user/sven/linux.git/security/commoncap.c, branch v4.14.236

security: commoncap: fix -Wstringop-overread warning

2021-05-22T08:57:21Z

commit 82e5d8cc768b0c7b03c551a9ab1f8f3f68d5f83f upstream. gcc-11 introdces a harmless warning for cap_inode_getsecurity: security/commoncap.c: In function ‘cap_inode_getsecurity’: security/commoncap.c:440:33: error: ‘memcpy’ reading 16 bytes from a region of size 0 [-Werror=stringop-overread] 440 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The problem here is that tmpbuf is initialized to NULL, so gcc assumes it is not accessible unless it gets set by vfs_getxattr_alloc(). This is a legitimate warning as far as I can tell, but the code is correct since it correctly handles the error when that function fails. Add a separate NULL check to tell gcc about it as well. Signed-off-by: Arnd Bergmann Acked-by: Christian Brauner Signed-off-by: James Morris Cc: Andrey Zhizhikin Signed-off-by: Greg Kroah-Hartman

Revert 95ebabde382c ("capabilities: Don't allow writing ambiguous v3 file capabilities")

2021-03-17T15:34:31Z

commit 3b0c2d3eaa83da259d7726192cf55a137769012f upstream. It turns out that there are in fact userspace implementations that care and this recent change caused a regression. https://github.com/containers/buildah/issues/3071 As the motivation for the original change was future development, and the impact is existing real world code just revert this change and allow the ambiguity in v3 file caps. Cc: stable@vger.kernel.org Fixes: 95ebabde382c ("capabilities: Don't allow writing ambiguous v3 file capabilities") Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

capabilities: Don't allow writing ambiguous v3 file capabilities

2021-03-03T17:22:44Z

[ Upstream commit 95ebabde382c371572297915b104e55403674e73 ] The v3 file capabilities have a uid field that records the filesystem uid of the root user of the user namespace the file capabilities are valid in. When someone is silly enough to have the same underlying uid as the root uid of multiple nested containers a v3 filesystem capability can be ambiguous. In the spirit of don't do that then, forbid writing a v3 filesystem capability if it is ambiguous. Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities") Reviewed-by: Andrew G. Morgan Reviewed-by: Serge Hallyn Signed-off-by: Eric W. Biederman Signed-off-by: Sasha Levin

cap: fix conversions on getxattr

2021-02-23T13:00:31Z

[ Upstream commit f2b00be488730522d0fb7a8a5de663febdcefe0a ] If a capability is stored on disk in v2 format cap_inode_getsecurity() will currently return in v2 format unconditionally. This is wrong: v2 cap should be equivalent to a v3 cap with zero rootid, and so the same conversions performed on it. If the rootid cannot be mapped, v3 is returned unconverted. Fix this so that both v2 and v3 return -EOVERFLOW if the rootid (or the owner of the fs user namespace in case of v2) cannot be mapped into the current user namespace. Signed-off-by: Miklos Szeredi Acked-by: "Eric W. Biederman" Signed-off-by: Sasha Levin

exec: Always set cap_ambient in cap_bprm_set_creds

2020-06-03T06:18:01Z

[ Upstream commit a4ae32c71fe90794127b32d26d7ad795813b502e ] An invariant of cap_bprm_set_creds is that every field in the new cred structure that cap_bprm_set_creds might set, needs to be set every time to ensure the fields does not get a stale value. The field cap_ambient is not set every time cap_bprm_set_creds is called, which means that if there is a suid or sgid script with an interpreter that has neither the suid nor the sgid bits set the interpreter should be able to accept ambient credentials. Unfortuantely because cap_ambient is not reset to it's original value the interpreter can not accept ambient credentials. Given that the ambient capability set is expected to be controlled by the caller, I don't think this is particularly serious. But it is definitely worth fixing so the code works correctly. I have tested to verify my reading of the code is correct and the interpreter of a sgid can receive ambient capabilities with this change and cannot receive ambient capabilities without this change. Cc: stable@vger.kernel.org Cc: Andy Lutomirski Fixes: 58319057b784 ("capabilities: ambient capabilities") Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin

cap_inode_getsecurity: use d_find_any_alias() instead of d_find_alias()

2018-09-09T17:56:01Z

commit 355139a8dba446cc11a424cddbf7afebc3041ba1 upstream. The code in cap_inode_getsecurity(), introduced by commit 8db6c34f1dbc ("Introduce v3 namespaced file capabilities"), should use d_find_any_alias() instead of d_find_alias() do handle unhashed dentry correctly. This is needed, for example, if execveat() is called with an open but unlinked overlayfs file, because overlayfs unhashes dentry on unlink. This is a regression of real life application, first reported at https://www.spinics.net/lists/linux-unionfs/msg05363.html Below reproducer and setup can reproduce the case. const char* exec="echo"; const char *newargv[] = { "echo", "hello", NULL}; const char *newenviron[] = { NULL }; int fd, err; fd = open(exec, O_PATH); unlink(exec); err = syscall(322/*SYS_execveat*/, fd, "", newargv, newenviron, AT_EMPTY_PATH); if(err<0) fprintf(stderr, "execveat: %s\n", strerror(errno)); gcc compile into ~/test/a.out mount -t overlay -orw,lowerdir=/mnt/l,upperdir=/mnt/u,workdir=/mnt/w none /mnt/m cd /mnt/m cp /bin/echo . ~/test/a.out Expected result: hello Actually result: execveat: Invalid argument dmesg: Invalid argument reading file caps for /dev/fd/3 The 2nd reproducer and setup emulates similar case but for regular filesystem: const char* exec="echo"; int fd, err; char buf[256]; fd = open(exec, O_RDONLY); unlink(exec); err = fgetxattr(fd, "security.capability", buf, 256); if(err<0) fprintf(stderr, "fgetxattr: %s\n", strerror(errno)); gcc compile into ~/test_fgetxattr cd /tmp cp /bin/echo . ~/test_fgetxattr Result: fgetxattr: Invalid argument On regular filesystem, for example, ext4 read xattr from disk and return to execveat(), will not trigger this issue, however, the overlay attr handler pass real dentry to vfs_getxattr() will. This reproducer calls fgetxattr() with an unlinked fd, involkes vfs_getxattr() then reproduced the case that d_find_alias() in cap_inode_getsecurity() can't find the unlinked dentry. Suggested-by: Amir Goldstein Acked-by: Amir Goldstein Acked-by: Serge E. Hallyn Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities") Cc: # v4.14 Signed-off-by: Eddie Horng Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

commoncap: Handle memory allocation failure.

2018-04-29T09:33:16Z

commit 1f5781725dcbb026438e77091c91a94f678c3522 upstream. syzbot is reporting NULL pointer dereference at xattr_getsecurity() [1], for cap_inode_getsecurity() is returning sizeof(struct vfs_cap_data) when memory allocation failed. Return -ENOMEM if memory allocation failed. [1] https://syzkaller.appspot.com/bug?id=a55ba438506fe68649a5f50d2d82d56b365e0107 Signed-off-by: Tetsuo Handa Fixes: 8db6c34f1dbc8e06 ("Introduce v3 namespaced file capabilities") Reported-by: syzbot Cc: stable # 4.14+ Acked-by: Serge E. Hallyn Acked-by: James Morris Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

capabilities: fix buffer overread on very short xattr

2018-01-05T14:48:57Z

commit dc32b5c3e6e2ef29cef76d9ce1b92d394446150e upstream. If userspace attempted to set a "security.capability" xattr shorter than 4 bytes (e.g. 'setfattr -n security.capability -v x file'), then cap_convert_nscap() read past the end of the buffer containing the xattr value because it accessed the ->magic_etc field without verifying that the xattr value is long enough to contain that field. Fix it by validating the xattr value size first. This bug was found using syzkaller with KASAN. The KASAN report was as follows (cleaned up slightly): BUG: KASAN: slab-out-of-bounds in cap_convert_nscap+0x514/0x630 security/commoncap.c:498 Read of size 4 at addr ffff88002d8741c0 by task syz-executor1/2852 CPU: 0 PID: 2852 Comm: syz-executor1 Not tainted 4.15.0-rc6-00200-gcc0aac99d977 #253 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xe3/0x195 lib/dump_stack.c:53 print_address_description+0x73/0x260 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x235/0x350 mm/kasan/report.c:409 cap_convert_nscap+0x514/0x630 security/commoncap.c:498 setxattr+0x2bd/0x350 fs/xattr.c:446 path_setxattr+0x168/0x1b0 fs/xattr.c:472 SYSC_setxattr fs/xattr.c:487 [inline] SyS_setxattr+0x36/0x50 fs/xattr.c:483 entry_SYSCALL_64_fastpath+0x18/0x85 Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities") Signed-off-by: Eric Biggers Reviewed-by: Serge Hallyn Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

commoncap: move assignment of fs_ns to avoid null pointer dereference

2017-10-19T02:09:33Z

The pointer fs_ns is assigned from inode->i_ib->s_user_ns before a null pointer check on inode, hence if inode is actually null we will get a null pointer dereference on this assignment. Fix this by only dereferencing inode after the null pointer check on inode. Detected by CoverityScan CID#1455328 ("Dereference before null check") Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities") Signed-off-by: Colin Ian King Cc: stable@vger.kernel.org Acked-by: Serge Hallyn Signed-off-by: James Morris

Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2017-09-24T18:40:41Z

Pull misc security layer update from James Morris: "This is the remaining 'general' change in the security tree for v4.14, following the direct merging of SELinux (+ TOMOYO), AppArmor, and seccomp. That's everything now for the security tree except IMA, which will follow shortly (I've been traveling for the past week with patchy internet)" * 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: security: fix description of values returned by cap_inode_need_killpriv