_get(const struct xattr_handler *handler, + struct dentry *dentry, struct inode *inode, + const char *name, void *buffer, size_t size) +{ + return -EOPNOTSUPP; +} + +static int ovl_own_xattr_set(const struct xattr_handler *handler, + struct mnt_idmap *idmap, + struct dentry *dentry, struct inode *inode, + const char *name, const void *value, + size_t size, int flags) +{ + return -EOPNOTSUPP; +} + +static int ovl_other_xattr_get(const struct xattr_handler *handler, + struct dentry *dentry, struct inode *inode, + const char *name, void *buffer, size_t size) +{ + return ovl_xattr_get(dentry, inode, name, buffer, size); +} + +static int ovl_other_xattr_set(const struct xattr_handler *handler, + struct mnt_idmap *idmap, + struct dentry *dentry, struct inode *inode, + const char *name, const void *value, + size_t size, int flags) +{ + return ovl_xattr_set(dentry, inode, name, value, size, flags); +} + +static const struct xattr_handler ovl_own_trusted_xattr_handler = { + .prefix = OVL_XATTR_TRUSTED_PREFIX, + .get = ovl_own_xattr_get, + .set = ovl_own_xattr_set, +}; + +static const struct xattr_handler ovl_own_user_xattr_handler = { + .prefix = OVL_XATTR_USER_PREFIX, + .get = ovl_own_xattr_get, + .set = ovl_own_xattr_set, +}; + +static const struct xattr_handler ovl_other_xattr_handler = { + .prefix = "", /* catch all */ + .get = ovl_other_xattr_get, + .set = ovl_other_xattr_set, +}; + +static const struct xattr_handler * const ovl_trusted_xattr_handlers[] = { + &ovl_own_trusted_xattr_handler, + &ovl_other_xattr_handler, + NULL +}; + +static const struct xattr_handler * const ovl_user_xattr_handlers[] = { + &ovl_own_user_xattr_handler, + &ovl_other_xattr_handler, + NULL +}; + +const struct xattr_handler * const *ovl_xattr_handlers(struct ovl_fs *ofs) +{ + return ofs->config.userxattr ? ovl_user_xattr_handlers : + ovl_trusted_xattr_handlers; +} + |