kernel/git/stable/linux-stable.git/fs/xattr.c, branch linux-3.16.y

getxattr: use correct xattr length

2018-12-16T22:08:52+00:00

commit 82c9a927bc5df6e06b72d206d24a9d10cced4eb5 upstream. 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 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 Signed-off-by: Ben Hutchings

lsm: fix smack_inode_removexattr and xattr_getsecurity memleak

2018-01-01T20:51:48+00:00

commit 57e7ba04d422c3d41c8426380303ec9b7533ded9 upstream. 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 Signed-off-by: James Morris [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

fs/xattr.c: zero out memory copied to userspace in getxattr

2017-08-26T01:14:47+00:00

commit 81be3dee96346fbe08c31be5ef74f03f6b63cf68 upstream. getxattr uses vmalloc to allocate memory if kzalloc fails. This is filled by vfs_getxattr and then copied to the userspace. vmalloc, however, doesn't zero out the memory so if the specific implementation of the xattr handler is sloppy we can theoretically expose a kernel memory. There is no real sign this is really the case but let's make sure this will not happen and use vzalloc instead. Fixes: 779302e67835 ("fs/xattr.c:getxattr(): improve handling of allocation failures") Link: http://lkml.kernel.org/r/20170306103327.2766-1-mhocko@kernel.org Acked-by: Kees Cook Reported-by: Vlastimil Babka Signed-off-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

simple_xattr: permit 0-size extended attributes

2014-07-23T22:10:55+00:00

If a filesystem uses simple_xattr to support user extended attributes, LTP setxattr01 and xfstests generic/062 fail with "Cannot allocate memory": simple_xattr_alloc()'s wrap-around test mistakenly excludes values of zero size. Fix that off-by-one (but apparently no filesystem needs them yet). Signed-off-by: Hugh Dickins Cc: Al Viro Cc: Jeff Layton Cc: Aristeu Rozanski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vfs: make lremovexattr retry once on ESTALE error

2012-12-20T23:50:11+00:00