6.6-stable review patch. If anyone has any objections, please let me know.
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From: Stephen Smalley stephen.smalley.work@gmail.com
[ Upstream commit 8b0ba61df5a1c44e2b3cf683831a4fc5e24ea99d ]
The vfs has long had a fallback to obtain the security.* xattrs from the LSM when the filesystem does not implement its own listxattr, but shmem/tmpfs and kernfs later gained their own xattr handlers to support other xattrs. Unfortunately, as a side effect, tmpfs and kernfs-based filesystems like sysfs no longer return the synthetic security.* xattr names via listxattr unless they are explicitly set by userspace or initially set upon inode creation after policy load. coreutils has recently switched from unconditionally invoking getxattr for security.* for ls -Z via libselinux to only doing so if listxattr returns the xattr name, breaking ls -Z of such inodes.
Before: $ getfattr -m.* /run/initramfs <no output> $ getfattr -m.* /sys/kernel/fscaps <no output> $ setfattr -n user.foo /run/initramfs $ getfattr -m.* /run/initramfs user.foo
After: $ getfattr -m.* /run/initramfs security.selinux $ getfattr -m.* /sys/kernel/fscaps security.selinux $ setfattr -n user.foo /run/initramfs $ getfattr -m.* /run/initramfs security.selinux user.foo
Link: https://lore.kernel.org/selinux/CAFqZXNtF8wDyQajPCdGn=iOawX4y77ph0EcfcqcUUj+... Link: https://lore.kernel.org/selinux/20250423175728.3185-2-stephen.smalley.work@g... Signed-off-by: Stephen Smalley stephen.smalley.work@gmail.com Link: https://lore.kernel.org/20250424152822.2719-1-stephen.smalley.work@gmail.com Fixes: b09e0fa4b4ea66266058ee ("tmpfs: implement generic xattr support") Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/xattr.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/fs/xattr.c b/fs/xattr.c index c20046548f218..5fed22c22a2be 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -1291,6 +1291,15 @@ static bool xattr_is_trusted(const char *name) return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); }
+static bool xattr_is_maclabel(const char *name) +{ + const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; + + return !strncmp(name, XATTR_SECURITY_PREFIX, + XATTR_SECURITY_PREFIX_LEN) && + security_ismaclabel(suffix); +} + /** * simple_xattr_list - list all xattr objects * @inode: inode from which to get the xattrs @@ -1323,6 +1332,17 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, if (err) return err;
+ err = security_inode_listsecurity(inode, buffer, remaining_size); + if (err < 0) + return err; + + if (buffer) { + if (remaining_size < err) + return -ERANGE; + buffer += err; + } + remaining_size -= err; + read_lock(&xattrs->lock); for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) { xattr = rb_entry(rbp, struct simple_xattr, rb_node); @@ -1331,6 +1351,10 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, if (!trusted && xattr_is_trusted(xattr->name)) continue;
+ /* skip MAC labels; these are provided by LSM above */ + if (xattr_is_maclabel(xattr->name)) + continue; + err = xattr_list_one(&buffer, &remaining_size, xattr->name); if (err) break;