kernel.git/fs/xattr.c, branch linux-5.4.y

fs: don't audit the capability check in simple_xattr_list()

2023-01-18T10:40:53Z

[ Upstream commit e7eda157c4071cd1e69f4b1687b0fbe1ae5e6f46 ] The check being unconditional may lead to unwanted denials reported by LSMs when a process has the capability granted by DAC, but denied by an LSM. In the case of SELinux such denials are a problem, since they can't be effectively filtered out via the policy and when not silenced, they produce noise that may hide a true problem or an attack. Checking for the capability only if any trusted xattr is actually present wouldn't really address the issue, since calling listxattr(2) on such node on its own doesn't indicate an explicit attempt to see the trusted xattrs. Additionally, it could potentially leak the presence of trusted xattrs to an unprivileged user if they can check for the denials (e.g. through dmesg). Therefore, it's best (and simplest) to keep the check unconditional and instead use ns_capable_noaudit() that will silence any associated LSM denials. Fixes: 38f38657444d ("xattr: extract simple_xattr code from tmpfs") Reported-by: Martin Pitt Suggested-by: Christian Brauner (Microsoft) Signed-off-by: Ondrej Mosnacek Reviewed-by: Christian Brauner (Microsoft) Reviewed-by: Paul Moore Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Sasha Levin

xattr: break delegations in {set,remove}xattr

2020-08-11T13:33:39Z

commit 08b5d5014a27e717826999ad20e394a8811aae92 upstream. set/removexattr on an exported filesystem should break NFS delegations. This is true in general, but also for the upcoming support for RFC 8726 (NFSv4 extended attribute support). Make sure that they do. Additionally, they need to grow a _locked variant, since callers might call this with i_rwsem held (like the NFS server code). Cc: stable@vger.kernel.org # v4.9+ Cc: linux-fsdevel@vger.kernel.org Cc: Al Viro Signed-off-by: Frank van der Linden Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45Z

Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

sysfs: Do not return POSIX ACL xattrs via listxattr

2018-09-18T11:30:48Z

Commit 786534b92f3c introduced a regression that caused listxattr to return the POSIX ACL attribute names even though sysfs doesn't support POSIX ACLs. This happens because simple_xattr_list checks for NULL i_acl / i_default_acl, but inode_init_always initializes those fields to ACL_NOT_CACHED ((void *)-1). For example: $ getfattr -m- -d /sys /sys: system.posix_acl_access: Operation not supported /sys: system.posix_acl_default: Operation not supported Fix this in simple_xattr_list by checking if the filesystem supports POSIX ACLs. Fixes: 786534b92f3c ("tmpfs: listxattr should include POSIX ACL xattrs") Reported-by: Marc Aurèle La France Tested-by: Marc Aurèle La France Signed-off-by: Andreas Gruenbacher Cc: stable@vger.kernel.org # v4.5+ Signed-off-by: Al Viro

Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2018-08-24T16:25:39Z

Pull namespace fixes from Eric Biederman: "This is a set of four fairly obvious bug fixes: - a switch from d_find_alias to d_find_any_alias because the xattr code perversely takes a dentry - two mutex vs copy_to_user fixes from Jann Horn - a fix to use a sanitized size not the size userspace passed in from Christian Brauner" * 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: getxattr: use correct xattr length sys: don't hold uts_sem while accessing userspace memory userns: move user access out of the mutex cap_inode_getsecurity: use d_find_any_alias() instead of d_find_alias()

getxattr: use correct xattr length

2018-08-23T18:42:57Z

When running in a container with a user namespace, if you call getxattr with name = "system.posix_acl_access" and size % 8 != 4, then getxattr silently skips the user namespace fixup that it normally does resulting in un-fixed-up data being returned. This is caused by posix_acl_fix_xattr_to_user() being passed the total buffer size and not the actual size of the xattr as returned by vfs_getxattr(). This commit passes the actual length of the xattr as returned by vfs_getxattr() down. A reproducer for the issue is: touch acl_posix setfacl -m user:0:rwx acl_posix and the compile: #define _GNU_SOURCE #include #include #include #include #include #include #include /* Run in user namespace with nsuid 0 mapped to uid != 0 on the host. */ int main(int argc, void **argv) { ssize_t ret1, ret2; char buf1[128], buf2[132]; int fret = EXIT_SUCCESS; char *file; if (argc < 2) { fprintf(stderr, "Please specify a file with " "\"system.posix_acl_access\" permissions set\n"); _exit(EXIT_FAILURE); } file = argv[1]; ret1 = getxattr(file, "system.posix_acl_access", buf1, sizeof(buf1)); if (ret1 < 0) { fprintf(stderr, "%s - Failed to retrieve " "\"system.posix_acl_access\" " "from \"%s\"\n", strerror(errno), file); _exit(EXIT_FAILURE); } ret2 = getxattr(file, "system.posix_acl_access", buf2, sizeof(buf2)); if (ret2 < 0) { fprintf(stderr, "%s - Failed to retrieve " "\"system.posix_acl_access\" " "from \"%s\"\n", strerror(errno), file); _exit(EXIT_FAILURE); } if (ret1 != ret2) { fprintf(stderr, "The value of \"system.posix_acl_" "access\" for file \"%s\" changed " "between two successive calls\n", file); _exit(EXIT_FAILURE); } for (ssize_t i = 0; i < ret2; i++) { if (buf1[i] == buf2[i]) continue; fprintf(stderr, "Unexpected different in byte %zd: " "%02x != %02x\n", i, buf1[i], buf2[i]); fret = EXIT_FAILURE; } if (fret == EXIT_SUCCESS) fprintf(stderr, "Test passed\n"); else fprintf(stderr, "Test failed\n"); _exit(fret); } and run: ./tester acl_posix On a non-fixed up kernel this should return something like: root@c1:/# ./t Unexpected different in byte 16: ffffffa0 != 00 Unexpected different in byte 17: ffffff86 != 00 Unexpected different in byte 18: 01 != 00 and on a fixed kernel: root@c1:~# ./t Test passed Cc: stable@vger.kernel.org Fixes: 2f6f0654ab61 ("userns: Convert vfs posix_acl support to use kuids and kgids") Link: https://bugzilla.kernel.org/show_bug.cgi?id=199945 Reported-by: Colin Watson Signed-off-by: Christian Brauner Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

Revert "ovl: don't allow writing ioctl on lower layer"

2018-07-18T13:44:43Z

This reverts commit 7c6893e3c9abf6a9676e060a1e35e5caca673d57. Overlayfs no longer relies on the vfs for checking writability of files. Signed-off-by: Miklos Szeredi

vfs: delete unnecessary assignment in vfs_listxattr

2018-05-29T17:22:41Z

It seems the first error assignment in if branch is redundant. Signed-off-by: Chengguang Xu Signed-off-by: Al Viro

make xattr_getsecurity() static

2018-05-14T13:51:34Z

many years overdue... Signed-off-by: Al Viro

lsm: fix smack_inode_removexattr and xattr_getsecurity memleak

2017-10-04T07:03:15Z

security_inode_getsecurity() provides the text string value of a security attribute. It does not provide a "secctx". The code in xattr_getsecurity() that calls security_inode_getsecurity() and then calls security_release_secctx() happened to work because SElinux and Smack treat the attribute and the secctx the same way. It fails for cap_inode_getsecurity(), because that module has no secctx that ever needs releasing. It turns out that Smack is the one that's doing things wrong by not allocating memory when instructed to do so by the "alloc" parameter. The fix is simple enough. Change the security_release_secctx() to kfree() because it isn't a secctx being returned by security_inode_getsecurity(). Change Smack to allocate the string when told to do so. Note: this also fixes memory leaks for LSMs which implement inode_getsecurity but not release_secctx, such as capabilities. Signed-off-by: Casey Schaufler Reported-by: Konstantin Khlebnikov Cc: stable@vger.kernel.org Signed-off-by: James Morris