commit bff117da3ebcedc486039a8d6644f1481037413e Author: Juergen Daubert <jue@jue.li> Date: Tue Feb 20 17:59:28 2018 +0100 [notify] shadow: fix for CVE-2018-7169, closes FS#1594 https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/1729357 diff --git a/shadow/.md5sum b/shadow/.md5sum index 06f99533..6424e4d5 100644 --- a/shadow/.md5sum +++ b/shadow/.md5sum @@ -1,3 +1,4 @@ +aad42ace9b3d450717355010b9344c56 CVE-2018-7169.patch 80756b2d5b3351b3757f48ae69fe866d login.defs be8f69c2701118093af3d7f3bc02af16 pwck c350da50c2120de6bb29177699d89fe3 shadow-4.5.tar.xz diff --git a/shadow/.signature b/shadow/.signature index 0711d487..6dbc8777 100644 --- a/shadow/.signature +++ b/shadow/.signature @@ -1,7 +1,8 @@ untrusted comment: verify with /etc/ports/core.pub -RWRJc1FUaeVeqpDsCheU2Flzc0CeEsEe3NNLiW1rztqmJbdJolKG3tJmJXgvIZDG5AmhN6URgAK9BoPhy46gWxv9CRZdtZgMvwU= -SHA256 (Pkgfile) = 28e4ab2a059acc5972ecbb882d0b08fbe36d8c6b026fc87c150df2d5f06cdc1e +RWRJc1FUaeVeqqLpIS3LGM3rjoF0kUdbtuIDL1UilPze46/DVrHdo27qHiHPLOaN8GLLukQJFkQRq8XV9obslWlWtguLSW/uTwo= +SHA256 (Pkgfile) = 4647cbfe01446ff33de8393e0a6d9dff1a4ac199acd417e66e6623cf6a705507 SHA256 (.footprint) = 196891826eef19be5e249380bc5c9560b10051556be4a3be5d33e099a56f23ae SHA256 (shadow-4.5.tar.xz) = fc8c858381ad577a5c25ff5beb6ee60a34f8719c73e4e7c61e74188b4e54b741 +SHA256 (CVE-2018-7169.patch) = 3b8896d8ac400692af1e2da17b9b8a447aa668c09fe16c1b9cee55e923b64820 SHA256 (pwck) = c62f1bf5785c2bb93bb269156bfa02b06728a01ff5d6c2e09cf6285701a1fda0 SHA256 (login.defs) = a5c63da222b9dd921b60a21be8fc888726b557fd3fde9f60c8899376d0311b0b diff --git a/shadow/CVE-2018-7169.patch b/shadow/CVE-2018-7169.patch new file mode 100644 index 00000000..30ad9e61 --- /dev/null +++ b/shadow/CVE-2018-7169.patch @@ -0,0 +1,180 @@ +From fb28c99b8a66ff2605c5cb96abc0a4d975f92de0 Mon Sep 17 00:00:00 2001 +From: Aleksa Sarai <asarai@suse.de> +Date: Thu, 15 Feb 2018 23:49:40 +1100 +Subject: [PATCH] newgidmap: enforce setgroups=deny if self-mapping a group + +This is necessary to match the kernel-side policy of "self-mapping in a +user namespace is fine, but you cannot drop groups" -- a policy that was +created in order to stop user namespaces from allowing trivial privilege +escalation by dropping supplementary groups that were "blacklisted" from +certain paths. + +This is the simplest fix for the underlying issue, and effectively makes +it so that unless a user has a valid mapping set in /etc/subgid (which +only administrators can modify) -- and they are currently trying to use +that mapping -- then /proc/$pid/setgroups will be set to deny. This +workaround is only partial, because ideally it should be possible to set +an "allow_setgroups" or "deny_setgroups" flag in /etc/subgid to allow +administrators to further restrict newgidmap(1). + +We also don't write anything in the "allow" case because "allow" is the +default, and users may have already written "deny" even if they +technically are allowed to use setgroups. And we don't write anything if +the setgroups policy is already "deny". + +Ref: https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/1729357 +Fixes: CVE-2018-7169 +Reported-by: Craig Furman <craig.furman89@gmail.com> +Signed-off-by: Aleksa Sarai <asarai@suse.de> +--- + src/newgidmap.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++------ + 1 file changed, 80 insertions(+), 9 deletions(-) + +diff --git a/src/newgidmap.c b/src/newgidmap.c +index b1e33513..59a2e75c 100644 +--- a/src/newgidmap.c ++++ b/src/newgidmap.c +@@ -46,32 +46,37 @@ + */ + const char *Prog; + +-static bool verify_range(struct passwd *pw, struct map_range *range) ++ ++static bool verify_range(struct passwd *pw, struct map_range *range, bool *allow_setgroups) + { + /* An empty range is invalid */ + if (range->count == 0) + return false; + +- /* Test /etc/subgid */ +- if (have_sub_gids(pw->pw_name, range->lower, range->count)) ++ /* Test /etc/subgid. If the mapping is valid then we allow setgroups. */ ++ if (have_sub_gids(pw->pw_name, range->lower, range->count)) { ++ *allow_setgroups = true; + return true; ++ } + +- /* Allow a process to map its own gid */ +- if ((range->count == 1) && (pw->pw_gid == range->lower)) ++ /* Allow a process to map its own gid. */ ++ if ((range->count == 1) && (pw->pw_gid == range->lower)) { ++ /* noop -- if setgroups is enabled already we won't disable it. */ + return true; ++ } + + return false; + } + + static void verify_ranges(struct passwd *pw, int ranges, +- struct map_range *mappings) ++ struct map_range *mappings, bool *allow_setgroups) + { + struct map_range *mapping; + int idx; + + mapping = mappings; + for (idx = 0; idx < ranges; idx++, mapping++) { +- if (!verify_range(pw, mapping)) { ++ if (!verify_range(pw, mapping, allow_setgroups)) { + fprintf(stderr, _( "%s: gid range [%lu-%lu) -> [%lu-%lu) not allowed\n"), + Prog, + mapping->upper, +@@ -89,6 +94,70 @@ static void usage(void) + exit(EXIT_FAILURE); + } + ++void write_setgroups(int proc_dir_fd, bool allow_setgroups) ++{ ++ int setgroups_fd; ++ char *policy, policy_buffer[4096]; ++ ++ /* ++ * Default is "deny", and any "allow" will out-rank a "deny". We don't ++ * forcefully write an "allow" here because the process we are writing ++ * mappings for may have already set themselves to "deny" (and "allow" ++ * is the default anyway). So allow_setgroups == true is a noop. ++ */ ++ policy = "deny\n"; ++ if (allow_setgroups) ++ return; ++ ++ setgroups_fd = openat(proc_dir_fd, "setgroups", O_RDWR|O_CLOEXEC); ++ if (setgroups_fd < 0) { ++ /* ++ * If it's an ENOENT then we are on too old a kernel for the setgroups ++ * code to exist. Emit a warning and bail on this. ++ */ ++ if (ENOENT == errno) { ++ fprintf(stderr, _("%s: kernel doesn't support setgroups restrictions\n"), Prog); ++ goto out; ++ } ++ fprintf(stderr, _("%s: couldn't open process setgroups: %s\n"), ++ Prog, ++ strerror(errno)); ++ exit(EXIT_FAILURE); ++ } ++ ++ /* ++ * Check whether the policy is already what we want. /proc/self/setgroups ++ * is write-once, so attempting to write after it's already written to will ++ * fail. ++ */ ++ if (read(setgroups_fd, policy_buffer, sizeof(policy_buffer)) < 0) { ++ fprintf(stderr, _("%s: failed to read setgroups: %s\n"), ++ Prog, ++ strerror(errno)); ++ exit(EXIT_FAILURE); ++ } ++ if (!strncmp(policy_buffer, policy, strlen(policy))) ++ goto out; ++ ++ /* Write the policy. */ ++ if (lseek(setgroups_fd, 0, SEEK_SET) < 0) { ++ fprintf(stderr, _("%s: failed to seek setgroups: %s\n"), ++ Prog, ++ strerror(errno)); ++ exit(EXIT_FAILURE); ++ } ++ if (dprintf(setgroups_fd, "%s", policy) < 0) { ++ fprintf(stderr, _("%s: failed to setgroups %s policy: %s\n"), ++ Prog, ++ policy, ++ strerror(errno)); ++ exit(EXIT_FAILURE); ++ } ++ ++out: ++ close(setgroups_fd); ++} ++ + /* + * newgidmap - Set the gid_map for the specified process + */ +@@ -103,6 +172,7 @@ int main(int argc, char **argv) + struct stat st; + struct passwd *pw; + int written; ++ bool allow_setgroups = false; + + Prog = Basename (argv[0]); + +@@ -145,7 +215,7 @@ int main(int argc, char **argv) + (unsigned long) getuid ())); + return EXIT_FAILURE; + } +- ++ + /* Get the effective uid and effective gid of the target process */ + if (fstat(proc_dir_fd, &st) < 0) { + fprintf(stderr, _("%s: Could not stat directory for target %u\n"), +@@ -177,8 +247,9 @@ int main(int argc, char **argv) + if (!mappings) + usage(); + +- verify_ranges(pw, ranges, mappings); ++ verify_ranges(pw, ranges, mappings, &allow_setgroups); + ++ write_setgroups(proc_dir_fd, allow_setgroups); + write_mapping(proc_dir_fd, ranges, mappings, "gid_map"); + sub_gid_close(); + diff --git a/shadow/Pkgfile b/shadow/Pkgfile index 25870198..e793f3c5 100644 --- a/shadow/Pkgfile +++ b/shadow/Pkgfile @@ -5,13 +5,17 @@ name=shadow version=4.5 -release=1 +release=2 source=(https://github.com/shadow-maint/shadow/releases/download/$version/shadow-$ve... + CVE-2018-7169.patch pwck login.defs) build() { cd $name-$version + # https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/1729357 + patch -p1 -i $SRC/CVE-2018-7169.patch + ./configure --prefix=/usr \ --sysconfdir=/etc \ --disable-shared \