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selinux: selinuxfs: avoid dynamic allocations in sel_write_access

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These are quite frequent and freed in the same function.
Selinux needs every perf improvement it can get...

Signed-off-by: Yaroslav Furman <yaro330@gmail.com>
Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>
This commit is contained in:
Yaroslav Furman
2020-08-22 13:57:33 +03:00
committed by UtsavBalar1231
parent efdb96d663
commit 36ea3c8bc4
1 changed files with 20 additions and 10 deletions
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30
security/selinux/selinuxfs.c
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@@ -815,6 +815,7 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
struct selinux_fs_info *fsi = file_inode(file)->i_sb->s_fs_info;
struct selinux_state *state = fsi->state;
char *scon = NULL, *tcon = NULL;
char scon_onstack[256], tcon_onstack[256];
u32 ssid, tsid;
u16 tclass;
struct av_decision avd;
@@ -826,15 +827,22 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
if (length)
goto out;
length = -ENOMEM;
scon = kzalloc(size + 1, GFP_KERNEL);
if (!scon)
goto out;
if (size + 1 > ARRAY_SIZE(scon_onstack)) {
length = -ENOMEM;
scon = kzalloc(size + 1, GFP_KERNEL);
if (!scon)
goto out;
length = -ENOMEM;
tcon = kzalloc(size + 1, GFP_KERNEL);
if (!tcon)
goto out;
length = -ENOMEM;
tcon = kzalloc(size + 1, GFP_KERNEL);
if (!tcon)
goto out;
} else {
scon = scon_onstack;
tcon = tcon_onstack;
memset(scon_onstack, 0, size + 1);
memset(tcon_onstack, 0, size + 1);
}
length = -EINVAL;
if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
@@ -856,8 +864,10 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
avd.auditallow, avd.auditdeny,
avd.seqno, avd.flags);
out:
kfree(tcon);
kfree(scon);
if (scon != scon_onstack) {
kfree(tcon);
kfree(scon);
}
return length;
}