| From 9cb07e7d82c7c4f28bbaa1478e1387e8ea3d03dd Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl> |
| Date: Wed, 5 Dec 2018 18:38:39 +0100 |
| Subject: [PATCH] journald: do not store the iovec entry for process |
| commandline on stack |
| |
| This fixes a crash where we would read the commandline, whose length is under |
| control of the sending program, and then crash when trying to create a stack |
| allocation for it. |
| |
| CVE-2018-16864 |
| https://bugzilla.redhat.com/show_bug.cgi?id=1653855 |
| |
| The message actually doesn't get written to disk, because |
| journal_file_append_entry() returns -E2BIG. |
| |
| Patch backported from systemd master at |
| 084eeb865ca63887098e0945fb4e93c852b91b0f. |
| |
| CVE: CVE-2018-16864 |
| Upstream-Status: Backport |
| Signed-off-by: Marcus Cooper <marcusc@axis.com> |
| --- |
| src/basic/io-util.c | 10 ++++++++++ |
| src/basic/io-util.h | 2 ++ |
| src/coredump/coredump.c | 31 +++++++++++-------------------- |
| src/journal/journald-server.c | 25 +++++++++++++++---------- |
| 4 files changed, 38 insertions(+), 30 deletions(-) |
| |
| diff --git a/src/basic/io-util.c b/src/basic/io-util.c |
| index 1f64cc933b..575398fbe6 100644 |
| --- a/src/basic/io-util.c |
| +++ b/src/basic/io-util.c |
| @@ -8,6 +8,7 @@ |
| #include <unistd.h> |
| |
| #include "io-util.h" |
| +#include "string-util.h" |
| #include "time-util.h" |
| |
| int flush_fd(int fd) { |
| @@ -252,3 +253,12 @@ ssize_t sparse_write(int fd, const void *p, size_t sz, size_t run_length) { |
| |
| return q - (const uint8_t*) p; |
| } |
| + |
| +char* set_iovec_string_field(struct iovec *iovec, size_t *n_iovec, const char *field, const char *value) { |
| + char *x; |
| + |
| + x = strappend(field, value); |
| + if (x) |
| + iovec[(*n_iovec)++] = IOVEC_MAKE_STRING(x); |
| + return x; |
| +} |
| diff --git a/src/basic/io-util.h b/src/basic/io-util.h |
| index ed189b5820..792a64ad5e 100644 |
| --- a/src/basic/io-util.h |
| +++ b/src/basic/io-util.h |
| @@ -71,3 +71,5 @@ static inline bool FILE_SIZE_VALID_OR_INFINITY(uint64_t l) { |
| #define IOVEC_MAKE(base, len) (struct iovec) IOVEC_INIT(base, len) |
| #define IOVEC_INIT_STRING(string) IOVEC_INIT((char*) string, strlen(string)) |
| #define IOVEC_MAKE_STRING(string) (struct iovec) IOVEC_INIT_STRING(string) |
| + |
| +char* set_iovec_string_field(struct iovec *iovec, size_t *n_iovec, const char *field, const char *value); |
| diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c |
| index 20a1cbdd45..18e4f61d72 100644 |
| --- a/src/coredump/coredump.c |
| +++ b/src/coredump/coredump.c |
| @@ -1053,19 +1053,10 @@ static int send_iovec(const struct iovec iovec[], size_t n_iovec, int input_fd) |
| return 0; |
| } |
| |
| -static char* set_iovec_field(struct iovec *iovec, size_t *n_iovec, const char *field, const char *value) { |
| - char *x; |
| - |
| - x = strappend(field, value); |
| - if (x) |
| - iovec[(*n_iovec)++] = IOVEC_MAKE_STRING(x); |
| - return x; |
| -} |
| - |
| static char* set_iovec_field_free(struct iovec *iovec, size_t *n_iovec, const char *field, char *value) { |
| char *x; |
| |
| - x = set_iovec_field(iovec, n_iovec, field, value); |
| + x = set_iovec_string_field(iovec, n_iovec, field, value); |
| free(value); |
| return x; |
| } |
| @@ -1115,36 +1106,36 @@ static int gather_pid_metadata( |
| disable_coredumps(); |
| } |
| |
| - set_iovec_field(iovec, n_iovec, "COREDUMP_UNIT=", context[CONTEXT_UNIT]); |
| + set_iovec_string_field(iovec, n_iovec, "COREDUMP_UNIT=", context[CONTEXT_UNIT]); |
| } |
| |
| if (cg_pid_get_user_unit(pid, &t) >= 0) |
| set_iovec_field_free(iovec, n_iovec, "COREDUMP_USER_UNIT=", t); |
| |
| /* The next few are mandatory */ |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_PID=", context[CONTEXT_PID])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_PID=", context[CONTEXT_PID])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_UID=", context[CONTEXT_UID])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_UID=", context[CONTEXT_UID])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_GID=", context[CONTEXT_GID])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_GID=", context[CONTEXT_GID])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_SIGNAL=", context[CONTEXT_SIGNAL])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_SIGNAL=", context[CONTEXT_SIGNAL])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_RLIMIT=", context[CONTEXT_RLIMIT])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_RLIMIT=", context[CONTEXT_RLIMIT])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_HOSTNAME=", context[CONTEXT_HOSTNAME])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_HOSTNAME=", context[CONTEXT_HOSTNAME])) |
| return log_oom(); |
| |
| - if (!set_iovec_field(iovec, n_iovec, "COREDUMP_COMM=", context[CONTEXT_COMM])) |
| + if (!set_iovec_string_field(iovec, n_iovec, "COREDUMP_COMM=", context[CONTEXT_COMM])) |
| return log_oom(); |
| |
| if (context[CONTEXT_EXE] && |
| - !set_iovec_field(iovec, n_iovec, "COREDUMP_EXE=", context[CONTEXT_EXE])) |
| + !set_iovec_string_field(iovec, n_iovec, "COREDUMP_EXE=", context[CONTEXT_EXE])) |
| return log_oom(); |
| |
| if (sd_pid_get_session(pid, &t) >= 0) |
| @@ -1212,7 +1203,7 @@ static int gather_pid_metadata( |
| iovec[(*n_iovec)++] = IOVEC_MAKE_STRING(t); |
| |
| if (safe_atoi(context[CONTEXT_SIGNAL], &signo) >= 0 && SIGNAL_VALID(signo)) |
| - set_iovec_field(iovec, n_iovec, "COREDUMP_SIGNAL_NAME=SIG", signal_to_string(signo)); |
| + set_iovec_string_field(iovec, n_iovec, "COREDUMP_SIGNAL_NAME=SIG", signal_to_string(signo)); |
| |
| return 0; /* we successfully acquired all metadata */ |
| } |
| diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c |
| index 4f1550ec5b..31be085c6b 100644 |
| --- a/src/journal/journald-server.c |
| +++ b/src/journal/journald-server.c |
| @@ -753,6 +753,7 @@ static void dispatch_message_real( |
| pid_t object_pid) { |
| |
| char source_time[sizeof("_SOURCE_REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t)]; |
| + _cleanup_free_ char *cmdline1 = NULL, *cmdline2 = NULL; |
| uid_t journal_uid; |
| ClientContext *o; |
| |
| @@ -769,20 +770,23 @@ static void dispatch_message_real( |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, c->uid, uid_t, uid_is_valid, UID_FMT, "_UID"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, c->gid, gid_t, gid_is_valid, GID_FMT, "_GID"); |
| |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->comm, "_COMM"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->exe, "_EXE"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->cmdline, "_CMDLINE"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->capeff, "_CAP_EFFECTIVE"); |
| + IOVEC_ADD_STRING_FIELD(iovec, n, c->comm, "_COMM"); /* At most TASK_COMM_LENGTH (16 bytes) */ |
| + IOVEC_ADD_STRING_FIELD(iovec, n, c->exe, "_EXE"); /* A path, so at most PATH_MAX (4096 bytes) */ |
| |
| - IOVEC_ADD_SIZED_FIELD(iovec, n, c->label, c->label_size, "_SELINUX_CONTEXT"); |
| + if (c->cmdline) |
| + /* At most _SC_ARG_MAX (2MB usually), which is too much to put on stack. |
| + * Let's use a heap allocation for this one. */ |
| + cmdline1 = set_iovec_string_field(iovec, &n, "_CMDLINE=", c->cmdline); |
| |
| + IOVEC_ADD_STRING_FIELD(iovec, n, c->capeff, "_CAP_EFFECTIVE"); /* Read from /proc/.../status */ |
| + IOVEC_ADD_SIZED_FIELD(iovec, n, c->label, c->label_size, "_SELINUX_CONTEXT"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, c->auditid, uint32_t, audit_session_is_valid, "%" PRIu32, "_AUDIT_SESSION"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, c->loginuid, uid_t, uid_is_valid, UID_FMT, "_AUDIT_LOGINUID"); |
| |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->cgroup, "_SYSTEMD_CGROUP"); |
| + IOVEC_ADD_STRING_FIELD(iovec, n, c->cgroup, "_SYSTEMD_CGROUP"); /* A path */ |
| IOVEC_ADD_STRING_FIELD(iovec, n, c->session, "_SYSTEMD_SESSION"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, c->owner_uid, uid_t, uid_is_valid, UID_FMT, "_SYSTEMD_OWNER_UID"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, c->unit, "_SYSTEMD_UNIT"); |
| + IOVEC_ADD_STRING_FIELD(iovec, n, c->unit, "_SYSTEMD_UNIT"); /* Unit names are bounded by UNIT_NAME_MAX */ |
| IOVEC_ADD_STRING_FIELD(iovec, n, c->user_unit, "_SYSTEMD_USER_UNIT"); |
| IOVEC_ADD_STRING_FIELD(iovec, n, c->slice, "_SYSTEMD_SLICE"); |
| IOVEC_ADD_STRING_FIELD(iovec, n, c->user_slice, "_SYSTEMD_USER_SLICE"); |
| @@ -803,13 +807,14 @@ static void dispatch_message_real( |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, o->uid, uid_t, uid_is_valid, UID_FMT, "OBJECT_UID"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, o->gid, gid_t, gid_is_valid, GID_FMT, "OBJECT_GID"); |
| |
| + /* See above for size limits, only ->cmdline may be large, so use a heap allocation for it. */ |
| IOVEC_ADD_STRING_FIELD(iovec, n, o->comm, "OBJECT_COMM"); |
| IOVEC_ADD_STRING_FIELD(iovec, n, o->exe, "OBJECT_EXE"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, o->cmdline, "OBJECT_CMDLINE"); |
| - IOVEC_ADD_STRING_FIELD(iovec, n, o->capeff, "OBJECT_CAP_EFFECTIVE"); |
| + if (o->cmdline) |
| + cmdline2 = set_iovec_string_field(iovec, &n, "OBJECT_CMDLINE=", o->cmdline); |
| |
| + IOVEC_ADD_STRING_FIELD(iovec, n, o->capeff, "OBJECT_CAP_EFFECTIVE"); |
| IOVEC_ADD_SIZED_FIELD(iovec, n, o->label, o->label_size, "OBJECT_SELINUX_CONTEXT"); |
| - |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, o->auditid, uint32_t, audit_session_is_valid, "%" PRIu32, "OBJECT_AUDIT_SESSION"); |
| IOVEC_ADD_NUMERIC_FIELD(iovec, n, o->loginuid, uid_t, uid_is_valid, UID_FMT, "OBJECT_AUDIT_LOGINUID"); |
| |
| -- |
| 2.11.0 |
| |