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author | Tejun Heo <tj@kernel.org> | 2022-01-06 11:02:29 -1000 |
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committer | Tejun Heo <tj@kernel.org> | 2022-01-06 11:02:29 -1000 |
commit | 613e040e4dc285367bff0f8f75ea59839bc10947 (patch) | |
tree | 5556aa81ceeed1f035d60bb5f72fe15edf1157cf /tools/testing/selftests/cgroup | |
parent | b09c2baa56347ae65795350dfcc633dedb1c2970 (diff) | |
download | linux-stable-613e040e4dc285367bff0f8f75ea59839bc10947.tar.gz linux-stable-613e040e4dc285367bff0f8f75ea59839bc10947.tar.bz2 linux-stable-613e040e4dc285367bff0f8f75ea59839bc10947.zip |
selftests: cgroup: Test open-time credential usage for migration checks
When a task is writing to an fd opened by a different task, the perm check
should use the credentials of the latter task. Add a test for it.
Tested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'tools/testing/selftests/cgroup')
-rw-r--r-- | tools/testing/selftests/cgroup/test_core.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/tools/testing/selftests/cgroup/test_core.c b/tools/testing/selftests/cgroup/test_core.c index 3df648c37876..01b766506973 100644 --- a/tools/testing/selftests/cgroup/test_core.c +++ b/tools/testing/selftests/cgroup/test_core.c @@ -674,6 +674,73 @@ cleanup: return ret; } +/* + * cgroup migration permission check should be performed based on the + * credentials at the time of open instead of write. + */ +static int test_cgcore_lesser_euid_open(const char *root) +{ + const uid_t test_euid = 65534; /* usually nobody, any !root is fine */ + int ret = KSFT_FAIL; + char *cg_test_a = NULL, *cg_test_b = NULL; + char *cg_test_a_procs = NULL, *cg_test_b_procs = NULL; + int cg_test_b_procs_fd = -1; + uid_t saved_uid; + + cg_test_a = cg_name(root, "cg_test_a"); + cg_test_b = cg_name(root, "cg_test_b"); + + if (!cg_test_a || !cg_test_b) + goto cleanup; + + cg_test_a_procs = cg_name(cg_test_a, "cgroup.procs"); + cg_test_b_procs = cg_name(cg_test_b, "cgroup.procs"); + + if (!cg_test_a_procs || !cg_test_b_procs) + goto cleanup; + + if (cg_create(cg_test_a) || cg_create(cg_test_b)) + goto cleanup; + + if (cg_enter_current(cg_test_a)) + goto cleanup; + + if (chown(cg_test_a_procs, test_euid, -1) || + chown(cg_test_b_procs, test_euid, -1)) + goto cleanup; + + saved_uid = geteuid(); + if (seteuid(test_euid)) + goto cleanup; + + cg_test_b_procs_fd = open(cg_test_b_procs, O_RDWR); + + if (seteuid(saved_uid)) + goto cleanup; + + if (cg_test_b_procs_fd < 0) + goto cleanup; + + if (write(cg_test_b_procs_fd, "0", 1) >= 0 || errno != EACCES) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + cg_enter_current(root); + if (cg_test_b_procs_fd >= 0) + close(cg_test_b_procs_fd); + if (cg_test_b) + cg_destroy(cg_test_b); + if (cg_test_a) + cg_destroy(cg_test_a); + free(cg_test_b_procs); + free(cg_test_a_procs); + free(cg_test_b); + free(cg_test_a); + return ret; +} + #define T(x) { x, #x } struct corecg_test { int (*fn)(const char *root); @@ -689,6 +756,7 @@ struct corecg_test { T(test_cgcore_proc_migration), T(test_cgcore_thread_migration), T(test_cgcore_destroy), + T(test_cgcore_lesser_euid_open), }; #undef T |