From 6298317e2d0dffb1ff4ecebedb8709645de36b6a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Wed, 5 Dec 2018 18:48:23 +0100 Subject: [PATCH] basic/process-util: limit command line lengths to _SC_ARG_MAX This affects systemd-journald and systemd-coredump. Example entry: $ journalctl -o export -n1 'MESSAGE=Something logged' __CURSOR=s=976542d120c649f494471be317829ef9;i=34e;b=4871e4c474574ce4a462dfe3f1c37f06;m=c7d0c37dd2;t=57c4ac58f3b98;x=67598e942bd23dc0 __REALTIME_TIMESTAMP=1544035467475864 __MONOTONIC_TIMESTAMP=858200964562 _BOOT_ID=4871e4c474574ce4a462dfe3f1c37f06 PRIORITY=6 _UID=1000 _GID=1000 _CAP_EFFECTIVE=0 _SELINUX_CONTEXT=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 _AUDIT_SESSION=1 _AUDIT_LOGINUID=1000 _SYSTEMD_OWNER_UID=1000 _SYSTEMD_UNIT=user@1000.service _SYSTEMD_SLICE=user-1000.slice _SYSTEMD_USER_SLICE=-.slice _SYSTEMD_INVOCATION_ID=1c4a469986d448719cb0f9141a10810e _MACHINE_ID=08a5690a2eed47cf92ac0a5d2e3cf6b0 _HOSTNAME=krowka _TRANSPORT=syslog SYSLOG_FACILITY=17 SYSLOG_IDENTIFIER=syslog-caller MESSAGE=Something logged _COMM=poc _EXE=/home/zbyszek/src/systemd-work3/poc _SYSTEMD_CGROUP=/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service _SYSTEMD_USER_UNIT=gnome-terminal-server.service SYSLOG_PID=4108 SYSLOG_TIMESTAMP=Dec 5 19:44:27 _PID=4108 _CMDLINE=./poc AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA> _SOURCE_REALTIME_TIMESTAMP=1544035467475848 $ journalctl -o export -n1 'MESSAGE=Something logged' --output-fields=_CMDLINE|wc 6 2053 2097410 2MB might be hard for some clients to use meaningfully, but OTOH, it is important to log the full commandline sometimes. For example, when the program is crashing, the exact argument list is useful. (cherry-picked from commit 2d5d2e0cc5171c6795d2a485841474345d9e30ab) Related: #1664976 --- src/basic/process-util.c | 73 ++++++++++++++-------------------------- 1 file changed, 25 insertions(+), 48 deletions(-) diff --git a/src/basic/process-util.c b/src/basic/process-util.c index 0a4f917cbd..a20f1e3ccf 100644 --- a/src/basic/process-util.c +++ b/src/basic/process-util.c @@ -128,6 +128,13 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char * (void) __fsetlocking(f, FSETLOCKING_BYCALLER); + if (max_length == 0) { + /* This is supposed to be a safety guard against runaway command lines. */ + long l = sysconf(_SC_ARG_MAX); + assert(l > 0); + max_length = l; + } + if (max_length == 1) { /* If there's only room for one byte, return the empty string */ @@ -138,32 +145,6 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char * *line = ans; return 0; - } else if (max_length == 0) { - size_t len = 0, allocated = 0; - - while ((c = getc(f)) != EOF) { - - if (!GREEDY_REALLOC(ans, allocated, len+3)) { - free(ans); - return -ENOMEM; - } - - if (isprint(c)) { - if (space) { - ans[len++] = ' '; - space = false; - } - - ans[len++] = c; - } else if (len > 0) - space = true; - } - - if (len > 0) - ans[len] = '\0'; - else - ans = mfree(ans); - } else { bool dotdotdot = false; size_t left; @@ -235,34 +216,30 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char * if (h < 0) return h; - if (max_length == 0) - ans = strjoin("[", t, "]"); - else { - size_t l; - - l = strlen(t); + size_t l = strlen(t); - if (l + 3 <= max_length) - ans = strjoin("[", t, "]"); - else if (max_length <= 6) { + if (l + 3 <= max_length) { + ans = strjoin("[", t, "]"); + if (!ans) + return -ENOMEM; - ans = new(char, max_length); - if (!ans) - return -ENOMEM; + } else if (max_length <= 6) { + ans = new(char, max_length); + if (!ans) + return -ENOMEM; - memcpy(ans, "[...]", max_length-1); - ans[max_length-1] = 0; - } else { - t[max_length - 6] = 0; + memcpy(ans, "[...]", max_length-1); + ans[max_length-1] = 0; + } else { + t[max_length - 6] = 0; - /* Chop off final spaces */ - delete_trailing_chars(t, WHITESPACE); + /* Chop off final spaces */ + delete_trailing_chars(t, WHITESPACE); - ans = strjoin("[", t, "...]"); - } + ans = strjoin("[", t, "...]"); + if (!ans) + return -ENOMEM; } - if (!ans) - return -ENOMEM; } *line = ans;