diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/file-has-acl.c | 37 |
1 files changed, 26 insertions, 11 deletions
diff --git a/lib/file-has-acl.c b/lib/file-has-acl.c index 38bc806dc4..4cddc80bd1 100644 --- a/lib/file-has-acl.c +++ b/lib/file-has-acl.c @@ -29,7 +29,10 @@ #include "acl-internal.h" +#include "minmax.h" + #if USE_ACL && HAVE_LINUX_XATTR_H && HAVE_LISTXATTR +# include <stdckdint.h> # include <string.h> # include <arpa/inet.h> # include <sys/xattr.h> @@ -181,32 +184,44 @@ file_has_acl (char const *name, struct stat const *sb) && errno == ERANGE) { free (heapbuf); - listbufsize = listxattr (name, NULL, 0); - if (listbufsize < 0) - return -1; - if (SIZE_MAX < listbufsize) + ssize_t newsize = listxattr (name, NULL, 0); + if (newsize <= 0) + return newsize; + + /* Grow LISTBUFSIZE to at least NEWSIZE. Grow it by a + nontrivial amount too, to defend against denial of + service by an adversary that fiddles with ACLs. */ + bool overflow = ckd_add (&listbufsize, listbufsize, listbufsize >> 1); + listbufsize = MAX (listbufsize, newsize); + if (overflow || SIZE_MAX < listbufsize) { errno = ENOMEM; return -1; } + listbuf = heapbuf = malloc (listbufsize); if (!listbuf) return -1; } + /* In Fedora 39, a file can have both NFSv4 and POSIX ACLs, + but if it has an NFSv4 ACL that's the one that matters. + In earlier Fedora the two types of ACLs were mutually exclusive. + Attempt to work correctly on both kinds of systems. */ + bool nfsv4_acl + = 0 < listsize && have_xattr (XATTR_NAME_NFSV4_ACL, listbuf, listsize); int ret - = (listsize < 0 ? -1 - : (have_xattr (XATTR_NAME_POSIX_ACL_ACCESS, listbuf, listsize) + = (listsize <= 0 ? listsize + : (nfsv4_acl + || have_xattr (XATTR_NAME_POSIX_ACL_ACCESS, listbuf, listsize) || (S_ISDIR (sb->st_mode) && have_xattr (XATTR_NAME_POSIX_ACL_DEFAULT, listbuf, listsize)))); - bool nfsv4_acl_but_no_posix_acl - = ret == 0 && have_xattr (XATTR_NAME_NFSV4_ACL, listbuf, listsize); free (heapbuf); - /* If there is an NFSv4 ACL but no POSIX ACL, follow up with a - getxattr syscall to see whether the NFSv4 ACL is nontrivial. */ - if (nfsv4_acl_but_no_posix_acl) + /* If there is an NFSv4 ACL, follow up with a getxattr syscall + to see whether the NFSv4 ACL is nontrivial. */ + if (nfsv4_acl) { ret = getxattr (name, XATTR_NAME_NFSV4_ACL, stackbuf.xattr, sizeof stackbuf.xattr); |