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mirror of https://sourceware.org/git/glibc.git synced 2025-08-08 17:42:12 +03:00

elf: Ignore GLIBC_TUNABLES for setuid/setgid binaries

The tunable privilege levels were a retrofit to try and keep the malloc
tunable environment variables' behavior unchanged across security
boundaries.  However, CVE-2023-4911 shows how tricky can be
tunable parsing in a security-sensitive environment.

Not only parsing, but the malloc tunable essentially changes some
semantics on setuid/setgid processes.  Although it is not a direct
security issue, allowing users to change setuid/setgid semantics is not
a good security practice, and requires extra code and analysis to check
if each tunable is safe to use on all security boundaries.

It also means that security opt-in features, like aarch64 MTE, would
need to be explicit enabled by an administrator with a wrapper script
or with a possible future system-wide tunable setting.

Co-authored-by: Siddhesh Poyarekar  <siddhesh@sourceware.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella
2023-11-06 17:25:36 -03:00
parent a72a4eb10b
commit 9c96c87d60
9 changed files with 299 additions and 161 deletions

View File

@@ -61,9 +61,6 @@ $1 == "}" {
if (!env_alias[top_ns,ns,tunable]) {
env_alias[top_ns,ns,tunable] = "{0}"
}
if (!security_level[top_ns,ns,tunable]) {
security_level[top_ns,ns,tunable] = "SXID_ERASE"
}
len = length(top_ns"."ns"."tunable)
if (len > max_name_len)
max_name_len = len
@@ -118,17 +115,6 @@ $1 == "}" {
if (len > max_alias_len)
max_alias_len = len
}
else if (attr == "security_level") {
if (val == "SXID_ERASE" || val == "SXID_IGNORE" || val == "NONE") {
security_level[top_ns,ns,tunable] = val
}
else {
printf("Line %d: Invalid value (%s) for security_level: %s, ", NR, val,
$0)
print("Allowed values are 'SXID_ERASE', 'SXID_IGNORE', or 'NONE'")
exit 1
}
}
else if (attr == "default") {
if (types[top_ns,ns,tunable] == "STRING") {
default_val[top_ns,ns,tunable] = sprintf(".strval = \"%s\"", val);
@@ -177,9 +163,9 @@ END {
n = indices[2];
m = indices[3];
printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, TUNABLE_SECLEVEL_%s, %s},\n",
printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, %s},\n",
types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
default_val[t,n,m], security_level[t,n,m], env_alias[t,n,m]);
default_val[t,n,m], env_alias[t,n,m]);
}
print "};"
print "#endif"